Interface Mechanisms of Catalytic Ozonation with ... - ACS Publications

Subscriber access provided by READING UNIV

Article

Interface mechanisms of catalytic ozonation with amorphous iron silicate for removal of 4-chloronitrobenzene in aqueous solution Lei Yuan, Jimin Shen, Pengwei Yan, and Zhonglin Chen Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b04875 • Publication Date (Web): 09 Jan 2018 Downloaded from http://pubs.acs.org on January 9, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 25

Environmental Science & Technology

1

Interface mechanisms of catalytic ozonation with amorphous iron

2

silicate for removal of 4-chloronitrobenzene in aqueous solution

3

Lei Yuan, ‡,* Jimin Shen,† Pengwei Yan, † and Zhonglin Chen,†,* *

4 5 6

†

State Key Laboratory of Urban Water Resource and Environment, School of Municipal and

7

Environmental Engineering, Harbin Institute of Technology, Harbin, 150090, People’s Republic

8

of China

9 10

‡

National and Provincial Joint Engineering Laboratory of Wetland Ecological Conservation, Heilongjiang Academy of Science, Harbin, 150040, People’s Republic of China

11 12

*Address correspondence to either author:

13

Tel.: +86 451 86053935 (L. Yuan); +86 451 86287000 (Z.L. Chen).

14

Fax: +86 451 86664613 (L. Yuan); +86 451 86283028 (Z.L. Chen).

15

E-mail address: [email protected] (L. Yuan); [email protected] (Z.L. Chen).

-1-

ACS Paragon Plus Environment


16

Abstract: Iron silicate was synthesized and characterized as an efficient ozonation catalyst.

17

Results indicated that iron silicate is a microporous material with poor crystallinity. Fe–O–Si and

18

Fe–O bonds were observed on its surface. The Fe–O bonds belonged to α-Fe2O3. Heterogeneous

19

catalytic ozonation test was performed in batch reaction mode, and 4-chloronitrobenzene was used

20

as model organic compounds. Amorphous iron silicate exhibited high catalytic activity, ozone

21

utilization efficiency, and stability in catalytic ozonation. Hydroxyl radical was the dominant oxide

22

species in this process. The reaction mechanism at the solid–water interface indicates that Fe–Si

23

binary oxides on iron silicate surface inhibited ozone futile decomposition. This behavior resulted

24

in enhanced probability of the reaction between ozone and α-Fe2O3 on the iron silicate surface to

25

generate hydroxyl radicals which promoted 4-chloronitrobenzene removal in aqueous solution.

26 27

Keywords: catalytic ozonation, iron silicate, hydroxyl radical, interface mechanisms

28 29 30

1. Introduction

31

Heterogeneous catalytic ozonation is interesting and effective technique for the removal of

32

refractory organic compounds in water 1. However, practical applications of this technique are still

33

limited in the field of water treatment 2. The ambiguous reaction mechanism at the solid–water

34

interface is a key factor for this limitation 3. The interface mechanisms include ozone mass

35

transformation and conversion on different catalyst surfaces, route of oxide species generation,

36

and interface synergistic effect between catalyst and ozone. Thus, the interface mechanism should

37

be elucidated to extensively employ this technique.

-2-


Page 2 of 25

Page 3 of 25


38

Production of hydroxyl radicals (•OH) 4, which is the primary secondary oxide species from

39

ozone decomposition in water, was deemed as an important characteristic in this process. Hydroxyl

40

radical has high oxidation rate constants with almost all organic compounds in water. In the past

41

decade, many studies have focused on promoting hydroxyl radicals production and ozone mass

42

transfer in the reaction system. Some transition metal oxides, namely, Fe2O3, MnO2, TiO2, and

43

CuO, are widely used ozonation catalysts for their high catalytic capability 5-9. However, several

44

studies have recently found that not all heterogeneous catalytic ozonation processes follow the

45

route of hydroxyl radicals oxidation 10-16. Among these processes, the application of ozone-loaded

46

silicon materials had received much attention because they can adsorb ozone, and adsorbed ozone

47

further reacts with organic compounds on their surfaces.

48

Some silicates, such as natural zeolite, volcanic sand, bauxite, pumice, cordierite, red mud

49

and ceramic honeycomb, have been used in catalytic ozonation because of their high mechanical

50

strength, chemical stability, and low costs 17–23. In this study, iron silicate was synthesized for the

51

catalytic ozonation of refractory organic compounds in aqueous solution. The adsorption property

52

of ozone and the ozone decomposition property at the solid–water interface were remarkably

53

significant in the design of this catalyst.

54

Synthetic 4-chloronitrobenzene (4-CNB) is a refractory organic compound that is usually

55

used as chemical material for dyes, pesticides, and other industries. It corresponds to probe

56

organic compounds for active radicals in catalytic ozonation because of its low reaction rate

57

constant with ozone molecules (k = 1.6 M−1·s−1) in aqueous solution 24.

58 59

The present test investigates the catalytic effectiveness of iron silicate, the dominant oxides species and its generation route, ozone mass transformation and conversion, and the reaction

-3-



60

mechanisms at the solid–water interface.

61 62

2. Methodology

63

2.1. Chemicals and reagents

64

Synthetic 4-CNB was supplied by Chem Service (USA). Synthetic 5,

65

5-dimethyl-1-pyrroline-N-oxide (DMPO) was supplied by Sigma (USA). The water used in the

66

experiment was supplied by an ultrapure water system. Other chemicals and reagents were of

67

analytical grade and used without further purification.

68

2.2. Synthesis of catalysts

69

The precursor solution consisted of Na2SiO3 and Fe(NO3)3 with different Si/Fe molar ratios. The

70

solution was slowly titrated to pH 12 with NaOH at 25 °C and then aged further at 60 °C for 24 h.

71

The solid was washed repeatedly with ultrapure water and baked at 350 °C for 2 h. The dry solid

72

catalyst was crushed and stored in a vacuum desiccator. This catalyst (iron silicate, Si/Fe molar

73

ratio = 0.5) exhibited the highest activity and was used in the experiments. As references, α-Fe2O3

74

was synthesized via the same procedure without Na2SiO3.

75

2.3. Experimental procedure

76

The tests were conducted in batch reaction mode. The reactor was a modified 1L glass flask

77

(Figure S1), and ozone was bubbled in ultrapure water within this reactor to achieve the desired

78

concentration via ozone generator (COM-AD-01, Germany). Then, the catalyst and 4-CNB were

79

quickly added to the stock ozone solution. A magnetic stirrer was used to mix the suspension

80

continuously. The reaction temperature was controlled at 25 °C using a thermostatic bath. The

81

suspensions collected from the reactor at different time intervals were immediately quenched with

-4-


Page 4 of 25

Page 5 of 25


82

Na2S2O3 solution. The quenched suspension was passed through 0.45 µm filter before the analysis

83

of the residual 4-CNB concentration in the solution.

84

2.4. Analytical method

85

X-ray diffraction (XRD, D8 Advance diffractometer, Germany) was performed to analyze the

86

crystalline structure of the catalyst. Accelerated surface area and porosimetry instrument (ASAP

87

2020, USA) was used to analyze the BET surface area and pore diameter of the catalyst.

88

Scanning electron microscopy (SEM, Quanta 200, Netherlands) was conducted to analyze the

89

surface morphology of the catalyst. Energy dispersive spectrometry (EDAX, Genesis, USA) was

90

performed to analyze the elemental concentration of the catalyst. Fourier transform infrared

91

spectroscopy (FT-IR, Spectrum One, USA) and X-ray photoelectron spectroscopy (XPS, PHI 5700,

92

USA) was also conducted to analyze surface chemical composition of the catalyst.

93

Electron spin resonance (ESR, EMX-8/2.7, Germany) was employed to analyze the intensity

94

of hydroxyl radicals generated in the system. High-performance liquid chromatograph (LC-1200,

95

USA) was used to analyze the concentration of 4-CNB in aqueous solution via the Extend-C18

96

(4.6 mm × 250 mm) column through UV detection at 265 nm. The mobile phase comprised 80%

97

CH3OH and 20% H2O. The concentration of residual ozone in aqueous solution was determined

98

using the indigo method 25. Total organic carbon analyzer (TOC-VCPH, Japan) was used to analyze

99

the concentration of TOC in aqueous solution. The acid–base titration method was used to analyze

100

the point of zero charge (pHPZC) of the catalyst 26. Inductively coupled plasma spectrometer

101

(Optima 5300DV, USA) was used to analyze Fe ions in the solution.

102 103

3. Results and discussion

-5-



104

3.1. Characterization

105

The crystalline structure of the two catalysts was assessed using the XRD patterns in Figure S2.

106

The crystallinity of iron silicate was poor, because its XRD patterns indicated two wide peaks at

107

34.4° and 62.1°. The peaks were excessively wide because of the lack of a relationship between

108

crystallinity and a specific Miller index. Therefore, iron silicate was believed to be amorphous,

109

and high-purity α-Fe2O3 was obtained.

110

The physisorption isotherms of catalysts are shown in Figure S3. The reversible isotherm of

111

iron silicate was a type I(b), indicating the presence of microporous materials 27. α-Fe2O3 exhibited

112

typical type IV(a) isotherm of mesoporous materials with a hysteretic loop in the range from 0.9

113

P/P0 to 1.0 P/P0 27. The pore size distribution was calculated according to the SF method and BJH

114

model in Figure S4. The results indicate that iron silicate displayed a significantly narrower pore

115

size distribution than α-Fe2O3. Doped Si increased the BET surface area from 55.2 m2/g of

116

α-Fe2O3 to 203.4 m2/g of iron silicate. Then, the average pore diameter decreased from 30.5 nm of

117

α-Fe2O3 to 0.9 nm of iron silicate.

118

The morphology of catalysts is shown in Figure S5. Iron silicate consisted of a flat surface

119

and agglomerated particles. The morphology of α-Fe2O3 was represented by aglobular particles.

120

As shown in Table S1, the EDAX results indicated an uneven elemental concentration on the iron

121

silicate surface.

122

3.2. Activity and stability of iron silicate

123

Control tests were performed according to three processes, namely, sole ozonation, catalytic

124

ozonation, and adsorption on catalysts. The curve of 4-CNB removal versus reaction time is

125

illustrated in Figure 1.

-6-


Page 6 of 25

Page 7 of 25


126

Minimal 4-CNB (less than 3.2%) was adsorbed on the surfaces of the tested catalysts after

127

30 min, suggesting that self-adsorption slightly contributes to the removal of 4-CNB during

128

catalytic ozonation. Only 49.2% of 4-CNB was removed after 30 min during sole ozonation,

129

indicating that 4-CNB cannot be effectively removed by this process.

130

4-CNB removal was significantly more effective in catalytic ozonation when two catalysts

131

were introduced than in sole ozonation. The best result was obtained with iron silicate, in which

132

82.8% of 4-CNB was removed. Analysis results showed 4-CNB removal followed

133

pseudo-first-order kinetics model in ozonation processes. The rate constants were determined to be

134

1.86×10−2 min−1 for sole ozonation. The rate constants were obviously accelerated in the presence

135

of α-Fe2O3 and iron silicate, with the removal rate increasing 1.4- and 2.5-fold, respectively.

136

Meanwhile, the presence of two catalysts increased TOC removal compared to sole ozonation.

137

Catalytic ozonation with α-Fe2O3 removed 45.1% of TOC compared to 27.2% by sole ozonation.

138

The enhancement of TOC removal is even more pronounced in the presence of iron silicate,

139

68.7% of TOC was removed after 30 min. This finding indicates that the presence of a

140

heterogeneous catalytic surface initiates an accelerated effect with the ozone molecules during the

141

removal and minerlization of 4-CNB in aqueous solution. After reaction, Fe ion concentration in

142

treatment water was below the detection limit. Furthermore, iron silicate maintains its catalytic

143

activity after five cycles because the removal of 4-CNB and TOC were 82.2% and 67.4%,

144

respectively (Figure S6). Thus, the amorphous iron silicate exhibited high catalytic activity and

145

fine stability in catalytic ozonation.

146

3.3. Ozone utilization efficiency

147

The evaluated ozone utilization efficiency is an important factor in catalyst performance. The

-7-



148

ozone utilization efficiency is expressed as the 4-CNB removal (total removal subtracted by the

149

removal in adsorption) per concentration of ozone used.

150

Figure 2 shows that this ratio considerably increased relative to sole ozonation when catalysts

151

were introduced. Calculation results indicated that the lowest ratio was 0.054 in sole ozonation

152

after 30 min. The ratio for catalytic ozonation with iron silicate was 0.091, which was 1.2 times

153

higher than that for ozonation with α-Fe2O3 after 30 min. Ozone reacts with organic compounds in

154

aqueous solution by either the direct oxidation of ozone molecules or the indirect oxidation of

155

active radicals derived from ozone decomposition 28. Therefore, the obtained enhancement of

156

ozone utilization efficiency in the catalytic ozonation with iron silicate is apparently caused by the

157

active radical production in the solution.

158

3.4. Effect of tert-Butanol

159

Because of its high oxidative capability and unselective reaction with organic compounds,

160

hydroxyl radicals are the most important active radical in catalytic ozonation system. tert-Butanol

161

(TBA) is an effective hydroxyl radicals scavenger which is often used to determine hydroxyl

162

radicals in catalytic ozonation 29.

163

Tests were performed to determine 4-CNB removal with TBA to identify hydroxyl radicals in

164

catalytic ozonation with iron silicate. Figure 3 shows that introducing different TBA

165

concentrations strongly inhibited 4-CNB removal, even at a very low concentration (1.0 mg/L).

166

High TBA concentration also negatively affected 4-CNB removal. The removed 4-CNB after

167

30 min of reaction without TBA reached 82.8%, whereas only 19.7% was removed with TBA

168

(20 mg/L). This result suggests that TBA competitively captured and rapidly consumed hydroxyl

169

radicals in the solution. Therefore, 4-CNB removal follows the route of hydroxyl radicals

-8-


Page 8 of 25

Page 9 of 25


170

oxidation in catalytic ozonation with iron silicate. The inhibitory effect in catalytic ozonation was

171

greater than that in sole ozonation, indicating that more hydroxyl radicals were generated in

172

catalytic ozonation with iron silicate.

173

3.5. Effect of solution pH

174

The solution pH strongly affects hydroxyl radicals generation because of ozone reactions with OH

175

–

to hydroxyl radicals 30, and solution pH adjusts to catalyst surface charge

176

S − OH + H + ↔ S − OH +2

177

S − OH + OH − ↔ S − O − + H 2 O

178

31

, as follows:

The catalyst surface becomes neutral, protonated, or deprotonated when the solution pH is

179

near, below, or above the pHPZC. The effect of pH on 4-CNB removal was investigated in different

180

processes, and the results are shown in Figure 4. The results indicated that iron silicate (pHPZC =

181

9.1) showed catalytic activity relative to sole ozonation in solution pH levels ranging from 3 to 11,

182

particularly at solution pH 7. Previous studies reported that neutral-charged catalyst surface was

183

beneficial for ozone decomposition to hydroxyl radicals 32, 33. This phenomenon was due to the

184

following factors. First, the neutral charge on iron silicate surface decreased in solution pH levels

185

ranging from 7 to 3. In addition, hydroxyl radicals were difficult to generate from ozone

186

decomposition in aqueous solution under acidic condition. Second, OH− competitively

187

decomposed the ozone to hydroxyl radicals with the surface active site of iron silicate when the

188

solution pH levels ranged from 7 to 11, although increasing neutral charge on iron silicate surface

189

was also considered. Consequently, the catalytic activity of iron silicate was inhibited when

190

solution pH either decreased to 3 or increased to 11.

191

3.6. Effect of Si/Fe molar ratio

-9-



192

The effect of the Si/Fe molar ratio of iron silicate on 4-CNB removal was investigated in catalytic

193

ozonation.

194

Figure 5 show that the five catalysts significantly enhanced 4-CNB removal relative to sole

195

ozonation. However, iron silicate with different Si/Fe molar ratios exhibited different catalytic

196

activities in catalytic ozonation. 4-CNB removal increased as molar ratio of Si/Fe increased from

197

0.1 to 0.5. However, further increase in molar ratio of Si/Fe to 2.0 resulted in a negative effect on

198

4-CNB removal in aqueous solution. These results indicated that optimal critical molar ratio of

199

Si/Fe was 0.5 under the present experimental conditions. Variation in the molar ratio of Si/Fe may

200

affect the surface properties of iron silicate which cause different concentrations of hydroxyl

201

radicals to be generated in aqueous solution.

202

3.7. Interface mechanisms

203

The FT-IR spectra of iron silicate are shown in Figure 6a. The surface hydroxyl group peaked at

204

3368 and 1622 cm−1 34. The Si–O–Fe bonds peaked at 1012 and 684 cm−1 35. The peaks at 532 and

205

451 cm−1 represented the Fe–O bonds. Furthermore, XPS analysis is carried out to study the

206

surface chemistry of iron silicate. It can be clearly seen that the spectrum contains Fe, O, Si, Na,

207

and C (Figure S7a). The peaks for Na and C can be attributed to contamination caused by sample

208

preparation and testing instrument. As shown in Figure S7b, the binding energy of Fe 2p3/2 is

209

711.2 eV for iron silicate. The wide Fe 2p3/2 signals obtain for iron silicate could be fitted

210

satisfactorily to two principal peaks after deconvolution. The peak at 710.5 eV belongs to Fe3+ of

211

α-Fe2O3 36. Meanwhile, another peak appears at 712.1 eV. The XPS spectra of Si 2p for iron

212

silicate showed a narrow, symmetrical peak (Figure S7c). The binding energy of Si 2p is found to

213

be 101.9 eV, which is higher than that of pure SiO2 (100.2 eV) 36. The analyses confirmed that the

- 10 -


Page 10 of 25

Page 11 of 25


214

core-level shifts of both Fe and Si were due to the formation of Si–O–Fe bonds. The asymmetric

215

O 1s peaks could be fit into four peaks with binding energies (Figure S7d). They corresponded to

216

α-Fe2O3 (529.9 eV), -OH (531.9 eV), Fe–Si binary oxides (532.1 eV), and adsorbed water (535.8

217

eV), respectively 36. Therefore, iron silicate denotes a mixture of Fe–Si binary oxides and α-Fe2O3.

218

The ESR spin-trap technique is suitable for investigating hydroxyl radicals generation. The

219

test results shown in Figure 6b indicated that hydroxyl radicals production was observed in sole

220

ozonation and catalytic ozonation. The presence of α-Fe2O3 and iron silicate significantly

221

enhanced the relative intensity of the DMPO-OH adduct signal compared with the intensity in sole

222

ozonation, especially iron silicate. Therefore, iron silicate enhanced ozone decomposition to

223

generate the highest amounts of hydroxyl radicals in the three reaction processes. Comparison of

224

Figure 6a with Figure 6b shows that high catalytic activity of iron silicate was possible because of

225

two hypothesises: (1) Fe–Si binary oxides on its surface exhibited high catalytic capability, or (2)

226

Fe–Si binary oxides enhanced catalytic capability of α-Fe2O3 on its surface.

227

Ozone concentration in aqueous solution decreased with reaction time in sole ozonation

228

because of self-decomposition (Figure 6c). Introduction of α-Fe2O3 promoted ozone

229

decomposition to hydroxyl radicals relative to that obtained from sole ozonation (Figures 6b and

230

6c). Meanwhile, the ozone concentration in aqueous solution decreased significantly in the

231

presence of iron silicate for 5 min. However, the reaction time was also extended by 5–20 min.

232

This extension exerted an obvious positive effect on the ozone concentration in the solution. This

233

phenomenon indicates that ozone is adsorbed on Fe–Si binary oxide surfaces because of

234

desorption in aqueous solution. Figure 5 also indicated that Si/Fe molar ratio of iron silicate had

235

no positive correlation with its catalytic activity. Therefore, these results suggest that Fe–Si binary

- 11 -



236

oxides have an assisted effect with α-Fe2O3 on the iron silicate surface in promoting the generation

237

of hydroxyl radicals in aqueous solution.

238 239 240

According to the test results and the aforementioned theory, the reaction mechanism at the solid –water interface is proposed and illustrated. First, Fe–Si binary oxides on iron silicate surface could adsorb ozone and adsorbed ozone

241

was desorbed, which inhibits ozone futile decomposition in aqueous solution. Second, adsorption

242

of ozone significantly increased the reaction probability between ozone in aqueous solution and

243

α-Fe2O3 on iron silicate surface that accelerate hydroxyl radicals generation from ozone

244

decomposition and promote 4-CNB removal. Finally, no decomposition adsorbed ozone on Fe–Si

245

binary oxides was desorbed into aqueous solution to begin the next cycle of reaction. It was

246

generally accepted that the reaction of ozone with catalyst surface involves two mechanisms: (1)

247

ozone was decomposed into active species to oxidize organic compounds, (2) adsorption of ozone

248

and organic compounds before interacting with each other 2. The findings would provide the new

249

ideas for the development of an efficient ozonation catalyst in the field of water treatment.

250 251

Supporting Information Available

252

A detailed discussion of the experimental apparatus schematic, catalyst characterization and

253

stability test. This material is available free of charge via the Internet at http://pubs.acs.org.

254

255

Acknowledgment

256

The support from the National Key R&D Program of China (Grant No. 2017YFA0207203), the

- 12 -


Page 12 of 25

Page 13 of 25


257

National Natural Science Foundation of China (Grant No. 51208186), the Open Project of State

258

Key Laboratory of Urban Water Resource and Environment (Grant No. HCK201711), and the

259

HAS Fund for Distinguished Young Scholars (Grant No. CXJQ2018ZR02) are greatly

260

appreciated.

- 13 -



References 1.

Kasprzyk-Hordern, B.; Ziolek, M.; Nawrocki, J. Catalytic ozonation and methods of enhancing molecular ozone reactions in water treatment. Appl. Catal., B 2003, 46 (4), 639−669.

2.

Nawrocki, J.; Kasprzyk-Hordern, B. The efficiency and mechanisms of catalytic ozonation. Appl. Catal., B 2010, 99, 27–42.

3.

Nawrocki, J. Catalytic ozonation in water: controversies and questions. Discussion paper. Appl. Catal., B 2013, 142−143, 465−471.

4.

Gligorovski, S.; Strekowski, R.; Barbati, S.; Vione, D. Environmental implications of hydroxyl radicals (•OH). Chem. Rev. 2015, 115, 13051−13092.

5.

Huang, R.H.; Yan, H.H.; Li, L.H.; Deng, D.Y.; Shu, Y.H.; Zhang, Q.Y. Catalytic activity of Fe/SBA-15 for ozonation of dimethyl phthalate in aqueous solution. Appl. Catal., B 2011, 106, 264–271.

6.

Bing, J.H.; Hu, C.; Nie, Y.L.; Yang, M.; Qu. J.H. Mechanism of catalytic ozonation in Fe2O3/Al2O3@SBA-15 aqueous suspension for destruction of ibuprofen. Environ. Sci. Technol. 2015, 49, 1690–1697.

7.

Yang, L.; Hu, C.; Nie, Y.; Qu, J.H. Catalytic ozonation of selected pharmaceuticals over mesoporous alumina-supported manganese oxide. Environ. Sci. Technol. 2009, 43, 2525–2529.

8.

Song, S.; Liu, Z.W.; He, Z.Q.; Zhang, A.L.; Chen, G.M. Impacts of morphology and crystallite phases of titanium oxide on the catalytic ozonation of phenol. Environ. Sci. Technol. 2010, 44, 3913–3918.

- 14 -


Page 14 of 25

Page 15 of 25


9.

Turkay, O.; Inan, H.; Dimoglo, A. Experimental and theoretical investigations of CuO-catalyzed ozonation of humic acid. Sep. Purif. Technol. 2014, 134, 110–116.

10. Zhang, T.; Li, W.; Croue, J.P. Catalytic ozonation of oxalate with a cerium supported palladium oxide: An efficient degradation not relying on hydroxyl radical oxidation. Environ. Sci. Technol. 2011, 45 (21), 9339−9346. 11. Zhang, T.; Croue, J.P. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related tometal–carboxylate complexes. Appl. Catal., B 2014, 144, 831–839. 12. Wang, Y.X.; Xie, Y.B.; Sun, H.Q.; Xiao, J.D.; Cao, H.B.; Wang, S.B. Efficient catalytic ozonation over reduced graphene oxide for p-hydroxylbenzoic acid (PHBA) destruction: active site and mechanism. ACS Appl. Mater. Interfaces 2016, 8, 9710−9720. 13. Ikhlaq, A.; Brown, D.R.; Kasprzyk-Hordern, B. Mechanisms of catalytic ozonation: An investigation into superoxide ion radical and hydrogen peroxide formation during catalytic ozonation on alumina and zeolites in water. Appl. Catal., B 2013, 129, 437−449. 14. Ikhlaq, A.; Brown, D.R.; Kasprzyk-Hordern, B. Catalytic ozonation for the removal of organic contaminantsin water on ZSM-5 zeolites. Appl. Catal., B 2014, 154–155, 110–122. 15. Tizaoui, C.; Slater, M.J. Uses of ozone in a three-phase system for water treatment: ozone adsorption. Ozone Sci. Eng. 2003, 25, 315–322. 16. Fujita, H.; Izumi, J.; Sagehashi, M.; Fujii, T.; Sakoda, A. Adsorption and decomposition of water-dissolved ozone on high silica zeolites. Water Res. 2004, 38, 159–165. 17. Valdes, H.; Farfan, V.J.; Manoli, J.A.; Zaror, C.A. Catalytic ozone aqueous decomposition promoted by natural zeolite and volcanic sand. J. Hazard Mater. 2008, 152, 915–922.

- 15 -



18. Qi, F.; Xu, B.B.; Chen, Z.L.; Ma, J.; Sun, D.Z.; Zhang, L.Q.; Wu, F.C. Ozonation catalyzed by the raw bauxite for the degradation of 2,4,6-trichloroanisole in drinking water. J. Hazard Mater.2009, 168, 246–252. 19. Yuan, L.; Shen, J.M.; Chen, Z.L.; Liu, Y. Pumice-catalyzed ozonation degradation of p-chloronitrobenzene in aqueous solution. Appl. Catal., B 2012, 117–118, 414–419. 20. Yuan, L.; Shen, J.M.; Chen, Z.L.; Guan, X.H. Synergistic role of pumice surface composition in hydroxyl radical initiation in the catalytic ozonation process. Ozone Sci. Eng. 2015, 38, 42–47. 21. Zhao, L.; Ma, J.; Sun, Z.Z.; Liu, H.L. Enhancement mechanism of heterogeneous catalytic ozonation by cordierite-supported copper for the degradation of nitrobenzene in aqueous solution. Environ. Sci. Technol. 2009, 43, 2047–2053. 22. Xu, B.B.; Qi, F.; Sun, D.Z.; Robert, D. Cerium doped red Mud catalytic ozonation for bezafibrate degradation in wastewater: Efficiency, Intermediates, and Toxicity, Chemosphere, 2016, 146, 22–31. 23. Zhao, L.; Ma, J.; Sun, Z.Z.; Zhai, X.D. Mechanism of Influence of Initial pH on the Degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation. Environ. Sci. Technol. 2008, 42, 4002–4007. 24. Shen, J.M.; Chen, Z.L.; Xu, Z.Z.; Li, X.Y.; Xu, B.B.; Qi, F. Kinetics and mechanism of degradation of p-chloronitrobenzene in water by ozonation. J. Hazard Mater. 2008, 152, 1325–1331. 25. Bader, H.; Hoigné, J. Determination of ozone in water by the indigo method. Water Res. 1981, 15, 449–456.

- 16 -


Page 16 of 25

Page 17 of 25


26. Mullet, M.; Fievet, P.; Szymczyk, A.; Foissy, A.; Reggiani, J.C.; Pagetti, J. Simple and accurate determination of the point of zero charge of ceramic membranes. Desalination 1999, 121, 41–48. 27. Thommes, M.; Kaneko, K.; Neimark, A. V.; Olivier, J. P.; Rodriguez-Reinoso, F.; Rouquerol, J.; Sing K. S. W. Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution. Pure Appl. Chem. 2015, 87, 1051–1069. 28. Legube, B.; Karpel, V.L.N. Catalytic ozonation: A promising advanced oxidation technology for water treatment. Catal. Today 1999, 53, 61–72. 29. Guan, Y.H.; Ma, J.; Ren, Y.M.; Liu, Y.L.; Xiao, J.Y.; Lin, L.Q.; Zhang, C. Efficient degradation of atrazine by magnetic porous copper ferrite catalyzed peroxymonosulfate, oxidation via the formation of hydroxyl and sulfate radicals. Water Res. 2013, 47, 5431–5438. 30. von Gunten, U. Ozonation of drinking water: part I. Oxidation kinetics and product formation. Water Res. 2003, 37, 1443–1467. 31. Stumm, W. Chemistry of the Solid–Water Interface, John Wiley & Sons, New York, 1992, PP. 15–20. 32. Yuan, L.; Shen, J.M.; Chen, Z.L.; Guan, X.H. Role of Fe/pumice composition and structure in promoting ozonation reactions. Appl. Catal., B 2016, 180, 707–714. 33. Zhang, T.; Li, C.J.; Ma, J.; Tian, H.; Qiang, Z.M. Surface hydroxyl groups of synthetic α-FeOOH in promoting •OH generation from aqueous ozone: property and activity relationship. Appl. Catal., B 2008, 82, 131–137. 34. Richmond, G.L. Molecular bonding and interactions at aqueous surfaces as probed by

- 17 -



vibrational sum frequency spectroscopy.Chem. Rev. 2002, 102, 2693–2724. 35. Seehra, M.S.; Roy, P.; Raman, A.; Manivannan, A. Structural investigations of synthetic ferrihydrite nanoparticles doped with Si. Solid State Commun. 2004, 130, 597–601. 36. B.V. Crist, Handbook of the elements and native oxides, XPS International, California, 1999.

- 18 -


Page 18 of 25

Page 19 of 25


Figures

Figure 1. Removal of 4-CNB in the ozonation process. Conditions: T = 25 °C, 1 mmol/L phosphate buffered pH = 7.0, 4-CNB dosage = 0.1 mg/L, ozone dosage = 0.9 mg/L, catalyst dosage = 100 mg/L

19



Figure 2. Effective ozone use ratio in the ozonation process. Conditions: T = 25 °C, 1 mmol/L phosphate buffered pH = 7.0, 4-CNB dosage = 0.1 mg/L, ozone dosage = 0.9 mg/L, catalyst dosage = 100 mg/L

20


Page 20 of 25

Page 21 of 25


Figure 3. Effect of radical scavenger on 4-CNB removal. Conditions: T = 25 °C, 1 mmol/L phosphate buffered pH = 7.0, 4-CNB dosage = 0.1 mg/L, ozone dosage = 0.9 mg/L, catalyst dosage = 100 mg/L

21



Figure 4. Effect of pH on 4-CNB removal. Conditions: T = 25 °C, 1 mmol/L phosphate buffered pH = 3, 7, 11, 4-CNB dosage = 0.1 mg/L, ozone dosage = 0.9 mg/L, catalyst dosage = 100 mg/L

22


Page 22 of 25

Page 23 of 25


Figure 5. Effect of Si/Fe molar ratio on 4-CNB removal. Conditions: T = 25 °C, 1 mmol/L phosphate buffered pH = 7.0, 4-CNB dosage = 0.1 mg/L, ozone dosage = 0.9 mg/L, catalyst dosage = 100 mg/L, reaction time = 30 min

23



Figure 6 (a) FT-IR spectra of iron silicate, (b) spectra of DMPO–OH signals and (c) ozone concentration in the solution. Conditions: T = 25 °C, initial pH of the ozone solution was adjusted to pH = 7.0 with NaOH, ozone dosage = 0.9 mg/L, catalyst dosage = 100 mg/L, DMPO = 100 mmol/L 24


Page 24 of 25

Page 25 of 25


Graphical Abstract

25


Interface Mechanisms of Catalytic Ozonation with ... - ACS Publications

Recommend Documents