Appendix A

Supporting Information

Ozonation reactivity characteristics of dissolved organic matter in secondary

petrochemical wastewater by single ozone, ozone/H2O2, and ozone/catalyst

Liya Fua,b,c, Changyong Wua,b*, Yuexi Zhoua,b*, Jiane Zuoc, Guangqing Songa,b,d, Yu Tana,b

a Research Center of Water Pollution Control Technology, Chinese Research Academy of Environment Sciences, Beijing 100012,

China

b State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environment Sciences,

Beijing 100012, PR China

c School of Environment, Tsinghua University, Beijing 100083, China

d College of Water Sciences, Beijing Normal University, Beijing 100875, PR China

To whom correspondence should be addressed

Tel.: +86-010-84922161; fax: +86-010-84922161.

E-mail address: Changyongwu@126.com (C. Wu); zhouyuexi@263.net (Y. Zhou).

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Determination of the semi-volatile organic compounds (SVOCs) in the wastewater

For SVOCs, 500 mL of wastewater was extracted with dichloromethane (Fu et al. 2016) and

analyzed using a gas chromatography-mass spectrometer (7890/5975c, Agilent, CA, USA) equipped

with a HP-5MS UI capillary column (60 m × 0.25 mm i.d. × 0.25 μm film thickness, Agilent, CA,

USA) (further details in the Supplementary Materials). The peaks at different retention times

represent different types of SVOCs, and these were preliminarily identified with reference to the

National Institute of Standards and Technology 05 mass spectral library database. Results are shown

in Table S1.

Table S1 Characterized main types, number of the detected compounds of the SVOCs, and average

concentration.

Main types of organic compounds Number of the detected compounds Reference concentration (μg L-1)

Benzene- 47 598.22

Hydrocarbon- 10 123.33

Heterocyclic- 18 111.70

Alcohol- 8 50.00

Esters- 5 21.24

Ketone- 7 44.89

Acids- 2 3.34

Nitriles- 3 23.38

Amines- 9 59.44

Others 7 297.24

Adsorption and effect of dissolved organic matter (DOM) on the volcanic rock grains

Organic matter exhibited weak adsorption on volcanic rock grains. Before the experiments were

performed, all reactors were injected with wastewater without ozonation to allow the filters to reach

DOM adsorption saturation, when the DOM fractions in the effluent did not change compared to the

influent. Therefore, it is believed that the volcanic rock grains are inert and only affect the retention

volume of the column.

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Pre-optimization study on reaction time and ozone dose in single ozone system

In this section, the chemical oxygen demand (COD) changes of wastewater within 80 min were

studied under 10 mg L-1 of ozone (Wu et al., 2015). The optimal reaction time is 15 min for raw

water treated by single ozone system, when the effluent COD was around 73 mg L -1 and the removal

efficiency was about 12% (Fig. S1(a)). At this optimal reaction time of 15 min, when the ozone

dosage reached 20 mg L-1, the COD was stabilized at 72.0 mg L-1 and the removal efficiency was

about 12.5% (Fig. S1(b)). Thus, the optimal ozone reaction time of the secondary wastewater treated

in the single ozone system is 15 min, and the optimal ozone dose is 20 mg L-1.

With different ozone reaction time and ozone dose, COD of wastewater decreased from 82.2 to

72.0 mg L-1 at most. The single ozone system cannot ensure that the secondary petrochemical

wastewater reach the standard (GB 31571-2015), in which the COD should be below 60 mg L-1. This

indicates that only 14.8% of the organic compounds can be directly oxidized by ozone molecules,

and it is difficult to further degrade organic matter by increasing the reaction time and ozone dose.

Fig. S1. COD changes of wastewater with (a) ozone reaction time and (b) ozone dose in the single ozone system.

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Pre-optimization study on reaction time and molar ratio of ozone/H2O2 (n(H2O2)/n(O3)) in

ozone/H2O2 system

Glaze and Kang (1988) found that better molar ratio of ozone/H2O2 (n(H2O2)/n(O3)) generally is

0.5–1.4. With the ozone dose was 20 mg L-1 and n(H2O2)/n(O3) was 1.0, the optimal reaction time

could be selected at 5 min (Fig. S2(a)), when the COD decreased and stabilized at 78.0 mg L-1 and

the removal efficiency reached 5.8%. Therefore, the optimal n(H2O2)/n(O3) of the secondary

wastewater treated in the ozone/H2O2 system is 1.0 (Fig. S2(b)).

At different ozone reaction time and n(H2O2)/n(O3), COD of wastewater decreased from 82.2 to

78.0 mg L-1 at most, indicating that only 5% of organic matter can be mineralized in the ozone/H2O2

system. It is difficult to remove more organic matter by increasing reaction time, ozone and H2O2

input. The ozone/H2O2 system cannot ensure that the secondary petrochemical wastewater reach the

standard (GB 31571-2015).

Fig. S2. COD changes of wastewater with (a) ozone reaction time and (b) n(H2O2)/n(O3) in ozone/H2O2 system.

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Pre-optimization study on reaction time and ozone dose in ozone/catalyst system

At 60 min in the ozone/catalyst system, COD rapidly decreased from 82.2 mg L-1 and then

stabilized about 63.3 mg L-1, with a removal efficiency of 23.5% (Fig. S3(a)). At the reaction time of

60 min and the ozone dose of 45 mg L-1, the average COD decreased rapidly to 47.8 mg L-1 with a

removal efficiency of 42.3% (Fig. S3(b)). Thus, in the ozone/catalyst system, at the reaction time of

60 min and the ozone dose of 35–45 mg L-1, the average COD reached 47.8 mg L-1, below the

corresponding limited value (60 mg L-1) in the standard (GB 31571-2015).

The ozone/catalyst system showed a clear effective treatment effect on the dissolved organic

matters (DOM) in the refractory wastewater.

Fig. S3. COD changes of wastewater with (a) ozone reaction time and (b) ozone dose in ozone/catalyst system.

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Detailed fractionation procedures for the DOM

The detailed fractionation procedures for the DOM in the wastewater are illustrated in Fig. S4.

(1) Hydrophilic substances (HiS): 150 mL of 0.45 m-filtered water (raw or ozonated) was

firstly pumped through a glass column filled with the XAD-8 resin. The sample effluent from XAD-

8 resin was HiS.

(2) Hydrophobic base (HoB): The first absorbed HoB was then eluted from XAD-8 by a

sequential flow of 0.1 mol L-1 HCl.

(3) Hydrophilic neutral (HiN): HiS was firstly acidified to pH 2 with 6 mol L-1 HCl and then

was cycled over three connected DAX-8, MSC-H and AG-MP-1 resin. The effluent from the

connected three columns was HiN.

(4) Hydrophobic acid (HoA): HoA was eluted from XAD-8 with 0.1 mol L-1 NaOH in a forward

direction.

(5) Hydrophobic neutral (HoN): After HoA was desorbed, the XAD-8 resin was air-dried for

about 12 h and was soxhlet-extracted with methanol to obtain HoN. The excess methanol was

removed by vacuum-rotary evaporation at 40 °C.

(6) Hydrophilic base (HiB) and hydrophilic acid (HiA): HiB and HiA were desorbed by gravity

flow from Dowex Marathon MSC and AG-MP-1with 0.1 mol L-1 NaOH, respectively.

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Fig. S4. DOM fractionation procedures.

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Fig. S5. Calibration function obtained by linear regression of the logMW-RV of standards.

The calibration figure shows that the first two and the last two standards seemed to be outside the straight-line

range and showed the curve deflections. Therefore, it would be suitable for the selective exclusion range ending

with a mass of approx. 200 Da.

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Table S2 Fluorescence peaks, intensity and representational substances of the raw water and effluents from the

three ozonation systems.

Fluorescence

peakex (nm) em (nm)

Fluorescence intensityRepresentational substances

(Hudson et al., 2008)Raw

water

Single

ozone

Ozone

/H2O2

Ozone

/catalyst

Peak A 280–285 340–350 6110 1207 927 1574 Soluble metabolites

Peak B 320–330 400–420 3284 756 891 / Humic-like substances

Peak C 230–235 340–350 9900 2472 1719 3676 Aromatic proteins

Peak D 250–260 400–460 6533 3468 2636 / Fulvic acid-like substances

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Excitation–emission matrix fluorescence spectroscope of the DOM fractions

IIIIII

IV V

IIIII100.0200.0300.0400.0500.0600.0700.0800.0900.0

I

IV V

IIIII0.000100.0200.0300.0400.0500.0600.0700.0800.0900.0

I

IV V

IIIII0.000100.0200.0300.0400.0500.0600.0700.0800.0900.0

I

IV V

IIIII0.000100.0200.0300.0400.0500.0600.0700.0

I

IV V

IIIII0.000

50.00

100.0

150.0

200.0

I

IV V

300 350 400 450 500

IIIII

Em (nm)

0.000100.0200.0300.0400.0500.0600.0700.0

(au)强度

I

IV V

300 350 400 450 500

IIIII

Em (nm)

I

IV V

IIIIII

IV V

IIIIII

IV V

IIIIII

IV V

IIIIII

IV V

IIIIII

IV V

IIIIII

IV V

IIIIII

IV V

IIIIII

IV V

300 350 400 450 500

IIIII

Em (nm)

I

IV V

250

300

350

Ex (n

m)

IIIIII

IV V

250

300

350

IIIII

Ex (n

m)

I

IV V

250

300

350

IIIII

Ex (n

m)

I

IV V

250

300

350

IIIII

Ex (n

m)

I

IV V

300 350 400 450 500

250

300

350

Em (nm)

IIIII

Ex (n

m)

I

IV V

IIIIII

IV V

250

300

350

IIIII

Ex (n

m)

I

IV V

Raw water Single ozone Ozone/H2O2 Ozone/Catalyst

HoA

HoB

HoN

HiA

HiB

HiN

Intensity (au)

Fig. S6. The excitation–emission matrix (EEMs) fluorescence spectroscope of the DOM fractions before and after

ozonation via the single ozone, ozone/H2O2, and ozone/catalyst systems.

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Table S3 Φi values and the reduction efficiency of Φi (%) of the DOM fractions in the raw water and effluents from

the three ozonation systems.

Fractions

Influent Effluent

Raw water Single ozone

(% removal)

Ozone/H2O2

(% removal)

Ozone/catalyst

(% removal)

Φi

HoA 2,632,582 1,142,798 (56.6) 1,125,001 (57.3) 728,505 (72.3)

HoB 1,244,463 413,376 (66.8) 579,756 (53.4) 946,463 (23.9)

HoN 3,472,085 1,335,907 (61.5) 1,451,010 (58.2) 2,762,908 (20.4)

HiA 103,697 189,802 (-83.0) 88,338 (14.8) 71,949 (30.6)

HiB 1,313,217 765,680 (41.7) 916,536 (30.2) 693,476 (47.2)

HiN 571,212.6 635,274 (-11.2) 829,161 (-45.2) 518,639 (9.2)

Table S4 Total organic carbon (TOC) content (mg L-1) of each DOM fractions in raw water and the effluent from

single ozone, ozone/H2O2 and ozone/catalyst system.

HoA HoB HoN HiA HiB HiNRaw water 4.1 1.84 1.79 1.01 2 10.07

Single ozone 3.36 1.5 1.66 1.28 1.98 11.28Ozone/H2O2 2.8 0.47 1.41 1.11 1.84 7.16

Ozone/catalyst 2.69 2.17 0.99 0.94 1.74 2.81

Table S5 The ratio of Φi to TOC in the wastewater fractions (Φi/TOC (mg L-1)×105).

HoA HoB HoN HiA HiB HiNRaw water 6.42 6.76 19.40 1.03 6.57 0.57

Single ozone 3.40 2.76 8.05 1.48 3.87 0.56 Ozone/H2O2 4.02 12.34 10.29 0.80 4.98 1.16

Ozone/catalyst 2.71 4.36 27.91 0.77 3.99 1.85

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Analysis of Fourier transform infrared spectroscopy(FTIR) of the raw water and effluent of the

single ozone, ozone/H2O2, and ozone/catalyst systems)

The DOM powder and the fractions obtained through freeze-drying were analyzed by Fourier

transform infrared spectroscopy (FTIR) (Spectrum 100; PerkinElmer, USA) to determine their

structural characteristics. KBr was mixed with DOM powder at a ratio of 300:1, which was scanned

to obtain the FTIR spectra.

The FTIR spectra of the DOM fractions in the raw water and ozonation wastewater are shown

in Fig. S7. The interpretations of the absorption bands are shown in Table S6, as described in the

literature.

Table S6 Infrared absorption peak and its corresponding functional group.

Wave number

(cm-1)Representative absorption band

3473Stretching vibration of O–H of phenols, alcohols, and carboxyl class; stretching vibration of

N–H of the amines

3054, 470, 610 Stretching vibration of aromatic C–H

2470, 1700 Stretching vibration of C=O, O–H of the carboxylates

1460 Bending vibration of saturate C–H of the fatty compound

1141 Stretching vibration of C–C of carbohydrate; stretching vibration of C–C of alcohols

851 In-plane bending vibration of the aromatic C–H

618, 466 Stretching vibration of N–H and O–N=O of amines and amides

(Leenheer, 1981; Leenheer et al., 2001; Kim and Yu, 2005)

The FTIR adsorption spectrum of the HoA fraction indicated the existence of fulvic acid-like

substances, consisted with EEM results (i.e., a high concentration of fulvic acid-like substances in

HoA). The spectral transmittance of the ozonation effluent decreased at 3474 and 1700 cm-1 for the

effluents from single ozone and ozone/H2O2 system (Fig. S6(a)). The content of carboxylic acids

increased in the single ozone and ozone/H2O2 system, showing that ozone could degrade aromatic

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compounds into ketones and anomeric carbon organics, which might produce carboxyl compounds

[6]. In addition, the spectral transmittance at 3474 and 1700 cm-1 increased markedly of the HoA

sample in Fig. S7(a), indicating that carboxylic acids in the HoA fraction could be removed by the

ozone/catalyst system.

Fig. S7. FTIR spectra of the DOM fractions before and after ozonation via the single ozone, ozone/H2O2, and

ozone/catalyst systems: (a) HoA, (b) HoB, (c) HoN, (d) HiA, (e) HiB, and (f) HiN.

At 1500–400 cm-1, the absorption spectrum of the HiA fraction was similar with that of the HoA

fraction. For instance, substances with an absorption peak at 642 cm-1 (e.g., aromatic compounds)

were clearly removed by the ozone/catalyst system. Meanwhile, spectral transmittance of HiN did

not changed markedly in the effluent from the single ozone system, showing that HiN compounds

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were not as reactive with ozone as compounds in the other fractions. The spectral transmittance at

453 and 580 cm-1 decreased during ozone/H2O2 treatment, showing that amines and amides might

have increased in the HiN fraction. The spectral transmittance of 1000–400 cm-1 decreased after the

treatment by ozone/catalyst system, showing that aliphatic compounds were effectively removed.

Finally, the results also suggested that the ozone/catalyst had a clear advantage in the removal of

aliphatic compounds (C–C, 700–600 cm-1).

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FTIR spectral analysis of the filter media

Fig. S8. FTIR spectra of the filter medias of the (a) volcanic rock and (b) catalyst before and after ozonation.

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Contact angle of the filter media

The contact angle is conventionally measured through a liquid, where a liquid–vapor interface

meets a solid surface. Contact angles are extremely sensitive to contamination. If the liquid

molecules are strongly attracted to the solid molecules, then the liquid drop will completely spread

out on the solid surface, corresponding to a small contact angle (Bruus, 2008; Dana and Saguy,

2006). If the contact angle of water is larger than 90°, it is a hydrophobic surface, where smaller

contact angles represent more hydrophobic surfaces. Meanwhile, contact angles less than 90°

represent hydrophilic surfaces, and larger contact angles are indicative of more hydrophobic surfaces

(Zhang et al., 2007). The contact angles between the different fractions and the catalyst were much

smaller than those with the volcanic rocks (Fig. S10). This showed that the fractions were easily

spread out over the catalyst, which would enhance the interactions between the organics and ozone

adsorbed onto the filter media. Therefore, the contaminants in the wastewater could be adsorbed onto

the catalyst and react with the ozone on the catalyst surface. On the catalyst, HoA, HoB, HiB, and

HiN showed the contact angles with the catalyst, indicative of high reaction activity with ozone.

HoA HoB HoN HiA HiB HiN

Con

tact

ang

le (d

egre

e)

0

20

40

60

80

100

120

140RawOzoneOzone/H2O2Ozone/catalyst

Volcanic rock

HoA HoB HoN HiA HiB HiN

Con

tact

ang

le (d

egre

e)

0

20

40

60

80

100

120

140RawOzoneOzone/H2O2Ozone/catalyst

Catalyst

Fig. S9. Contact angles between different fractions and the the filter medias, (a) volcanic rock and (b) catalyst,

before and after ozonation.

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