THE FATE OF A PERFLUOROPOLYETHER-COATED PAPER IN A ...

THE FATE OF A PERFLUOROPOLYETHER-COATED PAPER IN A COMPOSTING

SYSTEM: COMPOSTABILITY AND CHEMICAL ANALYSIS

By

Tracy J. Westbury

A Thesis

Submitted in partial fulfillment of the requirements of the degree

MASTER OF SCIENCE

IN

NATURAL RESOURCES (SOIL & WASTE RESOURCES)

College of Natural Resources

UNIVERSITY OF WISCONSIN

Stevens Point, WI

June 2014

ii

APPROVED BY THE GRADUATE COMMITTEE OF:

Dr. Robert Michitsch, Committee Chairman

Assistant Professor of Soil & Waste Resources

Dr. John Droske

Professor of Chemistry

Dr. Paul Fowler

Executive Director of the Wisconsin Institute for Sustainable Technology

Dr. Kyle Herrman

Assistant Professor of Water Resources

iii

ABSTRACT

THE FATE OF A PERFLUOROPOLYETHER-COATED FOOD CONTACT PAPER IN A

COMPOSTING SYSTEM: COMPOSTABILITY AND INSTRUMENTAL CHEMICAL

ANALYSIS

Fluorosurfactant-coated paper has been and continues to be a convenient grease, moisture

and heat proof product for the packaging and preparation of food. Paper packaging materials

are often suitable for composting environments given their natural origin and close

relationship to food and ultimately food waste. However, the suitability of fluorosurfactant

amendments such as PFPE for composting is unknown. This work examined the fate of

PFPE-coated paper in a laboratory-scale composting system. The PFPE-coated paper

performed equal to uncoated paper in terms of overall material loss and carbon dioxide (CO2)

evolution in a compostability experiment. The finished compost containing PFPE performed

equal to PAPER compost when used in an eco-toxicity experiment to examine pea and wheat

germination and growth. Solvent extraction of finished PFPE compost and 19F NMR analysis

revealed that PFPE was extractable from finished compost and that the PFPE polymer was

unchanged despite undergoing 12 weeks of thermophilic composting. The chemical and

instrumental analyses that were conducted suggested that the PFPE polymer in the paper

coating did not biodegrade when subjected the industrial composting conditions of the in-

vessel experiment.

iv

ACKNOWLEDGEMENTS

I am sincerely grateful to my advisor Dr. Rob Michitsch for introducing me to and guiding me

through the world of composting. Rob, your willingness to help and your flexibility for last

minute brainstorming was instrumental in seeing this work through. For nearly 3 years you

have been coaching me to follow my instinct and find the beauty in science. A hearty and

sincere thank you is also in order for Dr. Kyle Herrman. The compostability portion of my

research would not have been possible without your tireless attention to detail, your

admirable knack for troubleshooting and most of all your faith in my abilities as a scientist.

Thank you for being on my committee. I also want to thank Dr. Paul Fowler at WIST for

allowing me to explore research possibilities and participate in the nascent stages of

compostability testing at UWSP. My graduate experience has truly been a unique journey

thanks to your collaboration.

The awe I have for the chemists involved in this research extends beyond words. I was

fortunate to attend UWSP as a graduate student, but doubly fortunate that it is home to a

number of talented faculty members in the Chemistry department. I am deeply grateful to

Dr. John Droske for being on my committee. Your sound advice and support throughout this

process has been invaluable. I would also like to thank Dr. Bob Badger for helping me to

decipher the secrets within NMR spectra. His time and insight was much appreciated.

Perhaps the most memorable part of this experience has been the opportunity to work with

the Mabury Group at the University of Toronto. I extend my sincerest gratitude to Dr. Scott

Mabury, Dr. Derek Jackson, Dr. Leo Yeung and Lisa D’Agostino. Witnessing the combined

fluorosurfactant expertise and instrumental know-how of these scientists was positively

overwhelming. Their help exceeded all my expectations of what was achievable for the

chemical and instrumental analysis portion of this research.

This research was supported in part by the Solid Waste Research Grant through the UW

System, the Student Research Fund and the Scholar Society at UWSP. The research would

not have been possible without the donation of paper materials and PFPE-surfactant from

Expera Specialty Solutions.

To my parents, thank you for allowing me to disappear into the academic abyss these last few

years. I’ll be back!

To my family in-law, I’m eternally grateful for your love and support. You took me in to

your home and embraced me as a daughter and a sister.

To John, you weathered the storm with me, had my back and held my hand. Best of all, you

always thought my research was super cool. You are the best person I know and I’m excited

to ride off into the sunset together.

v

LIST OF ABBREVIATIONS

19F NMR Fluorine Nuclear Magnetic Resonance

ASTM American Society of Testing and Materials

BPI Biodegradable Products Institute

C4 Chain of four perfluorinated carbon atoms

C6 Chain of six perfluorinated carbon atoms

C8 Chain of eight perfluorinated carbon atoms

CFC Chlorofluorocarbon

DiPAP Diester perfluoroalkyl phosphate

ECF Electrochemical fluorination

FTCA Fluorotelomer carboxylic acid

FTCUA Fluorotelomer carboxylic unsaturated acid

FTOH Fluorotelomer alcohol

GC/MS Gas chromatography-mass spectrometry

HCFC Hydrochlorofluorocarbon

HFC Hydrofluorocarbon

LC/ARC Liquid chromatography-

LC/MS/MS Liquid chromatography tandem mass spectrometry

NCP New Chemicals Program

N-EtFOSE N-ethyl perfluorooctane sulfonamidoethanol

PAPER Uncoated paper material

PFC Perfluorinated carbons

PFCA Perfluorocarboxylic acid

PFHxA Perfluorohexanoic acid

PFOA Perfluorooctanoic acid

PFOS Perfluorooctane sulfonate

PFPE Perfluoropolyether

PFPeA Perfluoropentanoic acid

PFPMIE Perfluoromethylisopropyl ether

SAmPAP Sulfonamide perfluoroalkyl phosphates

TOF-CIC Total organofluorine combustion ion chromatography

TSCA Toxic Substances Control Act

WWTP Wastewater treatment plant

vi

LIST OF TABLES

Page

Table 2.1 Average cumulative percent weight loss from the original material by

harvest week of dry PAPER and PFPE at 15% and 25% loading levels.

51

Table 2.2 Average dry weight and percent of the original material at week 12 harvest

for dry PAPER and PFPE at 15% and 25% loading levels.

51

Table 2.3 Average compost pH and EC for PAPER, PFPE and blank at T=0 and Week

12.

51

Table 3.1 Spike recovery results (%) for polar solvents combined with TBAS and

hydrochloric acid

73

Table 3.2 Average integrated peak area ratios comparing the center peak at -53 ppm

to each of the doublet peaks at -77.5 ppm and -80 ppm from T=0, Week 6 and Week

12.

73

Table 3.3 Total average extractable fluorine (F) in ng/g (ppb) in compost extracts from

T=0, Weeks 6 and 12.

73

Table 4.1: Theoretical carbon content (mg) based on organic carbon (%) expected for

50 g of cellulose, Paper and PFPE.

98

Table 4.2: Total actual cumulative carbon (mg) produced by of cellulose, Paper, PFPE

and blank compost at Day 45 of Biodegradation.

98

Table 4.3: Average cumulative carbon (mg) produced by cellulose, Paper, PFPE less

the blank compost and percent biodegradation at Day 45.

98

Table 4.4: Average total vessel weight and dry solids, moisture content,

carbon/nitrogen ratio and pH for PFPE and Paper treatments, cellulose and blank at

the start and end of biodegradation testing (i.e. day 45).

98

Table 4.5: Disintegration results based on recoverable PAPER and PFPE material with

a 2 mm sieve. .

98

Table 4.6: Average total vessel weight and dry solids, moisture content, C/N ratio and

pH for PFPE and PAPER treatments at the start and end of disintegration testing (i.e.

day 90).

99

Table 5.1: Total number of pots in a treatment for wheat and peas at the 25% and 50%

concentration; reference soil at 100% loading rate.

121

Table 5.2: Top germination rates (%) for wheat and peas grown in compost treatments

at 25 and 50% concentrations.

121

Table 5.3: Seedling survival rates of wheat and peas grown in a blank control at 25

and 50% concentration.

121

Table 5.4: Seedling percent survival rates of wheat and peas grown in Paper and PFPE

compost mixtures at 25 and 50% concentration.

121

Table 5.5: Average heights of wheat and pea plants at the time of harvest for blank

control, PFPE and PAPER treatments at 25% and 50% concentration.

122

Table 5.6: Average dry biomass of pea and wheat plants at the time of harvest for

blank control, PFPE and Paper treatments at 25% and 50% concentration.

122

vii

LIST OF FIGURES

Page

Figure 1.1: Chemical structure of a perfluoropolyether diphosphates polymer in

Fomblin® and Solvera®.

34

Figure 1.2: Twenty year trend of all fluorinated greenhouse gas emissions, i.e. HFCs,

PFCs and SF6.

34

Figure 2.1: 1-liter glass composting vessels topped with clear plastic Petri dishes and

arranged in a complete randomized design in an incubator.

50

Figure 2.2: Average cumulative percent weight loss of dry paper material by harvest

week for PFPE and PAPER treatments at 15% and 25% loading levels.

51

Figure 2.3: Average compost moisture content (%) by harvest week for PFPE and

PAPER treatments at 15% and 25% loading levels.

52

Figure 2.4: Average compost pH by harvest week for PFPE and PAPER treatments at

15% and 25% loading levels.

53

Figure 3.1: 700 MHz 19F NMR spectrum of PFPE standard Solvera® XPH-723.

Molecular structure and peak locations are indicated with the arrows.

71

Figure 3.2: Chemical structure of Perfluoropolyether phosphate polymer in Fomblin®

and Solvera®.

71

Figure 3.3: 700 mHz 19F NMR spectrum of a T=0 compost extract. Solvera® XPH 723

peaks were circled. New peaks appeared at -75 and -76 ppm.

72

Figure 3.4: 700 mHz 19F NMR spectrum of Week 6 Blank compost extract. Solvera®

XPH 723 peaks were not present. New peaks appeared at -75 and -76 ppm.

73

Figure 3.5: 700 mHz 19F NMR spectrum of Week 6 compost extract. The same peaks

found in Solvera® XPH-723 were present. New peaks appeared at -75 and -76 ppm

and the peaks at -77.5 and –80.5 ppm region experienced splitting.

74

Figure 3.6: 700 mHz 19F NMR spectrum of Week 12 compost extract. The same peaks

found in Solvera® XPH-723 were present. New peaks appeared at -75 and -76 ppm

and the peaks at -77.5 and –80.5 ppm region experienced splitting.

75

Figure 4.1: Incubated closed system composting with aerated and hydrated compost

mixtures in 2-liter glass vessels. Incoming air was routed through a hydrating vessel

containing deionized water (Pictured to the left of the composting vessel) before

entering the compost matrix. Air was exhausted from a tube at the cap and exited to

the right of the incubator.

100

Figure 4.2: Covered 30 liter polypropylene pre-incubation compost container with 0.5

cm holes drilled equidistant (≈15 cm) from the top for air exchange.

101

Figure 4.3: Compressed air tank fitted with an air regulating manifold system to

supply the compost matrix, within the composting vessel with continual and

humidified air flow via the hydrating vessels.

102

Figure 4.4: Moisture trap system for the humidified composting exhaust air entering

the Li-Cor CO2 analyzer. The air first flowed through a condensation collection bottle

before passing through a particulate filter and entering the Li-Cor analyzer. Li-Cor

103

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exhaust air was further scrubbed of moisture by flowing through a flask of desiccant

before being measured by a flow meter for flow rate.

Figure 4.5: Average cumulative carbon (mg) produced per day for the cellulose

reference, PAPER and PFPE treatments and the blank compost.

104

Figure 4.6: Average percent biodegradation (%) of the cellulose reference and Paper

and PFPE treatments.

104

Figure 5.1: Wheat seedlings, prior to harvest, grown in a PFPE treatment at 25% (a)

and at 50% (b).

123

Figure 5.2: Wheat seedlings, prior to harvest, grown in a Paper treatment at 25% (a)

and at 50% (b)

123

Figure 5.3: Wheat seedling, prior to harvest, grown in PFPE at 25% concentration

with signs of leaf tip necrosis on a majority of leaves.

124

Figure 5.4: Pea seedlings, prior to harvest, in PFPE treatment at 25% (a) and at 50%

(b).

124

Figure 5.5: Pea seedlings, prior to harvest, grown in a Blank control at 50% (a) and a

Paper treatment at 50% (b).

125

ix

LIST OF APPENDICES

Page

Appendix 1. Graph of average weekly percent weight loss between harvest weeks for

dry PAPER and PFPE at 15% and 25% loading levels.

139

Appendix 2. Table of average weekly percent weight loss between harvest weeks for

dry PAPER and PFPE at 15% and 25% loading levels. Negative values indicate weight

gain.

139

Appendix 3. Jar Disintegration Significant Differences: pH by Harvest Week 140

Appendix 4. Jar Disintegration Significant Differences: EC by Harvest Week and Jar Disintegration Kruskal-Wallis ANOVA on Ranks Significant Differences: EC Week 8

141

Appendix 5. 700 mHz 19F NMR spectrum of a Week 1.1 (duplicate) compost extract. 142

Appendix 6. 700 mHz 19F NMR spectrum of a Week 1.2 compost extract. 143



Appendix 9. 700 mHz 19F NMR spectrum of a Week 6.1 (duplicate) compost extract. 146



Appendix 12. 700 mHz 19F NMR spectrum of a Week 6 blank compost extract. . 149



Appendix 15. 700 mHz 19F NMR spectrum of a Week 12.3 compost extract (overnight

scan).

152


Appendix 17. 700 mHz 19F NMR spectrum of a T=0.1 compost extract. 154

Appendix 18. 700 mHz 19F NMR spectrum of a T=0.2 compost extract. 155

Appendix 19. 700 mHz 19F NMR spectrum of a T=0.3 compost extract.

156

x

TABLE OF CONTENTS

Page

LIST OF ABBREVIATIONS v

LIST OF TABLES vi

LIST OF FIGURES vii

LIST OF APPENDICES ix

CHAPTER 1.0: GENERAL INTRODUCTION AND LITERATURE REVIEW 1

1.1 Introduction 1

1.2 Fluorosurfactant Technology: 1974-2000 4

1.2.1 Electrochemical Fluorination: SAmPAPs 4

1.2.2 Degradation Analysis of N-EtFOSE 5

1.2.3 Environmental and Health Concerns of PFOS 6

1.3 Fluorosurfactant Technology: 2000-2010 6

1.3.1 Telomerization: DiPAPs and Fluoroacrylate Polymers 7

1.3.2 Degradation Analysis of DiPAPs and Fluoroacrylate Polymers 8

1.3.3 Environmental and Health Concerns of FTOH and PFOA 13

1.4 Industry and Regulatory Response to PFOA and Fluorotelomer-based Surfactants 15

1.4.1 United States Environmental Protection Agency 15

1.4.2 United States Food and Drug Administration 16

1.5 Alternative Fluorosurfactants 17

1.5.1 Electrochemical Fluorination: C4 Alternative 17

1.5.2 Fluorotelomer: C6 Alternative 18

1.5.3 Photooxidation: PFPE Alternative 19

1.5.3.1 Degradation Analysis of PFPE 21

1.5.3.2 Environmental and Health Concerns of PFPE 22

1.6 Analysis and Characterization of Fluorinated Compounds 23

1.6.1 Liquid Chromatography-Tandem Mass Spectrometry 23

1.6.2 Gas Chromatography-Mass Spectrometry 24

1.6.3 Liquid Chromatography-Accurate Radioisotope Counting 24

1.6.4 Nuclear Magnetic Resonance Spectroscopy 25

1.6.5 Total Organofluorine-Combustion Ion Chromatography 26

1.7 Composting 27

1.7.1 Compostability Testing 29

1.8 Summary and Objectives 33

CHAPTER 2.0: IN-VESSEL DISINTEGRATION 36

2.1 Introduction 36

2.2 Methodology 37

2.2.1 Experimental Design 37

2.2.2 Compost Matrix 38

2.2.3 Treatments 39

2.2.4 Sample Harvesting and Processing 40

2.2.4.1 Moisture Content 41

xi

2.2.5 Statistical Analysis 42

2.3 Results 42

2.3.1 Cumulative Percent Weight Loss during Active Composting: 15% and 25%

Loading Levels

43

2.3.2 Cumulative Percent Weight Loss during Active Composting: PAPER and

PFPE Treatments

43

2.3.3 Physical and Chemical Characteristics 43

2.3.3.1 Moisture Content 43

2.3.3.2 pH and Electrical Conductivity (EC) 44

2.4 Discussion 45

2.4.1 Cumulative Percent Weight Loss 45

2.4.2 Moisture Content 48

2.4.3 pH and Electrical Conductivity (EC) 48

2.5 Conclusion 49

CHAPTER 3.0: CHEMICAL AND INSTRUMENTAL ANALYSIS 56

3.1 Introduction 56

3.2 Methodology 59


3.2.2 Extraction Procedure 60

3.2.3 19F NMR Procedure 62


3.3 Results 66

3.3.1 19F NMR Spectra 66

3.3.2 TOF-CIC: Weeks 6 and 12 67

3.4 Discussion 68

3.4.1 19F NMR Spectra 68

3.4.2 TOF-CIC: Weeks 6 and 12 71

3.5 Conclusion 71

CHAPTER 4.0: COMPOSTABILITY: BIODEGRADATION AND DISINTEGRATION 80

4.1 Introduction 80

4.2 Methodology 81


4.2.1.1 Compost Pre-Incubation 82


4.2.3 Treatments 84

4.2.4 Biodegradation Set-up 86

4.2.5 Biodegradation Data Collection and Analysis 87


4.3 Results and Discussion 90

4.3.1 Cumulative Carbon and Percent Biodegradation 90

4.3.2 Physical and Chemical Characteristics: Biodegradation 91

4.3.3 Disintegration 92

4.4 Discussion 94

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4.5 Conclusion 96

CHAPTER 5.0: COMPOSTABILITY: ECO-TOXICITY 105

5.1 Introduction 105

5.2 Methodology 106



5.2.3 Reference Soil 107

5.2.4 Plant Material 108

5.2.5 Treatments 108

5.2.6 Germination and Seedling Growth 109

5.2.7 Harvest 110


5.3 Results 110

5.3.1 Germination and Seedling Survival 110

5.3.1.1 Germination: Wheat and Peas 111

5.3.1.2 Seedling Survival: Wheat and Peas 113

5.3.2 Seedling Height: Wheat and Peas 113

5.3.3 Dry Biomass: Wheat and Peas 114

5.4 Discussion 115

5.4.1 Germination and Seedling Survival: Wheat and Peas 115

5.4.2 Seedling Height: Wheat and Peas 117

5.4.3 Dry Biomass: Wheat and Peas 118

5.5 Conclusion 119

CHAPTER 6.0: OVERALL SUMMARY AND RECOMMENDATIONS 126

REFERENCES CITED 130

APPENDICES 139

1

1.0 GENERAL INTRODUCTION AND LITERATURE REVIEW

1.1 Introduction

Fluorine chemistry has been an expanding industrial endeavor since the 1950’s. The

benefits to society of fluorine technology, in the form of fluoropolymers and fluorotelomers,

have made the industry worth $1.4 billion in the United States alone; in particular demand is

projected to rise in applications that rely on water-based dispersions (The Freedonia Group,

2009). According to Ritter (2010) fluoropolymers and fluorotelomers are used in a variety of

products such as fast food wrappers, textiles and automotive manufacturing. Textile and

apparel applications make up nearly 50% of production, carpet and upholstery treatments are

the second largest use and coatings such as those used for food contact paper and packaging

are the third major category of consumer applications (US EPA, 2009b). The major

participants in the fluoro-products industry, which also incorporates pharmaceuticals,

manufacturing and agriculture include the following corporations: Arkema, Inc.;

Asahai/America, Inc.; BASF Corporation; Clariant; Daikin America, Inc.; E.I. DuPont de

Nemours and Company; 3M/Dyneon, LLC; and Solvay Solexis.

Since 1970, fluorinated surfactants have been used commercially to impart grease and

moisture resistance to paper. Fluorinated is a general term to indicate a fluorine containing

compound (Kissa, 2001). The term surfactant is a combination of the words surface-active

agent. A fluorosurfactant lowers surface tension and causes grease and moisture to bead

instead of absorbing into the medium. In regards to fluorinated-based chemicals (e.g.

fluorotelomers and perfluoropolyethers) a fluorine (F) atom bonded with a carbon (C) atom

makes a surfactant that is grease proof and twice as effective as hydrocarbon-based surfactants

at lowering the surface tension of water. The C–F bond is one of the strongest bonds in

2

organic chemistry and produces surfactants that are relatively inert in a variety of conditions

and stable in a range of temperatures (Denkenberger et al., 2007; Parsons et al., 2008; Fromel

and Knepper, 2010). These characteristics are indispensable to the food contact paper

industry, as well as textile and durable goods industries (e.g. carpet and stone). Food contact

paper treated with fluorinated surfactants ranks third in production, but the amount of post-

consumer paper waste entering recycling and disposal systems (i.e. composting systems,

landfills, incinerators) outpaces both textiles and carpets (US EPA, 2009a). This type of paper

waste has traditionally been landfilled or incinerated and there is no published information

about the degradation behavior in composting systems.

Composting is a waste management practice that decomposes organic wastes (e.g. food

scraps, grass clippings, paper) into a usable soil or landscaping amendment. Successful

composting environments are aerobic (i.e. oxygen rich), high in moisture (e.g. 50-60%) and

high in microbial activity that generate enough heat to keep the core temperature at or above

58˚C (BPI, 2011). Under these conditions paper will disintegrate, which benefits the compost

by adding carbon and absorbing excess moisture from water-rich organics such as fruits and

vegetables. However, the effects to compost quality and residual byproducts that food

contact paper treated with fluorosurfactants may leave behind are unknown.

Compostability testing is a means for determining a material’s suitability for composting.

Paper and packaging materials coated with plastics or polymers are subjected to the

compostability specifications in ASTM D6868-11 and biodegradation methodology in ASTM

D5338-11. Formerly known as the American Society of Testing and Materials, ASTM

International is an international standards organization that utilizes collaborative industry

3

and academic efforts to develop standard protocols, definitions and specifications for a range

of applications and testing (ASTM International, 2014). The compostability standards for

paper and packaging (i.e. ligno-cellulosic substrates) coated with plastics or polymers specify a

3-phase testing protocol to include biodegradation, disintegration and eco-toxicity (ASTM

D6868, 2011). Biodegradation is the measurement of CO2 production as a result of material

degradation and requires an aerated closed system in a laboratory (ASTM D5338, 2011).

Disintegration is the measurement of material loss as a result of physical fragmentation and is

also performed in an aerated closed system in a laboratory. Eco-toxicity is the observation of

seed germination and early plant growth when grown in the finished compost containing the

test material (OECD 208, 2006). The combined results of the 3-phase compostability testing

determine the overall suitability of a material for an industrial-scale composting system.

In addition to compostability testing, chemical analysis of finished compost is a beneficial

means to determining compost safety in terms of heavy metal or volatile organics content.

Current regulations set forth by the US Environmental Protection Agency (US EPA) and

followed by ASTM D6868-11 require the testing of compost for the presence of heavy metals

(e.g. zinc, cadmium, lead) and volatile organic compounds (VOCs) such as formaldehyde. No

regulation or acceptable limit has yet been set forth for the presence of fluorosurfactants,

fluorinated precursors or degradation metabolites. However, fluorosurfactant ingredients

have been shown to be highly mobile in the atmosphere and susceptible to biological

degradation in terrestrial systems and may require further detection in finished compost.

Alternative fluorosurfactants for the treatment of food paper and packaging are presumably

safer; however degradation processes in waste systems need further examination. As

4

individuals and businesses become more interested in sustainable practices, such as

composting, the feasibility and safety of composting paper treated with fluorinated surfactants

must be determined, not only through compostability testing, but also with comprehensive

chemical analyses.

1.2 Fluorosurfactant Technology: 1974-2000

Commercial production of fluorinated surfactants began in the 1950s, but took off in the

1970s as food packaging became more centered on convenience. The ability to cook food

directly in the package required that packages be durable and disposable without being cost

prohibitive.

1.2.1 Electrochemical Fluorination: SAmPAPs

The alcohol, N-ethyl perfluorooctane sulfonamidoethanol (N-EtFOSE), was an important

manufacturing intermediate used in fluorosurfactant processes from 1974 to 2000 (Parsons et

al., 2008). During this time fluorosurfactants, effective for grease-proofing food contact

paper, were N-EtFOSE based polyfluoroalkyl phosphate esters (Lee and Mabury, 2011). The

fluorinated portion, N-EtFOSE repelled the grease and moisture from food, while the

phosphate ester was instrumental in bonding the polymer to the paper (Trier, 2012). These

polyfluoroalkyl phosphate esters were known commercially as sulfonamide perfluoroalkyl

phosphates (SAmPAPs). SAmPAPs were produced by combining N-EtFOSE, a sulfonamido

alcohol and a sulfonamido acrylate monomer (Buck et al., 2011).

Both the N-EtFOSE alcohol and the sulfonamido acrylate monomer were produced in a

process called electrochemical fluorination (ECF). Octane sulfonyl fluoride (OSF) was used as

an organic feedstock in the ECF process. The OSF was dispersed in a liquid anhydrous

5

hydrogen fluoride solution that was charged with electric current. This caused the hydrogen

atoms bonded to carbon to be replaced with fluorine atoms (3M, 1999; Buck et al., 2011). The

resultant fully fluorinated product of the electrochemical fluorination of OSF was

perfluorooctane sulfonyl fluoride (POSF). The POSF combined with a sulfonamide acrylate

monomer created N-EtFOSE based polymers, including SAmPAPs, used for a variety of

coating applications (Buck et al., 2011).

1.2.2 Degradation Analysis of N-EtFOSE

During manufacturing and processing of SAmPAPs, excess N-EtFOSE volatilized into the

atmosphere (Rhoads et al., 2008). Also found terrestrially, N-EtFOSE was detected in

wastewater treatment plant discharge and sludge byproducts which suggested mobility in a

variety of media. For example, in activated sludge, aerobic microorganisms rapidly work to

biodegrade N-EtFOSE into metabolites (Fromel and Knepper, 2010). The primary metabolite

of N-EtFOSE breakdown is N-ethyl perfluorooctane sulfonamide acetic acid (N-EtFOSAA).

Transformation occurs when the hydroxyl group of N-EtFOSE is oxidized. The less volatile

N-EtFOSAA is detected in sludge at higher concentrations than N-EtFOSE (Rhoads et al.,

2008). Subsequent metabolite pathways are less well known and tend to vary among studies

(Fromel and Knepper, 2010). However, degradation of N-EtFOSE inevitably leads to

perfluorooctane sulfonate (PFOS). In an aerobic degradation study, PFOS was found in

activated sludge (Remde and Debus, 1996). The authors determined PFOS, an acid with eight

perfluorinated carbon atoms, to be a terminal metabolite of N-EtFOSE breakdown.

Davie et al. (1994) studied the compostability of a variety of coated paper products being

used in a fast food restaurant. Low density polyethylene coated paper used for cups,

6

petroleum wax-based coated paper (possibly combined with a N-EtFOSE-based fluorocarbon

treatment for grease resistance) used as food wrap and uncoated paper were selected. The

paper substrates coated with wax and polyethylene disintegrated fully following 143 days of

active composting. While the wax coated paper easily composted, the polyethylene film

inhibited the decomposition of paper 5×5 cm and larger and remained in the compost matrix

after the paper substrate had disintegrated. The finished compost was used to amend pots in a

rye grass growth trial and no negative plant growth effects were observed. If there was a

fluorosurfactant fraction to the coated paper no research was carried out to investigate the

presence of N-EtFOSE, PFOS or related metabolites in the compost.

1.2.3. Environmental and Health Concerns of PFOS

Due to the soluble nature of PFOS, drinking water was believed to be the greatest exposure

risk to humans (Harada and Koizumi, 2008). As a result, the EPA became concerned with

toxicity of PFOS in the late 1990’s (US EPA, 2010). While toxicity to humans has been

suggested in the literature (Harada and Koizumi, 2008), the ultimate toxicity of PFOS is still

relatively unknown. The persistent and bioaccumulative nature of PFOS was of concern to

3M, the sole producer of N-EtFOSE (i.e. a known PFOS precursor) and the company chose to

cease production in 2000. At that time, 3M continued to manufacture surfactants via ECF;

however, the use of N-EtFOSE-based surfactants on food contact paper was halted altogether.

1.3 Fluorosurfactant Technology: 2000-2010

When 3M ceased ECF operations of SAmPAPs in 2000, a telomerization process became the

dominant production method for fluorotelomer-based surfactants used in food contact paper

and packaging (Lee et al., 2010). From 2000 to 2002 fluorotelomer production was

7

approximately 5,000 tonnes per year and by 2006 yearly production had reached 9000 tonnes

(US EPA, 2009b). Fluorotelomers are used to produce 2 types of surfactants for paper

treatments: diester perfluoro-alkyl phosphates (i.e. DiPAPs) and fluoroacrylate polymers.

1.3.1 Telomerization: DiPAPs and Fluoroacrylate Polymers

During telomerization, fluorotelomer-based materials are produced by linking together 2

fluorinated feedstocks, a perfluoroalkyl iodide (Telomer A) and a fluorotelomer iodide

(Telomer B; Buck et al., 2011). According to a definition by Kissa (2001), telomerization is

“…a process of reacting a molecule, called telogen, with two or more ethylenically

unsaturated molecules called taxogens” to produce a telomer. Telomerization produces even

length, linear telomer chains that are low molecular weight polymers (Ameduri et al., 1999;

Buck et al., 2011). A taxogen is also known as a monomer or a polymerizable material. A

fluorotelomer alcohol (FTOH) is an intermediate product during the production of

fluorotelomer iodides. The addition of FTOH is fundamental to fluorinated polymer and

fluorotelomer synthesis for the manufacture of paper grease-repellent surfactants

(Prevedouros et al., 2006).

Fluorotelomer properties are unique depending upon telomer chain length (Arakaki et al.,

2010). Fluorotelomers are characterized by X:Y, where X represents the number of

fluorinated carbons in the chain and Y represents the hydrocarbon segment (e.g. 8:2 and 6:2;

Parsons et al., 2008; Myers and Mabury, 2010). A greater number of fluorinated carbons in a

molecule increases overall stability and usability for durable applications (i.e. TeflonTM and

Gore-TexTM). Lower numbers of fluorinated carbon chains can be found in aerosol products

designed for post-production stain protection (e.g. Scotch-GuardTM) and are easily volatized.

8

Polyfluoroalkyl phosphate esters (PAPs) impart grease resistance on food contact papers and

are fluorotelomer-based surfactants that have maintained the phosphate end groups used in

N-EtFOSE-based surfactants for bonding the molecule to paper (D’eon et al., 2009; Trier,

2012). These anionic surfactants (Kissa, 2001) are commonly referred to as monoPAPs

(polyfluoro-alkyl phosphate monoesters) with one ester linkage and diPAPs (polyfluoroalkyl

diesters; D’eon, et al., 2009) with two ester linkages. When applied to paper mono- and

diester phosphates are used as blends of X:Y perfluoroalkyl chain lengths (6, 8, or less

commonly 10; Buck et al., 2011).

A fluorotelomer-based acrylate polymer (fluoroacrylate polymer) has a higher molecular

weight than PAPs and is a treatment typically applied to textiles; however, fluoroacrylate

polymers have been mentioned in the literature as a means of providing grease and moisture

repellency to food contact paper and packaging (Russell et al., 2008 and Washington et al.,

2009). Similar in function to diPAPs, the fluoroacrylate polymer is produced by the

telomerization of an acrylate monomer. A fluorotelomer acrylate monomer is prepared via

aqueous emulsion polymerization with hydrocarbon acrylate monomers and vinylidene

chloride monomers (Fromel and Knepper, 2010). The monomers polymerize in the emulsion

(Russell et al., 2008). The aqueous emulsion is either added to paper pulp slurry, in a process

known as wet-end for flexible paper applications, or is applied directly to the paper surface, in

a process known as size-press for more rigid board applications (Kissa, 2001; Trier, 2012).

1.3.2 Degradation Analysis of DiPAPs and Fluoroacrylate Polymers

Laboratory-based degradation research of fluorotelomer-and fluoroacrylate-based products

performed by chemists from the US EPA, DuPont and the University of Toronto unanimously

9

finds that FTOH is the product of microbial degradation in environmental simulations (Wang

et al., 2005; Russell et al., 2008; Washington et al., 2008; 2009; Buck et al., 2009; Lee et al.,

2010; Myers and Mabury, 2010). Ultimately FTOH degradation will yield a persistent and

bioaccumulative perfluorinated carboxylic acid (PFCA) known as perfluorooctanoic acid

(PFOA; Section 1.3.3).

In a study by Wang et al. (2005) the activated sludge from a wastewater treatment plant

(WWTP) was examined. Degradation of 8:2 FTOH by alcohol dehydrogenase produced 8:2

fluorotelomer aldehyde (FTAL), a transient metabolite, within the first few days of exposure

to microbial activity. Wang et al. (2005) discovered that activated sludge from WWTPs was a

fast moving biological competitor for the atmospheric partitioning of FTOH. A study by

Myers and Mabury (2010) found that atmospheric oxidation of FTOH (i.e. partitioning) also

produced FTCA and ultimately a PFCA (i.e. PFOA) that has the potential to enter

precipitation and contaminate widespread and remote areas (i.e. Arctic ecosystems; Section

2.3.3). Transformation of the 8:2 FTAL by aldehyde dehydrogenase produced a saturated 8:2

fluorotelomer carboxylic acid (FTCA). The 8:2 FTCA lost hydrogen atoms via

dehydrofluorination to produce an 8:2 fluorotelomer unsaturated carboxylic acid (FTUCA).

A hydrofluoric acid (HF) byproduct was also formed during the dehydrofluorination process;

HF is a water soluble strong acid and toxic gas that is highly toxic to humans and animals

(Myers and Mabury, 2010; Wang et al., 2009). Wang et al. (2009) proposed that multiple

pathways of transformation were possible from 8:2 FTUCA and all the pathways involved

unknown metabolites. One such pathways suggested that enzymatic defluorination and

mineralization of the 8:2 FTUCA somehow bypassed PFOA formation to produce

10

perfluorohexanoic acid (PFHxA), a PFCA with six fluorinated carbons to a chain that is less

likely to be bioaccumulative than PFOA (Section 2.5.2).

A study by Lee et al. (2010) examined the fate of PAPs (i.e. mono- and diPAPs) in incubated

microbial systems simulating the environment of a wastewater treatment plant (WWTP) in a

92 day degradation study. The key finding in the study was that microbial hydrolysis of the

phosphate ester severed the linkage to a 8:2 diPAP and produced 8:2 FTOH, likely formed

from the reduced 8:2 monoPAP after hydrolysis. Lee et al. (2010) suggested that the presence

of microbial activity in activated sludge broke down the phosphate ester linkages to the

fluorinated body of the PAPs and thereby released FTOH. When samples of 8:2 monoPAPs

and diPAPs and 6:2 monoPAPs and diPAPs (Section 2.5.2) were inoculated with bacteria

typical to a WWTP environment FTOH was biologically produced (i.e. via mono- and diPAP

degradation) and readily sampled in the headspace gas. According to Lee et al. (2010) the

presence of FTOH following the inoculation with bacteria proved that the increase in

microbial activity caused the hydrolysis of the phosphate ester linkage in the PAPs.

Using sediment-water microcosms, Myers and Mabury (2010) also examined the interaction

and fate of fluorotelomer acids (i.e. FTCA and FTUCA). Myers and Mabury suggested that

FTCA may be 10,000 times more toxic to aquatic invertebrate species (i.e. Daphnia magna)

than PFCAs since FTCA degradation in biological systems was a suspected vehicle for HF

release (Wang et al., 2005; 2009). The dehydrofluorination of FTCAs produced FTUCAs that

produced several PFCAs including PFOA. Like the studies in WWTPs, the microbial activity

within soil was necessary in facilitating degradation of FTCA to FTUCA and ultimately

11

PFCA. Results of this study did not give evidence of FTUCA produced from FTCA, unlike

the study performed by Wang et al. (2005).

The fluoroacrylate polymer is physically less degradable than diPAPs given a higher

molecular weight and overall size. According to a study by Russell et al. (2008) the

fluoroacrylate polymer did not show signs of degradation. Over a 2-year period, Russell et al.

(2008) examined the potential of an aqueous dispersion of fluoroacrylate polymer to degrade

to PFOA via the release of FTOH in an aerobic soils environment. The polymer was used to

treat textiles for stain and soil repellency. Russell et al. (2008) proposed that the polymer

would release FTOH if the covalent bond of the fluoroacrylate ester was broken, as was

shown in the study conducted by Lee et al. (2010). Gas from the vessel headspace and soil

and vessel (i.e. surface testing) samples were tested for 8:2 FTOH each time soil samples were

obtained. In order to differentiate between analytes from residuals and analytes from

fluoroacrylate polymer degradation this study developed a model based on the molar mass of

the polymer. According to this model, the observed formation of PFOA and other FTOH

metabolites was most likely from residual impurities and not from degradation of the added

fluoroacrylate polymer. In addition, Russell et al. (2008) indicated that the model predicted a

fluoroacrylate polymer half-life of 1200-1700 years. This model suggested that the polymer

could not be a major source of PFOA in the environment. However, residual FTOH is still a

source of PFOA in the atmosphere and environment.

In a similar study, Washington et al. (2009) examined the degradation of an acrylate-linked

fluorotelomer polymer (fluoroacrylate polymer) in aerobic soil microcosms, but found

polymer degradation to be possible. The polymer was added to a sandy loam soil (8.7%

12

organic matter) and incubated at 25°C. Each test microcosm was wetted to maintain a mix of

aerobic and anaerobic conditions as well as to keep the polymer surface moist. In a fresh (i.e.

non-degraded) fluorotelomer polymer, residual precursors such as FTOH can be mistaken for

analytes of polymer degradation. This study examined analytes from day 497 and again at day

546 as a means of allowing fresh residual FTOH to volatilize prior to testing. Analytes such as

FTOH and PFOA were observed to be present at higher levels in the aged polymer samples

versus the fresh polymer. This suggested that degradation of the fluoroacrylate polymer

occurred. Washington et al. (2009) also used modeling to determine the degradation rate

related to the surface area of a commercially produced fluoroacrylate polymer. Based on the

assumption that enzymatic and microbial degradation occurs at the polymer surface, the

fluoroacrylate polymer half-life was found to be 10-17 years, which was two magnitudes

lower than findings reported by Russell et al. (2008). Washington et al. (2009) concluded that

fluoroacrylate polymers are degraded over time in environmental systems, thus making the

polymer a likely source of PFOA.

A composting study by Hoppenheidt et al. (2000) examined the compostability of textiles

treated with two fluoroacrylate polymer surfactants, Oleophobol® C and Oleophobol® S

(Ciba Specialty Chemicals, Basel, Switzerland). A perfluorinated polyurethane was the main

ingredient in both surfactants used to treat the test textiles; Oleophobol® C was applied to

natural fibers and Oleophobol® S was applied to synthetic fibers. In a survey of compost pile

temperatures the incorporation of raw, treated, or untreated textiles was not observed to

inhibit internal composting temperatures from reaching 70˚C which indicated an active

13

microbial community. Although the fluorosurfactant treated textiles were observed to

adequately decompose, they decomposed more slowly than raw and untreated textiles.

The transformation of FTOH involves a variety of metabolites and degradation follows

several different pathways depending on the environmental conditions and microbial activity

(Wang et al., 2005; Lee et al., 2010; Myers and Mabury, 2010). Despite discrepancies among

researchers regarding degradation pathways and fluoroacrylate polymer degradation, FTOH

degradation is known to occur and has been determined to be a source of the terminal

metabolites such as perfluorocarboxylic acids (PFCAs; Yamada et al., 2005; Lee et al., 2010).

Overall, after screening and removal of coarse remnants all finished composts appeared

equal upon observation (Hoppenheidt et al., 2000). In comparison with the performance of

other biowaste composts in plant toxicity tests (i.e. eco-toxicity), the treated textile compost

did not adversely affect plant biomass yields. Final chemical analyses revealed there was no

added fluoride to the compost as a result of treated textile decomposition. The lack of

fluoride suggested that the polymer used to treat the textiles did not degrade to the point of

fluorine release into the compost matrix.

1.3.3 Environmental and Health Concerns of PFOA

Concern has grown in recent years as degradation studies have shown diPAPs and

fluoroacrylate polymers to be biological precursors of long chained perfluorinated (i.e. fully

fluorinated carbon atoms) acids, such as PFOA (D’eon et al., 2009; Washington et al., 2009).

Similar to previous surveys involving PFOS in human blood samples, low concentrations of

PFOA have been found in the blood samples of the general human population. According to

a long term survey of perfluoroalkyl acids (e.g. PFOA) in the Canadian environment the

14

highest concentrations of PFOA are found in urban areas, landfill leachates and gases,

wastewater treatment facilities (e.g. influent and effluent, biosolids, air and water) and indoor

dust (Gewurtz et al., 2013). In 2005 DuPont was sued in a West Virginia circuit court and

part of the class action settlement was the creation of the C8 Science Panel. This panel

consisted of 3 epidemiologists, with no connection to DuPont, who were to investigate the

link between PFOA exposure and human disease. In 2009, the panel tested the blood of

children and adults living near a DuPont’s Washington Works fluorochemical plant in West

Virginia. They found a correlation between elevated blood cholesterol and uric acid levels

with elevated levels of PFOA. Whether PFOA is responsible for the elevated cholesterol and

uric acid levels, or vice versa, is still unsubstantiated (C8 Science Panel, 2009). According to

research conducted by Harada and Koizumi (2008) in a review of related literature, they

found elevated levels of PFOS to be linked with bladder cancer and low birth weights in rats.

Perhaps the next greatest source of PFOA in consumers is hot foods that have been in

contact with diPAP treated paper. Food contact paper surfactants, specifically diPAP

treatments have been observed to migrate from paper to hot or emulsified foods that are

subsequently ingested by humans (Begley et al., 2008; D’eon et al., 2009). As a result the

United States Food and Drug Administration (FDA) were interested in the implications of

fluorotelomer and possible PFOA toxicities for humans (Begley et al., 2008). Begley et al.

(2008) found that high temperature emulsified foods (i.e. buttered popcorn) were adept at

extracting diPAPs from treated paper thus allowing for migration into human biological

systems. As well, residual FTOH in fluorotelomer-based food contact paper may biologically

transform to PFOA in human systems as was shown to occur in rat-based studies (Dinglasan-

15

Panlilio and Mabury, 2006). A study done on the biodegradation of PAPs in wastewater

treatment plants (WWTPs) found that PFCA (e.g. PFOA) concentrations increased from

influent to effluent likely as a result of FTOH biotransformation (Lee et al., 2010).

1.4 Industry and Regulatory Response to PFOA and Fluorotelomer-based Surfactants

1.4.1 United States Environmental Protection Agency

Conversations between the United States Environmental Protection Agency (US EPA) and

global fluoropolymer and fluorotelomer manufacturers about PFOA began as early as 2000

(US EPA, 2010). By 2003, the US EPA drafted a preliminary risk assessment. Industry leaders

were summoned to submit letters of intent regarding PFOA related toxicity, manufacturing

volumes, environmental releases and other relevant topics (US EPA, 2006). This information

laid the groundwork for the US EPA’s Enforceable Consent Agreements (ECAs) under the

Toxic Substances Control Act (TSCA) of 1976. Enforceable Consent Agreements were legally

binding agreements negotiated between industry leaders and the US EPA and required

manufacturers to conduct and publish research on fluorotelomer and polymer degradation

(Daikin Industries, 2011; US EPA, 2011).

Through industry research and participation the US EPA compiled data on the processes

leading to PFOA formation (US EPA, 2011). By 2005, the knowledge of widespread human

exposure, persistence and bioaccumulative properties of PFOA were cause for concern.

However, the US EPA was not inclined to alert consumers to PFOA exposure due to the lack

of evidence regarding specific risks to human health and safety.

With continued industry cooperation and in response to lingering concerns with PFOA, the

US EPA proactively instituted the PFOA 2010/15 Stewardship Program. The eight leaders in

16

the fluoropolymer and fluorotelomer industry (section 1.1) committed to goals that would

reduce PFOA in emissions, discharges and products by 95% by 2010 and eliminate all PFOA

by 2015. The stewardship program is a global effort that uses PFOA emission and product

baseline data from 2000 to track company progress (US EPA, 2010). As a positive example,

Daikin Industries has been active in the program and achieved 68% reduction in PFOA

emissions and product content as of 2006, which surpassed the US EPA goal of 50% (Daikin

Industries, 2011). However, as a negative example, in 2004 the US EPA took legal action

against DuPont for failing to provide information, under the TSCA, regarding PFOA studies

from 1981 to 2001 (US EPA, 2010). DuPont paid $10.25 million to the EPA in 2005; to date

this is the largest settlement received by the US EPA for statute violations.

1.4.2 United States Food and Drug Administration

The Food and Drug Administration (FDA) is among other US agencies (e.g. US Consumer

Product Safety Commission, US EPA) to review fluoropolymers and fluorotelomers for health

and safety. Fluoropolymers used in the manufacture of non-stick coatings for cookware were

of particular interest. The FDA has not found any evidence that the routine use of non-stick

coated cookware would cause bodily harm to humans.

In response to the increased concern from the US EPA regarding human PFOA exposure

risks, the Office of Food Additive Safety (OFAS), within the FDA, began an investigation into

the potential of PFOA migration from fluorotelomer-based paper coatings to food (Begley et

al., 2008). The OFAS at this time does not equate fluorotelomer migration with subsequent

human exposure to PFOA (i.e. the transformation of FTOH to PFOA within human biological

systems). The FDA continues to examine PFOA exposure related to food and food contact

17

substances (FCS) and continues to maintain the overall safety of fluorotelomer-based

surfactants for use in food contact coatings.

1.5 Alternative Fluorosurfactants

Concerns with PFOA (i.e. known as C8 for the 8 perfluorinated carbons within a telomer

chain) and PFOS have prompted global fluorotelomer-based surfactant and polymer

manufacturers to move towards technologies utilizing shorter perfluorinated carbon chains

that cannot break down to PFOA or PFOS (Arakaki et al., 2010; DuPont, 2010; Liu et al.,

2010; Ritter, 2010). The transition to alternative technologies has been necessary to lessen

environmental and health impacts; however, given the global magnitude of the industry

maintaining overall efficacy and value was also imperative (Ritter, 2010). In the last decade,

technology based on shorter chains has managed to maintain product integrity while

potentially minimizing environmental impacts.

1.5.1 Electrochemical Fluorination: C4 Alternative

Products based on chains of 4 perfluorinated carbons (i.e. C4) are manufactured via

electrochemical fluorination (ECF) of the raw material perfluorobutanesulfonyl fluoride

(PBSF) and are typically aerosol fluoropolymer treatments for carpet and upholstery stain

resistance (i.e. industrial and consumer applications; Quinete et al., 2010). This type of

surfactant is not used in the manufacture of treatments for food contact papers. In terms of

ECF manufacturing, chain lengths that are ≥6 fluorinated carbons bioaccumulate in terrestrial

and biological systems (Buck et al., 2011). Known terminal metabolites, perfluorobutanoic

acid (PFBA) and perfluorobutane sulfonate (PFBS) are thought to be less bioaccumulative,

although the metabolites are still persistent in environmental matrices (Quinete et al., 2010).

18

1.5.2 Fluorotelomer: C6 Alternative

Products based on chains of 6 perfluorinated carbons (i.e. C6) are manufactured identical to

C8 products via telomerization (Buck et al., 2011). However the raw ingredients (i.e.

perfluoroalkyl iodides and 6:2 fluorotelomer iodides) produce a FTOH with 6 fluorinated

carbons to a chain instead of 8 which is then used to manufacture 6:2 diPAPs and 6:2 acrylate

monomers. The industry transition from 8:2 FTOH to 6:2 FTOH has been underway since

2006 with the sole purpose of limiting PFOA emissions by 95% from manufacturing (Liu et

al., 2010). According to T. Krasnic (Personal communication, 2011) from the US EPA the

leading fast food companies, which are top purchasers of fluorotelomer-based food contact

paper, have already made the switch to paper and packaging with C6- or PFPE-based (Section

2.5.3) chemistries. Mr. Krasnic also stated that several fluorotelomer manufacturers had long

term goals to phase out fluorinated treatments for food contact paper, including C6, to pursue

equivalent non-fluorinated alternatives (e.g. hydrocarbon- and plant-based treatments).

The degradation research for C6 has been available for the last few years and is required of

manufacturers and importers that want to market new products under the EPA’s New

Chemicals Program (NCP). The NCP falls under the Toxic Substances Control Act (TSCA)

and was developed as a measure to stop the production and the importation of newly

marketed chemicals if they were discovered to be a health or environmental hazard (US EPA,

2010). A study done by Liu et al. (2010), found that the aerobic degradation routes in soil

with mixed bacterial cultures for 6:2 FTOH were different than those of 8:2 FTOH in the

same environment. Degradation of 6:2 FTOH produced the terminal metabolites

perfluorohexanoic acid (PFHxA, C6) and perfluoropentanoic acid (PFPeA, C5) and was not

19

observed to break down to PFOA. Presently, these metabolites have been shown to have

shorter half-lives than PFOA and appear unlikely to bioaccumulate. Liu et al. (2010)

suggested additional research was needed to examine the bioavailability of short-chained

metabolites to plants and potential pathways into human biological systems.

1.5.3 Photooxidation: PFPE Alternative

First marketed in the early 1970’s, perfluoropolyethers (PFPEs) are commercially important

surfactants used primarily as lubricants where extreme thermal stability and low chemical

reactivity is required (Ameduri et al., 1999, Denkenberger et al., 2007). Perfluoropolyether

(PFPE) based lubricants are the most common form of PFPEs and are used in computer

technology (e.g. magnetic recording), for aviation and aeronautic applications where low

chemical reactivity with fuels is crucial and for moving parts and bearings in satellites (Strom

et al., 1993; Young et al., 2006; Denkenberger et al., 2007). The expansion of PFPE-based

surfactants into the realm of food contact paper followed at the heels of PFOA concerns and

subsequent alternative technologies. As a fluorinated surfactant that cannot break down into

PFOA due to chain lengths of 2-3 fluorinated carbons PFPE maintains efficacy and value and

is a particularly attractive alternative to biologically reactive fluorotelomers (Solvay Solexis,

2011).

Perfluoropolyethers used for paper treatments are fluorinated polymers made up of chains

with 2-3 perfluorinated carbons separated by oxygen atoms (i.e. ethers) and have 2 phosphate

end groups (Buck et al., 2011; Solvay-Solexis, 2012a; 2012b). The fluorinated body of the

PFPE polymer from the paper treatment Solvera® XPH-723 (Expera Specialty Solutions,

Kaukauna, WI) is comprised of reduced methyl ester ethoxylates (i.e. ethylene oxide added to

20

an alcohol to produce a surfactant) and tetrafluoroethylene (TFE) gas that has been

photooxidized, polymerized and reduced to form a short perfluorinated carbon segment

(Figure 1.1).

Photooxidation to produce PFPE is a process that distinguishes itself from ECF and

telomerization by polymerizing a fluorinated gas rather than a fluorinated alcohol via light

and oxygen. The PFPE polymer end groups are comprised of diphosphoric acid (Figure 1.1).

The end groups are responsible for increasing hydrophobicity, decreasing surface tension of

the polymer and allowing the otherwise insolvent polymer to be emulsified in polar solvents

(i.e. water and dipropylene glycol; Keene, 1978 and Solvay-Solexis, 2012a; 2012b).

Solvera® XPH-723 is identical in structure to Fomblin® HC/P2-1000, a cosmetics

ingredient manufactured by Solvay-Solexis and both surfactants are identified by the same

CAS number (Chemical Abstract Service; 200013-65-6) on their respective safety and

technical data sheets (Solvay-Solexis, 2012a; 2012b). However, Solvera® surpasses Fomblin®

in molecular weight and is less dense which is indicative of the intended applications (Karis et

al., 2002). Polymer molecular weight can vary depending on the number of segments and

repeating segments within the molecule; in this case p, q and n indicate which moieties (i.e.

functional groups) may be present as repeating segments (Figure 1.1). The p/q ratios

associated with the Solvera® polymer assuming a molecular weight between 1000-6000

atomic mass units (amu) may range from 0.3 to 10 and n is an integer ≥1 (Russo, 2005; Tonelli

et al., 2013).

21

1.5.3.1 Degradation Analysis of PFPE

Degradation analysis of PFPE has mainly focused on the thermal degradation of PFPE-based

lubricants and thin films. According to a review by Walther et al. (2013) PFPEs are not

biologically degradable in the environment. Any decomposition of PFPEs that does occur

takes place very slowly which prevents the small quantities of toxic byproducts produced,

such as COF2CF2COF, perfluoroolefins and volatile acid fluorides from accumulating.

Research reported by Walther et al. (2013) also found PFPEs to be non-toxic to animals and

humans in a variety of topical and internal applications which make PFPEs ideal for

cosmetics and food contact paper.

Magnetic recording disks are protected from wear with the application of PFPE-based thin

film lubricants (Strom et al., 1993; Denkenberger et al., 2007). Disks are typically comprised

of a metal substrate (e.g. aluminum-magnesium) and coated with magnetic metals (e.g.

cobalt-platinum-nickel; Strom et al., 1993). The PFPE thin film lubricant is applied between

2-3 mm thick. In studies by Strom et al. (1993) and Denkenberger et al. (2007) PFPE

degradation was observed when applied to a metal disk surface composed of aluminum oxide

(i.e. AlO3; alumina) and exposed to heat caused by friction. Strom et al. (1993) discovered

that even in the case of low heat generation thermal degradation of PFPE into gaseous

products (e.g. CF2, HCF2, CF3 and HCF3; Section 2.5.3.2) occurred likely as a result of the

metal oxide surface. Denkenberger et al. (2007) also found that thermal conditions combined

with a metal oxide such as AlO3 produced an acid catalyzed degradation of the PFPE thin film

lubricant. Acid catalyzed degradation also appeared to depend upon PFPE structure and only

occurred in polymers with a –CF2O– group (Walther et al., 2013). As a result of the findings

22

with AlO3 surfaces Denkenberger et al. (2007) also suggested the possibility for acid catalyzed

PFPE degradation in soils high in aluminum; a potential pathway to the biological

degradation of PFPE.

1.5.3.2 Environmental and Health Concerns of PFPE

The Montreal Protocol in 1987 was an international agreement for the protection of the

ozone layer and the identification, reduction and eventual elimination of ozone depleting

chemicals (UNEP, 2013). Chlorofluorocarbons and hydrochlorofluorocarbons (CFCs and

HCFCs) were perhaps the most cited ozone depleting substances due to their widespread

presence as refrigerants, fire retardants and aerosols in commonly used products (Young et al.,

2006; US EPA, 2013). Hydrofluorocarbons (HFCs) were the preferred replacements for CFCs

and HCFCs because they maintained effectiveness without depleting the ozone layer. Since

1990 all fluorinated gas emissions have increased, particularly HFC emissions that have

increased by 249%, as industries began replacing ozone depleting chemicals with fluorinated

alternatives (US EPA, 2013; Figure 1.2).

The rise of fluorinated gas emissions from 1990-2010 was dominated by the release of HFCs

from consumer products (US EPA, 2013). In fact, during that 20 year period, fluorinated gas

emissions decreased from perfluorinated carbons (PFCs) used in aluminum manufacturing

and sulfur hexafluoride (SF6) used in the electricity transmission and distribution industry.

Young et al. (2006) reported that the PFPE ingredient primarily used in cosmetics,

perfluoromethylisopropyl ether (PFPMIE), could volatilize into the atmosphere like a

fluorinated gas and effectively trap Earth’s radiative heat. Perhaps most notable about the

study conducted by Young et al. (2006) was the discussion that PFPMIE had the ability to

23

trap heat in the “atmospheric window”, a wavelength region in the Earth’s atmosphere where

few compounds absorbed energy thus allowing heat to escape. Overall, fluorinated gases and

PFPE ingredients in the atmosphere have long lifetimes (i.e. 300 years) and are much more

effective at trapping heat than other greenhouse gases (e.g. CO2, CH4) in much smaller

concentrations (US EPA, 2006).

1.6 Analysis and Characterization of Fluorinated Compounds

1.6.1 Liquid Chromatography–Tandem Mass Spectrometry

Liquid chromatography-tandem mass spectrometry (LC/MS/MS) is an analysis technique

that separates, detects and characterizes all the components that make up a molecule (Pitt,

2009). Liquid chromatography is a widely used analytical tool for a variety of organic

compounds and is better suited than gas chromatography for non-volatile (e.g. soil sample

extracts) and thermally sensitive molecules. Mass spectrometry is able to determine a range

of data such as sample purity, molecular weight, structure, characterization and

concentration. Results of LC/MS/MS appear as characteristic peaks along the x-axis of a

spectrum. Overall, mass spectrometry combined with liquid chromatography increases the

accuracy of interpreting both qualitative and quantitative results.

Based on the literature reviewed for fluorotelomer analysis LC/MS/MS has been the

dominant method for metabolite characterization especially in studies examining the large

fluoroacrylate polymer. In addition, acetonitrile (ACN) was the solvent most often used to

extract the fluoroacrylate polymer, fluorotelomer precursors and PFCAs from the soil and

sludge media (Wang et al., 2005; 2009; Russell et al., 2008; Washington et al., 2009; Liu et al.,

2010). Myers and Mabury (2010) extracted the soil-water microcosm using a combination of

24

isopropanol and water. Washington et al. (2009) also reported having success in dissolving

the fluoroacrylate polymer with methyl tert-butyl ether (MTBE) in order to extract FTOH for

LC/MS/MS analysis. Degradation studies have used LC/MS/MS to not only determine the

extractability of fluorotelomer precursors and metabolites from various media (e.g. activated

sludge, soil, water), but to also characterize the breakdown products associated with

fluorotelomers (i.e. FTOH and PFCAs; Russell et al., 2008; Wang et al., 2009; Washington et

al., 2009; Liu et al., 2010; Myers and Mabury, 2010).

1.6.2 Gas Chromatography–Mass Spectrometry

Gas chromatography-mass spectrometry (GC/MS), like LC/MS/MS, is an analysis technique

to separate, detect and characterize molecules with results appearing as peaks along the x-axis

of a spectrum. Unlike LC/MS/MS, GC/MS is particularly suited for analyses of trace levels of a

compound and volatile metabolites. The GC/MS analysis was used in studies examining the

contents of incinerated materials containing fluoroacrylate polymers (Yamada et al., 2005),

detecting residual FTOH from a fluoroacrylate polymer (Russell et al., 2008) and detecting

residual 8:2 FTOH and 8:2 FTA from a fluoroacrylate polymer (Washington et al., 2009).

1.6.3 Liquid Chromatography–Accurate Radioisotope Counting

Liquid chromatography-accurate radioisotope counting system (LC/ARC) is an analysis used

in comprehensive metabolite research and is able to detect radioactive metabolites (i.e. low

level). The LC/ARC functions in such a way that the liquid chromatography flow can be

stopped periodically to more accurately count the metabolites (Nassar and Bjorge, 2003). In

the study by Wang et al. (2005) LC/ARC was used to monitor FTOH degradation in

wastewater and enabled the authors to add proposed pathways that were previously

25

unknown to FTOH degradation. Two studies monitoring FTOH degradation in aerobic soils

used LC/ARC to examine the metabolites of 8:2 FTOH biodegradation (Wang et al., 2009) and

6:2 FTOH degradation (Liu et al., 2010).

1.6.4 Nuclear Magnetic Resonance Spectroscopy

Nuclear magnetic resonance spectroscopy (NMR; Section X.2.3) is a non-destructive

analysis suited for the characterization and detection of fluorinated compounds extracted

from a variety of media (i.e. soil, compost, biosolids). Liquid samples are dissolved in a

deuterated solvent (i.e. a solvent with H atoms removed) that is typically chloroform (CDCl3)

or methanol (CD3OD) and analyzed in a glass NMR tube (Lambert and Mazzola, 2004).

The most common types of NMR examine the nuclei of 1H, 13C and 19F isotopes by utilizing

magnetic force and radio wave resonance to analyze molecular characteristics such as

molecular weight, concentration and structure (Lambert and Mazzola, 2004)). A nucleus

with an odd number of protons (e.g. 1H, 13C and 19F) spins and aligns the protons to an applied

magnetic force; the nuclear spin becomes energized when a radio frequency is introduced

(Lambert and Mazzola, 2004). The energy absorbed by the nucleus produces a higher energy

spin that appears as peaks along the x-axis of a spectrum, this is known as chemical shift.

Peaks can be sharply defined or split as doublets (i.e. 2 peaks) or triplets (i.e. 3 peaks)

depending on the magnetic interaction between nuclei (i.e. 19F–19F, 19F–1H, 19F–13C) within a

molecule. Nuclei in isolated chemical environments within a molecule have no interactions

with other nuclei and produce singlet peaks. Molecule characterization can be determined by

chemical shifts and peak appearance.

26

In a study conducted by Ellis et al. (2001) NMR was used to examine the structure and

behavior of fluorotelomer metabolites (i.e. PFCAs) in the environment; the sample was

analyzed in a deuterated dimethyl sulfoxide ((CD3)2SO) solvent. Another study by Weiner et

al. (2013) used NMR in combination with combustion ion chromatography and liquid and gas

chromatography to determine the characterization and manufacturing origin of fluorinated

surfactants (e.g. telomer- and ECF-based) used in firefighting foams; the samples were

analyzed in either deuterated water (D2O) or deuterated methanol (CD3OD). Nuclear

magnetic resonance analysis appears to be highly suited for PFPE studies. NMR has been

used to characterize the synthesis of various PFPE-phosphates in CD3OD (Russo et al., 2005),

to observe the thermal degradation via oxidation of PFPE greases applied to metal oxides

(Denkenberger et al., 2007) and to understand the link between specific physical properties of

PFPE greases and characterization (Karis et al., 2002).

1.6.5 Total Organofluorine–Combustion Ion Chromatography

Combustion ion chromatography is an analysis that determines the concentration of a

specific element in gaseous, solid or liquid samples (Metrohm, 2013). Total organofluorine

combustion ion chromatography specifically examines the trace concentrations (parts per

billion) of inorganic and organic fluorine. A sample is introduced via a gas inlet or is placed

in a ceramic boat as a solid or a liquid (i.e. most extraction solvents are suitable); from there

the sample goes to a 900-1000˚C oven (Metrohm, 2013; Weiner et al., 2013). In the oven a

sample is combusted in the presence of oxygen, the combustion process produces HF gas

which is carried to the absorption chamber with argon (Weiner et al., 2013). The toxic and

27

corrosive HF gas is absorbed in water to produce F- ions. The concentration of F- ions is then

determined by ion chromatography.

In a study conducted by Weiner et al. (2013) TOF-CIC analysis was used to determine the

concentration of fluorine in firefighting foams. The Mabury Group at the University of

Toronto employs TOF-CIC for much of their ongoing analytical and environmental

fluorochemical research (Mabury, 2011).

1.7 Composting

Composting is a controlled waste management tool that repurposes organic wastes (e.g. food

scraps and yard trimmings) as a finished compost product that can be used as a structural or

nutritive amendment for soil, turf, landscaping and remediation projects (USCC, 2001).

Composting organic wastes is a process largely aided by an active microbial community that

metabolizes organic material and consumes oxygen, a process that produces heat, water, CO2

and humic substances (Trautmann and Olynciw, 1996). A productive composting

environment is aerobic, high in moisture content (e.g. 50-60%) and has a carbon food source

(USCC, 2001). Microbial communities vary in purpose during the composting process and

specific composting temperature phases (e.g. mesophilic, thermophilic, psychrophilic) are

aptly named to reflect which microbial populations are dominant and when (Trautmann and

Olynciw, 1996; NRCS, 2000).

The mesophilic temperature range (i.e. 10-40˚C) indicates the beginning of the composting

phase and can last several days (NRCS, 2000). Mesophilic temperatures signify a lag phase

when biodegradation is in the nascent stage and the microbial population is growing into a

community that is able to actively assimilate a new carbon source. Mesophilic bacteria are

28

present in vast numbers from 0-40˚C and are able to quickly biodegrade simple carbon

sources (e.g. sugar, starch) which increases the population and the temperature within the

compost pile (Trautmann and Olynciw, 1996; NRCS, 2000). The thermophilic temperature

range (>50˚C) destroys pathogens (e.g. E. coli, Salmonella) and weed seeds which is important

for end-use applications of compost where human and animal health and soil quality are at

stake (NRCS, 2000). Thermophilic temperature indicates an active biodegradation phase with

ubiquitous microbial consumption and reproduction (Trautmann and Olynciw, 1996; NRCS,

2000). Bacteria such as actinomycetes and those in the genus Bacillus dominate the microbial

community at temperatures between 50-55˚C (Trautmann and Olynciw, 1996).

Actinomycetes are bacteria that behave as fungi, but with greater temperature tolerance and

enzymes suitable for decomposing lignin and cellulose. As temperatures within the compost

matrix approach 60˚C, species of bacteria in the Bacillus genus will produce spores that

germinate when temperatures cool to 50-55˚C. Thermophilic temperatures can last several

days to several months depending upon the amount and accessibility of organic carbon

(Trautmann and Olynciw, 1996; NRCS, 2000).

The psychrophilic phase, also known as cooling or maturation can last several months and

indicates the waning of microbial activity as the carbon food source becomes scarcer (NRCS,

2000). Mesophilic bacteria and fungi are dominant during the psychrophilic phase. Fungi are

more tolerant than bacteria to a variety of moisture and pH conditions; however, they have

low tolerance for thermophilic temperatures and thrive during the cooling phase of

composting. Fungi are instrumental in the biodegradation and assimilation of woody

materials with complex cellular structures (i.e. lignin, hemicelluloses) and degradation

29

resistant waxes and proteins. During the psychrophilic phase fungi break down complex

materials to a point where the carbon becomes accessible to the microbial community and

biodegradation can be completed (Trautmann and Olynciw, 1996; NRCS, 2000). Following a

sufficient cooling period compost is typically considered mature (Wichuk and McCartney,

2010). Many characteristics define maturity; however, one of the most basic is the inability

of compost to self-heat due to the overall inactivity of the microbial community and stability

of the carbon source that has been converted to humic material and plant-available nutrients.

A mature compost matrix is suitable for the previously mentioned end-uses and as a medium

for compostability testing.

1.7.1 Compostability Testing

Compostability is the determination of a material’s suitability for an industrial/municipal

composting environment based on sufficient decomposition and no adverse impacts on

compost quality (ASTM D6400, 2012; ASTM D6868, 2011). The ASTM International and

European/British EN standards organizations provide compostability testing specifications for

plastics and plastic/polymer coated materials, interchangeably. The specification for plastics

is ASTM D6400-12 Labeling of Plastics Designed to be Aerobically Composted in Municipal

or Industrial Facilities. The specification for coated paper and packaging is ASTM D6868-11:

Labeling of End Items that Incorporate Plastics and Polymers as Coatings or Additives with

PAPER and Other Substrates Designed to be Aerobically Composted in Municipal or

Industrial Facilities. The equivalent European specification is EN 13432 (2000) Packaging

Requirements for Packaging Recoverable through Composting and Biodegradation–Test

Scheme and Evaluation Criteria for the Final Acceptance of Packaging.

30

According to the specifications for compostability testing (i.e. plastics and coated paper) the

composting process can effectively be divided into and qualified by the biodegradation (i.e.

CO2 production) and disintegration (i.e. physical fragmentation) of organic wastes or other

materials of interest (e.g. coated paper, bio-based plastics). The specifications also determine

that finished compost (i.e. the product of a completed composting process that includes the

fully and partially assimilated test material) is effectively qualified by the demonstration of no

adverse impacts on plant growth, also referred to as eco-toxicity.

Compostability laboratories certified by the Biodegradable Products Institute (BPI) follow

the testing specifications found in ASTM D6400-12 and D6868-11 and methods in ASTM

D5338-11 and OECD 208 (2006) for the purpose of labeling materials ‘compostable’. BPI is an

organization interested in scientific approaches to composting through compostability

analysis and industry recognized labeling of ‘compostable’ materials (BPI, 2011). The types of

products chosen for compostability testing are made from bio-based plastic or mixed bio-

based materials, have the potential for entering composting waste streams and are generally

single use items with a commingled relationship with food (e.g. coated paper, packaging and

utensils).

Biodegradation analysis is conducted in reference to ASTM D5338-11: Standard Test

Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled

Composting Conditions, Incorporating Thermophilic Temperatures or the equivalent EN

14855 (2007) Determination of the Ultimate aerobic Biodegradability of Plastic Materials

under Controlled Composting Conditions–Method by Analysis of Evolved Carbon Dioxide.

The methodology specifies the construction of a controlled composting environment in a

31

laboratory where thermophilic conditions are simulated via an incubator or heated water

bath. The controlled composting environment is continually aerated and hydrated and CO2

evolution is monitored for a minimum of 45 days. Test material must achieve 90% CO2

evolution (i.e. percent biodegradation) of a positive reference material and standard

deviations of replicates must be within a 20% margin of error. Disintegration testing overlaps

biodegradation and is conducted for a period of 90 days, or 45 days past the end of

biodegradation. Any remaining test material is removed from the compost matrix using a 2

mm sieve and gravimetrically assessed to determine percent disintegration. Test material

must have less than 10% of the material remaining after 90 days.

Due to the cellular complexities of lignin and fungal degradation processes, as opposed to

the microbial production of CO2 within the 45 day minimum, ligno-cellulosic substrates are

exempted from biodegradation criteria. Amended in ASTM D6868-11 the exemption states

that if the substrate is 95% bio-based and can be proven as such using radiocarbon analysis

the material does not have to meet biodegradation specifications (i.e. percent biodegradation).

An exemption for plastic and polymer coatings was also amended in ASTM D6868-11 to

include applications that are less than 1% of the dry weight of the material. The exemptions

are particularly important when considering the compostability of food contact paper and

packaging treated with fluorinated surfactants. Essentially a fluorinated surfactant is applied

to paper and packaging at low concentrations (e.g. 0.1-1%), which will typically fall under

the exemption for polymer coatings. If the paper and packaging substrates also fall under the

ligno-cellulosic exemption the materials are a third of the way to achieving compostability

status.

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Eco-toxicity analysis conducted with finished compost is the final component in

compostability testing. Eco-toxicity guidelines required to meet the specifications in D6868-

11 are detailed in the OECD (2006) Guidelines for the Testing of Chemicals 208 Terrestrial

Plant Test: Seedling Emergence and Seedling Growth Test and Appendix E of EN 13432

(2000). The OECD 208 (2006) Guideline typically employed for the testing of chemicals, was

combined with EN 13432 (2000) Appendix E to expand the parameters of the methodology to

include compost amended soil toxicity. Finished compost is also required by the ASTM

specifications to pass heavy metals limits set forth in the US EPA Class A standard 40 CFR §

503.13 (ASTM D6400, 2012; ASTM D6868, 2011; US EPA, 2012).

Eco-toxicity analysis is designed to assess the impacts that a finished compost matrix may

have on the germination and early growth of a plant (OECD 208, 2006). The analysis utilizes

both quantitative results (e.g. plant height and biomass measurements) and qualitative results

(e.g. visual observations) to determine the impacts compost may have when incorporated

with soil or a growing medium. Seeds grown in finished compost must achieve 70% seedling

emergence in reference to seeds grown in a blank finished compost (ASTM D6400, 2012;

ASTM D6868, 2011). Seedlings harvested 3-4 weeks after 50% germination of seeds grown in

the blank finished compost must achieve 90% of the biomass harvested from the blank

finished compost mixtures. The successful completion of each phase of compostability testing

is equivalent to a compostable product and the subsequent labeling as such. Any failed

portion of analyses deems the material unsuitable for the industrial/municipal composting

environment and cannot be labeled compostable.

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1.8 Summary and Objectives

The advent of fluorosurfactant treated food contact paper and packaging promoted the ease

of food preparation and accessibility of take-out foods. Fluorosurfactants are adept at repelling

grease and moisture and have the added benefit of being stable at high temperatures.

However, the persistent and pervasive tendencies of fluorosurfactant ingredients in

environmental and biological systems have given cause for concern and elimination from

many North American and European industries. The development of alternatives addressed

legitimate health and safety concerns without sacrificing quality. However, degradation

processes of the newer fluorosurfactants such as PFPE remain unknown in composting waste

systems. Compostability testing is one tool to determining the fundamental suitability of

PFPE-coated materials in industrial/municipal composting systems. Further chemical

analysis of the finished compost matrix is another tool for understanding the presence and

possible biodegradation of PFPE.

The examination of fluorosurfactant decomposition and accumulation in compost is thus an

important component of the compostability determination of coated paper materials. The

main objective of this work was achieved by addressing the following three specific aims: (1)

to determine if a PFPE-coated paper was compostable according to the ASTM D6868-03

specification; (2) to determine if the PFPE was extractable from the compost matrix and

detectable using 19F NMR and if the PFPE polymer had undergone biodegradation; and (3) to

observe the disintegration of a PFPE-coated over time and compare it to the disintegration of

an uncoated paper. Industrial composting conditions were simulated in an incubator at 58 ±

2°C, with continual aeration and hydration (i.e. compostability experiment) and manual

34

aeration and hydration (disintegration over time experiment). Compost from the

compostability experiments was then incorporated into soil for eco-toxicity analysis and

compost from the disintegration over time experiment was prepared for chemical analysis at

the University of Toronto (Canada).

35

Figure 1.1 Chemical structure of a perfluoropolyether diphosphate polymer in Fomblin® and

Solvera® (Solvay-Solexis, 2012a).

Figure 1.2. Twenty year trend of all fluorinated greenhouse gas emissions, i.e. HFCs, PFCs and

SF6 (Source: US EPA, 2013).

36

2.0 IN-VESSEL DISINTEGRATION

2.1 Introduction

The degradation of organic wastes (e.g. food scraps, grass clippings) and natural origin end-

use items (e.g. soiled paper, packaging, bio-based plastics) in composting systems are often

researched to observe levels of decomposition and impacts on compost quality. This type of

research is known as compostability testing. Observing material in composting environments

can be conducted in large-scale windrow or small-scale laboratory systems. Compostability

testing determines the suitability of materials for composting systems and is determined in

three phases of analysis: (1) biodegradation (i.e. CO2 production); (2) disintegration (i.e.

physical fragmentation); and (3) eco-toxicity (i.e. seed germination and plant growth). The

specifications and methodology for compostability testing ASTM D6400-12, D6868-11 and

D5338-11 allow for biodegradation and disintegration experiments to follow laboratory-scale

composting.

Laboratory-scale composting utilizes in-vessel systems where aeration, hydration and

heating variables are controlled manually (ASTM D5338, 2011). Temperature is a fixed

variable where thermophilic conditions of active compost are maintained in an incubator or

water bath at 58 ±2°C. Aeration and hydration, as indicated in ASTM D5338-11, are supplied

continually to the compost matrix within the vessels, which is important for the collection of

CO2 in biodegradation experiments. Although windrow composting is a more accurate

depiction of the industrial-scale and municipal composting environments, the scale is too

large to directly examine disintegration or effectively capture CO2. The clear advantages of

laboratory-scale composting is the ability to observe the composting process in individual

37

vessels, capture CO2 and compost multiple materials using little space, unlike windrow

operations that require considerable amounts of outdoor or building space.

The main objective of the in-vessel disintegration analysis was to determine the degree of

material loss from a perfluoropolyether-coated paper (hereafter referred to as PFPE) over

time in compost utilizing a reproducible laboratory-composting method with fixed

temperature, controlled aeration via manual mixing and weekly moisture additions. The

secondary objective was to compare the degree of PFPE-coated paper disintegration to that of

uncoated paper (hereafter referred to as PAPER). These objectives were achieved by the

gravimetric analysis of paper material harvested at 7 designated weeks throughout the 12-

week composting period and comparing material loss between PFPE and PAPER after the

final Week 12 harvest.

2.2 Methodology

The laboratory-scale composting of PFPE-coated paper was adapted from the

compostability specification ASTM D6868-03 and disintegration methodology ASTM D5338-

11. An incubated, in-vessel system was used to house individual composting environments.

Weekly manual aeration (i.e. mixing) and hydration was employed to manage the composting

environments instead of the continual supply of humidified air as specified in ASTM D5338

(2011). The use of a manual system allowed for the expansion of the number of vessels that

were needed for destructive sampling.

2.2.1 Experimental Design

Industrial composting conditions were simulated in a laboratory incubator set to 58 ± 2°C

for 12 weeks in the Trainer Natural Resources building at UWSP. Composting vessels were

38

1-liter vessels (i.e. glass jars) topped with clear plastic Petri dishes that limited moisture loss

and allowed for air exchange. There were two main treatments of paper: perfluoropolyether

(PFPE) coated paper and uncoated paper (PAPER; Section 2.2.3). Both treatments were

combined with mature compost (Section 2.2.2) at 2 levels: 15% paper to dry compost and 25%

paper to dry compost. A control of unamended compost was also included (Figure 2.1).

Each paper treatment at each level and the blank were replicated four times for a total of 20

experimental units. Sacrificial sampling was implemented to observe PFPE and PAPER

weight loss over time. Experimental units were homogenously sub-divided into 7 individual

1-liter vessels (i.e. mason jars) so that 1 unit was harvested and prepared for analysis at the

end of every designated harvesting week (i.e. Weeks 1, 2, 3, 4, 6, 8 and 12). With 5 different

treatments (i.e. blank, PFPE at 15%, PFPE at 25%, PAPER at 15% and PAPER at 25%) each

replicated 4 times with experimental units sub-divided over 7 harvesting weeks, there were

140 vessels at time zero (T=0) of the experiment. Vessels were placed in the incubator in a

complete randomized design (Figure 2.1) and were re-randomized weekly.

2.2.2 Compost Matrix

Leaf compost was obtained from Hsu Growing Supply (Wausau, WI). The ASTM D5338-

11 method for biodegradation required that mature compost between 2 to 4 months old be

used. The compost was estimated to be between 4 and 6 months old (Theiss, 2013) and was

comprised of degraded deciduous leaf material. Hsu’s deciduous leaf compost is certified

through the United States Composting Council (USCC) according to the Seal of Testing

Assurance (STA) program (USCC, 2010). A total of 4 bags of leaf compost were homogenized

39

on a tarp by manual mixing. The compost matrix was sieved using an 8 mm sieve to remove

and discard large debris (e.g. rocks, woody material, glass and plastic).

The initial compost moisture content was analyzed gravimetrically to determine the as-

received mass for each vessel. Five 5 g samples were taken from the as-received compost,

weighed into tins and dried for 48 hours in a 105°C drying oven. The as-received compost

was determined to have a moisture content of 51.2% and in order to add 150 g of dry compost

307.5±2 g of wet compost was added in each vessel.

2.2.3 Treatments

The paper samples (PFPE, PAPER) were sourced from Expera Specialty Solutions

(Kaukauna, WI; formerly Thilmany Papers). A paper manufacturer and coater, Expera

Specialty Solutions specializes in manufacturing coated papers for use in food service and

packaging, construction and adhesive labeling. The unbleached PFPE-coated paper obtained

for compostability and chemical analysis (Chapter 3) is marketed as a grease protective layer

for the interior of pizza boxes, a use that does not require large concentrations of PFPE

(Schneider personal communication, 2013). An uncoated and unbleached paper (PAPER)

was used as a side by side comparison.

The paper was manually cut into 2×2 cm squares according to ASTM D5338-11, placed into

beakers and weighed. A 6:1 (i.e. 16%) dry compost:material ratio was required for

disintegration testing. Instead, 15% (150 g: 22.5 g) and 25% (150 g: 37.5 g) dry compost:paper

ratios were established to closely mimic the standard, but to also examine the composting

efficiency with the addition of more material. PAPER and PFPE treatments at the 15% and

40

25% loading levels are herein abbreviated to be represented as PAPER 15 and PAPER 25 and

PFPE 15 and PFPE 25.

The as-received compost was weighed into each of the 140 vessels and the pre-weighed

paper was added according to the treatment specifications. Deionized water was added to

bring the entire compost and paper matrix up to 60 ± 2% moisture content (i.e. 101 mL for

15% paper addition and 125 mL for 25% paper addition). The compost, paper and water were

then mixed thoroughly. Each vessel was labeled by indicating the week of harvest, the

treatment and the paper addition level.

2.2.4 Sample Harvesting and Processing

Harvesting or sacrificing of PFPE and PAPER samples from composting vessels occurred at

the end of every harvest week (i.e. 1, 2, 3, 4, 6, 8 and 12). The respective papers were sieved

from the compost using a series of three brass sieves (8 mm, 4 mm and 2 mm) and removed

from the compost using tweezers. Paper too large to pass through the 2 mm sieve was

weighed (including residual compost and moisture) and photographed. The sieved compost

was also weighed as received; cleaning occurred at a later date. Paper and compost samples

were packaged individually and frozen at < 0°C for cleaning at a later date.

The compost matrix was thawed to room temperature. Prior to cleaning, the paper material

was sieved from each compost vessel and dried at 70˚C for 24 hours. Residual compost was

gently brushed from paper surfaces using a soft bristle toothbrush. Small aggregates of dry

compost that had fallen away from the paper were hand crushed over a 2 mm sieve and paper

fragments larger than 2 mm were removed and brushed clean. Remaining clean and dry

paper fragments were weighed and recorded as final harvesting week weights.

41

2.2.4.1 Moisture Content

Every week, during the 12-week active composting period, the compost vessels that were

not designated for harvest were weighed to determine moisture additions. Moisture was

maintained between 50% and 60% throughout the 12-week trial. Moisture additions were

based on individual vessel weight loss and visual observations of the compost matrix

structure.

Moisture additions for weeks 2 through 7 were determined by calculating a mass for 50%

moisture content of the total dry weight at T=0, 345 g for 15% level and 375 g for 25% level

(Michitsch, 2012). Those 50% moisture weights were then subtracted from the as-received

compost matrix weights (minus the empty vessel weight). A negative difference of 1 g or

greater indicated that moisture was needed. The value of the difference was the amount of

deionized water (in grams) added to the vessel. This process estimated the moisture

requirements of each experimental unit without having to remove compost matrix for

gravimetric moisture analysis prior to harvest. Moisture additions for weeks 8 through 12

were decreased to the difference between 48% moisture content of the total dry weight at

T=0 (332 g for 15% level and 361 g for 25% level) and total vessel weight (minus the empty

vessel weight). Deionized water was added and the compost matrix was mixed by hand using

a flat soil knife or spatula. Mixing promoted aeration and consistent moisture distribution

throughout the compost matrix and occurred twice a week, once with gravimetric moisture

additions and once without. Odor and mold development observations were also noted at

these times.

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2.2.5 Statistical Analysis

All statistical analyses were performed using SigmaPlot 11.0 (San Jose, CA) and α = 0.05.

One-way ANOVAs were run to compare the cumulative percent weight losses of all

treatments during harvest weeks (e.g. 1, 2, 3, 4, 6, 8 and 12). One-way ANOVA for moisture

content, pH and electrical conductivity compared all treatment means and the blank during

the harvest weeks. All post-hoc comparisons were tested using the Bonferroni t-test. The

normality assumptions for percent weight loss, moisture content, pH and electrical

conductivity were met for all harvest weeks with the exception of Week 8 one-way ANOVA

comparisons for moisture content. A Dixon’s Q test could not reject outliers and a Kruskall-

Wallis ANOVA on ranks was run to compare median values. Variance homogeneity

assumptions were not met for the electrical conductivity comparisons for Week 8 and a

Kruskall-Wallis ANOVA on ranks was run to compare median values.

2.3 Results

The ASTM D6868-03 standard was used as a disintegration guideline for this experiment to

determine if the paper was sufficiently composted (i.e. ≥90% weight loss). The average

percent loss achieved by the treatments at the 15% loading level was: PAPER 15 with a 98.24

± 0.62% loss (0.69 ± 0.59 g remaining) and the PFPE 15 with a 98.09 ± 1.45% loss (0.59 ± 0.33

g remaining; Table 2.1; Figure 2.2). The PFPE 25 achieved a 92.40 ± 2.93% loss (2.85 ± 1.10 g)

while the PAPER 25 achieved an 88.35 ± 3.56% loss (4.37 ± 1.41 g) and failed to meet the 90%

loss requirement for disintegration.

Significant differences were detected in the Week 12 percent weight loss comparisons. The

PAPER 15 percent weight loss was significantly greater than the PAPER 25 results (t=4.930

43

and P=0.004). The comparison between PFPE 15 and PFPE 25 percent weight losses was not

significantly different (t=2.838 and P=0.106). Percent weight loss results from week to week

can be found in appendices 1 and 2.

2.3.1 Percent Weight Loss during Active Composting Weeks: 15% and 25% Loading Levels

Percent weight loss comparisons were made within materials (i.e. PAPER and PFPE) and

between loading levels (i.e. 15% and 25%; Figures 2.3 and 2.4). One-way ANOVA

comparisons between the PAPER 15, PAPER 25 and PFPE 15, PFPE 25 percent weight losses

in Weeks 1, 2, 3, 4, 6 and 8 were not significantly different.

2.3.2 Percent Weight Loss during Active Composting Weeks: PAPER and PFPE Materials

Percent weight loss comparisons were also made between materials (i.e. PAPER and PFPE)

and within loading levels (i.e. 15% and 25%; Figures 2.5 and 2.6). One-way ANOVA

comparisons between the PAPER 15, PFPE 15 and PAPER 25, PFPE 25 percent weight losses

in Weeks 1, 2, 4, 6, 8 and 12 were not significantly different.

2.3.3 Physical and Chemical Compost Characteristics

2.3.3.1 Moisture Content

All treatments experienced fluctuations in percent moisture content throughout the active

composting period (Figure 2.3). By the Week 12 harvest moisture content comparisons

between treatments and the blank were not significantly different. Moisture content

comparisons during the harvest weeks did not reveal significant differences between

treatments. The blank moisture content, however, was significantly less than treatments

during Weeks 3 (PFPE 15: t=3.159, P=0.026 and PAPER 25: t=3.017, P=0.035) and 6 (PFPE 15:

t=4.472, P=0.002; PAPER 15: t=3.447, P=0.014; and PFPE 25: t=3.447, P=0.014). Moisture

44

content data from Week 8 did not meet the normality assumptions for one-way ANOVA

comparisons and outliers were not detected, however, a Kruskal-Wallis analysis on ranks

revealed significance differences (H=12.186, df=4, P=0.016). The median moisture for the

blank was significantly less than PFPE 15(q=4.057) and PFPE 25 (q=4.395).

2.3.3.2 pH and Electrical Conductivity (EC)

All treatments experienced fluctuations in pH throughout the active composting period

(Table 2.3 and Figure 2.4). By the Week 12 harvest, the pH comparisons between the PAPER

15 and PFPE 15 and between the PAPER 25 and PFPE 25 were not significantly different.

The Week 12 harvest revealed significant differences between the PAPER 15 and PAPER 25

(t=4.521, P=0.004) and between the PFPE 15 and PFPE 25 (t=5.116, P=<0.001). Also at Week

12, the blank pH was significantly lower than the PAPER 25 (t=7.675, P=<0.001) and the

PFPE 25 (t=7.437, P=<0.001). Additional significant differences in pH between treatments

during the harvest weeks can be found in Appendix 3.

Electrical conductivity (EC) increased during the active composting period (Table 2.3). In

particular, the blank compost displayed the highest levels of soluble salts in Week 12 and was

significantly greater than the PAPER 15 (t=3.979 and P=0.012), PFPE 15 (t=4.073 and

P=0.010), PAPER 25 (t=4.083 and P=0.010) and PFPE 25 (t=3.612 and P=0.026; Table 2.3).

Additional significant differences in EC between treatments during the harvest weeks can be

found in Appendix 4.

45

2.4 Discussion

2.4.1 Cumulative Percent Weight Loss

The PAPER and PFPE weight loss was calculated as percent loss from the weight of the

original material at T=0 for each of the 7 harvest weeks (e.g. 1, 2, 3, 4, 6, 8 and 12). Original

weights for the 15% and 25% loading levels were 22.5 g and 37.5 g, respectively. Data

presented as percent weight loss allowed comparisons to be made between the 15% and 25%

loading levels whereas weight data was limited to the PAPER and PFPE treatment

comparisons only. Percent weight loss increased during the 12 weeks of composting for all

treatments (Figure 2.2). Percent weight loss during Week 1 for the PFPE 15 was -0.67% and

the PAPER 25 was -0.14%; the negative values indicated small percent weight gains (Table

2.1). The PAPER 15 experienced a 3.1% weight loss and the PFPE 25 experienced a 9.5%

weight loss in Week 1.

The weight losses achieved during the first week of composting by the PAPER 15 and PFPE

25 treatments were anomalies when compared to the <1% weight gains of the PAPER 25 and

PFPE 15. When material is incorporated into compost the microbial community must

acclimate to the new carbon source, this is known as the lag phase (Midscale Composting

Manual, 1999). Little to no degradation occurs during the lag phase; putrescible wastes have a

relatively short lag phase of 12 to 24 hours, but wastes containing cellulose and lignin, such as

paper, may take several days to a week before the bacteria and fungi adjust and begin

degradation. The Week 1 percent weight losses for the PAPER 15 and PFPE 25 indicated

that paper fragments may have been left in the compost matrix, perhaps due to incomplete

sieving of wet compost. The PFPE 15 and PAPER 25 experienced weight gain in Week 1

46

likely due to the adherence of residual compost to the paper surfaces that could not be fully

cleaned during the dry brush process.

Overall, the percent weight loss comparisons between the PAPER and PFPE treatments did

not detect significant differences in Week 12, thus indicating that the PFPE coating did not

inhibit sufficient disintegration. At Week 12, the harvest the 25% loading level in the

PAPER material did appear to inhibit disintegration and limit the final percent weight loss.

Lignin is resistant to biodegradation (Richard, 1996) and was likely the greatest limiting

factor for percent weight loss in the PAPER material at the 25% loading level. Percent lignin

content for the PAPER material was 1.17% and for the PFPE material lignin content was

0.76%. Lignin structurally blocks carbon from decomposition processes and is limited as a

food source to the microbial community. Although the amount of carbon present in the

composting vessel was in greater supply at the 25% loading level the amount of lignin also

increased, thus making the carbon less bioavailable to microbial degradation (Vikman et al.,

2002).

Research examining the amount of time needed for and the quantity of lignin degradation

in aerobic systems is conflicting (Richard, 1996). However, Vikman et al. (2002) found

decreased paper biodegradability with increased lignin content and increased temperatures.

Their research among others discovered that a greater amount of lignin is degraded by fungi

when mesophilic and psychrophilic (Section 1.7) conditions (0-40°C) are maintained

(Trautmann and Olynciw, 1996; NRCS, 2000). Prior research also concluded that fungi were

responsible for the degradation of woody components of compost when readily available

carbon and microbial activity decrease (Midscale Composting Manual, 1999). The 58 ± 2°C

47

temperatures within the incubator likely inhibited the fungal activity necessary for lignin

biodegradation. However, thermophilic conditions are conducive to lignin degrading

bacteria known as actinomycetes that thrive in temperatures between 50-55˚C (Trautmann

and Olynciw, 1996). Weight loss fluctuations, evident from week to week, may have been

linked to changes in actinomycete activity due to temperature variations within the compost

matrix. Although the temperature within the incubator was 58 ± 2˚C, internal compost

temperatures could have ranged above or below acceptable microbial temperature tolerances

thus affecting the types of communities and overall microbial productivity responsible for

paper biodegradation. Redistribution of any variable temperature zones would have occurred

during the weekly manual mixings.

Shifts in microbial communities may have had the most to do with fluctuations in weekly

percent weight loss particularly in the PFPE treatments where starches were bioavailable.

The decreases in weekly percent loss may have been directly caused by an increase in overall

matrix temperature thus inhibiting fungal activity and lignin biodegradation (i.e. high weight

loss), but still allowing for starch metabolism (i.e. low weight loss). Increases in weekly

percent loss may have indicated pockets of slightly lower temperature zones within the

compost matrix that created the ideal environment for starch and lignin biodegradation to

take place. White rot fungus was observed as early as Week 1 of composting, was prevalent

in the compost matrix as well as on the surfaces of the PFPE and PAPER treatments and

remained for the 12-week composting duration. Fungi were likely not responsible for

actively degrading the paper or lignin for the full duration of composting due to the sustained

high temperatures, but their presence was an indicator of a fungi-friendly environment

48

(Vikman et al., 2002). Little is yet known about the intricate behaviors of these communities

and how they impact degradation at different times (Neher et al., 2013).

2.4.2 Moisture Content

Adequate moisture content in compost promotes microbial activity and the degradation of

organic materials. For this experiment moisture was assumed to be an independent variable.

To preserve overall mass during active composting gravimetric moisture analysis was

performed only after jars were harvested. Without prior analysis moisture was added as a

percentage based on weekly total jar weights (Section 2.2.4). Moisture was reduced from

Weeks 8-12 to prevent anaerobic conditions in the vessels and was based upon visual

observations that the compost appeared muddy. Muddiness was the result of decreased

organic matter and water holding capacity in the compost matrix and the inability of water to

escape the vessel via leaching or evaporation (Midscale Composting Manual, 1999). Moisture

variability appeared to have no direct effect on overall percent weight loss or disintegration

rate.

2.4.3 pH and Electrical Conductivity (EC)

Variables such as pH and electrical conductivity (EC) measure the chemical characteristics

of compost and are predictors of phytotoxicity in plants grown in compost mixtures.

Compost typically has a pH between 6.0 and 9.0 depending on feedstocks, but pH can vary

within the compost and at times during the composting period (Wichuk and McCartney,

2010). Microbial activity is highest in compost with a pH between 6.5 and 8.0; degradation

proceeds at a slower rate when the pH lies above or below that range and is significantly

inhibited with a pH lower than 6.0. The initial pH for the compost used in this disintegration

49

experiment was 8.76. One concern with high pH is that, when coupled with high

temperature, ammonia forms and the compost becomes toxic to bacterial communities. The

compost was monitored weekly for odor as ammonia has a pungent odor. Despite the high

initial pH, ammonia production did not become a problem during the composting period

based on odor observations. Weekly analysis of pH revealed variability between treatments

and loading levels (Figure 2.10). The blank compost saw a decrease in pH over the 12-week

composting period (Figure 2.11).

A review of literature that investigated compost maturity and stability indicators found that

pH should be interpreted cautiously due to the inherent variability of pH across composts,

conditions and time (Wichuk and McCartney, 2010). For purposes of this experiment pH was

reported to further illustrate the variability encountered in composting research.

Similar to pH, EC did not show consistent trends of increasing or decreasing. However,

research investigating maturity indicators for compost containing paper pulp found that EC

increased over time (Wichuk and McCartney, 2010).

2.5 Conclusion

Composting can be conducted in many ways, however, specific analysis of material

degradation and compost quality are best determined via laboratory-scale composting.

Methodology for a PFPE-coated paper composting experiment was adapted from the

compostability method ASTM D5338-11 as specified in ASTM D6868-03 for coated paper

substrates. Alterations were made to the delivery of aeration and hydration to the individual

composting vessels in return for an increase in individual composting units.

50

Eighty-four days of active composting revealed that loading level was the greatest inhibiting

variable for the PAPER material. Typical compostability testing requires a 6:1 (i.e. 16%)

loading level of compost:material (ASTM D5338, 2011). The 25% loading level employed in

this experiment inundated the composting system with carbon and lignin, a complex material

that resists biodegradation at thermophilic temperatures. The 15% loading level achieved a

significantly greater percent weight loss in the PAPER material and the PAPER 25 was the

only treatment not to achieve ≥90% weight loss. Results revealed that the PFPE coating did

not inhibit disintegration and overall percent weight loss at either loading level.

51

Table 2.1 Average cumulative percent weight loss from the original material

by harvest week of dry PAPER and PFPE at 15% and 25% loading levels.

% Weight Loss

Harvest Week PAPER 15 PFPE 15 PAPER 25 PFPE 25

1 03.10±1.06 -0.67±7.23 -0.13±3.32 09.50±1.75

2 22.86±6.90 32.10±11.02 12.81±3.57 19.53±5.02

3 28.40±9.78 53.14±16.60 28.89±6.19 37.12±6.50

4 41.31±15.10 55.18±11.42 28.75±3.51 39.89±7.74

6 62.93±11.50 81.43±2.65 43.97±6.30 63.98±14.67

8 81.08±3.73 84.23±3.13 59.17±9.07 78.57±8.17

12 96.94±2.63 98.09±1.45 88.35±3.56 92.40±2.93

Table 2.2 Average dry weight and percent of the original material at Week 12 harvest for

dry PAPER and PFPE at 15% and 25% loading levels.

PAPER 15 PFPE 15 PAPER 25 PFPE 25 Blank

Weight (g) 0.69±0.59 0.43±0.04 04.37±1.41 2.85±1.10 123.27±4.35

% of Original 3.10±2.63 1.91±0.19 11.65±3.76 7.60±2.93 082.18±2.90

Table 2.3 Average compost pH and EC for PAPER, PFPE

and blank at T=0 and Week 12.

pH EC (µS/cm)

Treatment T=0 Week 12 T=0 Week 12

PAPER 15 8.76 8.30±0.08 740 0860±78

PFPE 15 8.76 8.27±0.07 740 0851±103

PAPER 25 8.76 8.49±0.03 740 0850±233

PFPE 25 8.76 8.49±0.05 740 0898±65

Blank 8.76 8.17±0.05 740 1264±166

52

Figure 2.1 1-liter glass composting vessels topped with clear plastic Petri dishes and arranged

in a complete randomized design in an incubator.

53

Figure 2.2 Average cumulative percent weight loss from the original material by harvest week

of dry PAPER and PFPE at 15% and 25% loading levels.

54

Figure 2.3 Average compost moisture content (%) by harvest week for PAPER and PFPE at


55

Figure 2.4 Average compost pH by harvest week for PAPER and PFPE at 15% and 25%

loading levels.

56

3.0 CHEMICAL AND INSTRUMENTAL ANALYSIS

3.1 Introduction

The chemical analysis of a compost matrix is a process whereby compost samples undergo

solvent extractions and the resulting extract is prepared for instrumental analysis to detect

heavy metal or other residual contaminants. The analysis process is performed to ensure the

quality and safety of finished compost for use as a soil amendment or topical landscaping

material (Dickerson, 1999). The United States Environmental Protection Agency (US EPA)

sets upper limits for heavy metals in soil and compost matrices in the Code of Federal

Regulations (CFR) 40 section 503.13 (USEPA, 2010). The ASTM compostability specifications

ASTM D6400-12 and D6868-11 require that finished compost adhere to the heavy metals

limits set forth by the US EPA.

Large-scale industrial or municipal composting operations source feedstock materials from

organic industrial byproducts (e.g. paper sludge, fruit and vegetable cuttings, sawdust) and

curbside waste collections (e.g. mixed paper, food wastes, lawn and garden trimmings).

Feedstock heterogeneity and likely inclusion of non-natural materials into the compost

matrix makes chemical analysis for the presence of heavy metals or other contaminants

necessary.

Chemical analyses to determine the presence of perfluoropolyether (PFPE) in compost have

not been conducted and do not fall under the requirements in CFR 40 section 503.13 (US

EPA, 2010). Perfluoropolyether (PFPE) is not a terrestrial contaminant of concern for

regulatory agencies such as the US Environmental Protection Agency (US EPA), which

instead classifies PFPE solvents and byproducts as air contaminants with strong global

57

warming potentials (GWP; Section 1.5.3.2: US EPA, 2013). Perfluoropolyether is a

fluorosurfactant used in the grease and moisture proofing of paper for food packaging and

preparation (i.e. fast food containers, microwaveable popcorn). Fuorosurfactant- and PFPE-

coated papers and convenience food are inextricably linked and are likely to follow similar

paths into waste systems, such as composting. If PFPE-coated paper is diverted into

composting systems further examination needs to be conduction to determine the suitability

of PFPE-coated paper in the compost matrix, as well as, the suitability of the composting

system for PFPE-coated paper disposal. The Solvera® XPH–723 treatment (i.e. commercially

known as Solvera® PT 5045) for the food-safe grease proofing of paper packaging is

advertised as ‘compostable’ by Solvay Solexis (Solvay-Solexis, 2014) and suggests that the

product has undergone compostability testing. The term ‘compostable’ refers to materials

that have satisfactorily completed the compostability testing that includes biodegradation,

disintegration and eco-toxicity (i.e. incorporated into a plant growing media) experiments.

The United States Composting Council (USCC), a compost and composting organization

that focuses on the quality control of finished compost and certification through the Seal of

Testing Assurance (STA) program does not recognize PFPE as a compost contaminant (USCC,

2010). The Biodegradable Products Institute (BPI), a compostable materials and packaging

organization, relies upon ASTM D6400-12 and D6868-11 specifications for the labeling of

products as compostable and also does not recognize PFPE as a compost contaminant (BPI,

2010).

Chemical analyses of representative samples taken from the heterogeneous compost matrix

are performed via solvent extractions (Woodbury and Breslin, 1992; Section 3.2.2). One form

58

of analysis suited for the detection of PFPE in a compost matrix extract is nuclear magnetic

resonance (NMR), a non-destructive spectroscopy technique (Section 3.2.3). The most

common types of NMR examine the nuclei of 1H, 13C and 19F isotopes by utilizing magnetic

force and radio wave resonance to analyze the molecular characteristics of solid and liquid

samples (Stanley, 2002). A nucleus with an odd number of protons (e.g. 1H, 13C and 19F) spins

and aligns with a magnetic force; the nucleus spin becomes energized when a radio frequency

is applied (Lambert and Mazzola, 2004). The energy absorbed by the nucleus creates a high

energy spin that is shown as NMR output with peaks along the x-axis of a spectrum; this is

known as chemical shift. Peaks can be sharply defined or split as doublets or triplets

depending on the magnetic interaction between nuclei within a chemical environment (i.e.

19F -19F, 19F -1H, 19F -13C). Nuclei in isolated chemical environments have no interactions with

other nuclei and produce singlet peaks. Molecule characterization can be determined by

chemical shifts and peak appearance. The combination of 19F NMR analysis with other

methods is often implemented to determine the extractability of a fluorinated substance

before a costly NMR analysis is performed (Mabury personal communication, 2013). One

such method involves total organo-fluorine combustion ion chromatography (TOF-CIC),

which can determine the concentration of inorganic and organic fluorine in solution.

The main objectives of this research were to determine the most effective extraction

procedure for PFPE in compost with the help of TOF-CIC, attempt to analyze and

characterize the PFPE surfactant in compost extract using 19F NMR and to determine if PFPE

degradation occurred in compost from Weeks 6 (mid-way) and 12 (end) by comparing their

19F NMR spectra to the spectrum of a control PFPE surfactant (Solvera® XPH-723).

59

3.2 Methodology

Extraction and NMR analyses methodology was adapted from the Mabury Group at the

University of Toronto (ON, Canada). This group is established in methods for fluorochemical

detection and degradation research in various media (i.e. soils, sediments and sewage sludge).

Method design was established via exploratory spike recovery experiments and analyses of

extracts with a TOF-CIC and 19F NMR. Additional 19F NMR experiments were performed to

adjust for the large size of the PFPE polymer and reduce the background noise along the

spectrum baseline.


All chemical analyses were performed with the environmental and analytical chemistry

team, the Mabury Group, at the University of Toronto (ON, Canada). Solvera® XPH-723

manufactured by Solvay-Solexis is a PFPE surfactant used in coating paper, was obtained from

Expera Specialty Solutions (formerly Thilmany Papers, Kaukauna, WI). Finished compost

(Section 2.2.4) from the disintegration experiment of PFPE-coated paper at the 25% level

from Weeks 1, 6 and 12 was freeze-dried and packaged into 150 mL polypropylene bottles.

Each of the 4 replicates from the 25% PFPE-coated paper compost were extracted with

acidified methanol (Section 3.2.2) and analyzed with 19F NMR (Section 3.2.3). Additionally,

samples from T=0 and Weeks 6 and 12 were analyzed with TOF-CIC to determined extract

concentrations. Duplicate extracts were also performed on compost samples from Weeks 1, 6

and 12. Extractions and analyses were performed on 22 compost samples. Blank compost

from Week 6 was also extracted and analyzed to determine if any latent fluorine (i.e. pre-

existing contaminant or naturally occurring) could be detected in the compost matrix.

60

3.2.2 Extraction Procedure

Extraction methodology was based on the results from a series of extraction efficiency

experiments. Spike recovery experiments were performed to determine the solvent most

effective at extracting PFPE from compost (i.e. extraction efficiency). Polar solvents,

methanol (MeOH) and methyl tert-butyl ether (MTBE) were each combined with tetra-butyl

ammonium silicate (TBAS); MeOH was paired with 0.1 M hydrochloric acid and also used

alone. Solvera XPH 723 diluted to 40 ppm was the standard PFPE spike to be added to the

solvents (i.e. final concentration was 0.4 ppm). Solvent blanks (i.e. solvent without PFPE

spike) were also screened.

The concentration of the PFPE spike was determined by calculating the concentration of

the PFPE surfactant applied to a 25 cm2 sample of paper which was 0.575 mg (i.e. 0.023 mg

cm-2). Based on the estimated abundance and density of PFPE in the Solvera XPH 723

surfactant, 18% and 1.1 g ml-1, the concentration was calculated to be 198 mg ml-1.

A 40 ppm stock solution of PFPE in methanol (MeOH) was prepared as the spike. A 101 µl

aliquot of Solvera XPH 723 was added to 10 ml of MeOH in a 15 ml polypropylene centrifuge

tube; the 198 mg ml-1 PFPE standard was diluted to 2 mg ml-1 (i.e. 2000 ppm; Equation 3.2).

A 195 µl aliquot of the 2000 ppm solution was added to 10 ml of MeOH in a 15 ml

polypropylene centrifuge tube.

The MeOH and MTBE solvents were combined with 0.5 M TBAS. The TBAS is an ion

pairing salt and was added to attract phosphate end groups and pull the PFPE polymer into

the polar solvent. Methanol, without amendments was used and a solution of 0.1 M

hydrochloric acid and MeOH was prepared thus providing 4 solvents for PFPE spike recovery

61

comparisons. A 1g freeze dried sample from the Week 6 blank compost was weighed into a

15 ml polypropylene centrifuge tube, 9.9 ml of solvent spiked with 100 µl of the 40 ppm stock

solution was added (i.e. 0.4 ppm PFPE spike) and the mixture was agitated on the vortex for

30 seconds and placed in a 60˚C sonicator for 1 hour. Following sonication the extract was

carefully pipetted into a micro-test tube.

The final concentration of the PFPE spike (i.e. 0.4 ppm) was an appropriate level for

analysis by a total organo-fluorine combustion ion chromatograph (TOF-CIC) that measures

fluorine content in nanograms (ng). The sample was placed in a ceramic boat and sent into

the oven portion of the TOF-CIC. The sample was combusted at temperatures between 900-

1000°C converting all the inorganic and organic fluorine to hydrogen fluoride (HF), a toxic

and corrosive gas. The HF gas was then dissolved into H+ and F- ions in an absorption

solution of water and methanosulfonic acid (i.e. an internal standard added to account for

changes in volume during sample combustion; Weiner et al., 2013). The concentration of F-

ions was determined by ion chromatography. Extraction efficiency comparisons revealed

that fluorine recovery was dependent upon the type of solvent used (Table 3.1).

The compost matrix within the MTBE/ TBAS solvent could not be saturated and appeared

to form clumps once in solution; TOF-CIC analysis revealed that no significant fluorine was

extracted (Table 3.1). Methanol acidified with 0.1M HCl yielded the greatest fluorine

concentration and was most efficient at extracting available PFPE surfactant from the

compost matrix (Table 3.1). Further experiments revealed that compost solids extracted two

times with the acidified MeOH yielded greater fluorine concentrations and produced stronger

peaks in 19F NMR spectra.

62

Two extractions were performed on 10 g of freeze dried compost samples. The first

extraction was performed by adding 25 mL of acidified methanol (0.1 M hydrochloric acid) to

the compost. The mixture was agitated on a vortex for 30 seconds and placed in a 60˚C

sonication bath (i.e. ultrasonic agitation) for 1 hour. Compost compaction was observed

during the sonication process which prompted additional vortex agitation for 30 seconds

following 30 minutes of sonication. Samples were transferred to a horizontal table shaker and

shaken at 250 rpm for 30 minutes, then centrifuged at 6000 rpm for 5 minutes. The

supernatant was transferred to a clean centrifuge tube and centrifuged at 6000 rpm for an

additional 20 minutes to settle any remaining compost matter. The compost solids remaining

after the first extraction were extracted a second time with 20 ml of acidified methanol

instead of 25 ml because the solids were already saturated. All previously detailed steps were

repeated and the supernatants from the first and second extractions were combined for an

average volume of 30 ml per sample. A nitrogen evaporator (N-evap) heated the supernatants

in a water bath as a gentle stream of nitrogen air evaporated the supernatant to dryness over a

period of 8-12 hours.

3.2.3 19F NMR Procedure

Characterization of the PFPE molecule in compost extract was done with 19F NMR. All 19F

NMR analyses were performed on a Varian 700 at 658.4 MHz with a fluorine specific probe to

reduce background fluorine and minimize noise along the spectrum baseline. Scanning

conditions were optimized by setting the relaxation delay to 1.2 seconds with a pulse angle of

90 degrees. Samples were run for 15 minutes each and obtained 600 scans.

63

The compost extract, dried to a residue (Section 3.2.2), was reconstituted with 1 ml of

acidified methanol (i.e. 0.1 M HCl). The sample was clear and brown in color and contained

some residual organic material from the compost matrix which could not be fully removed.

The reconstituted sample was agitated on a vortex for 10 seconds to re-dissolve the residue

into solution. A 500 µl aliquot of the reconstituted compost extract was pipetted into a

micro-test tube and prepared for 19F NMR analysis with 125 µl of deuterated methanol

(CD3OD) and 50 µl of the internal standard 4-trifluoromethoxyacetonilide (4-TFMeA).

Deuterated solvents contain deuterium, a “heavy” form of hydrogen, in place of hydrogen and

is predominately used in 1H NMR analyses to minimize solvent to signal noise; for the 19F

NMR analyses the deuterated methanol provided a “lock” for the instrument, a means of

instrument calibration during consecutive scans (Lambert and Mazzola, 2004). Internal

standards produce singlet peaks at a known chemical shift, a reference signal by which the

chemical shifts of other substances are measured. A 75 µl aliquot of Chromium (III)

acetylacetonate (Cr(acac)3) was added to the sample to reduce the relaxation time of the large

PFPE molecule and shorten the length of time needed to analyze samples (Ellis et al., 2001).

The NMR samples were agitated on the vortex for several seconds and transferred to a 5 mm

NMR tube using a pipette.

A standard sample of PFPE surfactant (Solvera® XPH-723) was prepared in 125 µl

deuterated methanol (CD3OD), spiked with 50 µl of the 4-TFMeA internal standard, agitated

using a vortex for several seconds and transferred to a 5 mm NMR tube. The resulting 19F

NMR spectrum for Solvera® XPH-723 provided a reference spectrum for the chemical shifts

associated with each of the fluorinated segments in the PFPE polymer (Figure 3.1).

64

The Solvera® XPH-723 scan showed 3 characteristic peak regions along the 19F NMR

spectrum that were consistent with previous PFPE peak assignments (Karis et al., 2002). The

strong singlet peak at -58 ppm was the internal standard, 4-TFMeA. Peak designations for

PFPE substances are the result of repeating unit arrangements within the polymer (Turri and

Barchiesi, 1995; Karis et al., 2002). The region furthest downfield with a chemical shift from

-51.0 to -54.0 ppm corresponded to three singlet peaks for the methylene oxide (CF2O)q

segment. The peak at -51.0 ppm indicated that (CF2O)q was situated between two (CF2CF2O)p

sections; at -52.5 (CF2O)q was bordered on one side by (CF2CF2O)p and on the other side by

(CF2O)q (Figure 3.1). The region furthest upfield with a chemical shift from -88.0 and -90.5

corresponded to two singlet peaks for the ethylene oxide (CF2CF2O)p segment (Figure 3.1).

The peak at -88.0 indicated that (CF2CF2O)p was bordered on one side by (CF2CF2O)p and on

the other side by a (CF2O)q; at -90.5 the (CF2CF2O)p was situated between two (CF2O)q

segments. The fluorinated terminus segment, CF2CH2, shows peaks at -77.5 and -80.5 ppm

(Figure 3.1). The two CF2CH2 segments indicate the fluorinated terminus of the polymer and

are linked to an ethylene oxide that is linked to the phosphate ester end groups. At -77.5 ppm

the CF2CH2 segment bordered by a (CF2O)q segment and at -80.5 ppm the CF2CH2 is bordered

by (CF2CF2O)p. Peak assignments for the fluorinated sections of Solvera® XPH-723 were

based on previous 19F NMR analyses of Fomblin® HC/P2-1000 (Di Lorenzo, 2012). Both

surfactants are identical in chemical structure, peak assignments were also identical with the

exception of a 2-3 ppm upfield chemical shift in Solvera® occurring at all regions (Figure 3.1).

According to the Solvay Specialty Polymers technical data sheet for Fomblin® HC/P2-1000

and the Safety Data Sheet (SDS) for Solvera® XPH-723 both surfactants have identical CAS

65

numbers (Chemical Abstract Service; 200013-65-6). The fluorinated body of the PFPE

polymer found in Solvera® and Fomblin® is comprised of reduced methyl ester ethoxylates

(i.e. ethylene oxide added to an alcohol to produce a surfactant) and tetrafluoroethylene

(TFE) that has been oxidized, polymerized and reduced to form a short perfluorinated carbon

segment (Figure 3.2).

The PFPE polymer end groups are comprised of phosphate esters, which are responsible for

increasing hydrophobicity, decreasing molecular surface tension for a more thorough coating

and allowing the polymer to be emulsified in polar solvents (i.e. water and dipropylene

glycol; Keene, 1978 and Solvay-Solexis, 2012a; 2012b).

Despite identical structure, Fomblin® and Solvera® surfactants differ in molecular weight

and density. The intended applications also differ, Fomblin® is primarily found in cosmetic

applications and Solvera® is used in food packaging coatings. Molecular weight of the PFPE

polymer is determined by the number of repeating segments within the molecule; in this case

p, q and n indicate which moieties (i.e. functional groups) may be present as repeating

segments (Figure 3.2: Karis et al., 2002). The p/q ratios within a polymer of a certain

molecular weight are therefore fixed and may range from 0.1 to 10 depending on the size of

the polymer (Russo, 2005). The reported p/q ratio for the (C2F4O)p and (CF2O)q segments in

Fomblin® is between 0.5-3; while the value for n, in the non-fluorinated (C2H4O)n, was

between 1-2 (Solvay-Solexis, 2012a).

66



One-way ANOVAs were run to compare the treatment peak ratios obtained from 19F NMR

analysis and the treatment fluorine concentrations obtained from TOF-CIC analysis. Post-

hoc comparisons were tested using a Bonferroni t-test. The peak area and ratio data

conformed to normality and variance parameters. The TOF-CIC concentration data did not

conform to homogeneity of variance assumptions and a Kruskall-Wallis ANOVA on ranks

was run to test the treatment medians.

3.3 Results

3.3.1 19F NMR Spectra

The sensitivity of the Varian 700 NMR combined with the fluorine specific probe and fine-

tuning of scan parameters (i.e. relaxation time, number of scans) provided high resolution

spectra of T=0, Weeks 1, 6 and 12 compost extracts that were compared to Solvera® XPH-

723. The spectrum of the T=0 demonstrated that the 0.1 M HCl/MeOH solvent was able to

successfully extract some amount of the PFPE surfactant from the paper fibers. The spectrum

also revealed that a source of fluorine was already present in the compost (i.e. latent source)

matrix with new peaks at -75 and -76 ppm (Figure 3.3).

To confirm that the peaks at -75 and -76 ppm were not the result of fluorine from non-

degraded PFPE-coated paper a sample of blank compost from Week 6 was also extracted and

analyzed with 19F NMR. A latent source(s) of fluorine with peaks at -75 and -76 ppm

appeared to be present in the blank compost prior to the addition of PFPE-coated paper

(Figure 3.4). The spectrum for the Week 6 Blank revealed two singlet peaks at -75 and -76

67

ppm as well as a singlet peak at -81 ppm (Figure 3.4). The Week 6 Blank 19F NMR spectrum

indicated that a source of fluorine was detectable in the compost.

The spectra for PFPE compost extracts from Weeks 6 and 12 revealed chemical shifts

identical to those of the Solvera® XPH-723 surfactant and indicated that the 0.1M

HCl/MeOH solution was successful at extracting some amount of the PFPE polymer from an

active (i.e. Week 6) and finished compost (i.e. Week 12) matrix containing degraded paper

(Figures 3.5, 3.6). Additional 19F NMR spectra can be found in appendices 5 through 19.

The 19F chemical shifts of the two –CF2CH2– segments (i.e. -77.5 and -80.5 ppm) were of

particular interest for monitoring any potential microbial degradation of PFPE. The peaks at

-77.5 and -80.5 ppm from Weeks 6 and 12 (Figures 3.5, 3.6) became increasingly complex

when compared to the respective peaks from Solvera® and T=0 (Figures 3.1, 3.2). Comparing

the Week 6 and 12 spectra revealed that, despite a six week time difference, the chemical

shifts were identical and the complex appearance of peaks at -77.5 and -80.5 ppm were

similar to one another. Both Weeks 6 and 12 retained peaks in the -53 to -56.5 ppm and -90

to -92 regions when compared to the Solvera® XPH-723 spectrum (Figure 3.1). The peaks

associated with –CF2CH2– at -79 and -81.5 ppm appeared to experience similar patterns of

peak splitting in Weeks 6 and 12 with additional peaks appearing at -75 and -76 ppm (Figures

3.5, 3.6).

3.3.2 TOF-CIC: Weeks 6 and 12

Despite the nearly identical 19F NMR spectra from Weeks 6 and 12 the concentration could

not be surmised by peak area and required additional analysis using TOF-CIC. Total fluorine

68

concentrations in Weeks 6 and 12 compost extracts were measured as nanogram per gram

(ng/g) or parts per billion (ppb; Table 3.3).

An ANOVA on ranks (H=9.846, df=2, P=<0.001) revealed that the concentration of

extractable PFPE in the compost matrix was significantly less in the T=0 samples than the

Week 12 samples (q=4.438).

3.4 Discussion

3.4.1 19F NMR Spectra

Peaks appearing at -75 and -76 ppm could indicate the presence of a short-chained

fluorinated acid such as, trifluoroacetic acid (TFA; CF3COOH) which has a chemical shift

range between -67 ppm and -85 ppm (Sloop, 2013). Trifluoroacetic acid is an important

industrial reagent (i.e. agrochemical, pharmaceutical and polymer) and is a byproduct of the

atmospheric degradation of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons

(HCFCs) which are chlorofluorocarbon (CFC) replacements (Richey et al., 1997; Boutonnet et

al., 1999; Ellis et al., 2001; Sloop, 2013). As a water soluble compound, TFA is found in

precipitation and is considered a pervasive environmental pollutant with no known

breakdown products (Ellis et al., 2001; Hanson and Solomon, 2004). Concentrations of TFA

in surface water and soil can range from 2-1100 ng l-1 depending upon a site’s proximity to

industrial activities (Ellis et al., 2001). Soils high in organic matter (i.e. wetlands, peat bogs

and boreal forests) were found to retain greater concentrations of TFA than soils low in

organic matter, which may allow for TFA retention in compost to occur (Richey, et al., 1997

and Boutonnet et al., 1999).

69

The phosphate esters at either end of the PFPE molecule are attached to –CF2CH2–

segments that are the most likely to be sensitive to changes at the tail ends of the polymer.

Previous research found that –CF2CH2– experienced a 2 ppm upfield chemical shift between

alcohol and phosphoric acid end groups (Di Lorenzo, 2012). The research suggested that the

terminal peaks at -77.5 and -80 ppm would be useful indicators of end group degradation (i.e.

phosphate esters for Solvera®) and ultimately PFPE polymer degradation. Any degradation

of the polymer would be contingent upon the degradation of one or both of the phosphate

ester end groups. The NMR spectra from Weeks 6 and 12 compost extracts, based on

–CF2CH2– sensitivity, may have indicated changes in the phosphoric acid ends groups and the

beginning of PFPE degradation.

Presumably, the changes in chemical shift and peak splitting that were observed in the

Weeks 6 and 12 scans (Figures 3.5, 3.6) would only occur in the event of phosphate ester end

group hydrolysis. Diphosphoric acid, like the fluorinated segment (i.e. functional group) of

the molecule, is resistant to degradation via oxidation, but hydrolysis at moderate

temperatures can degrade diphosphoric acid very slowly (Exxon Mobil, 2008). Ultimately,

the degradation of the phosphate ester end groups could spur the degradation of non-

fluorinated moieties of the PFPE polymer. If the fluorinated moieties were to degrade in

compost, the most likely degradation products would be short-chained fluorinated acids, such

as TFA (Ellis et al., 2001; Mabury personal communication, 2013).

In a study by Ellis et al. (2001) fluoropolymers comprised of short segments of fluorinated

carbons (CF3) produced TFA by way of thermolysis at 500°C (i.e. endothermic conditions that

chemically decompose a substance). Similar results could not be achieved at composting

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temperatures of 58 ±2°C thus rendering thermolysis of PFPE in compost unlikely. Therefore,

the peak splitting and peak appearances in the -77.5 to -82 ppm region cannot definitively

prove PFPE degradation, especially when considering the overall stability of PFPE for use in

cosmetics and food packaging as a non-degradable polymer. The more likely assumption is

that a form of TFA or a TFA precursor, prior to the addition of PFPE-coated paper, had

contaminated the compost via atmospheric deposition at a point during the composting

process.

Further 19F NMR peak analysis was performed to rule out PFPE disintegration. Normalized

peak areas at -53 ppm for Weeks 6 and 12 and T=0 were determined using MestReNova®

9.0.0 (Santiago de Compostela, Spain) and compared to the potential degradation peaks of

interest at -77.5 ppm and -80 ppm (Badger personal communication, 2013). The methylene

oxide peak associated with chemical shift -53 ppm (i.e. –CF2O–) was chosen to compare areas

with each of the peaks at -77.5 ppm and -80 ppm (i.e. –CF2CH2–) because of the segment’s

likely resistance to degradation. Evaluating peak ratios within the polymer is an accurate

method in determining degradation in a specific segment. The comparisons between peaks

(i.e. integrated peak area ratios) should not exhibit significant change from week to week

unless one of the peaks was associated with a segment experiencing degradation (Table 3.2).

Integrating peak areas is a process with some uncertainty and can exhibit error as high as

10% depending on NMR parameters and the type of sample being observed (Badger personal

communication, 2014). Although 19F NMR conditions were optimized the compost extract

samples were likely on the upper end of integration uncertainty given compost matrix

heterogeneity and the unavoidable presence of the organic matter in the extract. The

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comparison of peak ratios at -80.5 ppm and -77.5 ppm from Weeks 6 and 12 revealed no

significant change and subsequently no indication of degradation (Table 3.2). Peak area

comparisons between T=0 and Weeks 6 and 12 were also not significant (Table 3.2).

3.4.2 TOF-CIC: Weeks 6 and 12

An increase in total extractable fluorine from T=0 to Weeks 6 and 12 suggested that the

acidified methanol solvent was more effective at extracting PFPE from the degraded paper

fibers within the compost matrix than extracting PFPE from the intact paper surface. The

increase in extractable fluorine over 6 weeks of degradation suggested that PFPE became

increasingly accessible with the continued degradation and overall incorporation of paper

fibers into the compost matrix.

3.5 Conclusion

The chemical analysis of compost is typically done to determine heavy metal

concentrations. Regulations concerning the safety of finished compost do not include testing

for additives found in degradable materials, such as PFPE-coated paper. This work was

conducted to examine compost for the presence of a fluorinated surfactant with 19F NMR and

TOF-CIC analysis and the first to explore the likelihood of PFPE degradation in compost.

Extracting PFPE with acidified methanol from compost and paper proved successful. Finely

tuned 19F NMR parameters provided clear spectra of compost extract from T=0 and Weeks 6

and 12 to be compared to the standard Solvera® XPH-723 spectrum. The 19F NMR analyses

of a blank compost extract also revealed a latent source of fluorine that was possibly

trifluoroacetic acid, a prevalent substance in manufacturing and a pervasive pollutant in the

environment. Spectra from Weeks 6 and 12 indicated peak splitting at the chemical shift

72

associated with the most likely degraded segment, –CF2CH2–. Further analyses of integrated

peak areas and comparisons of peak ratios from T=0 and Weeks 6 and 12 suggested that

degradation had not occurred.

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Table 3.1 Spike recovery results (%) for polar solvents

combined with TBAS and hydrochloric acid

Solvent Spike Recovery (%)

Methanol 3.1

MeOH/TBAS 2.2

MeOH/HCl 9.9

MTBE/TBAS None detected

Table 3.2 Average integrated peak area ratios comparing

the center peak at -53 ppm to each of the peaks at -77.5

ppm and -80 ppm from T=0 and Weeks 6 and 12

Time -53 ppm:-77.5 ppm -53 ppm:-80 ppm

T=0 2.6±0.63:1 2.9±0.54:1

Week 6 2.6±0.15:1 2.5±0.15:1

Week 12 2.6±0.11:1 2.5±0.10:1

Table 3.3 Total average extractable fluorine (F) in ng/g

(ppb) in compost extracts from T=0 and Weeks 6 and 12.

Time Total Extracted F (ng g-1)

T=0 1130±1000

Week 6 3468±1014

Week 12 5545±8870

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Figure 3.1 700 MHz 19F NMR spectrum of PFPE standard Solvera® XPH-723. Molecular

structure and peak locations are indicated with the arrows.

75

Figure 3.2 Chemical structure of Perfluoropolyether phosphate polymer in Fomblin® and

Solvera® (Solvay-Solexis, 2012a).

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FIGURE 3.3 700 mHz 19F NMR spectrum of a T=0 compost extract. Solvera® XPH-723 peaks

were circled. New peaks appeared at -75 and -76 ppm.

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FIGURE 3.4 700 mHz 19F NMR spectrum of Week 6 Blank compost extract. Solvera® XPH

723 peaks were not present. New peaks appeared at -75 and -76 ppm.

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FIGURE 3.5 700 mHz 19F NMR spectrum of Week 6 compost extract. The same peaks found

in Solvera® XPH-723 were present. New peaks appeared at -75 and -76 ppm and the peaks at

-77.5 and -80.5 ppm were increasingly complex.

79

Figure 3.6 700 mHz 19F NMR spectrum of Week 12 compost extract. The same peaks found in

Solvera® XPH-723 were present. New peaks appeared at -75 and -76 ppm and the peaks at

-77.5 and -80.5 ppm were increasingly complex.

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4.0 COMPOSTABILITY: BIODEGRADATION AND DISINTEGRATION ANALYSES

4.1 Introduction

Biodegradation and disintegration analyses are important components in the compostability

testing methods specified by ASTM D6868-11 the Standard Specification for Labeling End

Items that Incorporate Plastics and Polymers as Coatings or Additives with Paper and Other

Substrates Designed to be Aerobically Composted in Municipal or Industrial Facilities. The

D6868-11 specification requires that biodegradation and disintegration methodology be

followed from ASTM D5338-11: Standard Test Method for Determining Aerobic

Biodegradation of Plastic Materials under Controlled Composting Conditions, Incorporating

Thermophilic Temperatures. The D5338-11 methodology describes a controlled composting

environment as a thermophilic (58±2˚C), aerated and hydrated closed vessel system where

CO2 evolution is monitored for a minimum of 45 days (i.e. biodegradation) and material

weight loss is assessed after 90 days (i.e. disintegration). Biodegradation and disintegration

processes can be run simultaneously, thus making the duration of the combined experiments

90 days.

Biodegradation and disintegration analyses within compostability testing determine the

impacts or potential adverse effects a material may have on compost quality (ASTM D5338,

2011). Plastic or mixed bio-based materials (e.g. coated paper and packaging) that are targets

for biodegradation and disintegration analyses are likely single use items paired with food

that have the potential for entering composting waste streams. Compostability laboratories

certified by BPI follow the testing specifications and methods found in ASTM D6868-11 and

D5338-11 for the purpose of certifying end items as ‘compostable’. Other laboratories

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without BPI certification utilize D6868-11 specifications and D5338-11 methodology for a

variety of purposes (e.g. material comparisons, durability, microbial and/or fungi research,

standards development).

The main objective of the biodegradation and disintegration analyses of this research was to

determine the degree of CO2 production and material loss from a PFPE-coated paper material

in compost utilizing a reproducible laboratory-composting method with controlled

temperature, aeration and humidity. The secondary objective was to compare the degree of

biodegradation and disintegration of PFPE-coated paper to that of uncoated paper (hereafter

referred to as PAPER). These objectives were achieved by comparing the % CO2 production

of PFPE-coated paper and PAPER to that of cellulose (used as a control) after 45 days in a

controlled composting environment. In addition, the disintegration results between PFPE

and PAPER were compared after 90 days.

4.2 Methodology

Biodegradation and disintegration methodology were followed from ASTM D5338-11 as

specified in ASTM D6868-03: Standard Specification for Biodegradable Plastics Used as

Coatings on paper and Other Compostable Substrates. The specifications from ASTM D6868-

03 were amended in the 2011 edition to include biodegradation exemptions for ligno-

cellulosic and plastics and polymers concentrations, while disintegration requirements were

unchanged. The exemption applies to ligno-cellulosic substrates if ≥95% of the carbon is bio-

based. Natural origin must be proven in accordance to ASTM D6866-12 Standard Test

Methods for Determining the Biobased Content of Solid, Liquid, and Gaseous Samples Using

Radiocarbon Analysis. This experiment was performed using the specifications of ASTM

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D6868-03 without implementing the ligno-cellulosic exemption in order to compare CO2

evolution between PFPE and PAPER. An exemption was also added for plastic or polymer

coatings if they were present in concentrations of <1% (Section 6.3 of D6400-12). The PFPE

coating in this experiment was determined to be 0.3% of the per vessel PFPE treatment

weight based upon the manufacturer’s 0.144 lb per ream application of the surfactant (K.

Coffey personal communication, 2012). Additionally, biodegradation requirements for the

PFPE coating were exempted under ASTM D6868-11 for individual packaging components.


Organimax Enhanced Compost Blend was obtained from Hsu Growing Supply (Wausau,

WI). The ASTM D5338 -11 method for biodegradation required that mature compost

between 2 to 4 months old be used. The compost was estimated to be between 4 and 6

months old (Theiss, 2013) and was comprised of degraded deciduous leaf material amended

with an amino acid package, mycorrhizae, humic acid, kelp, micronutrients, carbohydrates

and slow release fertilizers. Hsu’s deciduous leaf compost is certified through the United

States Composting Council (USCC) according to the Seal of Testing Assurance (STA) program

(USCC, 2010).

Large woody debris, rocks and other foreign objects were removed by passing the compost

through an 8 mm sieve. The sieved compost was stored for ten days in two 30-liter covered

polypropylene containers until pre-incubation (Section 4.2.2.1).

4.2.1.1 Compost Pre-incubation

A week long pre-incubation period at 58±2˚C was performed to condition the compost and

microbial community (i.e. bacteria, fungi) to the thermophilic temperatures of active

83

degradation (Degli-Innocenti et al., 1998; K. Herrman personal communication, 2012).

Sieved Organimax compost (15 kg) was added to a 30-liter polypropylene container with 0.5

cm holes drilled equidistant (≈15 cm) from the top (3 holes on the long side of the container

and 2 on each short end; Figure 4.2). The holes allowed for air exchange within the container

while incubating.

Analytical-grade cellulose powder (Section 4.2.3) was added to the compost at a ratio of 60:1

compost:cellulose based on dry weight. The cellulose was mixed well into the compost by

hand. Initial pH of the Organimax compost was 8.1, which was within the acceptable pH

range of 7.0 to 8.2 for D5338 (2011). However, previous biodegradation trials with paper and

cellulose (K. Herrman personal communication, 2013) found that pH increased over time and

suggested that a pH closer to 7.0 was more advantageous. 1.5 M nitric acid (HNO3) was added

to the compost at a ratio of 10:1 compost:HNO3 based on dry weight. In all, 700 ml of HNO3

was added to the compost and cellulose mixture in seven 100 ml (±10 ml) aliquots and mixed

thoroughly with a wooden spoon between additions. The HNO3 additions brought the pH to

7.1.

During the 7-day pre-incubation period the compost was hand-mixed to break up larger

aggregates, prevent anaerobic conditions and redistribute moisture. After 7 days the compost

moisture content was analyzed gravimetrically to determine the wet and dry weights for each

vessel. Five samples were taken from the wet compost and dried in a 105°C moisture

analyzer. Final moisture was calculated as the average of the five samples. Wet compost

weight was calculated to be 615±2g per vessel based on a moisture content of 51.2%. Volatile

solids of the compost were determined using a loss on ignition method, which combusted dry

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compost in a 500°C oven for three hours. Percent volatile solids were used to calculate

theoretical carbon accumulation (mg) of the blank compost (Section 4.3).


Industrial composting conditions were simulated in a laboratory incubator set to 58 ± 2°C

for 12-weeks in the Trainer Natural Resources building at UWSP. Composting vessels were

air-tight 2-liter glass bottles fitted with caps able to receive pressurized air while exhausting

composting-produced gases (Figure 4.1).

There were two treatments of paper: PFPE and PAPER; and two reference material

treatments: a positive reference of analytical grade cellulose and a negative reference of

polyethylene sheeting (Section 4.2.3). All treatments and reference materials were combined

with amended mature compost (i.e. Organimax; Section 4.2.2) at a ratio of six parts dry

compost to one part paper/reference material. Treatments and reference materials were

replicated four times. Unamended Organimax compost, replicated four times, was also

included. Vessels were not subjected to randomization within the incubator and treatment

replicates were grouped together for ease of observation and handling. Vessels remained on

the same aeration line for the duration of the experiment.

4.2.3 Treatments

The paper samples (PFPE, PAPER) were sourced from Expera Specialty Solutions

(Kaukauna, WI; formerly Thilmany Papers). A paper manufacturer and coater, Expera

Specialty Solutions specializes in manufacturing a variety of coated papers for use in food

service and packaging, construction and adhesive labeling. The unbleached PFPE-coated

paper obtained for compostability and chemical analysis (Chapter 3) is marketed as a grease

85

protective layer to be applied to the interior of pizza boxes, a use that does not require large

concentrations of PFPE (J. Schneider personal communication, 2013). An uncoated and

unbleached paper (PAPER) was used as a side by side comparison.

A positive reference with known biodegradability was included in the test. Analytical

grade cellulose powder (i.e. fine cotton fibers used in column chromatography), as specified in

ASTM D5338-11, was sourced from Sigma-Aldrich (St. Louis, MO, US). A negative reference

material, polyethylene, known for its resistance to biological degradation was included in this

experiment as a film (ASTM D5338, 2011). The polyethylene film was a construction-grade

sheeting made by Husky (Grand Prairie, TX) and was obtained from The Home Depot

(Wisconsin Rapids, WI).

Paper materials and polyethylene film were cut by hand into 2 cm × 2 cm squares (ASTM

D5338, 2011). All materials were incorporated into the compost at a ratio of 6:1

compost:material as specified in D5338-11. Fifty grams of cut paper and polyethylene film

were mixed with 615 g (± 2 g) of wet compost, respectively. Fifty grams of analytical grade

cellulose powder was mixed with 615 g (± 2 g) of wet compost and 50 ml of deionized water

per vessel to provide additional moisture. Additional water was included in the cellulose

treatment due to previous trial findings that the cellulose was not able to become sufficiently

and evenly hydrated (Section 4.2.4). PAPER and PFPE treatments did not exhibit early

hydration difficulties in a previous trial. The mixtures were added to the 2-liter glass

composting vessels using a funnel and a long wooden spoon handle. The composting vessels

were fitted with caps and each vessel was weighed.

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4.2.4 Biodegradation Set-up

Compressed breathing-grade air tanks were obtained from Northern Welding (Wausau,

WI). The compressed breathing-grade air contained between 19.5-23.5% oxygen, <10 ppm

carbon monoxide, <25 ppm of gaseous hydrocarbons (e.g. methane) and <1000 ppm of CO2 as

required by the Compressed Gas Association (CGA) Grade D requirements for breathing air

products. Compressed air via a pressure regulating manifold was supplied to the hydration

vessels (i.e. air-tight polypropylene bottles 75% filled with deionized water) where the air

was humidified before flowing through the composting vessels (Figure 4.3).

The composting vessels received humidified air directly into the compost matrix through a

short length of silicone tubing fitted with an aquarium air stone. The air stone was comprised

of compacted porous sand that prevented the tube from clogging and allowed for the

distribution of humidified air into the compost matrix with minimal channeling (i.e.

constrained air flow). Air was exhausted from the vessel at the cap through a hose barb fitted

with silicone tubing that exited the incubator.

Composting vessels were not randomized within the incubator and the same input air lines

and hydrating vessels were used for the duration of biodegradation and biodegradation

testing. Temperature and light conditions within the incubator along with air flow rates from

the air tanks were considered fixed variables providing identical environments for the

composting vessels. The non-randomized design thus allowed the vessels to be grouped by

treatment where they could be easily removed for weekly shaking, moisture and pH sampling

and qualitative observations.

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4.2.5 Biodegradation Data Collection and Analysis

Vessels were shaken once a week to prevent air channeling and the uneven distribution of

water. At the time of shaking the exhaust air was smelled for signs of anaerobic conditions

(i.e. methane and hydrogen sulfide gases) and any unusual visual observations were recorded.

Two 5±2 g compost samples were removed from specific vessels in each treatment on days 19,

45 and 90 to be analyzed for pH and moisture.

The flow rates of the composting vessel exhaust and manifold air were measured daily and

recorded. Minimum air flow required by D5338 -11 was 50 ml/min; typical flow rates for this

experiment ranged from 60-85 ml/min. Exhaust air from each vessel was measured for CO2

concentration in parts per million (ppm) using an infrared CO2 analyzer and corresponding

software from Li-Cor Biosciences (Lincoln, NE, USA). The exhaust tubing was connected to

the Li-Cor analyzer only at the time of analysis. Measurements were taken twice a day

during the first 7 days of biodegradation and once a day until the end of 45 days.

Measurements would take 5-20 minutes per vessel to complete depending on the length of

time needed for a stable CO2 concentration reading. The humidified exhaust from the vessels

flowed through a series of moisture traps to limit the amount of condensation entering the Li-

Cor analyzer (Figure 4).The average concentration of CO2 in the pressurized breathing grade

air was stable over time at 263 ppm and was subtracted from the cellulose, PFPE and PAPER

treatments to yield an adjusted ppm of CO2. The five minute blocks of data were converted

from ppm of CO2 (i.e. adjusted values) to mg of carbon L-1 using the modified Ideal Gas Law

(n/V=P/RT) to determine the molar mass of carbon dioxide gas using equation 1.

10001210

1 (ppm) CO

L

C mg62

RT

P (1)

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Where P was the cell pressure within the Li-Cor, R is the gas constant and T is the cell

temperature within the Li-Cor. The mg of carbon L-1 value was then converted into a mass

flux in mg of carbon min-1 by multiplying the value by the flow rate (mL min-1) using

equation 2.

mL 1000

L 1)

min

mL( rate Flow

L

C mg

min

C mg (2)

Linear regressions were performed on the mass flux data from the five minute time period

for each replicate. The area under the curve was integrated using the area under the curve

macro on SigmaPlot 11.0 (San Jose, CA) to determine the total flux of carbon (mg) over five

minutes. The value for cumulative carbon flux was interpolated over 12 hours for the first

seven days and 24 hours during the remainder of the experiment to obtain a per day and per

treatment release of carbon. Percent biodegradation values for replicates were measured

against the standard deviation of the treatment to ensure replicates were within a 20% margin

of error for CO2 production.

The D5338-11 methodology provided a standardized C (mg) range for blank compost in

order to assess compost validity and address percent carbon flux. During the first 10 days of

composting the blank compost must produce at least 50 mg of CO2 per gram of volatile solid

in the added material and cannot exceed 150 mg of CO2 per gram of volatile solid. The

Organimax compost had a dry weight of 300 g and percent volatile solids were 44%. The

actual 10-day cumulative C for the compost matrix was between 1906–2300 mg which was

well within the acceptable range for blank compost according to equation 3.

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(50 mg or 150 mg C × (12 g C

44 g CO2)) × (dry solids compost g × volatile solids) (3)

= 1800 or 5400 mg

Theoretical mg of carbon (ThCO2) was calculated in equation 4 for cellulose, paper and PFPE

using a dry material weight of 50 g (MTOT) multiplied by the carbon content (CTOT)

determined using a Perkin Elmer Series II 2400 Total CHNS/O Analyzer (Table 4.1).

MTOT × CTOT = ThCO2 (4)

The actual evolved CO2 (mg) as detected by the Li-Cor analyzer included the CO2 produced

from the blank (Table 4.2; Figure 4.5). Average blank compost cumulative C (Table 4.2) was

subtracted from the cumulative C of cellulose, PAPER and PFPE to obtain a C value for the

reference and treatment materials (Table 4.2). Results for cumulative carbon minus the

cumulative compost carbon were then calculated as percent biodegradation using equation 5.

Material C mg − Compost C mg

Material Theoretical C mg= % Biodegradation (5)



One-way ANOVAs were run to compare the percent biodegradation and total recovered

material weights on day 90 of disintegration between treatments (i.e. PAPER, PFPE,

cellulose) and the blank. One-way ANOVA was also used to compare pH, C/N ratio and

moisture between PAPER, PFPE, cellulose and blank compost. Post-hoc comparisons were

tested using Bonferroni t-tests. The data conformed to normality and variance assumptions.

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4.3 Results

4.3.1 Cumulative Carbon and Percent Biodegradation

Percent biodegradation showed actual cumulative carbon production relative to theoretical

carbon results and suggested that not all theoretical carbon, especially in the PFPE and

PAPER treatments, was readily available for consumption. Percent biodegradation of the

cellulose reference increased by the third day and continued to rise more steeply than either

PAPER or PFPE (Figure 4.6). The cellulose percent biodegradation began to taper by the

fourth week of composting as the majority of accessible carbon was metabolized by the

microbial community.

The reported results for the cellulose reference vessels were obtained from a trial that had

been assembled at half the original volume of compost and cellulose (Section 4.2.3). Initial

cellulose and compost mixtures with 300 g of dry compost and 50 g cellulose produced levels

of CO2 >50,000 ppm in the first four weeks. The Li-Cor CO2 analyzer was able to measure

CO2 concentrations up to 20,000 ppm with >97% accuracy; however, the error rate for

concentrations greater than 20,000 ppm fell between 10-20%. As a result, the cellulose

treatment was restarted during the fourth week of the experiment with 150 g of compost and

25 g of cellulose. Theoretical CO2 was calculated for 50 g of cellulose (Section 4.3.1; Table

4.1) and all cellulose CO2 production was doubled for the duration of the experiment. This

adjustment allowed for accurate Li-Cor analysis of CO2 within the 20,000 ppm range while

maintaining a relevant biodegradation comparison for PAPER and PFPE.

Percent biodegradation of the PAPER and PFPE materials, particularly PAPER, experienced

slow increases during the first five weeks of composting and began to taper off during the last

91

ten days of biodegradation (Figure 4.6). The D5338-11 biodegradation method allowed for

the continued collection and analysis of CO2 as long as there continued to be significant

biodegradation; the D6868-11 specification stated that biodegradation could be monitored for

up to 180 days. Results obtained during the last seven days (i.e. days 38-45) of biodegradation

suggested that daily CO2 production was waning for the cellulose reference and both PAPER

and PFPE treatments; CO2 data collection was subsequently stopped on day 45.

Comparisons between the PAPER and PFPE treatments revealed no significant difference

in percent biodegradation at day 45. Both the PAPER (t=9.589 and P<0.001) and the PFPE

(t=8.327 and P<0.001) had significantly less percent biodegradation than the Cellulose

reference. The biodegradability of PAPER and PFPE was dependent upon achieving 90% of

the biodegradation of Cellulose (Figure 4.2). According to the results from this experiment

and based on specifications from D6868-03, PAPER and PFPE-coated paper could not be

labeled as biodegradable materials (Figure 4.6).

4.3.2 Physical and Chemical Characteristics: Biodegradation

Final reporting for ASTM D5338 -11 required the inclusion of compost characteristics (i.e.

dry solids, pH, C/N ratio) for the blank compost, cellulose and PAPER and PFPE treatments

at the start and end of the biodegradation experiment (Table 4.4).

The physical and chemical characteristics of the compost (i.e. blank and material mixture

compost) contribute to overall test validity. Dry solids results revealed that after 45 days of

active composting all vessels for the PAPER and PFPE treatments, the cellulose reference and

the blank compost matrix experienced losses (Table 4.4). In order from greatest dry solids

decrease to least, the PFPE treatment decreased by 15%, the PAPER treatment by 13%, the

92

cellulose reference by 10% during biodegradation. The blank compost was reduced by 5%

which suggested that similar losses of native organic matter could be expected in the PAPER,

PFPE and cellulose treatments. The greatest source of error for dry solids results, based on

total vessel weight and moisture content, was changes made to vessels (e.g. caulk, Teflon tape,

cap changes) to improve air-tightness. All compost samples removed for analyses were

adjusted for moisture content and added to the final dry solids total, but not physically added

back to the active composting vessels.

Chemical results after 45 days of active composting revealed that the cellulose reference

compost pH was significantly higher than the PAPER (t=8.900, P<0.001) and PFPE (t=9.069,

P<0.001) treatments and the blank (t=6.316, P<0.001). The pH increased across both PAPER

and PFPE treatments, the cellulose reference and blank compost (Table 4.4). All other

metrics such as percent moisture, carbon and nitrogen ratio and dry solids (g) when compared

between PAPER and PFPE treatments were not significantly different. The initial C/N ratios

for the compost mixtures were calculated using the carbon and nitrogen values detected by

the Perkin Elmer Series II 2400 Total CHNS/O Analyzer. The C/N ratio decreased in the

PAPER, PFPE and cellulose (Table 4.4) and by a lesser degree in the blank compost.

The C/N ratio decreased in the PAPER, PFPE and cellulose (Table 4.4) and by a lesser degree

in the blank compost.

4.3.3 Disintegration

Disintegration testing continued for an additional 45 days after the conclusion of

biodegradation, for a total of 90 days. PAPER and PFPE passed the disintegration portion of

compostability with ≤ 1% of the materials remaining after 90 days of composting (Table 4.5).

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The ASTM D6868 (2003, 2011) standard called for the remaining material to be ≤10% of the

weight of the material added at the start of the experiment. The recovered PAPER and PFPE

material and the subsequent dry weights were not significantly different from one another

after 90 days. Although lignin content likely inhibited the biodegradation of PAPER and

PFPE, the physical fragmentation and overall incorporation of material into the compost

matrix was not affected.

Although ASTM D5338 -11 does not require physical and chemical characteristics reporting

for disintegration testing, the results were used to compare the PAPER and PFPE treatments

and the blank compost at day 90 (Table 4.6). Similar to the results at the end of

biodegradation (Section 4.3.2; Table 4.4) the blank, PAPER and PFPE treatments’ physical

and chemical characteristics were not significantly different at the end of disintegration. Dry

solids results revealed that the PAPER and PFPE treatments experienced further weight loss;

PAPER experienced the greatest weight loss with an average of 18% and PFPE with an

average of 17%. The blank compost matrix lost 8% weight overall with the majority of loss

occurring during the first 45 days (Section 4.3.2). Average percent moisture increased in both

the PFPE and PAPER treatments and decreased in the blank.

Chemical results revealed that pH increased overall, however between biodegradation end

(i.e. day 45) and disintegration end (i.e. day 90) pH decreased only slightly (Tables 4.5, 4.7).

The blank, PFPE and PAPER treatments saw small decreases in pH (e.g. 0.02-0.04) during the

45 days between the end of biodegradation and the end of disintegration. The C/N ratio

decreased overall in both treatments, however between biodegradation end and

disintegration end the C/N ratio increased in the PAPER treatment (Tables 4.5, 4.7).

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4.4 Discussion

Theoretical carbon determinations reveal optimal biodegradation for test materials and

allow for relative comparisons between how much CO2 was expected to evolve and how

much actually evolved. In terms of blank compost, theoretical carbon determines the

acceptable CO2 production range for mature compost and either validates or invalidates a

biodegradation test. “Cool” or cured compost is typically considered mature because the

labile carbon source has been converted to CO2 and humic materials or the remaining carbon

is not readily available for biotransformation. One characteristic of maturity is the inability

of compost to self-heat (Wichuk and McCartney, 2010). Pre-incubation (Section 4.2.2.1) was

a means of reintroducing the microbial community in mature compost to the thermophilic

temperatures of active degradation.

The combination of thermophilic temperatures and cellulose (Section 4.2.2.1) was a means

of stabilizing the mature compost CO2 production prior to introducing the test material.

Elevated CO2 production can occur after a new carbon source is added to a relatively young

or non-mature compost matrix (i.e. <2 months) and can be misinterpreted as material

biodegradation; this is also known as the priming effect (Degli-Innocenti et al., 1998; Tuomela

et al., 2002). Instead, increased CO2 production is likely indicative of the biodegradation of

native organic matter (i.e. inherent organic components within the compost) catalyzed by the

addition of a non-native carbon source. Mature compost is more suited for compostability

testing due to the advanced level of degradation of feedstocks and subsequent low risk for

priming effect. However, pre-incubation can be an important technique even with mature

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composts to minimize any excess CO2 production and ensure stability for biodegradation

testing.

PFPE did not pass the biodegradability requirements set forth by ASTM D6868-03.

However, the inadequate CO2 evolution of PFPE (66.6%) was not due to the presence of the

PFPE coating because PAPER (63.6%) also failed biodegradability (Figure 4.6). Previous

work suggested that the biodegradation of paper materials was inhibited by the structural

complexities of lignin and the resultant slow degradation via bacteria and fungi (Vikman et

al., 2002). In particular, the thermophilic conditions in compost that are beneficial for

decomposing a range of bio-based materials (e.g. poly-lactic acid), including the hemicellulose

of paper, may limit the mesophilic fungi most adept at attacking lignin (Vikman et al., 2002;

Huang, et al., 2010; Section 4.3.2.1). The continual thermophilic temperatures specified for

compostability testing in ASTM D6868 (2003, 2011) is most likely the reason why

compostability laboratories experience biodegradation conundrums with some ligno-

cellulosic substrates (i.e. depending upon lignin content; Venelampi et al., 2003). The ligno-

cellulosic amendment in ASTM D6868-11, while maintaining the thermophilic temperature

requirements from the 2003 specification, allowed compostability testers to bypass

biodegradation. By proving the natural origin of ligno-cellulosic test materials via

radiocarbon analysis (i.e. ASTM 6866) compostability testers could avoid failed

biodegradation tests. While this is beneficial for paper and packaging manufacturers looking

to market compostable products the ligno-cellulosic exemption fails to address the reality of

these materials in actual industrial-scale and municipal composting systems. Paper and

packaging materials that cannot meet the CO2 evolution parameters of cellulose may not be

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suitably compostable at large volumes or compostable within the typical 12-week period of

many composting systems.

4.5 Conclusion

Biodegradation and disintegration testing are two important components of the

compostability testing specification ASTM D6868-11 for ligno-cellulosic substrates combined

with plastics or polymers. Both components determine the suitability of end use materials for

municipal composting by observing the assimilation of organic carbon into CO2 and the

physical disintegration of a material. A previous edition of ASTM D6868 specifications

published in 2003 was utilized to observe and compare the biodegradation of a PFPE-coated

paper to that of an uncoated paper; D6868-03 did not include the 95% natural material or 1%

plastic/polymer concentration exemptions amended to the 2011 edition.

Forty-five days of composting and monitoring CO2 production revealed that percent

biodegradation was not significantly different between PAPER and PFPE materials. PAPER

and PFPE percent biodegradation were significantly lower than cellulose; however, both

treatments were unable to achieve 90% of the breakdown of cellulose to pass biodegradation

testing. The biodegradation failure experienced by PAPER and PFPE illustrated the need for

the ligno-cellulosic exemption included in the D6868-11 edition. An important

acknowledgement was made to the complexity of lignin degradation and the slow production

of CO2 with the D6868-11 amendment. However, the amendment may not realistically

address the challenges of composting paper and packaging materials in actual industrial and

municipal composting systems.

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The disintegration specification of ≥90% material loss was easily achieved by PAPER and

PFPE as both had 99.0% and 99.3% material loss (by weight), respectively. Despite the

difficulties surrounding lignin biodegradation the physical fragmentation of PAPER and

PFPE in the compost matrix was not inhibited. Similarly, the physical and chemical

characteristics following biodegradation and disintegration did not indicate any adverse

impacts on compost quality from the addition of PAPER or PFPE.

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Table 4.1 Theoretical carbon content (mg)

based on organic carbon (%) expected for

50 g of cellulose, Paper and PFPE.

Treatment Organic C (%) Th. C (mg)

Cellulose 44.0 21,980

PAPER 43.5 21,733

PFPE 43.1 21,550

Table 4.2. Average cumulative C (mg) produced by

of cellulose, Paper, PFPE and blank compost at Day

45 of Biodegradation.

Treatment C (mg) C w/o Compost (mg)

Cellulose 23,871 ±1023 17,774±1023

PAPER 19,922±346 13,826±346

PFPE 20,442±171 14,345±171

Blank 0,6097±403 0

Table 4.3. Average cumulative C (mg) produced by

cellulose, Paper, PFPE less the blank compost and

average percent biodegradation at Day 45.

Treatment C w/o Compost (mg) % Biodegradation

Cellulose 17,774±1023 80.9±4.7

PAPER 13,826±346 63.6±1.6

PFPE 14,345±171 66.6±0.8

Table 4.4. Average total vessel weight and dry solids, moisture content,

carbon/nitrogen ratio and pH for PFPE and Paper treatments, cellulose and blank at

the T=0 and Day 45 of biodegradation.

PFPE Paper Cellulose Blank

T=0 Day 45 T=0 Day 45 T=0 Day 45 T=0 Day 45

Total Vessel (g) 1696.7 1696.5 1701.0 1694.7 1423.4 1388.2 1650.0 1628.4

Dry Solids (g) 350.0 297.1 350.4 305.4 179.2 161.2 299.2 282.9

Moisture (%) 51.2 56.4 51.2 54.9 51.1 56.0 51.2 52.9

C:N 30.7 6.5 31.7 6.0 31.9 7.4 8.2 6.1

pH 7.1 7.3 7.1 7.3 7.2 8.5 7.1 7.6

Table 4.5 Average recovered PAPER and PFPE

material and average percent loss at Day 90 of

disintegration.

Treatment Recovered dry weight (g) Loss (%)

PAPER 0.5±0.1 99.0±0.2

PFPE 0.3±0.4 99.3±0.8

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Table 4.6 Average total vessel weight and dry solids, moisture

content, carbon/nitrogen ratio and pH for PFPE and PAPER.

treatments at T=0 and Day 90 of disintegration.

PFPE PAPER Blank

T=0 Day 90 T=0 Day 90 T=0 Day 90

Total Vessel (g) 1696.7 1672.9 1701.0 1671.6 1650.0 1591.5

Dry Solids (g) 350.0 291.0 350.4 286.0 299.2 275.2

Moisture (%) 51.2 54.5 51.2 55.0 51.2 50.3

C:N 30.7 6.2 31.7 6.5 8.2 -

pH 7.1 7.3 7.1 7.3 7.1 7.6

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Figure 4.1 Incubated closed system composting with aerated and hydrated compost mixtures

in 2-liter glass vessels. Incoming air was routed through a hydrating vessel containing

deionized water (Pictured to the left of the composting vessel) before entering the compost

matrix. Air was exhausted from a tube at the cap and exited to the right of the incubator.

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Figure 4.2 Covered 30 liter polypropylene pre-incubation compost container with 0.5 cm

holes drilled equidistant (≈15 cm) from the top for air exchange.

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Figure 4.3 Compressed air tank fitted with an air regulating manifold system to supply the

compost matrix, within the composting vessel with continual and humidified air flow via the

hydrating vessels.

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Figure 4.4 Moisture trap system for the humidified composting exhaust air entering the Li-

Cor CO2 analyzer. The air first flowed through a condensation collection bottle before passing

through a particulate filter and entering the Li-Cor analyzer. Li-Cor exhaust air was further

scrubbed of moisture by flowing through a flask of desiccant before being measured by a flow

meter for flow rate.

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Figure 4.5 Average cumulative carbon (mg) produced per day for the cellulose reference,

PAPER and PFPE treatments and the blank compost.

Figure 4.6 Average percent biodegradation (%) of the cellulose reference and PAPER and

PFPE treatments.

0

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5.0 COMPOSTABILITY ECO-TOXICITY

5.1 Introduction

Eco-toxicity analysis of finished compost is the final component in compostability testing as

specified by the ASTM D6868-11 standard for plastics or polymers incorporated with ligno-

cellulosic substrates (i.e. paper). Eco-toxicity guidelines required to meet the specifications in

D6868-11 are detailed in the OECD 208 Guideline (2006) and the European standard EN

13432 Appendix E (2000). The OECD 208 Guideline (2006) typically employed for the

testing of chemicals, was combined with EN 13432 Appendix E (2000) as a means for testing

concentrations of compost mixed with soil. The eco-toxicity experiment is performed using

two species of plants (e.g. crop species, optional non-crop species) and two concentrations of

compost (e.g. 25% and 50%) in a controlled greenhouse environment.

The objective of eco-toxicity analysis is to assess the impacts that a substance (e.g. chemical)

may have on the germination and early growth of a plant (OECD 208, 2006). The analysis

utilizes both quantitative results (e.g. plant height and biomass measurements) and qualitative

results (e.g. visual observations) to determine if any adverse effects occur after a substance is

incorporated with soils or a growing medium. In terms of compostability testing, eco-toxicity

analysis determines the suitability of finished compost (i.e. mature compost resultant of

biodegradation and disintegration analyses), when incorporated into soil or a growing

medium, for agricultural or horticultural applications. Outside of compostability research

OECD 208 Guideline (2006) is used in agrochemical (e.g. pesticides and herbicides), pollution

and land reclamation research (Kjaer et al., 2006; Marti et al., 2007; Domene et al., 2010).

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The main objective of eco-toxicity analysis was to determine the impacts on plant

germination and early growth when finished compost (i.e. PFPE, PAPER and blank compost

following disintegration analysis) was incorporated into a growing medium. The secondary

objective was to compare percent germination and percent biomass (i.e. dry harvest weight of

plant material) of plants grown in the PFPE finished compost to that of plants grown in the

PAPER finished compost and to compare both to plants grown in blank finished compost.

The objectives were achieved by following eco-toxicity guidelines and methodology for a

controlled greenhouse experiment where two concentrations (25% and 50%) of compost and

two plant species (wheat and peas) were used.

5.2 Methodology

Eco-toxicity methodology was followed from OECD 208 (2006) and EN 13432 (2000)

Annex E as specified in ASTM D6868-11. The specifications from ASTM D6868-11 required

that the germination and biomass results of plants grown in treatment compost achieve 90%

of the plants grown in blank compost.


Ideal plant growth conditions were simulated in an environmental growth chamber set to

25±2°C and 65-70% relative humidity for 4-weeks in the Trainer Natural Resources building

at UWSP. Treatments consisted of finished compost used in the disintegration experiment for

perfluoropolyether (PFPE) coated paper, uncoated paper at two concentrations (i.e. 25% and

50%) based on volume and a blank control at both concentrations was also included.

Finished compost was incorporated into a positive reference soil (Section 5.2.3). Each

treatment included two plant species, common wheat and garden peas (Section 5.2.4). The

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reference soil, PFPE and PAPER compost treatments were replicated four times while blank

compost was replicated three times for a total of 52 pots (Table 5.1). The pots were placed in

plastic trays in the growth chamber in a complete randomized design. The trays were moved

two locations to the left once a day in the growth chamber and the pots were re-randomized

within the trays on a weekly basis.


The finished compost was obtained from the 90-day PFPE and PAPER disintegration

experiment (Chapter 4). At the conclusion of the disintegration experiment the compost was

dried in a 105° C oven for 18 hours. Typical drying time is 24 hours to obtain moisture data

or to prepare samples for volatile solids analysis, however, after 18 hours the compost was

sufficiently dry for sieving. The dried compost was passed through a 2 mm sieve to remove

any remaining paper for processing per ASTM D6868-11 and D5338-11; other debris (e.g.

sticks, rocks) were discarded.

5.2.3 Reference Soil

The reference soil, Withee A (Clark County, WI) is a frigid Aquic Glossudalfs soil, fine-

loamy and somewhat poorly drained. Withee A is a cropland soil and can also be found in

deciduous forests. Soil organic matter could not exceed 3% as specified in OECD 208 (2006).

A loss on ignition experiment where a dry sample of Withee A was combusted in a 360°C

oven for two hours revealed an organic matter content of 2.9%.

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5.2.4 Plant Material

Hard red spring wheat plants fulfilled the OECD 208 (2006) requirement for a mono-

cotyledon species. Wheat was chosen for its high germination rate of 94-95%, its overall

heartiness and ease of care, as well as not being pretreated with fungicides or pesticides.

Pea plants fulfilled the OECD 208 (2006) requirement for a di-cotyledon species. Peas were

chosen for their high reported germination rate of 94%, large biomass potential, as well as not

being pretreated with fungicides or pesticides.

5.2.5 Treatments

Plants were grown in non-porous, 11.5 cm2, plastic pots. Each pot was lined with

cheesecloth and 3 cm of sterilized pea gravel to minimize the loss of mixture and prevent

anaerobic conditions in the bottom layer of the pot. OECD 208 (2006) allowed for compost

concentrations to be determined by mass or volume, for this experiment concentrations were

determined by volume. Compost from the 25% treatment was measured to a volume of 75

mL and mixed well with 225 mL of Withee A reference soil. The 50% treatment was

measured to 150 mL and mixed well with 150 mL of the Withee A reference soil. The

mixtures were added to the pots and 100 mL of deionized water was added to each mixture

and allowed to equilibrate for an hour.

Six wheat seeds were planted equidistantly per pot. A pre-marked wooden skewer was used

to make 6 equidistant depressions at the surface of the mixture to a depth of 0.60 cm (i.e.

twice the diameter of a wheat seed). The seeds were placed vertically into each depression

and the mixture was used to cover each seed site. Similarly, 2 pea seeds were planted per pot.

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A pre-marked wooden dowel was used to make 2 equidistant depressions at the surface of the

mixture to a depth of 1 cm (i.e. twice the diameter of a pea seed).

The pots were placed in plastic trays using a completely randomized design. Pots were

covered with black opaque trays to block out light and minimize soil moisture loss; pots were

bottom watered by adding 900 mL of deionized water and put into an environmental growth

chamber. Bottom watering occurred daily prior to germination, adding just enough water to

replace any moisture lost by evaporation.

5.2.6 Germination and Seedling growth

Prior to initiating the eco-toxicity experiment wheat and pea germination tests were

conducted using deionized water and compost extract. Wheat seed germination in deionized

water and compost extract resulted in a 99% germination rate. Pea seeds in deionized water

resulted in a 99% germination rate while the seeds in the compost extract resulted in a 93%

germination rate.

During the experiment, trays were monitored daily for germinating seeds. Pots with

germinated seedlings were combined and placed into uncovered trays while the

ungerminated seeds remained covered. According to OECD 208 (2006), when germination

reached 50% in the blank controls foliar height was measured and the experiment continued

for 21 days.

Foliar height for wheat plants was measured from the base of the stem to the tip of the plant

by gently straightening the main leaf vertically (ASTM E1963, 2009). Foliar height for pea

plants was similarly measured. Height measurements and qualitative observations (i.e. scale

of 1-5) were recorded every other day for 3 weeks.

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5.2.7 Harvest

All pea and wheat seedlings were harvested 3 weeks after the blank controls at the 25%

concentration achieved 50% germination (OECD 208, 2006). The blank controls at the 50%

concentration for the wheat similarly achieved 50% germination. However, the replanted

peas in the blank compost at 50% concentration failed to achieve 50% germination as had

occurred previously. The germinated and surviving pea seedlings in the blank compost and

corresponding PFPE and PAPER treatments at 50% concentration were harvested regardless

of the failed results in the blank compost (Section 5.3.1.1). Stems were cut 0.5 cm from the

soil surface and the fresh plant biomass was weighed. The fresh plants were dried for 24

hours in a 65°C oven and dry plant biomass was weighed.


All statistical analysis was performed using SigmaPlot 11.0 (San Jose, CA) and α=0.05. One-

way ANOVA tests were performed on all treatment, blank and soil control data for plant

height and biomass. Post-hoc comparisons were tested using the Bonferroni t-test. All

normality and variance assumptions were met for the data.

5.3 Results

5.3.1 Germination and Seedling Survival

Germination and seedling survival of plants grown in blank compost controls validate the

eco-toxicity experiment (OECD 208, 2006). Plants grown in the blank controls must achieve

70% germination and 90% seedling survival for the duration of the experiment for treatment

comparisons to be valid; if requirements are not achieved the experiment must be restarted.

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5.3.1.1 Germination: Wheat and Peas

Wheat seeds grown in the blank control at the 25% concentration reached 50%

germination by day 4, which initiated height measurements (Section 5.3.2). Blank control

germination was 72.5% overall and surpassed the 70% germination requirement for a valid

eco-toxicity experiment (Table 5.2). PAPER and PFPE treatments surpassed the 90% of blank

control requirement and achieved 70.8% and 95.8% wheat germination respectively.

Wheat seeds grown in the blank control at 50% concentration achieved 66.7% germination

but fell short by 3.3% of the requirement for a valid control or experiment (Table 5.2). The

failed wheat germination for the blank control disallowed these for compostability

comparisons to be made for the PAPER and PFPE treatments at the 50% concentration.

However, given that the 66.7% germination rate for the blank compost was relatively close to

the required 70% research assumptions were made to examine treatment germination rates.

PAPER 50 achieved 20.8% germination, a failed germination rate when compared to 90% of

the blank 50 rate and the PFPE 50 achieved 79.5%, a passed germination rate (Table 5.2).

Pea seeds grown in the blank compost control at the 25% concentration reached 50%

germination by day 4, which initiated height measurements (Section 5.3.2). Blank control

germination was 83.3% overall and surpassed the 70% germination requirement for a valid

eco-toxicity experiment (Table 5.2). The peas in the 25% concentration for PAPER achieved

50% germination overall and PFPE achieved 62.5% germination overall (Table 5.2). Both

treatments failed germination as they fell short of the required germination of 75% that is

90% of the blank control (Table 5.2). PAPER and PFPE treatments at the 25% concentration

failed germination for peas and eco-toxicity overall (Table 5.2).

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Pea seeds grown in the blank control at 50% concentration achieved 33.3% germination

and did not meet the 70% germination requirement for a valid control (Table 5.2). Mold was

observed growing at the seed sites requiring that the peas be replanted in the second week of

the experiment.

The finished compost from the disintegration experiment did not provide sufficient volume

to replant the pea seeds in new compost and soil mixtures. The compost and soil mixtures

were removed from the pots, all plant material was discarded, and the mixtures were dried in

a 105˚C oven for 24 hours. Once dry the mixtures were added back to clean, non-porous

plastic pots, rehydrated with deionized water and the pea seeds were similarly planted 2 per

pot (Section 5.2.5). Pea seeds planted in the blank control at 50% concentration did not

achieve 50% germination for the duration of the experiment (i.e. second planting), but height

measurements were taken regardless starting on day 4, the day the blank control at 25%

concentration achieved 50% germination.

PAPER and PFPE treatments surpassed the blank compost with germination results of

62.5% and 50% (Table 5.2). As with the wheat results for the 50% concentration,

comparisons of PAPER and PFPE germination to the corresponding blank could not be

legitimately made for compostability purposes. However, germination comparisons were

made for the sake of this work and both PAPER 50 and PFPE 50 treatments for peas passed

germination. OECD 208 (2006) requirements for eco-toxicity state that a failed blank control

is not valid and the experiment must be restarted.

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5.3.1.2 Seedling Survival: Wheat and Peas

Another OECD 208 (2006) determinant of test validity via the performance of blank control

compost was seedling survival. A 90% survival rate of germinated seeds (i.e. seedlings) grown

in blank controls was required for the duration of the test.

Although the blank control at 25% concentration had strong initial pea seed germination,

20% of pea seedlings were lost by day 6 and an additional 25% were lost by day 8. At the end

of 3 weeks the blank control at 25% concentration maintained 60% of the pea seedlings and

fell short of the 90% requirement disallowing treatment comparisons (Table 5.3).

Pea plants in the blank control at 50% concentration and wheat plants in the blank control

at 25% concentration both achieved 90% seedling survival for valid comparisons (Table 5.3).

The wheat seedlings in the blank control at 50% concentration had strong initial

germination, but lost 41.6% of seedlings during the second half of the test and achieved

58.3% survival overall (Table 5.3).

5.3.2 Seedling Height: Wheat and Peas

Wheat foliar height data was compiled as all replicate seedling heights within a treatment at

a concentration taken at the time of harvest. The mean wheat foliar heights of the blank

controls and the PAPER and PFPE composts at 25% and 50% concentrations were not

significantly different.

Pea foliar height data was compiled identical to the wheat data. The mean pea foliar

heights of the blank controls and the PAPER and PFPE composts at 25% and 50%

concentrations were not significantly different. The PFPE treatment at either 25% or 50%

concentration did not exhibit toxicity in the growth or appearance of the pea plants (Figure

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5.4). In personal communication with the product development engineers for Expera

Specialty Solutions (2013) the presence of the starch ingredients in the PFPE coating

emulsion may have aided seedling growth.

The pea seedling in the blank control at the 50% concentration was the only remaining

seedling in the replicate; however, the growth was stunted (Figure 5.5a). The pea seedlings

grown in the PAPER treatment at 50% concentration (Figure 5.5b) were observed to be

hearty and free of chronic health problems and nutrient deficiencies (R. Michitsch personal

communication, 2013; Figure 5.5a, b).

5.3.3 Dry Biomass: Wheat and Peas

Wheat seedlings grown in the PAPER and PFPE treatments and blank controls at the 25%

and 50% concentrations, with the exception of PAPER at 25%, passed biomass requirements

set forth in the ASTM D6868-11 specification. The Withee A reference soil surpassed all dry

biomass results, due to 100% germination and 95.8% seedling survival, with an average of

0.31 g for wheat.

Dry wheat biomass data revealed that treatments were not significantly different from one

another. Pea seedlings grown in the PAPER and PFPE treatments and blank controls at the

25% and 50% concentrations passed the biomass portion of eco-toxicity. The Withee A

reference soil achieved the highest dry biomass, due to 100% germination and 100% seedling

survival, with an average of 0.34 g for peas. The PAPER and PFPE and the blank control at

the 25% and 50% concentrations were not significantly different from one another.

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5.4 Discussion

5.4.1 Germination and Seedling Survival: Wheat and Peas

Wheat is tolerant of many growing conditions (e.g. arid, humid, hot and cool) and has a

moderate to high salt tolerance ≤8 mS cm-1 (AARD, 2001; Acevedo et al., 2002). The

likelihood that wheat germination failed because of growing conditions or compost toxicity

was low. In particular, compost toxicity was not plausible for the PFPE treatment because of

the strong wheat germination in the PFPE treatment at the 50% concentration (Table 5.2).

However, the eco-toxicity specifications found in ASTM E1963 (2009) caution attributing

toxicity to what could be a single or combined matrix interference (i.e. inherent physical or

chemical characteristics).

For this work eco-toxicity was not restarted after the second planting of pea seeds in the

original soil/compost mixture. Matrix interferences in the growth mixture may have affected

pea germination in the first planting; the difficulties were thus present in the second planting.

Matrix interferences are difficult to pinpoint as they may be a combination of factors and can

vary from one replicate to another. Possible matrix interference problems for seedling

emergence include pH, soluble salts, soil texture and structure, lack of aeration and soil

pathogens (ASTM E1963, 2009).

Unlike wheat, peas are intolerant and require specific growing conditions that include well-

drained soils for germination and growth (Cornell University, 2006). At harvest, the

ungerminated pea seeds at both compost concentrations (i.e. 25% and 50%) were observed to

be partially decomposed and moldy. This was also observed in ungerminated wheat seeds but

was not as pervasive. The mold development and decomposition of pea seeds was likely due

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to the high moisture content maintained throughout the experiment and inherent soil or

compost pathogens.

Another possible cause for the failed germinations of pea seeds was the climate inside the

environmental chamber. Peas are springtime vegetables that are typically planted when soil

and air temperatures are cool (Cornell University, 2006; Banks and Wolford, 2014). Peas are

best planted when air temperature is 15-18°C, germination thrives at 22° C and growth

thrives at temperatures <30°C. The growth chamber was kept at 25±2°C) during the day and

22±2°C) at night for the duration of the experiment per OECD 208 (2006) requirements; the

wheat plants were grown in the same growth chamber. The elevated daytime temperature

combined with high soil moisture likely caused the widespread mold growth that was

observed on germinated and ungerminated seeds. Some seeds were observed to germinate

despite the mold, however many seeds rotted and were unable to sprout.

Peas also have a low tolerance for soil salinity, acidity below 6 and alkalinity above 7, and

do best in soils with measured salinity of less than 4.00 milisiemens per centimeter (mS cm-1)

via electrical conductivity testing; Alberta Agriculture and Rural Development, 2001; Miles

and Sonde, 2003). Wheat tolerance for pH matches that of peas. Prior to planting the

composts were analyzed for salinity. The blank control compost exceeded the upper limit of

pea salt tolerance with an average of 4.42 mS cm-1, and PAPER and PFPE compost treatments

revealed salinities of 3.25 mS cm-1 and 3.03 mS cm-1 respectively. Salinity results were within

the acceptable range for wheat tolerance. Soil and compost pH was measured simultaneously

with salinity; all compost pH measurements exceeded the tolerance range of 6.0-7.0 for pea

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and wheat germination (e.g. PFPE 7.27, PAPER 7.29, blank control 7.58) and the reference

soil pH was measured at 6.05.

Both wheat and peas achieved high germination at the 25% concentration (Table 5.2);

however, pea seedlings did not achieve the same survival that wheat seedlings achieved

(Table 5.3). The germination and survival results of the wheat and peas suggested that the

blank control at 25% could achieve productive germination rates. However, long-term

survival of peas could not be expected due to compost matrix interferences or unsuitable

growing conditions. Conversely, while both pea and wheat germinations failed at the 50%

concentration (Table 5.2) the pea seedlings maintained 100% survival and wheat seedling

survival dipped to 58.3% (Table 5.3). The germination and survival results of the blank

controls (i.e. wheat and peas) at 50% suggested that the higher concentration of compost

inhibited germination of pea and wheat seeds and was especially detrimental to the survival

of wheat (Table 5.3).

The PAPER and PFPE compost mixtures, at the 25% concentration, experienced failed pea

germination with a valid blank control comparison. However, both treatments at both

concentrations achieved high seedling survival rates for peas and, in particular, for wheat

(Table 5.4).

5.4.2 Seedling Height: Wheat and Peas

According to ASTM D6868-11 height was not a required metric for eco-toxicity while

OECD 208 (2006) required that height be measured but not included in final reporting.

Height data is often collected during eco-toxicity research to better assess plant growth

(Michitsch, 2009) and was collected during this experiment. Pea and wheat foliar heights

118

were measured for both treatments and blank controls at both concentrations (Table 5.5)

despite failed wheat and germinations in the blank control at 50% concentration (Table 5.2).

Height and biomass comparisons between the PAPER and PFPE composts at the 50%

concentration could not be made for the purpose of compostability due to the problems with

the blank compost. Visual observations recorded at the time of height measurements did not

indicate chronic health problems or nutrient deficiencies for the wheat seedlings grown in

the blank or treatment composts (R. Michitsch personal communication, 2013; Figures 5.1,

5.2).

Most of the wheat seedlings experienced leaf tip necrosis which is a common characteristic

of high yielding wheat varieties (Joshi et al., 2004). Leaf tip necrosis in wheat can be

indicative of the presence of a gene associated with rust resistance (Figure 5.3).

5.4.3 Dry Biomass: Wheat and peas

Fresh and dry biomass data was collected for the wheat and peas. Eco-toxicity methodology

requires that either fresh or dry biomass be used to assess toxicity, but not both (OECD 208,

2006). Dry biomass was the focus of this experiment as several biomass determination

methods utilized air- or oven-dried samples (NRCS, 2014; Ghavri and Singh, 2012). As was

previously discussed, treatment biomass results must achieve ≥90% of the blank control

biomass in order to pass eco-toxicity. Although the overall test was rendered invalid due to

failed germination results for the blank controls at 50% for wheat and peas (Table 5.3) and

the PAPER and PFPE treatments at 25% failed for peas (Table 5.3), dry biomass from all

treatments at all concentrations was considered for comparison (Table 5.6).

119

The wheat leaves were prone to folding and some had been broken during wheat trays

rotation and plant randomization. The blank control at 50% only achieved 66.7%

germination (Table 5.2) and over the course of four weeks lost nearly 50% of the seedlings

(Table 5.4). The paper treatment at 50% only achieved 20.8% germination (Table 5.2) and

retained 100% of the seedlings (Table 5.5).

The lack of significant difference between pea biomass harvested from the PAPER and

PFPE composts and the blank controls at the 25% and 50% concentrations was likely due to

the small sample of pea seedlings to draw from and the similar growth patterns of the

surviving seedlings. In addition to the pea’s suspected intolerance to some compost

characteristics, the pea seedling sample size could not have been increased for this experiment

given plant size in relation to pot size. In particular, the pea plants were found to have

invasive tendrils early on in their growth. Overall, the natural tendency of peas to climb

limits the number of plants that are able to grow in close proximity to one another.

5.5 Conclusion

Eco-toxicity analysis is an important component within the testing suite for compostability

for determining end-use suitability of finished compost. The health and vigor of plants

(mono- and di-cotyledon) grown in two concentrations of compost (25% and 50%) are

assessed by observing germination, seedling survival and biomass production. Test validity

relies on 70% germination of seeds and 90% seedling survival in the blank controls.

Treatment composts must achieve 90% of blank control germinations and biomass (fresh or

dry) in order to pass eco-toxicity and compostability overall (i.e. assuming all biodegradation

and disintegration requirements are met).

120

Wheat was included in the OECD 208 (2006) list of acceptable mono-cotyledons and

chosen for germination success and tolerance to a variety of growing conditions, was

susceptible to leaf damage when trays and pots were moved. Peas, included in the OECD 208

(2006) list of acceptable di-cotyledons and chosen for germination success, were sensitive to

the required growing conditions and inherent compost characteristics. Peas are intolerant to

high soil moisture, high temperatures and high soluble salt contents and unfortunately these

characteristics were present throughout the experiment as required by the OECD 208 (2006)

method. Overall, the PFPE compost treatment at the 25% and 50% concentrations were not

considered toxic or non-toxic to plant growth due to the failed germination and seedling

survival of the corresponding blank composts.

121

Table 5.1 Total number of pots overall and per treatment

for wheat and peas at the 25% and 50% concentration;

reference soil at 100% loading rate

Wheat Peas

Treatment 25% 50% 25% 50% Total

PAPER Compost 4 4 4 4 16

PFPE Compost 4 4 4 4 16

Blank Compost 3 3 3 3 12

Control 100% 100%

Reference Soil 4 4 8

52

Table 5.2 Top germination rates (%) for wheat and peas grown in compost treatments at

25 and 50% concentrations. Pass/Fail results for PAPER and PFPE treatments are based

on actual results and not OECD 208 (2006) requirements for blank compost validation

(i.e. 70% germination).

Wheat Peas

Treatment

Required

(%)

Actual

(%) Pass/Fail

Required

(%)

Actual

(%) Pass/Fail

PAPER 25 65 70.8 Pass 75 50.0 Fail

PFPE 25 65 95.8 Pass 75 62.5 Fail

Blank 25 70 72.5 Pass 70 83.3 Pass

PAPER 50 60 20.8 Fail 30 62.5 Pass

PFPE 50 60 79.5 Pass 30 50.0 Pass

Blank 50 70 66.7 Fail 70 33.3 Fail

Table 5.4 Seedling percent survival rates of

wheat and peas grown in PAPER and PFPE

compost mixtures at 25 and 50% concentration.

Seedling Survival (%)

Treatment Wheat Peas

PAPER 25 100 100

PFPE 25 100 080

PAPER 50 100 080

PFPE 50 100 100

Table 5.3 Seedling survival rates of wheat and peas grown in a blank control at 25 and 50%

concentration.

Wheat Peas

Treatment Required (%) Actual (%) Pass/Fail Required (%) Actual (%) Pass/Fail

Blank 25 90 060 Fail 90 100 Pass

Blank 50 90 100 Pass 90 058 Fail

122

Table 5.5 Average heights of wheat and pea plants

at the time of harvest for blank control, PFPE and

PAPER treatments at 25% and 50% concentration.

Height (cm)

Treatment Wheat Peas

PAPER 25 28.45±2.20 12.58±5.58

PFPE 25 28.59±1.08 11.65±2.56

Blank 25 30.27±1.31 11.50±4.77

PAPER 50 29.43±0.61 9.59±1.93

PFPE 50 29.19±2.05 10.47±3.45

Blank 50 20.69±1.76 9.75±8.84

Table 5.6 Average dry biomass of pea and wheat plants at the time

of harvest for blank control, PFPE and PAPER treatments at 25%

and 50% concentration.

Wheat Peas

Treatment Biomass (g) Pass/Fail Biomass (g) Pass/Fail

PAPER 25 0.22±0.13 Fail 0.22±0.14 Pass

PFPE 25 0.31±0.08 Pass 0.24±0.12 Pass

Blank 25 0.27±0.07 - 0.19±0.10 -

PAPER 50 0.13±0.02 Pass 0.20±0.04 Pass

PFPE 50 0.23±0.08 Pass 0.23±0.20 Pass

Blank 50 0.13±0.01 - 0.17±0.16 -

b. PFPE 50: Wheat a. PFPE 25: Wheat

123

Figure 5.1 Wheat seedlings, prior to harvest, grown in a PFPE treatment at 25% (a) and at

50% (b).

Figure 5.2 Wheat seedlings, prior to harvest, grown in a PAPER treatment at 25% (a) and at

50% (b).

a. PAPER 25: Wheat b. PAPER 50: Wheat

a. PFPE 25: Wheat b. PFPE 50: Wheat

124

Figure 5.3 Wheat seedling, prior to harvest, grown in PFPE at 25% concentration with signs

of leaf tip necrosis on a majority of leaves.

Figure 5.4 Pea seedlings, prior to harvest, in PFPE treatment at 25% (a) and at 50% (b).

a. PFPE 25: Peas b. PFPE 50: Peas

PFPE 25: Wheat

125

Figure 5.5 Pea seedlings, prior to harvest, grown in a Blank control at 50% (a) and a PAPER

treatment at 50% (b).

a. Blank 50: peas b. PAPER 50: peas

126

6.0 CONCLUSION

Perfluoropolyether-coated (PFPE) paper has a close relationship with food and as a result

may have an increased presence in solid organic wastes in industrial-scale municipal

composting systems. Like the fluorosurfactants that came before, PFPE biodegradation and

accumulation in environmental and biological systems may be cause for concern, particularly

in regards to human health. Comprehensive compostability testing combined with chemical

analysis are helpful means to understanding the presence of PFPE in and the overall quality

of finished compost. This research was conducted to examine the detectability and

degradability of PFPE in finished compost, the degradability of a PFPE-coated paper substrate

and the differences in degradation between PFPE-coated paper and uncoated paper.

Literature pertaining to the degradation of PFPE polymers in composting systems does not

exist. The three main objectives of this work were to determine if:

1. A PFPE-coated paper could achieve compostability according to ASTM specifications,

methodology and OECD guidelines for CO2 evolution, disintegration and eco-toxicity.

2. The PFPE polymer was extractable from the compost matrix, detectable using 19F

NMR and if any discernible degradation had occurred.

3. Composting PFPE-coated paper produced significantly different results (i.e. CO2

evolution, disintegration, eco-toxicity) from composting a comparable uncoated

paper.

Research objectives pertaining to the degradability of PFPE-coated paper and the impact on

compost quality were achieved in three experiments: (1) jar disintegration; (2) compostability

analysis; and (3) eco-toxicity. The composting experiments were conducted in an incubator

127

that allowed for environmental conditions to be controlled and for individual composting

units in glass vessels to be easily handled and observed with minimal disturbance. The

manually mixed (i.e. jar disintegration) and continually aerated (i.e. compostability analysis)

approaches to composting were both competent systems for laboratory-scale composting

analysis. Compost productivity, as determined by CO2 evolution and material disintegration

was not negatively impacted by the presence of the PFPE polymer. The inherent resistance

of the PFPE polymer to grease, moisture and heat did not appear to create an environment

that was toxic to the microbial communities necessary for the degradation of paper nor did

the PFPE polymer appear to inhibit disintegration. Results from the biodegradation portion

of the compostability experiment indicated that the greatest inhibiting factor to CO2

production was lignin content rather than PFPE. The results ultimately contributed to the

need for the ligno-cellulosic substrate exemption amended to the ASTM D6868 (2011)

specification. The degradation processes of ligno-cellulosic substrates are slow and complex

and do not allow for the timely analysis of CO2 evolution for the purposes of compostability

analysis. However, given the natural origin of lignin and cellulose, CO2 evolution is inferred

and exempted from analysis. In both disintegration experiments and the biodegradation

experiment preliminary results revealed that the PFPE-coating did not adversely impact the

overall decomposition of the paper substrate. The eco-toxicity experiment, while not

validated by blank compost results, also indicated that PFPE compost did not pose adverse

impacts on seed germination at the highest level of incorporation with soil. Nor did the PFPE

compost adversely impact seedling survival or growth.

128

The experiments utilizing chemical and instrumental analyses produced fluorine

concentration results in parts per billion and 19F NMR spectra over time found PFPE polymer

degradation to be inconclusive. The 19F NMR spectra from Weeks 6 and 12 revealed complex

peak patterns in the region most likely to exhibit changes due to biodegradation. The

comparisons of specific peaks within the NMR spectra suggested that the PFPE polymer was

not changing over time due to the biodegradation of the terminal segments in the polymer.

However, the examination of peak ratios was not able to account for the additional peaks that

appeared in the compost extracts. These additional peaks in the compost extracts were the

result of other extractable fluorinated substances within the blank compost matrix that were

present prior to the addition of PFPE-coated paper and ultimately had an effect on spectra

appearances.

Fluorinated substances are pervasive atmospheric and terrestrial contaminants, particularly

linked to urban areas and industrial hubs. The Organimax compost (Wausau, WI) was

sourced from a region in Wisconsin that is not immune to the widespread presence of volatile

fluorinated chemicals in manufacturing processes such as paper, pharmaceutical and

agrochemical manufacturers. The ability of PFPE-coated paper to disintegrate with no

negative impact on compost quality indicated its suitability for industrial-scale municipal

composting systems. With the successful extraction and instrumental analysis of PFPE in

compost extracts there is also ample opportunity to carry on with PFPE polymer

biodegradation research in a variety of waste and environmental systems.

Recommendations for further research:

129

Directly incorporate a liquid PFPE surfactant into a plant growing medium and

conduct a germination and seedling growth experiment. Analyze the harvested

plant tissue for the presence of the PFPE polymer.

Compost paper that is coated in a range of PFPE concentrations to determine and

compare the levels of degradation.

Monitor the changes in microbial communities over the duration of a composting

period and compare the communities of PFPE-coated paper and uncoated paper.

Conduct a multi-year composting analysis to monitor the accumulation of PFPE

polymers in compost.

Increase the temperature of an in-vessel incubator composting experiment to

determine if high temperature composting promotes PFPE degradation.

Compost PFPE-coated paper in the presence of metal oxides to determine if they

promote PFPE degradation.

This work was able to show that the PFPE-coated paper exceeded disintegration

requirements and passed biodegradation requirements under ASTM D6868-11 due to the

natural origin exemption. The eco-toxicity results, however, were inconclusive due to the

inadequate seed germinations and seedling survival rates of the blank compost controls. The

overall claim of ‘compostable’ was therefore not possible for the PFPE-coated paper or the

uncoated paper examined in this work. Additionally, this work was not able to prove or

disprove PFPE polymer biodegradation when subjected to typical industrial composting

conditions.

130

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139

Appendix 1: Average percent weight loss between harvest weeks for dry PAPER and PFPE at


Appendix 2: Average weekly percent weight loss between harvest weeks

for dry PAPER and PFPE at 15% and 25% loading levels. Negative

values indicate weight gain.

Average Percent Loss from Previous Week

Harvest Wk PAPER 15 PFPE 15 PAPER 25 PFPE 25 Blank

1 3.10 -0.67 -0.13 9.50 9.04

2 23.50 32.50 12.90 11.10 6.51

3 7.20 31.00 18.40 21.90 -2.64

4 18.00 4.30 -0.20 4.40 2.09

6 36.80 58.60 21.40 40.10 1.14

8 48.90 15.10 27.10 40.50 -2.08

12 83.80 83.30 71.50 64.50 4.71

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Appendix 3: Jar Disintegration Significant Differences:

pH by Harvest Week.

Week Comparison t P

1

Blank vs. PAPER 15 9.186 <0.001

Blank vs. PFPE 15 7.308 <0.001

Blank vs. PAPER 25 5.430 <0.001

PAPER 15 vs. PAPER 25 3.756 0.019

PFPE 15 vs. PFPE 25 4.327 0.006

3

Blank vs. PAPER 15 5.118 0.002

Blank vs. PFPE 15 6.766 <0.001

PAPER 15 vs. PAPER 25 4.201 0.009

PFPE 15 vs. PFPE 25 4.503 0.005

4


PAPER 15 vs. PAPER 25 4.489 0.004

PFPE 15 vs. PFPE 25 4.298 0.006

PAPER 25 vs. PFPE 25 7.451 <0.001

6

Blank vs. PFPE 15 8.900 <0.001

Blank vs. PAPER 25 11.424 <0.001

Blank vs. PFPE 25 7.705 <0.001

PAPER 15 vs. PFPE 15 6.376 <0.001

PAPER 15 vs. PAPER 25 8.900 <0.001

PAPER 25 vs. PFPE 25 3.720 0.021

8

Blank vs. PAPER 15 5.932 <0.001

Blank vs. PFPE 15 11.687 <0.001


Blank vs. PFPE 25 11.156 <0.001

PAPER 15 vs. PFPE 15 5.755 <0.001

PAPER 25 vs. PFPE 25 5.656 <0.001

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Appendix 4: Jar Disintegration Significant Differences: EC by

Harvest Week.

Week Comparison t P

1 PAPER 15 vs. PFPE 15 4.102 0.009

PAPER 15 vs. PAPER 25 5.087 0.001

3

Blank vs. PAPER 15 7.335 <0.001

Blank vs. PFPE 15 7.666 <0.001

Blank vs. PAPER 25 8.723 <0.001

Blank vs. PFPE 25 8.990 <0.001

4 PAPER 15 vs. PFPE 15 4.795 0.002

PAPER 15 vs. PAPER 25 5.466 <0.001

6

Blank vs. PAPER 15 11.459 <0.001

Blank vs. PFPE 15 12.297 <0.001

Blank vs. PAPER 25 11.775 <0.001

Blank vs. PFPE 25 9.878 <0.001

Jar Disintegration Kruskal-Wallis ANOVA on Ranks Significant Differences: EC Week 8

Week Comparison H df q P

8 PAPER 15 vs. PFPE 15 14.940 4 3.972 0.005

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Appendix 5: 700 mHz 19F NMR spectrum of a Week 1.1 (duplicate) compost extract.

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Appendix 6: 700 mHz 19F NMR spectrum of a Week 1.2 compost extract.

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Appendix 9: 700 mHz 19F NMR spectrum of a Week 6.1 (duplicate) compost extract.

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Appendix 12: 700 mHz 19F NMR spectrum of a Week 6 blank compost extract.

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Appendix 15: 700 mHz 19F NMR spectrum of a Week 12.3 compost extract (overnight scan).

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Appendix 17: 700 mHz 19F NMR spectrum of a T=0.1 compost extract.

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