Zhihui Ai

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Name: 艾智慧; ZhiHui Ai

Organization: Central China Normal University , China

Department: Key Laboratory of Pesticide & Chemical Biology of Ministry of Education of College of Chemistry

Title: Professor(PhD)

TOPICS

Material Chemistry

Applied Chemistry

Chemicals
References

Enhanced aerobic degradation of 4-chlorophenol with iron-nickel nanoparticles

Co-reporter:Wenjuan Shen, Yi Mu, Bingning Wang, Zhihui Ai, Lizhi Zhang

Applied Surface Science 2017 Volume 393() pp:316-324

Publication Date(Web):30 January 2017

DOI:10.1016/j.apsusc.2016.10.020

Highlights

•: Bimetallic iron-nickel nanoparticles possessed an enhanced performance on aerobic degradation of 4-CP.
•: Hydroxyl radicals were the major active species contributed to aerobic 4-CP degradation with nZVI.
•: Superoxide radicals predominated the 4-CP degradation in the nZVIN/Air process.
•: The 4-CP degradation pathways were dependent on the generated superoxide radicals in the nZVIN/Air process.

Efficient removal of bromate with core-shell Fe@Fe2O3 nanowires

Co-reporter:Wenjuan Shen, Fangjing Lin, Xu Jiang, Hefei Li, Zhihui Ai, Lizhi Zhang

Chemical Engineering Journal 2017 Volume 308(Volume 308) pp:

Publication Date(Web):15 January 2017

DOI:10.1016/j.cej.2016.09.070

•Bromate was efficiently removed by core-shell Fe@Fe2O3 nanowires.•Surface bound ferrous ions of core-shell Fe@Fe2O3 nanowires promoted the BrO3− removal effectively.•O2− and H2O2 favored the bromate removal with core-shell Fe@Fe2O3 nanowires, but OH inhibited.In this study, we systematically investigated the removal of bromate (BrO3−) with core-shell Fe@Fe2O3 nanowires at neutral pH, especially the effects of surface bound ferrous ions and molecular oxygen. In the presence of Fe@Fe2O3 nanowires, bromate was reduced to Br− efficiently with the generation of HOBr intermediates. Bromide species analyses and nanowires characterizations indicated that surface bound ferrous ions of core-shell Fe@Fe2O3 nanowires could effectively promote the BrO3− removal. Meanwhile, molecular oxygen competed electrons from both Fe2+ and Fe0 to generate reactive oxygen species of O2−, H2O2, and OH during the bromate removal process. Among the generated reactive oxygen species, O2− and H2O2 favored of bromate removal, but OH inhibited. We proposed a bromate removal mechanism with core-shell Fe@Fe2O3 nanowires, which suggested that the effect of surface bound Fe(II) and molecular oxygen was taken into consideration when using nZVI for bromate remediation in waters. This study can not only deepen our understanding on the bromate removal with zero valent iron, and also shed light on the design of high performance bromate removal materials.Download high-res image (184KB)Download full-size image

Sulfite promoted photochemical cleavage of s-triazine ring: The case study of atrazine

Co-reporter:Yu Tian, Wenjuan Shen, Falong Jia, Zhihui Ai, Lizhi Zhang

Chemical Engineering Journal 2017 Volume 330(Volume 330) pp:

Publication Date(Web):15 December 2017

DOI:10.1016/j.cej.2017.08.048

•The presence of sulfite can alter the photochemical atrazine degradation pathway to cleave its s-triazine ring.•DFT results suggested that a reductive process might be highly possible to break the s-triazine ring of atrazine.•The presence of sulfite shifted a direct atrazine hydroxylated dechlorination pathway to an indirect photo-degradation route.•The degradation pathway could affect the s-triazine ring cleavage.Regarding the abundant solar energy on the earth, photochemical method is the most attractive approach for the decomposition of atrazine pollutant which is widely existed in surface water. In this study, we report that the presence of sulfite can alter the photochemical atrazine degradation pathway to cleave its s-triazine ring. Density functional theory calculation results first suggested that a reductive process might be highly possible to break the s-triazine ring of atrazine by comparing the highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap values of six possible atrazine degradation intermediates. The subsequent experimental results reveal that the presence of sulfite shifted a direct atrazine hydroxylated dechlorination pathway to an indirect photo-degradation route with the aid of hydrated electrons and hydrogen atoms, which were produced from the photolysis of sulfite solution under UV irradiation. This rational degradation pathway change increased the atrazine degradation and dechlorination rates by 4.3 times, and also effectively cleaved s-triazine ring, as confirmed by the generation of ammonium ions and small molecule acids during the degradation of 2,4-diamino-1,3,5-triazine with this sulfite promoted photochemical reduction process. This study provides a mild strategy to completely mineralize atrazine, and also sheds light on how the degradation pathway could affect the s-triazine ring cleavage.Download high-res image (77KB)Download full-size image

Insight into Core–Shell Dependent Anoxic Cr(VI) Removal with Fe@Fe2O3 Nanowires: Indispensable Role of Surface Bound Fe(II)

Co-reporter:Yi Mu, Zhihui Ai, Lizhi Zhang, and Fahui Song

ACS Applied Materials & Interfaces 2015 Volume 7(Issue 3) pp:1997

Publication Date(Web):December 26, 2014

DOI:10.1021/am507815t

In this study, we investigated the anoxic Cr(VI) removal with core–shell Fe@Fe2O3 nanowires. It was found the surface area normalized Cr(VI) removal rate constants of Fe@Fe2O3 nanowires first increased with increasing the iron oxide shell thickness and then decreased, suggesting that Fe@Fe2O3 nanowires possessed an interesting core–shell structure dependent Cr(VI) removal property. Meanwhile, the Cr(VI) removal efficiency was positively correlated to the amount of surface bound Fe(II). This result revealed that the core–shell structure dependent Cr(VI) removal property of Fe@Fe2O3 nanowires was mainly attributed to the reduction of Cr(VI) by the surface bound Fe(II) besides the reduction of Cr(VI) adsorbed on the iron oxide shell via the electrons transferred from the iron core. The indispensable role of surface bound Fe(II) was confirmed by Tafel polarization and high-resolution X-ray photoelectron spectroscopic depth profiles analyses. X-ray diffraction patterns and scanning electron microscope images of the fresh and used Fe@Fe2O3 nanowires revealed the formation of Fe(III)/Cr(III)/Cr(VI) composite oxides during the anoxic Cr(VI) removal process. This study sheds a deep insight into the anoxic Cr(VI) removal mechanism of core–shell Fe@Fe2O3 nanowires and also provides an efficient Cr(VI) removal method.Keywords: adsorption; anoxic; core−shell Fe@Fe2O3 nanowires; Cr(VI) removal; surface bound Fe(II)

Hydrothermal Synthesis of FeS2 as a High-Efficiency Fenton Reagent to Degrade Alachlor via Superoxide-Mediated Fe(II)/Fe(III) Cycle

Co-reporter:Wei Liu, Yueyao Wang, Zhihui Ai, and Lizhi Zhang

ACS Applied Materials & Interfaces 2015 Volume 7(Issue 51) pp:28534

Publication Date(Web):December 8, 2015

DOI:10.1021/acsami.5b09919

In this study, we demonstrate that hydrothermally synthesized FeS2 (syn-FeS2) is highly efficient at catalyzing the H2O2 decomposition for alachlor degradation at a wide range of initial pH (3.2–9.2). The alachlor degradation rate of syn-FeS2 heterogeneous Fenton system was almost 55 times that of its commercial pyrite (com-FeS2) counterpart at an initial pH of 6.2. Experimental results revealed that the alachlor oxidation enhancement in the syn-FeS2 Fenton system was attributed to the molecular oxygen activation induced by more surface-bound ferrous ions on syn-FeS2. The molecular oxygen activation process could generate superoxide anions to accelerate the Fe(II)/Fe(III) cycle on the syn-FeS2 surface, which favored the H2O2 decomposition to generate more hydroxyl radicals for the alachlor oxidation. It was found that the hydroxyl radicals generation rate constant of syn-FeS2 Fenton system was 71 times that of its com-FeS2 counterpart, and even 1–3 orders of magnitude larger than those of commonly used Fe-bearing heterogeneous catalysts. We detected the alachlor degradation intermediates with gas chromatography–mass spectrometry to propose tentatively a possible alachlor degradation pathway. These interesting findings could provide some new insights on the molecular oxygen activation induced by FeS2 minerals and the subsequent heterogeneous Fenton degradation of organic pollutants in the environment.Keywords: alachlor; Fe(II)/Fe(III) cycle; FeS2; molecular oxygen activation; superoxide anions

A dual-cell wastewater treatment system with combining anodic visible light driven photoelectro-catalytic oxidation and cathodic electro-Fenton oxidation

Co-reporter:Xing Ding, Zhihui Ai, Lizhi Zhang

Separation and Purification Technology 2014 Volume 125() pp:103-110

Publication Date(Web):7 April 2014

DOI:10.1016/j.seppur.2014.01.046

Core–shell Fe–Fe2O3 nanostructures as effective persulfate activator for degradation of methyl orange

Co-reporter:Linli Zhu, Zhihui Ai, Wingkei Ho, Lizhi Zhang

Separation and Purification Technology 2013 Volume 108() pp:159-165

Publication Date(Web):19 April 2013

DOI:10.1016/j.seppur.2013.02.016

In this study, core–shell Fe–Fe2O3 nanostructures (FNs) were used to effectively activate sodium persulfate (Na2S2O8) to induce sulfate radicals (SO4-) oxidation of methyl orange (MO) in aqueous solution (FNs/Na2S2O8). In this FNs/Na2S2O8 system, an enhanced degradation of MO was achieved in comparison with the Fe2+/Na2S2O8Fe2+/Na2S2O8 system using ferrous ions as persulfate activator under neutral pH condition. An acid pH and a high persulfate to FNs molar ratio (Na2S2O8:FNs) were favorable to the MO oxidation in the FNs/Na2S2O8 process. We characterized the prepared FNs and the used FNs during the FNs/Na2S2O8 process via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) systematically. On the basis of the degradation and characterization results, we proposed a mechanism for the degradation of MO in the FNs/Na2S2O8 process, which involved in situ homogenous and heterogeneous activation of persulfate simultaneously.Highlights► FNs could activate Na2S2O8 to generate sulfate radicals effectively. ► FNs/Na2S2O8 system showed an enhanced activity on degradation of MO. ► Sulfate radicals were responsible for degradation of MO in the FNs/Na2S2O8 system.

A stable single-crystal Bi3NbO7 nanoplates superstructure for effective visible-light-driven photocatalytic removal of nitric oxide

Co-reporter:Zhihui Ai, Wingkei Ho, Shuncheng Lee

Applied Surface Science 2012 Volume 263() pp:266-272

Publication Date(Web):15 December 2012

DOI:10.1016/j.apsusc.2012.09.041

Abstract

In this study, bismuth niobate (Bi₃NbO₇) single-crystal nanoplates superstructure (BNS) was prepared via a facile hydrothermal route without adding any surfactants and templates by using bismuth citric and niobium pentoxide as precursors. The as-prepared products were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption, X-ray photoelectron spectroscopy (XPS), and UV–vis diffuse reflectance spectrum (DRS). The characterization results revealed that the BNS nanostructures were self-assembled of single crystalline nanoplates under hydrothermal environment. These BNS exhibited excellent visible-light-driven (λ > 420 nm) photocatalytic performances for the removal of gaseous nitrogen monoxide (NO), the removal of NO reached 42.3% in 40 min at the presence of BNS, which was much higher than those of C-doped TiO₂ (25% of NO removal), the InVO₄ hollow microspheres (25% of NO removal), as well as the BiOBr nanoplates microspheres (30% of NO removal). Close investigation indicated that plenty of pores existed in the aggregation of BNS superstructures, which could serve as efficient transport paths for NO molecules and harvesting of more light. Moreover, the BNS exhibited high stability during multiple runs of photocatalytic removal of NO due to their special superstructures. The study provides a facile method to synthesize BNS with high efficiency and high stability in the visible-light spectral range.

Efficient Visible Light-Driven Photocatalytic Degradation of Pentachlorophenol with Bi2O3/TiO2–xBx

Co-reporter:Ke Su, Zhihui Ai, and Lizhi Zhang

The Journal of Physical Chemistry C 2012 Volume 116(Issue 32) pp:17118-17123

Publication Date(Web):July 19, 2012

DOI:10.1021/jp305432g

In this study, a new TiO2-based photocatalyst with both B doping and Bi2O3 coupling (Bi2O3/TiO2–xBx) was synthesized to degrade pentachlorophenol under visible light (λ > 420 nm) irradiation. The resulting Bi2O3/TiO2–xBx sample exhibited much higher photocatalytic performance than the counterparts with only B doping or Bi2O3 coupling or pure TiO2. This is because B doping could result in more visible light absorption to produce more photogenerated electron–hole pairs, while Bi2O3 coupling could favor the separation and transfer of photoinduced charge carriers to inhibit their recombination. We interestingly found that the visible light-driven degradation of pentachlorophenol was mainly attributed to photogenerated holes and ·O2– other than ·OH as reported previously because the hybridization of B 2p orbital and O 2p orbital could elevate the VB edge of Bi2O3/TiO2–xBx as compared to that of pure TiO2 and thus lower the oxidation ability of photogenerated holes, blocking the pathway of photogenerated holes induced oxidation of surface OH– and water to generate ·OH. The intermediates during the PCP photodegradation were systematically analyzed, ruling out the existence of high toxic polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. These results reveal that the visible light-driven photocatalytic degradation of PCP over Bi2O3/TiO2–xBx is an effective and green method to remove highly toxic halogenated aromatic compounds.

Aerosol-assisted flow synthesis of WxTi1−xO2 solid solution spheres with enhanced photocatalytic activity

Co-reporter:Zhihui Ai, Xiao Song, Yu Huang, Lizhi Zhang, Shuncheng Lee

Applied Surface Science 2011 Volume 257(Issue 10) pp:4725-4730

Publication Date(Web):1 March 2011

DOI:10.1016/j.apsusc.2010.12.145

Abstract

In this paper, W_xTi_1−xO₂ solid solutions (x = 0.000, 0.005, 0.010, 0.015, and 0.020) microspheres were synthesized with an aerosol-assisted flow synthesis method. The resulting samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption, UV–vis diffuse reflectance spectrum (DRS) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the as-prepared catalysts were measured by the degradation of rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm). All the solid solutions exhibited higher photocatalytic activities than pure TiO₂ and the W_0.015Ti_0.985O₂ solid solution possessed the highest photocatalytic activity. The degradation constant of RhB on W_0.015Ti_0.985O₂ solid solution catalyst was about 15 times of that of the pure TiO₂ and 25 times of that of Degussa P25, respectively. This study provides an effective method to prepare visible light photocatalysts on a large scale.

Efficient Visible Light Photocatalytic Removal of NO with BiOBr-Graphene Nanocomposites

Co-reporter:Zhihui Ai ; Wingkei Ho ;Shuncheng Lee

The Journal of Physical Chemistry C 2011 Volume 115(Issue 51) pp:25330-25337

Publication Date(Web):November 27, 2011

DOI:10.1021/jp206808g

In this study, we demonstrate that bismuth oxybromide and graphene nanocomposites (BGCs) exhibit superior performance on photocatalytic removal of gaseous nitrogen monoxide (NO) to pure BiOBr under visible light irradiation (λ > 420 nm). The photocatalytic NO removal rate constant of BGCs was 2 times that of pure BiOBr. The BGCs were prepared by a facile solvothermal route with using graphene oxide (GO), bismuth nitrite, and cetyltrimethyl ammonium bromide (CTAB) as the precursors. During the synthesis, both of the reduction of GO and the formation of BiOBr nanocrystals were achieved simultaneously. On the basis of the characterization results, we attributed the enhanced photocatalytic activity of the BGCs nanocomposites to more effective charge transportations and separations arisen from the strong chemical bonding between BiOBr and graphene, not to their light absorption extension in the visible region and higher surface area.

Rapid decolorization of azo dyes in aqueous solution by an ultrasound-assisted electrocatalytic oxidation process

Co-reporter:Zhihui Ai, Jinpo Li, Lizhi Zhang, Shuncheng Lee

Ultrasonics Sonochemistry 2010 Volume 17(Issue 2) pp:370-375

Publication Date(Web):February 2010

DOI:10.1016/j.ultsonch.2009.10.002

In this study, we developed a novel ultrasound-assisted electrocatalytic oxidation (US–EO) process to decolorize azo dyes in aqueous solution. Rhodamine B was decolorized completely within several minutes in this developed US–EO system. Oxidation parameters such as applied potentials, power of the ultrasound, initial pH of the solution, and initial concentration of RhB were systematically studied and optimized. An obvious synergistic effect was found in decolorization of RhB by the US–EO process when comparing with either ultrasound (US) process or electrocatalytic oxidation (EO) one. Additionally, the decolorization of other azo dyes, such as methylene blue, reactive brilliant red X-3B, and methyl orange, were also effective in the US–EO system. The results indicated that US–EO system was effective for the decolorization of azo dyes, suggesting its great potential in dyeing wastewater treatment.

Ultrasonic spray pyrolysis synthesis and visible light activity of carbon-doped Ti0.91Zr0.09O2 solid solution photocatalysts

Co-reporter:Yu Huang, Kejian Deng, Zhihui Ai, Lizhi Zhang

Materials Chemistry and Physics 2009 Volume 114(Issue 1) pp:235-241

Publication Date(Web):15 March 2009

DOI:10.1016/j.matchemphys.2008.09.008

Visible light active carbon-doped Ti0.91Zr0.09O2 solid solution photocatalysts were directly obtained by ultrasonic spray pyrolysis of an aqueous solution containing TiCl4, ZrOCl2·8H2O and CH3(CH2)17NH2. The samples were characterized by X-ray diffraction, scanning electron microscopy, nitrogen adsorption, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and infrared spectroscopy. The characterizations revealed the spherical structures of the resulting samples and the substitution of Ti4+ by Zr4+ ions and carbon in the TiO2 lattice. Meanwhile, partial carbon and zirconium existed in the form of carbonate and zirconia, respectively. Moreover, the pyrolysis temperature had significant effect on the amount of dopants substituted in the resulting samples. The carbon doping successfully extended the absorption edges of the solid solution to visible light region. We evaluated photocatalytic activities of the doped solid solution photocatalysts on degradation of rhodamine B in aqueous solutions under visible light irradiation (λ ≥ 420 nm). It was found that the carbon-doped solid solution photocatalysts exhibited enhanced photocatalytic activity under visible light irradiation comparing to the undoped counterpart. On the basis of characterization results, we attributed the enhanced visible light activity to the carbonate species in solid solution photocatalysts. This study provides a way to synthesize visible light active solid solution photocatalysts on a large scale.

Microwave-assisted green synthesis of MnO2 nanoplates with environmental catalytic activity

Co-reporter:Zhihui Ai, Lizhi Zhang, Fanhai Kong, Hao Liu, Wenting Xing, Jianrong Qiu

Materials Chemistry and Physics 2008 Volume 111(Issue 1) pp:162-167

Publication Date(Web):15 September 2008

DOI:10.1016/j.matchemphys.2008.03.043

In this paper, MnO2 nanoplates were synthesized in aqueous solution under the microwave irradiation, without using any templates, catalysts, and organic reagents. The as-prepared MnO2 nanoplates were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermo-gravimetric (TG) analysis, and nitrogen sorption measurements. Microwave irradiation could produce MnO2 with uniform size and well-defined shape as well as high crystallinity. On the basis of experimental results, a possible formation mechanism of MnO2 nanoplates was proposed. Furthermore, the resulting MnO2 nanoplates were found to exhibit remarkable environmental catalytic performance in degradation of Rhodamine B (RhB) in aqueous solution, indicating these MnO2 nanoplates is very promising for wastewater treatment.

Fe@Fe2O3 Core−Shell Nanowires as Iron Reagent. 4. Sono−Fenton Degradation of Pentachlorophenol and the Mechanism Analysis

Co-reporter:Tao Luo, Zhihui Ai and Lizhi Zhang

The Journal of Physical Chemistry C 2008 Volume 112(Issue 23) pp:8675-8681

Publication Date(Web):May 20, 2008

DOI:10.1021/jp800926n

In this study, a novel sono-Fenton system based on Fe@Fe2O3 core−shell nanowires was used to degrade a recalcitrant pollutant, pentachlorophenol (PCP). We studied the influence of the pH value and the atmosphere on the degradation efficiency and the production of oxidative free radicals (such as ·OH radicals). The intermediates and the final products were determined for the analysis of the possible pathway of the decomposition. We found that this sono-Fenton system was effective for oxidizing PCP. The results help to the understanding the synergistic mechanism of the Fe@Fe2O3 core−shell nanowires and ultrasound irradiation for the decomposition of the recalcitrant organic pollutant in the aqueous solution. This sono-Fenton system based on the Fe@Fe2O3 core−shell nanowires is a new economic and environmentally friendly technique to eliminate persistent organic pollutants in contaminated water.

Selective synthesis and visible-light photocatalytic activities of BiVO4 with different crystalline phases

Co-reporter:Xi Zhang, Zhihui Ai, Falong Jia, Lizhi Zhang, Xiaoxing Fan, Zhigang Zou

Materials Chemistry and Physics 2007 Volume 103(Issue 1) pp:162-167

Publication Date(Web):15 May 2007

DOI:10.1016/j.matchemphys.2007.02.008

Tetragonal and monoclinic bismuth vanadate (BiVO4) powders were selectively synthesized by aqueous processes. The characterizations of the as-prepared BiVO4 powders were carried out by X-ray diffraction, nitrogen adsorption, scanning electron microscopy and UV–vis diffuse reflectance spectroscopy. The photocatalytic activities of different BiVO4 samples were determined by degradation of methylene blue solution under visible-light irradiation (λ > 420 nm) and compared with that of TiO2 (Degussa P25). The band gaps of the as-prepared BiVO4 were determined from UV–vis diffuse reflectance spectra. It was found that monoclinic BiVO4 with a band gap of 2.34 eV showed higher photocatalytic activity than that of tetragonal BiVO4 with a band gap of 3.11 eV.

Aerosol flow synthesis of N, Si-codoped TiO2 hollow microspheres with enhanced visible-light driven photocatalytic performance

Co-reporter:Zhihui Ai, Zhiting Gao, Ke Su, Wingkei Ho, Lizhi Zhang

Catalysis Communications (5 December 2012) Volume 29() pp:189-193

Publication Date(Web):5 December 2012

DOI:10.1016/j.catcom.2012.10.015

In this study, porous N, Si-codoped TiO2 hollow microsphere photocatalysts have been prepared by a facile aerosol flow synthesis method. The prepared photocatalysts were characterized by XRD, SEM, TEM, UV–vis DRS, and XPS. The results indicated that both nitrogen doping and formation of TiOSi bond happened in the N, Si-codoped TiO2 hollow microspheres, leading to an enhanced visible-light driven photocatalytic performance on degradation of salicylic acid compared with pure TiO2 and single N or Si doped TiO2 counterpart catalysts.Highlights► N, Si-codoped TiO2 photocatalysts were prepared by an aerosol flow method. ► Both the nitrogen doping and the formation of TiOSi bond happened in the N, Si-codoped TiO2. ► N, Si-codoped TiO2 showed enhanced visible-light driven photocatalytic performance.

Ascorbic acid induced atrazine degradation

Co-reporter:Xiaojing Hou, Xiaopeng Huang, Zhihui Ai, Jincai Zhao, Lizhi Zhang

Journal of Hazardous Materials (5 April 2017) Volume 327() pp:71-78

Publication Date(Web):5 April 2017

DOI:10.1016/j.jhazmat.2016.12.048

•Atrazine could be degraded by AA in a wide range of pH from 4 to 12.•The reductive ability of AA at different pH values was compared.•The pH dependent reductive performance of AA was clarified.•A kinetic model was proposed to discuss the atrazine degradation mechanism.In this study, we systematically investigated the degradation efficiency and the degradation mechanism of atrazine in the presence of ascorbic acid at different pH values. Although atrazine could be degraded by ascorbic acid in a wide pH range from 4 to 12, its degradation under either acidic (pH ≤ 4) or alkaline (pH ≥ 12) condition was more efficient than under neutral condition (pH = 7). This pH dependent atrazine degradation was related to the reactive characteristic of atrazine and the reductive activity of ascorbic acid. The ascorbic acid induced atrazine degradation pathways at different pH were investigated by comparing the atrazine degradation intermediates with liquid chromatography-mass spectrometry, high performance liquid chromatography and ion chromatography. It was found that more products were detected in presence of ascorbic acid at alkaline condition. The appearance of chloride ions confirmed the dechlorination of atrazine by ascorbic acid in the absence of molecular oxygen, while its dechlorination efficiency reached highest at pH 12. These results can shed light on the application of AA for the organic pollutant remediation.Download high-res image (265KB)Download full-size image

In-situ generated H2O2 induced efficient visible light photo-electrochemical catalytic oxidation of PCP-Na with TiO2

Co-reporter:Wei Liu, Huichao Liu, Zhihui Ai

Journal of Hazardous Materials (15 May 2015) Volume 288() pp:97-103

Publication Date(Web):15 May 2015

DOI:10.1016/j.jhazmat.2015.02.024

•We demonstrate a novel visible light driven PEC system for efficient PCP-Na degradation.•The in-situ generated H2O2 reacts with TiO2 suspensions to form interfacial TiIVOOH species.•TiIVOOH species endow TiO2 with visible light photocatalytic activity.•O2− and OH are responsible for the dechlorination and mineralization of PCP-Na, respectively.In this study, we developed a novel photo-electrochemical catalytic oxidation wastewater treatment system by interacting the cathodic in-situ generated H2O2 with TiO2 suspension to form interfacial TiIVOOH species, which endowed the PEC system with superior efficiency for degrading sodium pentachlorophenate (PCP-Na) under visible light irradiation at neutral pH. The apparent PCP-Na degradation rate constant of the PEC system was more than 10 times that of the electrochemical oxidation counterpart. In the PEC system, the interfacial TiIVOOH species injected electrons to the conduction band of TiO2 to initiate the activation of O2 and the in-situ generated H2O2 adsorbed on the surface of TiO2, lead to producing reactive oxygen species of superoxide anions and hydroxyl radicals, which were responsible for the dechlorination and mineralization of PCP-Na during the PEC process, respectively. The dosage of TiO2 catalyst and the current intensity applied on PCP-Na degradation were optimized. This study develops a high efficient PEC oxidation system for wastewater treatment and provides new insight into the role of cathodic in-situ generated H2O2 on PEC oxidation of PCP-Na with TiO2 under visible light irradiation.We demonstrate a novel PEC system where the cathodic in-situ generated H2O2 interacts with TiO2 particles to form interfacial TiIVOOH species which endow TiO2 with visible light photocatalytic activity for efficient PCP-Na degradation for the first time.Download full-size image