Jianmeng Chen

Zhejiang University of Technology, Hang-hsien, Zhejiang Sheng, China

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Publications (83)235.05 Total impact

  • Separation and Purification Technology 08/2014; 132:62–69. · 3.07 Impact Factor
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    ABSTRACT: Ag supported on AgIO3 (Ag/AgIO3 particles), a plasmonic photocatalyst, was synthesized through a facile solid-state ion-exchange procedure followed by reduction with hydrazine hydrate. The particles displayed high activity and stability in the photocatalytic conversion of CO2 to CH4 and CO using water vapor under visible-light irradiation (> 400 nm wavelength).
    Nanoscale 07/2014; · 6.74 Impact Factor
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    ABSTRACT: Photocatalytic reduction of carbon dioxide can activate chemically inert carbon dioxide by the use of renewable energy. In the present work, the main products of photocatalytic reduction of CO2 in aqueous TiO2 suspensions were found to be methane, methanol, formaldehyde, carbon monoxide, and H2. Anatase TiO2 catalysts with various morphologies, such as nanoparticle, nanotube, and nanosheet, were synthesized through a hydrothermal method. The TiO2 nanosheets were more active than the nanotubes or nanoparticles in the reduction of CO2 in aqueous solution. This is because the photogenerated carriers prefer to flow to the specific facets. The TiO2 sheet with high-energy exposed {001} facets facilitates the oxidative dissolution of H2O with photogenerated holes, leaving more photogenerated electrons available for the reduction of CO2 on {101} facets. Moreover, surface fluorination promotes the formation of Ti3+ species, which is helpful in the reduction of CO2 to CO2– and in extending the lifetime of photogenerated electron–hole pairs. The optimum ratio of exposed {001} to {101} facets for surface-fluorinated TiO2 nanosheets was found to be 72:28, which corresponds to an initial F/Ti ratio of 1. From our analysis of the effect of adding of known intermediates on the photocatalytic reduction of CO2, we propose that the photocatalytic reduction of CO2 with H2O on surface-fluorinated TiO2 nanosheets proceeds via a mechanism involving generation of hydrogen radicals and carbon radicals.
    Energy & Fuels 06/2014; 28(6):3982–3993. · 2.73 Impact Factor
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    ABSTRACT: A strain Pandoraea pnomenusa LX-1 that uses dichloromethane (DCM) as sole carbon and energy source has been isolated and identified in our laboratory. The optimum aerobic biodegradation of DCM in batch culture was evaluated by response surface methodology. Maximum biodegradation (5.35 mg/(L·hr)) was achieved under cultivation at 32.8°C, pH 7.3, and 0.66% NaCl. The growth and biodegradation processes were well fitted by Haldane's kinetic model, yielding maximum specific growth and degradation rates of 0.133 hr−1 and 0.856 hr−1, respectively. The microorganism efficiently degraded a mixture of DCM and coexisting components (benzene, toluene and chlorobenzene). The carbon recovery (52.80%–94.59%) indicated that the targets were predominantly mineralized and incorporated into cell materials. Electron acceptors increased the DCM biodegradation rate in the following order: mixed > oxygen > iron > sulfate > nitrate. The highest dechlorination rate was 0.365 mg Cl−/(hr·mg biomass), obtained in the presence of mixed electron acceptors. Removal was achieved in a continuous biotrickling filter at 56%–85% efficiency, with a mineralization rate of 75.2%. Molecular biology techniques revealed the predominant strain as P. pnomenusa LX-1. These results clearly demonstrated the effectiveness of strain LX-1 in treating DCM-containing industrial effluents. As such, the strain is a strong candidate for remediation of DCM coexisting with other organic compounds.
    Journal of Environmental Sciences 05/2014; 26(5):1108–1117. · 1.92 Impact Factor
  • Qizhou Dai, Jiayu Wang, Jun Chen, Jianmeng Chen
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    ABSTRACT: The catalyst of cerium supported on activated carbon (Ce/AC) for ozonation was prepared and the catalytic activity was evaluated by the degradation of p-toluenesulfonic acid (p-TSA). The results showed that Ce/AC catalyst could not only greatly enhance the degradation of p-TSA but also significantly increase the efficiency of COD removal by ozonation. The COD removal could reach 74.1% with the Ce/AC catalyst at 60 min, while the effects of activated carbon (AC) catalyst and without catalyst were only 62.4% and 50.8%, respectively. The superiority of Ce/AC catalyst was attributed to the fact that cerium increased the generation of hydroxyl radicals (OH), which could react with p-TSA and intermediate to form oxidized products rapidly. Based on the intermediates detected by GC/MS, IC and HPLC, a possible degradation pathway of p-TSA was proposed. Our aim is to provide basic data and theoretical support for pharmaceutical wastewater treatment by catalytic ozonation.
    Separation and Purification Technology 04/2014; 127:112–120. · 3.07 Impact Factor
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    ABSTRACT: Fe3O4 magnetic nanoparticles (MNPs) were employed for electro-Fenton (Fe3O4–electro-Fenton) degradation of C.I. Reactive Blue 19 (RB19) in an undivided electrochemical reactor with an activated carbon fiber felt cathode and a platinum anode. On the basis of physicochemical characterization of the Fe3O4 MNPs as well as quantitative measurements of iron leaching and H2O2 generation, it is concluded that the Fe3O4 MNPs facilitated the decomposition of H2O2 to generate hydroxyl radicals (•OH). Moreover, the cathodic electro-Fenton facilitated electro-regeneration of ferrous ion and maintained continuous supply of H2O2. The effect of several operational parameters such as pH, current density, amount of added Fe3O4 MNPs, initial RB19 concentration, and temperature on the removal of total organic carbon was investigated. It was found that the Fe3O4–electro-Fenton degradation of RB19 followed two-stage first-order kinetics with an induction period and a rapid degradation stage. Mineralization of RB19 proceeded rapidly only at pH 3.0. Increasing the current density and the dosage of Fe3O4 MNPs enhanced the rate of RB19 degradation. However, higher current densities and Fe3O4 dosages inhibited the reaction. The rate of RB19 degradation decreased with the increase in initial RB19 concentration and increased with the increase in temperature. The removal efficiency of total organic carbon reached 87.0% after 120 min of electrolysis at an initial pH of 3.0, current density of 3.0 mA/cm2, 1.0 g/L concentration of added Fe3O4 MNPs, 100 mg/L initial dye concentration, and 35 °C temperature. On the basis of the analytical results for the intermediate products and the assumption that •OH radicals are the major reactive species, we propose a possible pathway of RB19 degradation during the cathodic electro-Fenton process using Fe3O4 MNPs as iron source.
    Industrial & Engineering Chemistry Research 02/2014; 53(9):3435–3447. · 2.24 Impact Factor
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    ABSTRACT: A novel visible-light-active BiOCl/BiVO4 photocatalyst with a p–n heterojunction structure was prepared using a hydrothermal method. The photocatalytic activity of the heterojunction was investigated by monitoring the change in methyl orange (MO) concentration under visible-light irradiation. The results reveal that the composite exhibited markedly improved efficiency for MO photodegradation in comparison with pure BiVO4, BiOCl, and Degussa P25. This is ascribed to the B-type heterojunction structure with a strong oxidative ability and efficient charge separation and transfer across the BiOCl/BiVO4 p–n junction. The highest activity was obtained in the BiOCl/BiVO4 heterojunction using a composite of 13 mol % BiOCl and 87 mol % BiVO4. The removal of MO was mainly initiated by valence-band holes, but dissolved oxygen also played a crucial role in consuming the conduction-band electrons. This was verified by the effects of scavengers and N2 purging.
    The Journal of Physical Chemistry C 12/2013; 118(1):389–398. · 4.84 Impact Factor
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    ABSTRACT: A series of TiO2 with different crystal phases and morphologies was synthesized via a facile hydrothermal process using titanium n-butoxide and concentrated hydrochloric acid as raw materials. The photocatalytic activity of the samples was evaluated by degradation of Methyl Orange in aqueous solution under UV-Visible light irradiation. On the basis of detailed analysis of the characterizing results of high-resolution transmission electron microscopy, X-ray powder diffraction measurements, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurement, it was concluded that the photo-activity of the catalyst is related directly to the 3D morphology and the crystal phase composition. An excellent catalyst should have both a rutile 3D flower-like structure and anatase granulous particles. The 3D flower-like structure could enhance light harvesting, as well as the transfer of reactant molecules from bulk solution to the reactive sites on TiO2. In addition, the optimum anatase/rutile phase ratio was found to be 80:20, which is beneficial to the effective separation of the photogenerated electron–hole pairs.
    Journal of Environmental Sciences 12/2013; 25(12):2460–2468. · 1.92 Impact Factor
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    ABSTRACT: The goal of this study was to identify promising new biomarkers of phenanthrene by identifying differentially expressed proteins in Eisenia fetida after exposure to phenanthrene. Extracts of earthworm epithelium collected at days 2, 7, 14, and 28 after phenanthrene exposure were analyzed by two dimensional electrophoresis (2-DE) and quantitative image analysis. Comparing the intensity of protein spots, 36 upregulated proteins and 45 downregulated proteins were found. Some of the downregulated and upregulated proteins were verified by MALDI-TOF/TOF-MS and database searching. Downregulated proteins in response to phenanthrene exposure were involved in glycolysis, energy metabolism, chaperones, proteolysis, protein folding and electron transport. In contrast, oxidation reduction, oxygen transport, defense systems response to pollutant, protein biosynthesis and fatty acid biosynthesis were upregulated in phenanthrene-treated E. fetida. In addition, ATP synthase b subunit, lysenin-related protein 2, lombricine kinase, glyceraldehyde 3-phosphate dehydrogenase, actinbinding protein, and extracellular globin-4 seem to be potential biomarkers since these biomarker were able to low levels (2.5mgkg(-1)) of phenanthrene. Our study provides a functional profile of the phenanthrene-responsive proteins in earthworms. The variable levels and trends in these spots could play a potential role as novel biomarkers for monitoring the levels of phenanthrene contamination in soil ecosystems.
    Chemosphere 07/2013; · 3.14 Impact Factor
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    ABSTRACT: In the present work, reduction of Cr(VI) induced by UV–visible light in aqueous solution was investigated. The aqueous medium contained TiO2 nanosheets and no additional reducing agents or hole scavengers. A hydrothermal method was used to synthesize fluorinated TiO2 nanostructures with various percentages of exposed {001} facets and initial F/Ti ratios. Fluorine-free TiO2 nanosheets were obtained by washing the TiO2 samples with NaOH solution. The surface fluorination facilitates the adsorption process by increasing the number of surface OH groups generated. Moreover, fluorination efficiently inhibits the recombination of photogenerated electron–hole pairs. The {001} facets have an indirect role in the photocatalytic reduction of Cr(VI) because oxidative dissolution of H2O occurring on {001} facets and Cr(VI) reduction occurring on {101} facets are simultaneous reactions. The optimal ratio of exposed {001} to {101} was found to be 72:18.
    Industrial & Engineering Chemistry Research 07/2013; 52(28):9556–9565. · 2.24 Impact Factor
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    ABSTRACT: In bioelectrochemically reductive dechlorination of chlorinated organic compounds (COCs), the electrons transfer from enzyme in the electrode to COCs was the key step, which determined the average current efficiency (CE) and was influenced by the pH and temperature of the systems. In this work, the effect of temperature (288–318 K) and pH (2–11) of the electrolyte on decholrination of trichloroacetic acid (TCA) was investigated in the sodium alginate/hemoglobin-multiwalled carbon nanotubes-graphite composite electrode (Hb/SA–MWCNT–GE). The results showed that the most favourable degradation conditions for TCA by Hb/SA–MWCNT–GE were found to be pH 3 and 310 K. By varying the pH of the systems, it was found that a proton accompanied with an electron transfer between the electrode and heme Fe(III)/Fe(II) of Hb during the reaction. Additionally, the activation energy of 26.2 kJ mol−1 was also calculated by the Arrhenius equation for the reaction. The total mass balance of the reactant and the products was in the range of 97–105% during the bioelectrochemically reductive reaction. The CE only decreased from 87% to 83% when the Hb/SA–MWCNT–GE was used 5 times. Based on the intermediates detected, a pathway was proposed for TCA degradation in which it underwent dechlorination process. The main degradation mechanism described by a parallel reaction rather than by a sequential reaction for dechlorination of TCA in Hb/SA–MWCNT–GE system was proposed. These data provided relevant information about the applicability of bioelectrocatalytic systems for treatment of wastewater contaminated by COCs.
    Electrochimica Acta 03/2013; 92:153–160. · 4.09 Impact Factor
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    ABSTRACT: To enhance the activity of chemi-deposited palladium/nickel foam (Pd/Ni) electrodes used for an electrochemical dechlorination process, silver or copper was deposited electrochemically onto the nickel foam substrate (to give Ag/Ni or Cu/Ni) before the chemical deposition of palladium. The physicochemical properties of the resulting materials (Pd/Ni, Pd/Ag/Ni and Pd/Cu/Ni) were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their electrochemical catalytic activities were evaluated by monitoring the electrochemical dechlorination of 2-chlorobiphenyl (2-CB) in strongly alkaline methanol/water solution. The results show that the Pd/Ag/Ni and Pd/Cu/Ni electrodes had consistently higher electrocatalytic activities and current efficiencies (CEs) compared with the untreated Pd/Ni electrode. The Pd/Ag/Ni electrode exhibited the highest activity. The dechlorination was also studied as a function of Pd loading, the Ag or Cu interlayer loadings, and the current density. The Pd loading and the interlayer loadings both had positive effects on the dechlorination reaction. Increasing the current density increased the reaction rate but reduced the CE. The improvement of the electrocatalytic activities of the Pd/Ni electrode by applying the interlayer of Ag or Cu resulted from the enlargement of the effective surface area of the electrode and the adjustment of the metalH bond energy to the appropriate value, as well as the effective adsorption of 2-CB on Ag. Moreover, the high catalytic activity of the Pd/Ag/Ni electrode was maintained after six successive cyclic experiments, whereas Pd/Cu/Ni electrodes deactivate severely under the same conditions.
    Journal of hazardous materials 02/2013; 250-251C:181-189. · 4.33 Impact Factor
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    ABSTRACT: In this study, the novel PbO2 electrodes co-doped with rare earth (La and Ce) were prepared by electrodeposition technique. The rare earth co-doped electrode applied as an anode was carefully studied for the degradation of cationic gold yellow X-GL, in sono-electrochemical oxidation system. Optimal degradation conditions were achieved by investigating the effects of different parameters, such as initial concentrations, pH levels, electrolyte concentrations, current densities, on the constant frequency and power of ultrasound. Under the optimal conditions, removal rates of cationic gold yellow X-GL and COD were about 99.95% and 74.03%, respectively, after 2 h degradation. Moreover, the synergistic effect in sono-electrochemical oxidation system was also certificated and discussed. In addition, SEM images indicated that the surface of Ti/SnO2–Sb2O3/PTFE-La-Ce-β-PbO2 electrode had the dense structure and the preferred crystalline orientation, which could be helpful to improve the mass transportation and mineralization of cationic gold yellow X-GL.
    Separation and Purification Technology 02/2013; 104:9–16. · 3.07 Impact Factor
  • Shijin Wu, Lili Zhang, Jianmeng Chen
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    ABSTRACT: Paracetamol (4'-hydroxyacetanilide, N-acetyl-p-aminophenol, acetaminophen, and paracetamol) is a widely used over-the-counter analgesic and antipyretic drug. Paracetamol and structural analogs are ubiquitous in the natural environment and easily accumulate in aquatic environment, which have been detected in surface waters, wastewater, and drinking water throughout the world. Paracetamol wastewater is mainly treated by chemical oxidation processes. Although these chemical methods may be available for treating these pollutants, the harsh reaction conditions, the generation of secondary pollutants, and the high operational cost associated with these methods have often made them not a desirable choice. Biodegradation of paracetamol is being considered as an environmentally friendly and low-cost option. The goal of this review is to provide an outline of the current knowledge of biodegradation of paracetamol in the occurrence, degrading bacteria, and proposed metabolic/biodegrading pathways, enzymes and possible intermediates. The comprehensive understanding of the metabolic pathways and enzyme systems involved in the utilization of paracetamol means will be helpful for optimizing and allowing rational design of biodegradation systems for paracetamol-contaminated wastewater.
    Applied Microbiology and Biotechnology 10/2012; 96(4):875-84. · 3.81 Impact Factor
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    ABSTRACT: The photodegradation of gaseous dichloromethane (DCM) by a vacuum ultraviolet (VUV) light in a spiral reactor was investigated with different reaction media and initial concentrations. Through the combination of direct photolysis, O3 oxidation and HO* oxidation, DCM was ultimately mineralized into inorganic compounds (such as HCl, CO2, H2O, etc.) in the air with relative humidity (RH) of 75%-85%. During the photodegradation process, some small organic acids (including formic acid, acetic acid) were also detected and the intermediates were more soluble than DCM, providing a possibility for its combination with subsequent biodegradation. Based on the detected intermediates and the confirmed radicals, a photodegradation pathway of DCM by VUV was proposed. With RH 75%-80% air as the reaction medium, the DCM removal followed the second-order kinetic model at inlet concentration of 100-1000 mg/m3. Kinetic analysis showed that the reaction media affected the kinetic constants of DCM conversion by a large extent, and RH 80% air could cause a much lower half-life for its conversion. Such results supported the possibility that VUV photodegradation could be used not only for the mineralization of DCM but also as a pretreatment before biodegradation.
    Journal of Environmental Sciences 10/2012; 24(10):1777-84. · 1.92 Impact Factor
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    ABSTRACT: Biodegradation has become a popular alternative remediation technology for its economic and ecological advantages. An aerobic bacterium (strain ZW) capable of degrading alpha-pinene was isolated from a biofilter by a selective enrichment. Based on the 16S rRNA gene analysis and physiochemical properties, this strain was identified as Pseudomonas veronii. Under the optimized condition achieved by the response surface methodology (RSM), as well as pH 6.82, temperature 26.3 degrees C and NaCl concentration 1.36%, almost 100% a-pinene could be removed within 45 hr. Enzymatic biodegradation by the crude intracellular enzyme could be described well by the Michaelis-Menten model in which the maximum degradation rate Vmax and the half-saturation constant K(m) were calculated to be 0.431 mmol/(L x min) and 0.169 mmol/L, respectively. Activity assay of catechol suggested that the strain ZW possessed a catechol-1,2-dioxygenase and could decompose benzene-ring through ortho ring cleavage. Based on the identified intermediates by GC/MS, a new metabolic pathway was proposed, in which the final metabolites were some simpler organic and inorganic compounds. The present work demonstrated that the strain ZW would have a great application prospect for the remediation of alpha-pinene-contaminated environment.
    Journal of Environmental Sciences 10/2012; 24(10):1806-15. · 1.92 Impact Factor
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    ABSTRACT: A new strain Mycobacterium cosmeticum byf-4 able to simultaneously degrade benzene, toluene, ethylbenzene, and o-xylene (BTE(o-)X) compounds has been isolated and identified previously in our laboratory. We further report here the extent of degradation of every BTE(o-)X component, and unravel the initial mechanism involved in BTE(o-)X degradation. This organism efficiently degrades all the BTE(o-)X components when these compounds are added either individually or as a composite mixture, and has a preference for toluene followed by benzene, ethylbenzene and then o-xylene. The significantly high carbon recovery indicated that the predominant fate for BTE(o-)X compounds was mineralization and incorporation into cell materials. The presence of BTE compounds in binary or ternary mixtures consistently had a negative effect on o-xylene degradation. The initial steps involved in the degradation of BTE(o-)X were investigated by isolation of metabolites and assay of reverse transcription RT-PCR. Isolation of metabolites suggested that the BTE(o-)X compounds were initially converted by a dioxygenase to their respective catechols. The gene sequence of the PCR amplicons revealed that this isolate contained a 454-bp toluene dioxygenase (TOD) fragment. The BTE(o-)X-specific induction of the genes encoding TOD was confirmed by RT-PCR analysis. These results indicated that TOD was possibly responsible for the initial steps of BTE(o-)X catabolism in M. cosmeticum byf-4.
    Chemosphere 09/2012; · 3.14 Impact Factor
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    ABSTRACT: A series of iodine-doped titanium dioxide (I-TiO2) photocatalysts was synthesized by using silica-coated Fe3O4 (SF) as the magnetic core (abbreviated here as ITSF), in order to facilitate the efficient recovery of these photocatalysts. Transmission electron microscopy and X-ray diffraction results indicated that the ITSF nanoparticles had a ternary structure with a core of Fe3O4, a SiO2 mesosphere and an I-TiO2 crust with a mixture of anatase and rutile phases. Magnetic measurements with a vibrating sample magnetometer showed that the ITSF core–shell structures exhibited favorable superparamagnetic behaviors and the magnetic saturation value decreased after coating with the non-magnetic I-TiO2 layer. The photocatalytic activity of the particles was tested by degrading an aqueous phenol solution under visible-light illumination. The photocatalytic activity of the multi-functional hybrid magnetite nanoparticles was enhanced with increasing content of TiO2, while the magnetism of the composite particles decreased. Moreover, an optimum molar ratio of 1:10 I/TiO2 was determined for the efficient degradation of phenol. The study showed that the presence of SF magnetic core would be helpful in the separation and recovery of I-TiO2 photocatalysts.
    Separation and Purification Technology 08/2012; 96:50–57. · 3.07 Impact Factor
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    ABSTRACT: Three bacterial strains utilizing paracetamol as the sole carbon, nitrogen, and energy source were isolated from a paracetamol-degrading aerobic aggregate, and assigned to species of the genera Stenotrophomonas and Pseudomonas. The Stenotrophomonas species have not included any known paracetamol degraders until now. In batch cultures, the organisms f1, f2, and fg-2 could perform complete degradation of paracetamol at concentrations of 400, 2,500, and 2,000 mg/L or below, respectively. A combination of three microbial strains resulted in significantly improved degradation and mineralization of paracetamol. The co-culture was able to use paracetamol up to concentrations of 4,000 mg/L, and mineralized 87.1 % of the added paracetamol at the initial of 2,000 mg/L. Two key metabolites of the biodegradation pathway of paracetamol, 4-aminophenol, and hydroquinone were detected. Paracetamol was degraded predominantly via 4-aminophenol to hydroquinone with subsequent ring fission, suggesting new pathways for paracetamol-degrading bacteria. The degradation of paracetamol could thus be performed by the single isolates, but is stimulated by a synergistic interaction of the three-member consortium, suggesting a possible complementary interaction among the various isolates. The exact roles of each of the strains in the consortium need to be further elucidated.
    Applied Microbiology and Biotechnology 05/2012; · 3.81 Impact Factor
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    ABSTRACT: Semiconducting silver iodate (AgIO(3)) was used to modify the visible light response of an AgI/TiO(2) (AIT) catalyst by a facile method. The uncalcined AIT (AITun) and AIT calcined at 200°C (AIT200) consisted of AgIO(3), AgI, and TiO(2) semiconductors, while that calcined at 450 °C (AIT450) was composed of AgI and TiO(2). The activity in p-chlorophenol (PCP) degradation under visible light irradiation using either AITun or AIT200 was much higher than that with AIT450, which was mainly attributed to the fact that the presence of AgIO(3) provided a new matching band potential. AIT200 exhibited better photocatalytic properties than AITun due to its higher crystallinity after calcination. Moreover, the high catalytic activity of AIT200 was maintained after five successive cyclic experiments under visible irradiation. Considering the effect of radical scavengers and N(2) purging on the photocatalysis process, we deduced that the probable pathway of PCP degradation was mainly a surface charge process, caused by valence band holes.
    Journal of Colloid and Interface Science 04/2012; 378(1):159-66. · 3.55 Impact Factor