Removal of Wastewater Pharmaceutical Chemical Contaminants Using AOPs

Stephen P. MezykDepartment of Chemistry and Biochemistry

California State University at Long BeachLong Beach, CA, 90840, USA

HN

NO

O

S

OOH

It’s all about potable water!

▪ Current lack of potable water▪ Human population increasing

▪ Water pollution increasing▪ Climate change occurring

▪ Increased water demand:▪ Human consumption▪ Agricultural needs

• Desalination? – Costly, but getting better – Environmental problems (retentate)

• Conservation? YES of course!

• Reusing our wastewater?– ~1012 litres wastewater/day in US!

• Direct toilet to tap – Public perception is bad– Costs????

Where can we get more water?

What’s in our wastewater?PathogensPesticides

Carcinogens

Pharmaceuticals

Industrial chemicals

NH

N

O

F

OH

OOHOHNH

N

O

F

OH

OOHOH

NH

N

NN

NH

Cl

HO

HO

R

N N

O

R'

H3C

CO

CH3

CH3

H3C

HN

NO

O

S

OOH

DOM HCO3-

NO3-/NO2

-

How do we clean wastewater?

▪ More than current 1o and 2o wastewater

treatment!

▪ Use ionizing radiation radical based treatment?

▪ Orange County Water District CA!

▪ Advanced Oxidation Processes (AOPs)

▪ Most work on ●OH, can maybe use SO4-●?

▪●OH radicals (Eo = 2.8V), SO4

-● (Eo = 2.4V)

▪ What is the cost of using AOPs?

An •OH radical is an •OH radical!

•OH

Electron beam

Beams

Gamma Radiation

Non-thermal

Plasmas

Electrohydraulic

Cavitation &

Sonolysis

O3/UV

H2O2/O3

H2O2/UV

H2O2/O3/UV

Supercritical Water

Oxidation

H2O -/\/\ 0.28 •OH + 0.27e-aq +0.06H•

+ 0.07H2O2 + 0.05H2 + 0.27H+

Orange County Water CA District approach:

Why Do We Care?• Trace antibiotic levels can cause

major health problems

• Unnecessary environmental exposure causes development of dangerous resistant strains MRSA, NDM-1, CRE of bacteria

• Allergies and sensitivities• Public concern over detection

of estrogenic chemicals in waterHO

HO

What do we need to understand the chemistry?

▪ Computer models that accurately predicts chemistry

of removal for quantifying costs of AOPs

▪ Contaminants minor wastewater constituents (< 0.1%)

▪ Kinetic computer models combine engineering and

chemistry:

▪ Rate constants for all relevant radical reactions

▪ Mechanisms of reactions

▪ Efficiencies of contaminant removal (impact of

wastewater matrix)

b-lactam antibiotics:

▪ Rate constants for ●OH and SO4-● radical in pure water

well established.

H2O -/\/\ 0.28 •OH + 0.27e-aq +0.06H•

+ 0.07H2O2 + 0.05H2 + 0.27H+

N2O saturated soln:

e-aq/H

● + N2O → ●OH

t-BuOH/N2/S2O82-

●OH/H● + t-BuOH → R●

e-aq + S2O8

2- → SO42- + SO4

-●

Compound k•OH (109M-1s-1)

Aminopenicillanic Acid 3.35 ± 0.06

Penicillin G 8.70 ± 0.32

Penicillin V 9.14 ± 0.12

Ampicillin 8.21 ± 0.29

Carbenicillin 7.31 ± 0.11

Cloxacillin 6.27 ± 0.13

Cephalothin 4.93 ± 0.15

Cefotaxime 9.29 ± 0.12

Kinetic data for β-lactams and •OH

Dail and Mezyk, JPCA, 114, 8391-5 (2010)

Average: kav ~

7.15 x 109 M-1 s-1

0.0 2.0 4.0 6.0 8.0-2.0

0.0

2.0

4.0

6.0

8.0

10.0

12.0

10

3 A

bsorb

ance

Time (s)

SO4•- and β-lactams

Compound kSO4• - (109 M-1s-1)

6-amino-

penicillanic acid

2.41 0.08

Amoxicillin 3.48 0.05

Ampicillin 1.87 0.30

Carbenicillin 0.59 0.30

Cloxacillin 0.86 0.13

Penicillin G 1.44 0.04

Penicillin V 2.00 0.05

Piperacillin 1.17 0.11

Ticarcillin 0.80 0.02

kav ~1.6 x 109 M-1 s-1N

S

HN

O

H

COOH

R1

Rickman and Mezyk, Chemosphere, 81, 359-365 (2010)

0.0 5.0 10.0 15.0

0.0

5.0

10.0

15.0

20.0

10

3 A

bsorb

ance

Time (s)

1.80 mM

1.38 mM

1.02 mM

0.61 mM

0.37 mM

0.20 mM

Species k•OH

M-1s-1

kSO4-•

M-1s-1

b-lactamsav 7.2 x 109 1.6 x 109

HCO3- 8.5 x 106 ~ 5 x 106

CO32- 4.0 x 108 4.1 x 106

NO3- ~ 0 5.0 x 104

NO2- 1.1 x 1010 9.0 x 108

DOM 6.27 x 108 3.8 x 107

Sulfate radical may be better choice!

vs

• HPLC measures parent loss

• •OH + β-lactam → β-lactam•

Watch peak area decrease

with degradation of compound

•●OH Efficiency

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0 1 2 3

Ab

so

lute

Dif

fer

en

ce

Dose (kGy)

Cefazolin 60Co

•OH Reaction EfficiencyCompound ●OH Reaction

Efficiency

Ampicillin 49.7 ± 2.5%

Cefaclor 45.6 ± 2.6%

Cefazolin 78.4 ± 4.9%

Penicillin-G 75 ± 10%

• This means that we require 1-2 •OH reactions to

chemically remove one antibiotic molecule

• Have to quantitatively account for radical rate

constant and efficiency

What about biological efficiency?

• One oxidation will change chemical

structure, but may not perturb function.

• Monitor bacterial growth when exposed to

oxidized product. As the dose increases,

growth should increase as well.

Structure/Function Relationships:

Macrolides

prevent protein

elongation

MTS Assay

Metabolically Active Cell

Required Oxidations – β-lactams

Measured Parameters

Compound k•OH

(109 M-1s-1)

•OH

Oxidations

Penicillin 8.70 ± 0.32 5

Penicillin V 9.14 ± 0.12 6

Ampicillin 8.21 ± 0.29 4

Amoxicillin 6.94 ± 0.44 6

Cloxacillin 6.27 ± 0.13 5

Roxithromycin 4.85 ± 0.25 12

Neomycin 4.73 ± 0.12 11

SO4-• + Pen G P1

SO4-• + DOM P2

SO4-• + t-butanol P4

Pen G + DOM = Complex + t-butanol

k1

k4

k3k2

P1 P2P3 P4

K

Pen G + DOM = Complex K = ?SO4

-• + Complex P3

Real world - Interactions of Pen G and DOM

k3 =?

Second order rate constant for Pen G/DOM + SO4

-• was much slower than 2.08 x 109, so there must be an

interaction

Results

K = 130.0 ± 26

LCMS Oxidation productsNH2H

N

HN

SCH3

CH3

OHO

OOOH

NH2HN

N

SCH3

CH3

OHO

OO

HO

NH2HN

N

SCH3

CH3

OHO

OO

O OHN

N

SCH3

CH3

OHO

OO

HN

NO

O

S

OOH

Where are we now?• Understand kinetics, radical reaction efficiencies,

and products of multiple classes of antibiotics

• Initiated estrogenic steroid study• Estrogen-sensitive

MCF-7 human breast cancer cells

• Ultimately studyestrogen mimics

Thanks:• Radiation Laboratory, Univ.

of Notre Dame

• OCWD: Ken Ishida

• Any questions??