Co-reporter:Dan Wu, Songtao Yue, Wei Wang, Tiacheng An, Guiying Li, Liqun Ye, Ho Yin Yip, Po Keung Wong
Applied Surface Science 2017 Volume 391(Part B) pp:516-524
Publication Date(Web):1 January 2017
DOI:10.1016/j.apsusc.2016.05.144
Highlights
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Bi5+ self-doped BiOBr nanosheets are achieved under UV irradiation.
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Bi5+ is formed due to the oxidation of surface Bi3+ by photoexcited h+ of BiOBr.
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Two photoinduced h+ mediated oxidation processes happen simultaneously.
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Self-doped BiOBr is superior in phenol degradation and bacterial inactivation.
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Bi5+ electron trapping induced photocatalytic enhancement mechanism is proposed.
Co-reporter:Guocheng Huang, Tsz Wai Ng, Taicheng An, Guiying Li, Dehua Xia, Ho Yin Yip, Huijun Zhao, Po Keung Wong
Water Research 2017 Volume 110(Volume 110) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.watres.2016.12.032
•First use of fractionation procedure and PARAFAC analysis to study IOM of E. coli.•Released IOM decelerated the inactivation rate during photocatalytic inactivation.•Four components were found in EEM-PARAFAC analysis.•Toxicity occurred during inactivation then decreased with prolonged reaction time.•Toxicity was found to positively correlate with one EEM-PARAFAC components.Photocatalysis provides a “green” and effective strategy for water disinfection. During the photocatalytic disinfection process, intracellular organic matter (IOM) from bacterial cells may be released into the bulk solution. In this study, the role of released IOM in the photocatalytic bacterial inactivation was investigated by fractionation procedure and fluorescence excitation-emission-matrix (EEM) combined with parallel factor analysis (PARAFAC) approaches. The normal bacterial cells treated by TiO2-UVA in the presence and absence with fractionated IOM results implied that the released IOM would be either absorbed on the surface of the photocatalysts or reacted by the photo-generated reactive species, and thereby affecting the kinetics of photocatalytic bacterial inactivation. Fluorescence EEM-PARAFAC results showed that two components (C1 and C3) associated with tryptophan- and tyrosine-like proteins were released. While another two components (C2 and C4) were the oxidation products, and their intensities were found to negatively correlate with those of C1 and C3, respectively. Microtox® test results indicated that toxicity occurred during the photocatalytic bacterial inactivation process. The toxicity was found to decrease after the bacteria were completely inactivated, and completely removed if provided a sufficient reaction time. Of particular interest is that a significant high linear correlation was observed between the toxicity and the maximum fluorescence intensity of C4. The results and information obtained in this study will be important for further developing photocatalysis in water/wastewater disinfection.Download high-res image (211KB)Download full-size image
Co-reporter:Ranran Liu, Jiangyao Chen, Guiying Li, Taicheng An
Chemical Engineering Journal 2017 Volume 318(Volume 318) pp:
Publication Date(Web):15 June 2017
DOI:10.1016/j.cej.2016.05.004
•Pilot-scale removal of VOCs was carried out during electronic waste dismantling.•Water-soluble VOCs and particles were pretreated before photocatalysis.•Photocatalysis prefers degradation of VOCs with higher dielectric constant.•Integrated reactor show high and stable removal ability to emitted VOCs.•Health risks of individual and total VOCs decrease significantly after treatment.Recycling e-waste is increasingly recognized as an important resource management strategy; however, the process emits different pollutants, including volatile organic compounds (VOCs). Sixteen dominant VOCs, with total concentrations ranging from 1.6 × 103 to 6.7 × 103 μg m−3, were presented during the manual process of dismantling television printed circuit boards using electric heating furnaces. An integrated treatment technique, involving a spray tower (ST), electrostatic precipitation (EP), and photocatalysis (PC), was used to eliminate these VOCs. The highest VOC removal efficiency during the 60-day treatment period was 69.5%. The removal efficiency was mainly due to the combined effect of preferential elimination of hydrosoluble VOCs and efficient interception of large-sized particles by ST; the enhanced capture efficiency of micro-sized particles by EP; and the dominant degradation of particle-free VOCs by PC. The PC treatment was able to remove more hydrocarbons (an average 62.7%) than nitrogen- and oxygen-containing and aromatic compounds (36.4% and 27.3% in average), due to the hydrocarbons’ higher dielectric constants. Risk assessment revealed that the non-cancer and cancer risks associated with VOCs significantly decreased after the integrated technique was applied, indicating that the treatment is an efficient approach for purifying the atmosphere and protecting human health inside e-waste recycling workshops.Download high-res image (88KB)Download full-size image
Co-reporter:Dionissios Mantzavinos, Ioannis Poulios, Santiago Esplugas, Taicheng An, Gianluca Li Puma, Dionysios D. Dionysiou
Chemical Engineering Journal 2017 Volume 318(Volume 318) pp:
Publication Date(Web):15 June 2017
DOI:10.1016/j.cej.2017.03.053
Co-reporter:Dan Wu, Bo Wang, Wei Wang, Taicheng An, Guiying Li, Tsz Wai Ng, Ho Yin Yip, Chunmei Xiong, Hung Kay Lee and Po Keung Wong
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:15148-15155
Publication Date(Web):11 Jun 2015
DOI:10.1039/C5TA02757H
Bismuth oxybromide (BiOBr) nanosheets with fully exposed {001} and {010} facets are synthesized via a facile hydrothermal method. Significant differences in photocatalytic inactivation towards Escherichia coli K-12 under visible light irradiation are found to be highly dependent on the dominantly exposed facets. In comparison with BiOBr with dominant {010}-facet (B010) nanosheets, BiOBr with dominant {001}-facet (B001) nanosheets exhibit remarkably higher photocatalytic activity in bacterial inactivation. This superior activity is ascribed to the more favorable separation and transfer of photogenerated electron–hole pairs as well as more oxygen vacancies of B001 nanosheets. Due to the faster production and further accumulation of ˙O2− and h+ within a short time, the VLD photocatalyst of B001 nanosheets can completely inactivate 107 colony forming unit (CFU) mL−1 (i.e. 7-log reduction) bacterial cells within 2 h; while only 1- and 6.5-log reductions of bacterial cells can be achieved within 2 and 6 h, respectively, by B010 nanosheets due to limited amounts of h+ and ˙O2− generated.
Co-reporter:Jiangyao Chen, Haimin Zhang, Porun Liu, Yibing Li, Guiying Li, Taicheng An, Huijun Zhao
Carbon 2015 Volume 92() pp:339-347
Publication Date(Web):October 2015
DOI:10.1016/j.carbon.2015.04.090
The co-doping of heteroatoms into the pre-synthesized graphitic carbons normally requires the use of different doping reagents as heteroatom sources, leading to difficulties in controlling the contents of doped heteroatoms and their chemical bonding forms with graphitic structures. Graphitic carbon-based electrocatalysts with a relatively large size, rich microporous structure and high surface area could possess better structural stability and enhanced conductivity than those of small-sized carbon nanostructures (e.g., nanodots). This study reported the use of a sole reagent (thiourea) as heteroatoms doping source to achieve controllable N, S co-doping of the pre-synthesized graphitic microporous carbon nanospheres (∼100 nm in diameter) via a facial thermolysis process to produce high performance oxygen reduction reaction electrocatalysts. Results showed that the contents of the doped N, S and their chemical bonds with graphitic carbon structures could be simply controlled by controlling the thermolysis temperatures. With the experimental conditions investigated, the best performed electrocatalyst was obtained from 1100 °C doping process that possessed the most suitable N, S doping contents with 100% of doped N being in electrocatalytically active pyridinic-N and graphitic-N forms. The approach reported in this work could be useful for controllable heteroatoms co-doping of other types of new generation graphitic carbon materials.
Co-reporter:Dan Wu, Taicheng An, Guiying Li, Wei Wang, Yuncheng Cai, Ho Yin Yip, Huijun Zhao, Po Keung Wong
Applied Surface Science 2015 Volume 358(Part A) pp:137-145
Publication Date(Web):15 December 2015
DOI:10.1016/j.apsusc.2015.08.033
Highlights
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The GO–ZnO composites exhibited efficient VLD bacterial inactivation performance.
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Strong interfacial interaction existed between GO and ZnO.
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GO served as a photosensitizer in the inactivation process.
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Excellent antibacterial activity by GO–ZnO composite was shown under sunlight.
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An inactivation mechanism based on the GO photosensitizer induction was proposed.
Co-reporter:Tsz Wai Ng, Taicheng An, Guiying Li, Wing Kei Ho, Ho Yin Yip, Huijun Zhao, Po Keung Wong
Journal of Photochemistry and Photobiology B: Biology 2015 Volume 149() pp:164-171
Publication Date(Web):August 2015
DOI:10.1016/j.jphotobiol.2015.06.007
•Light irradiation increases the susceptibility of E. coli against H2O2.•Light pretreatment study to confirms the importance of bacterial physiology.•Mutants study suggests the change involving intracellular Fe(II) and DNA protection.•Mechanism of synergy between the light irradiation and H2O2 is proposed.Inactivation of Escherichia coli K-12 was conducted by applying a continuous supplying of commercial H2O2 to mimic the H2O2 production in a photocatalytic system, and the contribution of H2O2 in photocatalytic inactivation was investigated using a modified “partition system” and five E. coli mutants. The concentration of exogenous H2O2 required for complete inactivation of bacterial cells was much higher than that produced in-situ in common photocatalytic system, indicating that H2O2 alone plays a minor role in photocatalytic inactivation. However, the concentration of exogenously produced H2O2 required for effective inactivation of E. coli K-12 was much lower when the light irradiation was applied. To further investigate the possible physiological changes, inactivation of E. coli BW25113 (the parental strain), and its corresponding isogenic single-gene deletion mutants with light pretreatment was compared. The results indicate that light irradiation increases the bacterial intracellular Fe2+ level and favors hydroxyl radical (OH) production via the catalytic reaction of Fe2+, leading to increase in DNA damage. Moreover, the results indicate that the properties of light source, such as intensity and major emission wavelength, may alter the physiology of bacterial cells and affect the susceptibility to in-situ resultant H2O2 in the photocatalytic inactivation processes, leading to significant influence on the photocatalytic inactivation efficiencies of E. coli K-12.
Co-reporter:Yuemeng Ji, Honghong Wang, Jiangyao Chen, Guiying Li, Taicheng An, and Xiaolei Zhao
The Journal of Physical Chemistry A 2015 Volume 119(Issue 46) pp:11376-11383
Publication Date(Web):October 27, 2015
DOI:10.1021/acs.jpca.5b09065
This study investigated the heterogeneous atmospheric reactions of acetaldehyde, propanal, and butanal with NO2 onto silica (SiO2) clusters using a theoretical approach. By analyzing spectral features and adsorption parameters, the formation of hydrogen bonds and negative adsorption energies provide evidence that an efficient spontaneous uptake of aliphatic aldehydes onto SiO2 could occur. The atmospheric reaction mechanisms show that when aldehydes and NO2 react on the surface model, the H atom abstraction reaction from the aldehydic molecule by NO2 is an exclusive channel, forming nitrous acid and acyl radicals. This study included kinetics exploring the reaction of aldehydes with NO2 using a canonical variational transition state theory. The reaction rate constants are increased in the presence of SiO2 between the temperatures 217 and 298 K. This may explain how aldehydes can temporarily stay on mineral particles without chemical reactions. The results suggest that silica can depress the rate at which the studied aldehydes react with NO2 and possibly reduce air pollution generated by these atmospheric reactions.
Co-reporter:Huixian Shi, Guocheng Huang, Dehua Xia, Tsz Wai Ng, Ho Yin Yip, Guiying Li, Taicheng An, Huijun Zhao, and PoKeung Wong
The Journal of Physical Chemistry B 2015 Volume 119(Issue 7) pp:3104-3111
Publication Date(Web):January 20, 2015
DOI:10.1021/jp511201w
This study investigated how a natural sphalerite (NS) photocatalyst, under visible light irradiation, supports photocatalytic bacterial inactivation. This was done by comparing parent E. coli BW25113, and its two isogenic single-gene knock-out mutants, E. coli JW0797-1 (dps– mutant) and JW1721-1 (katE– mutant), where both dps and KatE genes are likely related to H2O2 production. NS could inactivate approximately 5-, 7- and 7-log of E. coli BW25113, JW0797-1, and JW1721-1 within 6 h irradiation, respectively. The two isogenic mutants were more susceptible to photocatalysis than the parental strain because of their lack of a defense system against H2O2 oxidative stress. The ability of in situ resultant H2O2 to serve as a defense against photocatalytic inactivation was also confirmed using scavenging experiments and partition system experiments. Studying catalase activity further revealed that in situ H2O2 played an important role in these inactivation processes. The destruction of bacterial cells from the cell envelope to the intracellular components was also observed using field emission-scanning electron microscopy. Moreover, FT-IR was used to monitor bacterial cell decomposition, key functional group evolution, and bacterial cell structures. This is the first study to investigate the photocatalytic inactivation mechanism of E. coli using single-gene deletion mutants under visible light irradiation.
Co-reporter:Qili Wu, Xianfeng Yang, Jia Liu, Xin Nie, Yongliang Huang, Yuping Wen, Javid Khan, Wasim U. Khan, Mingmei Wu, and Taicheng An
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 20) pp:17730
Publication Date(Web):September 18, 2014
DOI:10.1021/am5041847
Layered titanates with selective adsorption ability and adsorption-driven photocatalytic property can be quite attractive due to their potential applications in water purification. In this work, lepidocrocite-like layered protonated titanate (H2Ti2O5·H2O, denoted as HTO) nanosheets were successfully synthesized by an ion-exchange process. It turns out that this layered structure displays an abundant and selective adsorption toward the fluoroquinolone pharmaceutical compared with some large dye molecules due to a size selectivity of the interlayer spacing of HTO and the molecular horizontal size, as well as their electrostatic interaction. The uptake ability of HTO could be readily controlled through adjusting the pH values of adsorbate solution, and the maximum uptake capacity was achieved at the pH value of about 5.5 for ciprofloxacin (CIP) and 6.5 for moxifloxacin (MOX). The adsorption amount of smaller nalidixic acid (NAL) showed an increasing tendency as the pH value decreased. Moreover, the two-dimensional layered crystal structure also permits such HTO nanosheets to have a large percentage of (010) faces exposed, which is considerably provided by the interlayer surfaces of these nanosheets. The (010) surface has a similar Ti and O atomic arrangement as to the highly reactive anatase TiO2(001) one. Due to these specific characteristics, these HTO nanosheets show excellent photocatalytic activity in degrading CIP under UV light irradiation as well as possess a superior adsorption ability to remove CIP from aqueous solution selectively and efficiently. The photocatalytic reaction is believed to be mainly conducted on the active anatase (001)-like interlayer (010) surfaces of the layered structures since the as-prepared HTO performs an adsorption-driven molecular recognitive photocatalytic reaction.Keywords: adsorption-driven photocatalysis; anatase (001)-like surface; ciprofloxacin; layered titanate; selective adsorption
Co-reporter:Taicheng An, Yanpeng Gao, Guiying Li, Prashant V. Kamat, Julie Peller, and Michelle V. Joyce
Environmental Science & Technology 2014 Volume 48(Issue 1) pp:641-648
Publication Date(Web):December 10, 2013
DOI:10.1021/es404453v
The hydroxyl radical (•OH) is one of the main oxidative species in aqueous phase advanced oxidation processes, and its initial reactions with organic pollutants are important to understand the transformation and fate of organics in water environments. Insights into the kinetics and mechanism of •OH mediated degradation of the model environmental endocrine disruptor, dimethyl phthalate (DMP), have been obtained using radiolysis experiments and computational methods. The bimolecular rate constant for the •OH reaction with DMP was determined to be (3.2 ± 0.1) × 109 M–1s–1. The possible reaction mechanisms of radical adduct formation (RAF), hydrogen atom transfer (HAT), and single electron transfer (SET) were considered. By comparing the experimental absorption spectra with the computational results, it was concluded that the RAF and HAT were the dominant reaction pathways, and OH-adducts (•DMPOH1, •DMPOH2) and methyl type radicals •DMP(-H)α were identified as dominated intermediates. Computational results confirmed the identification of transient species with maximum absorption around 260 nm as •DMPOH1 and •DMP(-H)α, and these radical intermediates then converted to monohydroxylated dimethyl phthalates and monomethyl phthalates. Experimental and computational analyses which elucidated the mechanism of •OH-mediated degradation of DMP are discussed in detail.
Co-reporter:Hongwei Sun, Guiying Li, Xin Nie, Huixian Shi, Po-Keung Wong, Huijun Zhao, and Taicheng An
Environmental Science & Technology 2014 Volume 48(Issue 16) pp:9412-9419
Publication Date(Web):July 25, 2014
DOI:10.1021/es502471h
A systematic approach was developed to understand, in-depth, the mechanisms involved during the inactivation of bacterial cells using photoelectrocatalytic (PEC) processes with Escherichia coli K-12 as the model microorganism. The bacterial cells were found to be inactivated and decomposed primarily due to attack from photogenerated H2O2. Extracellular reactive oxygen species (ROSs), such as H2O2, may penetrate into the bacterial cell and cause dramatically elevated intracellular ROSs levels, which would overwhelm the antioxidative capacity of bacterial protective enzymes such as superoxide dismutase and catalase. The activities of these two enzymes were found to decrease due to the ROSs attacks during PEC inactivation. Bacterial cell wall damage was then observed, including loss of cell membrane integrity and increased permeability, followed by the decomposition of cell envelope (demonstrated by scanning electronic microscope images). One of the bacterial building blocks, protein, was found to be oxidatively damaged due to the ROSs attacks, as well. Leakage of cytoplasm and biomolecules (bacterial building blocks such as proteins and nucleic acids) were evident during prolonged PEC inactivation process. The leaked cytoplasmic substances and cell debris could be further degraded and, ultimately, mineralized with prolonged PEC treatment.
Co-reporter:Haimin Zhang, Yibing Li, Xiaolu Liu, Porun Liu, Yun Wang, Taicheng An, Huagui Yang, Dengwei Jing, and Huijun Zhao
Environmental Science & Technology Letters 2014 Volume 1(Issue 1) pp:87-91
Publication Date(Web):November 14, 2013
DOI:10.1021/ez400137j
The development of analytical methods for rapidly, sensitively, and selectively detecting iodide (I–) in aqueous media is critically important because I– is closely related to human health because of a number of diseases caused by the deficiency and radioactivity of I–. In this work, we describe N-doped carbon quantum dots as the fluorophores for the direct determination of I– fluorescence, achieving a detection limit of 10 μM with an analytical linear range up to 2.0 mM. The experimental results also demonstrate that the N-doped carbon quantum dot fluorophores possess high selectivity for I– detection. The presence of nitrogen functional groups results in a positively charged carbon quantum dot surface, which is advantageous for the detection of I– fluorescence because of the strong electrostatic interaction between carbon quantum dots and I–. This work demonstrates the possibility of developing carbon quantum dot fluorophore-based fluorescence methods for the determination of other anions.
Co-reporter:Jiangyao Chen, Haimin Zhang, Porun Liu, Yun Wang, Xiaolu Liu, Guiying Li, Taicheng An, Huijun Zhao
Journal of Colloid and Interface Science 2014 Volume 429() pp:53-61
Publication Date(Web):1 September 2014
DOI:10.1016/j.jcis.2014.05.012
•Rutile TiO2 film with exposed pyramid-shaped (1 1 1) surface is fabricated by VPH method.•High photoelectrocatalytic activity to water oxidation and RhB removal for rutile TiO2 film.•Lower inherent resistance leads to higher photoelectrocatalytic activity of rutile TiO2 film.Rutile TiO2 nanostructured film with exposed pyramid-shaped (1 1 1) surface was successfully fabricated using metal titanium foil as substrate through a facile vapor-phase hydrothermal method. The fabricated rutile TiO2 film was composed of vertically aligned rod-like structures with diameters ranged from 400 to 700 nm and thickness of ca. 2.0 μm. The obtained rutile TiO2 film as photoanode exhibited excellent photoelectrocatalytic activity toward water oxidation and rhodamine B decolorization under UV illumination, which was more than 3.5 and 1.2 times of that obtained by highly ordered anatase TiO2 nanotube array film photoanode under the same experimental conditions, respectively. The excellent photoelectrocatalytic performance of the rutile TiO2 film photoanode could be due to the superior photoelectron transfer property and the high oxidative capability of {1 1 1} crystal facets. The superior photoelectron transfer capability of the photoanodes was manifested by the inherent resistance (R0) of the photoanodes using a simple photoelectrochemical method. The calculated R0 values were 50.5 and 86.2 Ω for the rutile TiO2 nanostructured film and anatase TiO2 nanotube array film, respectively. Lower R0 value of the rutile TiO2 photoanode indicated a superior photoelectron transfer capability owing to good single crystal property of the rod-like rutile nanostructure. Almost identical valence band level (1.94 eV) of the rutile TiO2 nanostructured film and anatase TiO2 nanotube array film (meaning a similar oxidation capability) further confirmed the significant role of photoelectron transfer capability and exposed high-energy {1 1 1} crystal facets for improved photoelectrocatalytic performance of the rutile TiO2 nanostructured film photoanode.Graphical abstract
Co-reporter:Huixian Shi, Jiangyao Chen, Guiying Li, Xin Nie, Huijun Zhao, Po-Keung Wong, and Taicheng An
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 15) pp:6959
Publication Date(Web):July 10, 2013
DOI:10.1021/am401459c
A series of novel well-defined Ag/AgX (X = Cl, Br, I) loaded carbon nanotubes (CNTs) composite photocatalysts (Ag/AgX-CNTs) were fabricated for the first time via a facile ultrasonic assistant deposition–precipitation method at the room temperature (25 ± 1 °C). X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption analysis, scanning electron microscopy, and ultraviolet–visible light absorption spectra analysis were used to characterize the structure, morphology, and optical properties of the as-prepared photocatalysts. Results confirmed the existence of the direct interfacial contact between Ag/AgX nanoparticles and CNTs, and Ag/AgX-CNTs nanocomposites exhibit superior absorbance in the visible light (VL) region owing to the surface plasmon resonance (SPR) of Ag nanoparticles. The fabricated composite photocatalysts were employed to remove 2,4,6-tribromophenol (TBP) in aqueous phase. A remarkably enhanced VL photocatalytic degradation efficiency of Ag/AgX-CNTs nanocomposites was observed when compared to that of pure AgX or CNTs. The photocatalytic activity enhancement of Ag/AgX-CNTs was due to the effective electron transfer from photoexcited AgX and plasmon-excited Ag(0) nanoparticles to CNTs. This can effectively decrease the recombination of electron–hole pairs, lead to a prolonged lifetime of the photoholes that promotes the degradation efficiency.Keywords: carbon nanotube supporter; photocatalytic activity; plasmonic photocatalyst; silver halides; visible light;
Co-reporter:Hansun Fang, Yanpeng Gao, Guiying Li, Jibin An, Po-Keung Wong, Haiying Fu, Side Yao, Xiangping Nie, and Taicheng An
Environmental Science & Technology 2013 Volume 47(Issue 6) pp:2704-2712
Publication Date(Web):February 22, 2013
DOI:10.1021/es304898r
The absolute kinetic rate constants of propylparaben (PPB) in water with different free radicals were investigated, and it was found that both hydroxyl radicals (HO•) and hydrated electrons could rapidly react with PPB. The advanced oxidation kinetics and mechanisms of PPB were investigated using photocatalytic process as a model technology, and the degradation was found to be a pseudo-first-order model. Oxidative species, particularly HO•, were the most important reactive oxygen species mediating photocatalytic degradation of PPB, and PPB degradation was found to be significantly affected by pH because it was controlled by the radical reaction mechanism and was postulated to occur primarily via HO•-addition or H-abstraction reactions on the basis of pulse radiolysis measurements and observed reaction products. To investigate potential risk of PPB to humans and aqueous organisms, the estrogenic assays and bioassays were performed using 100 μM PPB solution degraded by photocatalysis at specific intervals. The estrogenic activity decreased as PPB was degraded, while the acute toxicity at three trophic levels first increased slowly and then decreased rapidly as the total organic carbon decreased during photocatalytic degradation.
Co-reporter:Dehua Xia, Tsz Wai Ng, Taicheng An, Guiying Li, Yan Li, Ho Yin Yip, Hunjun Zhao, Anhuai Lu, and Po-Keung Wong
Environmental Science & Technology 2013 Volume 47(Issue 19) pp:11166-11173
Publication Date(Web):September 6, 2013
DOI:10.1021/es402170b
Motivated by recent studies that well-documented mineral photocatalyst for bacterial inactivation, a novel natural magnetic sphalerite (NMS) in lead–zinc deposit was first discovered and evaluated for its visible-light-driven (VLD) photocatalytic bactericidal properties. Superior to the reference natural sphalerite (NS), vibrating sampling magnetometeric (VSM) analysis revealed the ferromagnetic property of NMS, indicating its potential for easy separation after use. Under the irradiation of fluorescence tubes, NMS could inactivate 7 log10 Gram-negative Escherichia coli K-12 without any regrowth and metal ions leached out from NMS show no toxicity to cells. The cell destruction process starting from cell wall to intracellular components was verified by TEM. Some products from damaged cells such as aldehydes, ketones and carboxylic acids were identified by FTIR with a decrease of cell wall functional groups. The relative amounts of potassium ion leakage from damaged cells gradually increased from initial 0 to approximately constant concentration of 1000 ppb with increasing reaction time. Superoxide radical (•O2–) rather than hydroxyl radical (•OH) was proposed to be the primary reactive oxidative species (ROSs) responsible for E. coli inactivation by use of probes and electron spin resonance (ESR). H2O2 determined by fluorescence method is greatly involved in bacterial inactivation in both nonpartition and partition system. Multiple cycle runs revealed excellent stability of recycled NMS without any significant loss of activity. This study provides a promising natural magnetic photocatalyst for large-scale bacterial inactivation, as NMS is abundant, easily recycled and possessed an excellent VLD bacterial inactivation ability.
Co-reporter:Xin Nie;Jiangyao Chen;Guiying Li;Huixian Shi;Huijun Zhao;Po-Keung Wong
Journal of Chemical Technology and Biotechnology 2013 Volume 88( Issue 8) pp:1488-1497
Publication Date(Web):
DOI:10.1002/jctb.3992
Abstract
BACKGROUND
In this study, highly ordered titanium dioxide (TiO2) nanotube arrays with tunable inner-diameter and morphology were synthesized by an anodizing method from titanium (Ti) foil by optimizing different preparation parameters, and acyclovir was degraded to test the photoelectrocatalytic activity of prepared nanotubes in a thin layer reactor.
RESULTS
The results indicated that anodization time, the concentrations of NH4F and HAc had significant effect on the surface morphology and inner-diameter of TiO2 nanotubes. Various morphologies including honeycomb films and nanotube arrays were obtained under given conditions. Photoelectrocatalysis showed higher degradation efficiency than that of photocatalysis or electrolysis due to TiO2 nanotubes regular nanotubular effectively reducing the recombination of photo-generated electron–hole pairs. The photoelectrochemical responses and degradation efficiencies of acyclovir were well related to the TiO2 crystallinity and morphology of TiO2 nanotube photoanodes. Regular nanotube array photoanodes displayed better crystallinity, higher photoelectrochemical response and higher photoelectrocatalytic activity than those of nanopore photoanodes. The best TiO2 nanotube photoanode was prepared at 30 V for 24 h in the ethylene glycol solution containing 0.20 mol L−1 NH4F and 0.50 mol L−1 HAc.
CONCLUSION
TiO2 nanotube photoelectrocatalysis technology is an effective way to decontaminate organic contaminants in water. © 2012 Society of Chemical Industry
Co-reporter:Taicheng An, Jiangyao Chen, Xin Nie, Guiying Li, Haimin Zhang, Xiaolu Liu, and Huijun Zhao
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 11) pp:5988
Publication Date(Web):November 6, 2012
DOI:10.1021/am3016476
The carbon nanotube (CNT)–sub-micrometer-sized anatase TiO2 sphere composite photocatalysts were synthesized by a facile one-step hydrothermal method using titanium tetrafluoride as titanium source and CNTs as structure regulator. Various technologies including X-ray diffraction, UV–visible absorption spectra, N2 adsorption–desorption, scanning electron microscopy, and transmission electron microscopy were employed to characterize the structure properties of the prepared composite photocatalysts. The results indicated that the composite photocatalysts consisted of CNTs wrapping around the sub-micrometer-sized anatase TiO2 spheres with controllable crystal facets and that the aggregated particles with average diameter ranged from 200 to 600 nm. The fabricated composite photocatalysts were used to degrade gaseous styrene in this work. As expected, a synergistic effect that remarkably enhancing the photocatalytic degradation efficiency of gaseous styrene by the prepared composite photocatalysts was observed in comparison with that the degradation efficiency using pure anatase TiO2 and the adsorption of CNTs. Similar results were also confirmed in the decolorization of liquid methyl orange. Further investigation demonstrated that the synergistic effect in the photocatalytic activity was related to the structure of the sub-micrometer-sized anatase TiO2 spheres and the significant roles of CNTs in the composite photocatalysts. By controlling the content of CNTs, the content of TiO2 or the temperature during the hydrothermal synthesis process, anatase TiO2 spheres with controllable crystallite size and dominant crystal facets such as {001}, {101}, or polycrystalline could be obtained, which was beneficial for the increase in the synergistic effect and further enhancement of the photocatalytic efficiencies.Keywords: CNT-based composite photocatalyst; photocatalytic activity; structure regulation; synergistic effect; TiO2 spheres;
Co-reporter:Shungang Wan;Guiying Li
Journal of Chemical Technology and Biotechnology 2011 Volume 86( Issue 9) pp:1166-1176
Publication Date(Web):
DOI:10.1002/jctb.2624
Abstract
BACKGROUND: In this work, the feasibility of biodegradation and the removal performance of sole and mixed odorous vapors, such as dimethyl disulfide (DMDS), methyl phenyl sulfide (MPS), and ethanethiol (EtSH) in an EtSH-acclimated biotrickling filter seeded with commercially available B350 microorganisms, were investigated.
RESULTS: Removal efficiencies (REs) for DMDS as a sole substrate were evaluated under different inlet concentrations and empty bed residence times (EBRT), 100% RE was achieved at concentration below 0.4 g m−3 at EBRT 110 s. In addition, 100% RE was obtained for binary EtSH and DMDS (3:2) at the same EBRT. According to the Michaelis–Menten type kinetic equation, the maximum removal rates (Vmax) were calculated as 28.7 and 13.9 g m−3 h−1 for DMDS and MPS as sole substrate, respectively, while Vmax was 22.1 and 10.1 g m−3 h−1 for DMDS and MPS in the presence of EtSH and EtSH-DMDS mixture, respectively. After 5 and 20 days starvation, the re-acclimation times were only 2 and 8 days, respectively, for the binary system. An EtSH:DMDS:MPS (3:2:1) ternary mixture was removed efficiently by the rebooted system after starvation.
CONCLUSION: The proposed system can be applied to cost-effectively decompose a mixture of volatile organic sulfide compounds at pilot scale. Copyright © 2011 Society of Chemical Industry
Co-reporter:Taicheng An, Meng Qiao, Guiying Li, Hongwei Sun, Xiangying Zeng and Jiamo Fu
Environmental Science: Nano 2011 vol. 13(Issue 5) pp:1457-1463
Publication Date(Web):05 Apr 2011
DOI:10.1039/C0EM00542H
The Pearl River Delta (PRD) region is one of the most population-dense areas in China. The safety of its drinking source water is essential to human health. Polycyclic aromatic hydrocarbons (PAHs) have attracted attention from the scientific community and the general public due to their toxicity and wide distribution in the global environment. In this work, PAHs pollution levels from the drinking source water in nine main cities within the PRD were investigated. ∑15 PAHs concentrations during the wet season varied from 32.0 to 754.8 ng L−1 in the dissolved phase, and from 13.4 to 3017.8 ng L−1 in the particulate phase. During the dry season, dissolved PAHs ranged from 48.1 to 113.6 ng L−1, and particulate PAHs from 8.6 to 69.6 ng L−1. Overall, ∑15 PAHs concentrations were extremely high in the XC and ZHQ stations during the wet season in 2008 and 2009. In most sites, PAHs originated from mixed sources. Hazard ratios based on non-cancerous and cancerous risks were extremely higher in XC compared with the others during the wet season, though they were much less than 1. Nevertheless, risks caused by the combined toxicity of ∑15 PAHs and other organics should be seriously considered. PAHs toxic equivalent quantities ranged from 0.508 to 177.077 ng L−1.
Co-reporter:Maolin Zhang, Taicheng An, Xiaolu Liu, Xiaohong Hu, Guoying Sheng, Jiamo Fu
Materials Letters 2010 Volume 64(Issue 17) pp:1883-1886
Publication Date(Web):15 September 2010
DOI:10.1016/j.matlet.2010.05.054
The nano-scale ZnO/TiO2 coupled oxide photocatalyst was successfully synthesized by a two-step method, the homogeneous hydrolysis and low temperature crystallization. The resultant photocatalyst was characterized by ultraviolet–visible absorption spectroscopy (UV–vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) techniques. The photocatalytic activity of coupled oxides was also evaluated by the degradation of methyl orange (MO) as a model compound. The experimental results showed that the prepared ZnO/TiO2 at low hydrothermal crystallization temperature exhibited higher photocatalytic activity for the decomposition of MO than either pure phase ZnO or anatase TiO2, and even higher than that of the Degussa P25 TiO2.
Co-reporter:Taicheng An, Lei Sun, Guiying Li, Shungang Wan
Journal of Molecular Catalysis A: Chemical 2010 Volume 333(1–2) pp:128-135
Publication Date(Web):1 December 2010
DOI:10.1016/j.molcata.2010.10.009
The photocatalytic degradation of toluidine over titanium oxide (TiO2) thin films under UV irradiation was investigated. The degradation efficiency of 98.7% was obtained for a toluidine concentration of about 4500 μg L−1 and illumination of 240 min. The degradation intermediates produced during photocatalytic oxidation were identified using Fourier transform-infrared spectrometry (FTIR) and gas chromatography–mass spectrometry (GC–MS). Only a small amount of intermediates, including phenol and toluene, were found in the gas phase. Many other trace amount intermediates, such as 2-hydroxybenzaldehyde, 2-nitrobenzaldehyde, 2-hydroxybenzenemethanol, 2-hydroxybenzoic acid, phenol etc., were detected on the TiO2 surface. An Ames assay of the Salmonella typhimurium strains TA98 and TA100 was employed to evaluate the mutagenicity of toluidine and its gaseous photocatalytic degradation intermediates. With or without rat liver microsomal fraction (S9 mix) activation, neither toluidine nor its gaseous intermediates presented mutagenic activity against strains TA98 (±S9) and TA100 (−S9) at all tested doses. Toluidine, however, can induce a weak positive response to the TA100 strain with an S9 mix at doses as high as 4000 μg plate−1. An increase of revertants per plate was obtained after 30 min photocatalysis in the TA100 strain with S9 mix. As reaction time further increased, photocatalytic technology exhibited the ability to completely and efficiently detoxify toluidine. Both our chemical analysis and toxic evaluation indicate that all mutagenic intermediates in the gas can be completely eliminated within 240 min, which further suggests that photocatalytic technology is an effective approach for degrading aromatic amines.Graphical abstractAs for a mutagenic pollutant, toluidine, the mutagenicity to strains TA100 (+S9) increase firstly after 30 min photocatalytic oxidation and then decrease and totally detoxify with further increasing degradation time..Research highlights▶ Two intermediates of toluene and phenol were found in the gas phase. ▶ Six trace amounts degradation intermediates were found on the surface of TiO2. ▶ o-Toluidine presented weak mutagenic activity against the TA100 strain with S9. ▶ Mutagenic toxicity of gaseous intermediates increased first and then decrease soon. ▶ Gaseous o-toluidine was successfully detoxified using photocatalytic technology.
Co-reporter:Meng Qiao, Taicheng An, Xiangying Zeng, Delin Zhang, Guiying Li, Guoying Sheng, Jiamo Fu, Guoxia Zhang and Jun Guo
Environmental Science: Nano 2010 vol. 12(Issue 9) pp:1666-1677
Publication Date(Web):08 Jul 2010
DOI:10.1039/C002019B
The safety of source water is a noticeable problem in the Pearl River Delta, one of the densely populated areas in China. In this study, 20 individual organochlorine pesticides (OCPs) were investigated in 15 water sources within this area using gas chromatography-electron capture detector, and the hazard risks to human health were assessed in terms of individual OCPs based on daily water consumption according to the standard recommended by the United States Environmental Protection Agency. Results showed that the total OCP concentrations ranged from 2.42 ng l−1 to 39.52 ng l−1 during the years 2008 and 2009. The hazard ratios based on both non-cancer and cancer benchmarks were less than 1 for all the water samples, which indicated that individual OCPs posed no risk to human health. However, the risks caused by the combined toxicity of total OCPs in this area should not be ignored.
Co-reporter:Lincheng Zhou;Guiying Li;Yanfeng Li
Research on Chemical Intermediates 2010 Volume 36( Issue 3) pp:277-288
Publication Date(Web):2010 April
DOI:10.1007/s11164-010-0134-5
The objective of this work was to prepare novel magnetic Fe3O4/polyurethane foam (Fe3O4/PUF) composites applied to the carriers of immobilized microorganisms for toluene-containing wastewater treatment. The morphology and structure of Fe3O4/PUF composite were characterized by X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and magnetic property measurement system. These morphological investigations revealed that Fe3O4 nano-particles were well dispersed into the matrix of PUF with nano-scale diameter particles. TG experiments indicated that the initial thermal weight loss temperatures of composite with the content of 2.5 wt% and 7.5% Fe3O4 were increased by 7 and 16 °C, compared with pure PUF. The degradation efficiency of toluene with magnetic PUF composite was much higher than that of pure PUF carrier, and the reason why the immobilization of microbial biomass of microorganisms on the magnetic PUF composite was much higher than that of the pure PUF. The prepared magnetic Fe3O4/PUF composite offered excellent thermal stability and medium paramagnetic properties. And this composite could not only increase the immobilized biomass of the microorganisms, but also enhance the COD removal efficiency of wastewater.
Co-reporter:Taicheng An, Hai Yang, Weihua Song, Guiying Li, Haiying Luo and William J. Cooper
The Journal of Physical Chemistry A 2010 Volume 114(Issue 7) pp:2569-2575
Publication Date(Web):January 29, 2010
DOI:10.1021/jp911349y
Pharmaceutical compounds and metabolites are being found in surface and ground waters which is indicative of inefficient removal by conventional wastewater treatment technologies. Advanced oxidation processes (AOPs), which utilize free-radical reactions to degrade chemical contaminates, are an alternative to traditional water treatment. Three fluoroquinolone pharmaceutical compounds were studied and the absolute rate constants for hydroxyl radical (•OH) and hydrated electron (e−aq) are reported. For norfloxacin, levofloxacin, and lomefloxacin, the bimolecular reaction rate constants with •OH were determined as (6.18 ± 0.18) × 109, (7.59 ± 0.16) × 109 and (8.04 ± 0.62) × 109 M−1 s−1, and with e−aq were (1.18 ± 0.10) × 1010, (2.46 ± 0.05) × 1010 and (2.79 ± 0.05) × 1010 M−1 s−1, respectively. To provide insights into the chemistry of destruction of these three target pharmaceuticals, transient spectra were obtained for the reaction of hydroxyl radicals with the three compounds. Photocatalysis was chosen as a representative advanced oxidation technology to degrade these three fluoroquinolones and their degradation pathways were proposed. Elimination of piperazynilic ring in fluoroquinolone molecules, addition of hydroxyl radical to quinolone ring, and ipso attack at the F atoms on the aromatic ring by hydroxyl radicals occurred. These results indicate that AOPs involving production of •OH radicals are efficiently alternative treatment technologies for degradation of fluoroquinolones in aqueous solution.
Co-reporter:Jikai Liu, Taicheng An, Guiying Li, Ningzhong Bao, Guoying Sheng, Jiamo Fu
Microporous and Mesoporous Materials 2009 Volume 124(1–3) pp:197-203
Publication Date(Web):August–September 2009
DOI:10.1016/j.micromeso.2009.05.009
Mesoporous TiO2 photocatalysts have been synthesized in acetic acid aqueous solutions by using the amphiphilic triblock copolymer (Pluronic P123) template. The prepared photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption/desorption analysis. The phase and structural qualities of the obtained mesoporous TiO2 have been improved by using hydrothermal treatment. The hydrolysis reaction of titanium sources has been controlled by using a low concentrated acetic acid aqueous solution used as both hydrolytic retardants and acid catalysts because of the strong chelating effect and acidity of acetic acid. The obtained mesoporous TiO2 exhibits uniform mesoporous structure with different mean pore sizes of up to 9.0 nm. The photocatalytic activity of the obtained photocatalysts was investigated, using dimethyl phthalate as a modal pollutant. Over 90% of dimethyl phthalate can be photocatalytically degraded within 2 h under UV irradiation in the presence of the obtained photocatalysts with a concentration of 2 g/L. The calcination temperature is the most remarkable factor that can affect the ultimate photocatalytic activity of the prepared photocatalysts.
Co-reporter:Hexing Li;Jinlong Zhang;Hui Li
Research on Chemical Intermediates 2009 Volume 35( Issue 6-7) pp:
Publication Date(Web):2009/09/01
DOI:10.1007/s11164-009-0106-9
Co-reporter:Xiangying Zeng;Jiangbo Wu;Delin Zhang;Guiying Li
Research on Chemical Intermediates 2009 Volume 35( Issue 6-7) pp:827-838
Publication Date(Web):2009 September
DOI:10.1007/s11164-009-0102-0
To eliminate volatile organic compounds (VOCs) from contaminated air, a novel medium-scale baffled photocatalytic reactor was designed and fabricated, using immobilized ZnO/SnO2 coupled oxide photocatalysts. Toluene was chosen as a representative pollutant of VOCs to investigate the degradation mechanism and the parameters affecting photocatalytic degradation efficiency. The preliminary experimental results indicate that the degradation efficiency of toluene increased with the increase of the light irradiation dosage, while it decreased with the increase of concentrations of toluene. The degradation efficiency increased rapidly with the increase of the relative humidity in a low humidity range from 0 to 35%, but decreased gradually in a high relative humidity (i.e., >35%). The optimum experimental conditions for toluene degradation is a toluene concentration of 106 mg m−3, a relative humidity of 35%, and an illumination intensity of ca. 6 mW cm−2 at the surface of ZnO/SnO2 photocatalysts. The intermediates produced during the gaseous photocatalytic degradation process were identified using the GC–MS technique. Based on these identified intermediates, the photocatalytic mechanism of toluene into ZnO/SnO2 coupled oxide catalyst was also deduced.
Co-reporter:Lei Sun, Taicheng An, Shungang Wan, Guiying Li, Ningzhong Bao, Xiaohong Hu, Jiamo Fu, Guoying Sheng
Separation and Purification Technology 2009 68(1) pp: 83-89
Publication Date(Web):
DOI:10.1016/j.seppur.2009.04.011
Co-reporter:Guiying Li;Ze He;Xiangying Zeng;Guoying Sheng;Jiamo Fu
Journal of Chemical Technology and Biotechnology 2008 Volume 83( Issue 7) pp:1019-1026
Publication Date(Web):
DOI:10.1002/jctb.1908
Abstract
BACKGROUND: To investigate the microbial degradation performance of organic pollutants in the atmosphere using a biotrickling filter, two microorganism strains, Bacillus cereus S1 and Bacillus cereus S2, were selected, identified and inoculated into a twin biotrickling filter for comparison.
RESULTS: Both strains showed good performance towards the degradation of model organic pollutants when gas flow rates ranged from 100 to 600 L h−1. For S1, the total maximum removal efficiency (RE) of toluene was maintained nearly 100% not only at gas flow rates of 100 L h−1 corresponding to empty bed residence time (EBRT) 199.44 s, but also at gas flow rates of 200 L h−1 (EBRT = 99.72 s) and 300 L h−1 (EBRT = 66.48 s). However, S2 had a much lower degradation capability; near 100% removal efficiency was obtained only at the gas flow rate of 100 L h−1 although both bacteria belong to the same Bacillus cereus. With further increase in gas flow rate, the total REs for both S1 and S2 decreased slightly at first and then dropped sharply to 46% and 35%, respectively, at an EBRT of 33.24 s, corresponding to a gas flow rate of 600 L h−1. Starvation for between 2 and 10 days resulted in the re-acclimation times of both strains ranging between 1.0 and 15.5 h.
CONCLUSION: Strain S1 would be a better choice for inoculation into a biotrickling filter than strain S2, because of its much higher toluene removal capacity and rapid recovery to full performance. Copyright © 2008 Society of Chemical Industry
Co-reporter:Xuejun Ding;Guiying Li;Jiaxin Chen
Research on Chemical Intermediates 2008 Volume 34( Issue 1) pp:67-83
Publication Date(Web):2008 January
DOI:10.1007/BF03039136
TiO2 pillared montmorillonites were prepared by introducing Ti4+ into a layer of montmorillonite modified with or without cetyltrimethylammonium bromide. The components and texture of the prepared composites were characterized by thermogravimetric analysis, X-ray powder diffraction and scanning electron misroscopy. The adsorption and photocatalytic degradation performance of a model environmental endocrine disruptor, dimethyl phthalate ester, were investigated using this newly prepared hydrophobic TiO2 pillared montmorillonite photocatalyst. The adsorption of dimethyl phthalate ester from water varied from 9% to 28% on the prepared hydrophobic photocatalyst. Although the experimental results showed that the photocatalytic activity of the hydrophobic photocatalyst was slightly lower than that of hydrophilic one, electron spin resonance verified that hydroxyl radicals were also generated in hydrophobic TiO2 pillared montmorillonite photocatalyst under UV irradiation. To elucidate the decomposition mechanism of dimethyl phthalate ester, 12 main photocatalytic intermediates were identified during the photocatalytic degradation process, and a plausible degradation mechanism was also proposed.
Co-reporter:Taicheng An, Ya Xiong, Guiying Li, Xihai Zhu, Guoying Sheng, Jiamo Fu
Journal of Photochemistry and Photobiology A: Chemistry 2006 Volume 181(2–3) pp:158-165
Publication Date(Web):31 July 2006
DOI:10.1016/j.jphotochem.2005.11.019
A novel three-dimensional electrode–hollow quartz tube photoelectrocatalytic reactor was designed and characterized by the photocurrent enhancement and COD removal efficiency, and the packed-bed photoelectrocatalytic reactor was used to investigate the feasibility of synergetic photoelectrocatalytic degradation of oxalic acid. By comparison of the COD removal efficiencies of three processes, direct electrooxidation, photocatalysis, and photoelectrocatalysis, the results showed that not only a significant photoelectrochemical synergetic effect, but also good photocatalytic efficiency, were observed in the photoelectrocatalytic reactor. It was found that successful design of the photoelectrocatalytic reactor by introducing the hollow quartz tubes into the three-dimensional electrode-packed-bed photoelectrocatalytic reactor presented a good solution to the drawbacks for poorly treating the high concentration and low-transmittance wastewater by photocatalytic technology.
Co-reporter:Wenbing Zhang;Guoying Sheng;Mingchao Cui;Jiamo Fu
Journal of Chemical Technology and Biotechnology 2005 Volume 80(Issue 2) pp:223-229
Publication Date(Web):8 DEC 2004
DOI:10.1002/jctb.1185
The effects of various anions, Cl−, ClO4−, SO42−, NO3−, HCO3−, H2PO4− and C2O42−, on the photocatalytic and photoelectrocatalytic degradation of reactive Brilliant Orange K-R have been investigated in a packed-bed photoelectrocatalytic reactor. It was found that the nature and concentrations of these inorganic anions significantly affected the photocatalytic and photoelectrocatalytic degradation performance of the reactive dye. The results indicated that the external electric field was successfully applied to improve the photocatalytic efficiency of reactive Brilliant Orange K-R in the presence of Cl−, especially at higher concentrations, while other inorganic anions displayed more or less negative effects on the degradation of the dye. The strongest inhibition effect on photocatalytic and photoelectrocatalytic degradation of the dye was observed in the presence of HCO3− ions. Copyright © 2004 Society of Chemical Industry
Co-reporter:Maolin Zhang;Xinming Wang;Jiamo Fu;Guoying Sheng
Journal of Chemical Technology and Biotechnology 2005 Volume 80(Issue 3) pp:251-258
Publication Date(Web):9 DEC 2004
DOI:10.1002/jctb.1187
The photocatalytic degradation of gaseous trichloroethene (TCE) was investigated on immobilized ZnO/SnO2 coupled oxide in a flow-through photocatalytic reactor. It was found that gaseous photocatalysis is an efficient method for volatile organic compounds' abatement and air purification. Degradation of ∼100% was found for TCE at the concentrations examined, up to 400 ppmv, in a flow-through dry synthetic gas stream. In our tested conditions, the flow rate had little influence on the photocatalytic degradation efficiencies of TCE, while the relative humidity had a significant influence on the photocatalytic degradation of TCE. The photocatalytic degradation efficiencies of TCE increased slowly below 20% relative humidity and then decreased as the relative humidity increased further. The deactivation of used immobilized photocatalyst was not observed within the 200 h testing period in the present experiment, although the surface of the photocatalyst changed greatly during the use of the photocatalyst. Copyright © 2004 Society of Chemical Industry
Co-reporter:Taicheng An, Wenbing Zhang, Xianming Xiao, Guoying Sheng, Jiamo Fu, Xihai Zhu
Journal of Photochemistry and Photobiology A: Chemistry 2004 Volume 161(2–3) pp:233-242
Publication Date(Web):30 January 2004
DOI:10.1016/j.nainr.2003.08.004
Photoelectrocatalytic degradation performance of quinoline in saline water was assessed with a newly designed continuous flow three-dimensional electrode-packed bed photocatalytic reactor. The efficiency of the three-dimensional electrode electrochemically assisted photocatalytic process was measured in terms of degradation and mineralization of quinoline. It was found that quinoline could be degraded more efficiently by photoelectrochemical process than by photocatalytic or electrochemical oxidation in saline water. The experimental results showed that oxidation of quinoline by photoelectrochemical process were well described with a pseudo first-order kinetics. The dependence of the rate constants on various parameters in the photoelectrocatalytic reactor, such as initial concentration of chloride ion, applied cell voltage, airflow and pH value were investigated in detail. Photoelectrocatalytic degradation of quinoline was more favorable in alkali solution than in acidic solution. It is also interesting to note that chloride ion had an obvious enhancement effect rather than a scavenging effect on the photoelectrocatalytic degradation of quinoline in saline water. A kinetic synergetic effect was observed with an enhancement of the rate constant by a factor of 3.7 compared to photoelectrocatalytic degradation of quinoline without addition of Cl− ion.
Co-reporter:Wenbing Zhang;Xianming Xiao;Zhiguang Song;Guoying Sheng;Jiamo Fu;Mingchao Cui
Journal of Chemical Technology and Biotechnology 2003 Volume 78(Issue 7) pp:788-794
Publication Date(Web):13 JUN 2003
DOI:10.1002/jctb.864
Photooxidation of 4-nitrophenol (4-NP) in water by the UV/H2O2 advanced oxidation process was carried out in order to investigate the kinetics and pathway of 4-NP degradation. The experimental results showed that the photodegradation of 4-NP accorded well with pseudo-first order kinetics. The effects of different parameters, such as H2O2 dosage, pH value and various anion scavengers on the degradation of 4-NP have been investigated in detail. It was found that acidic conditions are more favorable to the degradation of 4-NP but many anions, such as HCO3−, NO3− and Cl−, slow down the photooxidation rate of 4-NP. Hydroquinone, 1,2,4-trihdroxybenzene, 4-nitropyrogallol, and 4-nitrocatechol were tentatively identified as the intermediates of 4-NP degradation by GC/MS after samples were derivatized by N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA). A degradation pathway was proposed to account for the observed intermediates produced during 4-NP degradation by the UV/H2O2 process. Copyright © 2003 Society of Chemical Industry
Co-reporter:Haofei Gu;Xihai Zhu;Weiguo Chen;Guoying Sheng;Ya Xiong;Jiamo Fu
Journal of Chemical Technology and Biotechnology 2003 Volume 78(Issue 11) pp:1142-1148
Publication Date(Web):17 SEP 2003
DOI:10.1002/jctb.915
Decolourization and COD removal from synthetic wastewater containing Reactive Brilliant Orange K-R (RBOKR) dye using sonophotocatalytic technology was investigated. Experimental results showed that this hybrid technology could efficiently remove the colour and reduce COD from the synthetic dye-containing wastewater, and that both processes followed pseudo first-order kinetics. At the condition of 0.1 m3 h−1 airflow, 0.75 g dm−3 titanium dioxide and 0.5 mmol dm−3 RBOKR solution, the rate constants of decolourization and COD removal were 0.0750 and 0.0143 min−1 respectively for the sonophotocatalytic process; 0.0197 and 0.0046 min−1 respectively for the photocatalytic process and 0.0005 and 0.0001 min−1 respectively for the sonochemical process. The rate constants of sonophotocatalysis were greater than that of both the photocatalytic and sonochemical processes either in isolation or as a sum of the individual process, indicating an apparent synergetic effect between the photo- and sono-processes. Copyright © 2003 Society of Chemical Industry
Co-reporter:Taicheng An, Ya Xiong, Guiying Li, Changhong Zha, Xihai Zhu
Journal of Photochemistry and Photobiology A: Chemistry 2002 Volume 152(1–3) pp:155-165
Publication Date(Web):20 September 2002
DOI:10.1016/S1010-6030(02)00211-3
Degradation of formic acid was investigated using a novel photoelectrocatalytic reactor with a porous titanium plate as an air distributor as well as an electrode. By the comparison of the COD removal efficiencies from the solution containing formic acid for three processes, direct electro-oxidation, photocatalysis and photoelectrocatalysis, a significant photoelectrochemical synergetic effect was observed in the photoelectrocatalysis process. The synergetic effect was assessed with a new parameter, synergetic factor (SF). The effects of various operating conditions, such as applied cell voltage, treating time, airflow, initial pH value, catalyst amounts and conductivity of solution, on the SF were investigated as well. It was found that the SF was considerably dependent on these operating conditions, moreover, not simply proportional to them.
Co-reporter:Lei Zu, Guiying Li, Jibin An, Jianjun Li, Taicheng An
International Biodeterioration & Biodegradation (January 2013) Volume 76() pp:18-23
Publication Date(Web):1 January 2013
DOI:10.1016/j.ibiod.2012.06.014
2,4,6-Tribromophenol (2,4,6-TBP) is one of hazardous brominated flame retardants with acute toxicity which had an enormous applications in electronic devices and wood preservation. A bacterium Bacillus sp. GZT isolated in our lab was used to degrade 2,4,6-TBP and the response surface methodology was applied to optimize the biodegradation and debromination kinetics of 2,4,6-TBP. The central composite design model was chose to mathematically describe those affecting parameters of biodegradation. Three factors were determined to be the function of parameters, such as 2,4,6-TBP concentration (X1), initial pH value (X2) and the inoculum volume (X3). The results showed that two responses, degradation efficiency (%) (Y1) and debromination efficiency (%) (Y2), were coincidently affected by significant factors of the linear terms of x2 and x3 with synergistic effect, but quadratic terms of x22 and x32 with antagonistic effect, and linear terms of x1 also had antagonistic effect on those two responses. The optimal conditions for Y1 and Y2 were 3.0 mg/L 2,4,6-TBP with 20.7 ml inoculum volume at pH value 7.3, and the estimated maximum responses were 94.6% and 88.6%, respectively. The experimental values were agreed with the theoretical results very well, indicating that the models employed to optimize the biodegradation and debromination of 2,4,6-TBP were effective.
Co-reporter:Taicheng An, Yong Huang, Guiying Li, Zhigui He, Jiangyao Chen, Chaosheng Zhang
Environment International (December 2014) Volume 73() pp:186-194
Publication Date(Web):1 December 2014
DOI:10.1016/j.envint.2014.07.019
•The work was conducted in the real on-site e-waste dismantling process.•Pollution profiles of VOCs emitted during e-waste dismantling were studied.•Using rotary incinerator to dismantle e-wastes can lead to heavy pollution of VOCs.•Health risk of VOCs emitted during dismantling process was assessed using 2 methods.Pollution profiles of typical volatile organic compounds (VOCs) emitted during dismantling of various printed circuit board assemblies (PCBAs) of e-wastes using different methods were comparatively investigated in the real e-waste dismantling workshops in South China in April 2013. Similar pollution profiles and concentrations of VOCs were observed between dismantling mobile phone and hard disk PCBAs by using electric blowers and between dismantling television and power supplier PCBAs using electric heating furnaces. Aromatic hydrocarbons (accounting for > 60% of the sum of VOCs) were the dominant group during using electric blowers, while aromatic (accounting for > 44% of the sum of VOCs) and halogenated hydrocarbons (accounting for > 48% of the sum of VOCs) were the two dominant groups which contributed equally using electric heating furnaces. However, the distribution profiles of VOCs emitted during dismantling of televisions, hard disks and micro motors using rotary incinerators varied greatly, though aromatic hydrocarbons were still the dominant group. The combustion of e-wastes led to the most severe contamination of VOCs, with total VOCs (3.3 × 104 μg m− 3) using rotary incinerators about 190, 180, 139, and 40 times higher than those using mechanical cutting, electric soldering iron, electric blower, and electric heating furnace, respectively. Both cancer and non-cancer risks existed for workers due to exposure to on-site emitted VOCs in all workshops especially in those using rotary incinerators according to the USEPA methodology, whereas only cancer risks existed in rotary incinerator workshops according to the American Conference of Industrial Hygienists methodology.
Co-reporter:Zhigui He, Guiying Li, Jiangyao Chen, Yong Huang, Taicheng An, Chaosheng Zhang
Environment International (April 2015) Volume 77() pp:85-94
Publication Date(Web):1 April 2015
DOI:10.1016/j.envint.2015.01.004
•VOC pollution profiles during the melting extrusion of 7 plastics were analyzed.•Emitted VOC patterns were dependent on different plastic types.•Occupational exposure limits were evaluated for the assembling line workers.•VOC pollution in the indoor microenvironment was correlated with PSW extrusion process.•Health risks were assessed for the residents near the plastic recycling workshops.The pollution profiles of volatile organic compounds (VOCs) emitted from different recycling workshops processing different types of plastic solid waste (PSW) and their health risks were investigated. A total of 64 VOCs including alkanes, alkenes, monoaromatics, oxygenated VOCs (OVOCs), chlorinated VOCs (ClVOCs) and acrylonitrile during the melting extrusion procedure were identified and quantified. The highest concentration of total VOCs (TVOC) occurred in the poly(acrylonitrile-butadiene styrene) (ABS) recycling workshop, followed by the polystyrene (PS), polypropylene (PP), polyamide (PA), polyvinyl chloride (PVC), polyethylene (PE) and polycarbonate (PC) workshops. Monoaromatics were found as the major component emitted from the ABS and PS recycling workshops, while alkanes were mainly emitted from the PE and PP recycling processes, and OVOCs from the PVC and PA recycling workshops. According to the occupational exposure limits' (OEL) assessment, the workers suffered acute and chronic health risks in the ABS and PS recycling workshops. Meanwhile, it was found that most VOCs in the indoor microenvironments were originated from the melting extrusion process, while the highest TVOC concentration was observed in the PS rather than in the ABS recycling workshop. Non-cancer hazard indices (HIs) of all individual VOCs were < 1.0, whereas the total HI in the PS recycling workshop was 1.9, posing an adverse chronic health threat. Lifetime cancer risk assessment suggested that the residents also suffered from definite cancer risk in the PS, PA, ABS and PVC recycling workshops.Download full-size image
Co-reporter:Jiangyao Chen, Haiying Luo, Huixian Shi, Guiying Li, Taicheng An
Applied Catalysis A: General (5 September 2014) Volume 485() pp:188-195
Publication Date(Web):5 September 2014
DOI:10.1016/j.apcata.2014.08.004
Co-reporter:Xiaolu Liu, Jiangyao Chen, Porun Liu, Haimin Zhang, Guiying Li, Taicheng An, Huijun Zhao
Applied Catalysis A: General (5 July 2016) Volume 521() pp:34-41
Publication Date(Web):5 July 2016
DOI:10.1016/j.apcata.2015.10.005
Co-reporter:Taicheng An, Hongwei Sun, Guiying Li, Huijun Zhao, Po Keung Wong
Applied Catalysis B: Environmental (5 July 2016) Volume 188() pp:360-366
Publication Date(Web):5 July 2016
DOI:10.1016/j.apcatb.2016.02.014
Co-reporter:Taicheng An, Jikai Liu, Guiying Li, Shanqing Zhang, Huijun Zhao, Xiangying Zeng, Guoying Sheng, Jiamo Fu
Applied Catalysis A: General (30 November 2008) Volume 350(Issue 2) pp:237-243
Publication Date(Web):30 November 2008
DOI:10.1016/j.apcata.2008.08.022
Co-reporter:Lei Sun, Taicheng An, Shungang Wan, Guiying Li, Ningzhong Bao, Xiaohong Hu, Jiamo Fu, Guoying Sheng
Separation and Purification Technology (30 June 2009) Volume 68(Issue 1) pp:83-89
Publication Date(Web):30 June 2009
DOI:10.1016/j.seppur.2009.04.011
In the present study, design of experiments (DOE) was used to find an optimal combination for the factors affecting the preparation, morphology and catalytic activity of nano-crystalline TiO2 thin films synthesized by sol–gel method. Nine TiO2 thin films were prepared onto indium–tin oxide (ITO) substrates by changing four operating parameters at three levels. The four operating parameters are the volume of 20% acetic acid aqueous solution, the volume of co-solvent alcohol, the amount of template reagent (triblock copolymer Pluronic P123), and the calcination temperature. The resulting films were characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and Fourier transform-infrared (FT-IR) spectra. The results of DOE are examined by both the direct observation analysis (also called range analysis) and the analysis of variance (ANOVA) with 90 or 95% confidence intervals. The parameter settings have been optimized as the combination of precursor solution constitution of Ti(OC4H9)4/20%HAC/EtOH/P123 (2 g/15 ml/8 ml/1.1 g), calcination temperature of 450 °C, calcination time of 3 h, and air reaction atmosphere. The thin film prepared under the optimal combination consists of ordered compact anatase nanoparticles with an average grain size of approximately 17.2 nm and an average roughness of 3.653 nm. The 1-h photodegradation efficiency of methyl orange (MO) in aqueous solution and toluene in gaseous phase is 98.9 and 100%, respectively. The factor analysis results of degradation efficiencies show that the calcinations temperature plays an important role in determining the photocatalytic activity of the prepared TiO2 thin film. Furthermore, the surface morphology-dependent photocatalytic activity of the prepared thin films was also found.
Co-reporter:Jiangyao Chen, Xiaolu Liu, Guiying Li, Xin Nie, Taicheng An, Shanqing Zhang, Huijun Zhao
Catalysis Today (30 April 2011) Volume 164(Issue 1) pp:364-369
Publication Date(Web):30 April 2011
DOI:10.1016/j.cattod.2010.11.014
A series of SiO2 and TiO2 co-pillared montmorillonite photocatalysts with excellent adsorption capacity and high photocatalytic activity were synthesized via a sol–gel method by pillaring both SiO2 and TiO2 mixed sol into sodium montmorillonite. Various material characterization techniques such as powder X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms and scanning electron microscopy (SEM) were used to examine the pillared montmorillonites. 2,4,6-trichlorophenol, a typical hydrophobic organic pollutant, was used as a model pollutant to evaluate the adsorption capacity and photocatalytic activity of the prepared co-pillared montmorillonites. The experimental results showed that large SiO2 content in the pillared montmorillonite was in favor of large adsorption capacity, while large TiO2 content in the co-pillared montmorillonite was beneficial for the high photocatalytic activity, and the highest photocatalytic activity was obtained for the prepared co-pillared montmorillonite with a SiO2/TiO2 molar ratio of 1:2. Additionally, nine intermediates including 2,4-dichlorophenol, 2-chloro-1,5-diphenol, 1,3,7-trichlorodibenzo-p-dioxin, 2,6-dichlorodibenzo-p-dioxin, hexadiene diacid, butyl alkyd, oxalic acid, phloroglucinol and diphenol were detected, and a photocatalytic degradation mechanism of TCP was tentatively proposed.
Co-reporter:Guiying Li, Xiaolu Liu, Haimin Zhang, Taicheng An, Shanqing Zhang, Anthony R. Carroll, Huijun Zhao
Journal of Catalysis (3 January 2011) Volume 277(Issue 1) pp:88-94
Publication Date(Web):3 January 2011
DOI:10.1016/j.jcat.2010.10.011
A bactericidal technique (PEC–Br) utilizing in situ photoelectrocatalytically generated photoholes (h+), long-lived di-bromide radical anions (Br2-) and active oxygen species (AOS) for instant inactivation and rapid decomposition of Gram-negative bacteria such as Escherichia coli (E. coli) was proposed and experimentally validated. The method is capable of inactivating 99.90% and 100% of 9 × 106 CFU/mL E. coli within 0.40 s and 1.57 s, respectively. To achieve the same inactivation effect, the proposed method is 358 and 199 times faster than that of the photoelectrocatalytic method in the absence of Br−, and 2250 and 764 times faster than that of the photocatalytic method in the absence of Br−. The decomposition experimental results obtained from 600-s PEC–Br-treated samples demonstrated that over 90% of E. coli body mass was decomposed and 42% biological carbon contents in the sample was completely mineralized and converted into CO2. The mechanistic pathways of disinfection/decomposition by photocatalysis (PC), photoelectrocatalysis (PEC), and photoelectrocatalysis in presence of Br− (PEC–Br) were also illustrated based on experimental evidence.Graphical abstractThe proposed bactericidal method utilizes in situ photoelectrocatalytically generated bactericides to achieve instant inactivation and rapid decomposition of Gram-negative bacteria. The method is capable of inactivating 99.90% of Escherichia coli within 0.4 s and mineralizing over 40% biomass within 600 s.Download high-res image (110KB)Download full-size imageResearch highlights► A novel bactericidal technique was proposed and experimentally validated ► In situ generated bactericide can inactivate 99.90% of E. coli within 0.4 s ► In situ generated bactericide can rapid decompose bacteria ► The method is capable of mineralizing over 40% biomass within 600 s ► The mechanistic pathways of disinfection/decomposition were proposed.
Co-reporter:Taicheng An, Jiaxin Chen, Guiying Li, Xuejun Ding, Guoying Sheng, Jiamo Fu, Bixian Mai, Kevin E. O'Shea
Catalysis Today (15 December 2008) Volume 139(Issues 1–2) pp:69-76
Publication Date(Web):15 December 2008
DOI:10.1016/j.cattod.2008.08.024
A novel TiO2 immobilized hydrophobic montmorillonite photocatalysts were designed and prepared for the advanced oxidation of persistent organic pollutants in water, which combined the pre-adsorption and concentrated effects for aqueous micro-organic pollutants with the photocatalytic destruction of organic pollutants. The photocatalysts were synthesized by immobilizing TiO2 onto surfactant-pillared montmorillonite via ion exchange reaction between sodium montmorillonite with cation surfactant, cetyl trimethyl ammonium bromide (CTMAB). The Degussa P25 catalyst loading amounts varied between 20 and 80%. The composition and texture of the prepared composites were characterized with X-ray powder diffraction, scanning electron microscope, and energy-dispersive spectrometry. The adsorption performance and photocatalytic activities of prepared composite photocatalysts were evaluated using decabromodiphenyl ether (BDE 209) as a model pollutant in aqueous solution. The results were found that these composite photocatalysts can effectively degrade BDE 209, and the complete removal can be achieved within 180 min of irradiation. The removal efficiency of BDE 209 increased with the percentage of immobilized TiO2 on the hydrophobic clay. Highly hydrophobic substrates (BDE 209) can effectively adsorb (concentrate) in or near the hydrophobic surfactant regions of TiO2 immobilized CTMAB-pillared montmorillonite photocatalysts. The degradation pathways involving photochemical debromination and hydroxyl radical addition are proposed based on the identification of specific by-products.
Co-reporter:Taicheng An, Hai Yang, Guiying Li, Weihua Song, William J. Cooper, Xiangping Nie
Applied Catalysis B: Environmental (10 February 2010) Volume 94(Issues 3–4) pp:288-294
Publication Date(Web):10 February 2010
DOI:10.1016/j.apcatb.2009.12.002
Co-reporter:Taicheng An, Meng Qiao, Guiying Li, Hongwei Sun, Xiangying Zeng and Jiamo Fu
Environmental Science: Nano 2011 - vol. 13(Issue 5) pp:NaN1463-1463
Publication Date(Web):2011/04/05
DOI:10.1039/C0EM00542H
The Pearl River Delta (PRD) region is one of the most population-dense areas in China. The safety of its drinking source water is essential to human health. Polycyclic aromatic hydrocarbons (PAHs) have attracted attention from the scientific community and the general public due to their toxicity and wide distribution in the global environment. In this work, PAHs pollution levels from the drinking source water in nine main cities within the PRD were investigated. ∑15 PAHs concentrations during the wet season varied from 32.0 to 754.8 ng L−1 in the dissolved phase, and from 13.4 to 3017.8 ng L−1 in the particulate phase. During the dry season, dissolved PAHs ranged from 48.1 to 113.6 ng L−1, and particulate PAHs from 8.6 to 69.6 ng L−1. Overall, ∑15 PAHs concentrations were extremely high in the XC and ZHQ stations during the wet season in 2008 and 2009. In most sites, PAHs originated from mixed sources. Hazard ratios based on non-cancerous and cancerous risks were extremely higher in XC compared with the others during the wet season, though they were much less than 1. Nevertheless, risks caused by the combined toxicity of ∑15 PAHs and other organics should be seriously considered. PAHs toxic equivalent quantities ranged from 0.508 to 177.077 ng L−1.
Co-reporter:Meng Qiao, Taicheng An, Xiangying Zeng, Delin Zhang, Guiying Li, Guoying Sheng, Jiamo Fu, Guoxia Zhang and Jun Guo
Environmental Science: Nano 2010 - vol. 12(Issue 9) pp:NaN1677-1677
Publication Date(Web):2010/07/08
DOI:10.1039/C002019B
The safety of source water is a noticeable problem in the Pearl River Delta, one of the densely populated areas in China. In this study, 20 individual organochlorine pesticides (OCPs) were investigated in 15 water sources within this area using gas chromatography-electron capture detector, and the hazard risks to human health were assessed in terms of individual OCPs based on daily water consumption according to the standard recommended by the United States Environmental Protection Agency. Results showed that the total OCP concentrations ranged from 2.42 ng l−1 to 39.52 ng l−1 during the years 2008 and 2009. The hazard ratios based on both non-cancer and cancer benchmarks were less than 1 for all the water samples, which indicated that individual OCPs posed no risk to human health. However, the risks caused by the combined toxicity of total OCPs in this area should not be ignored.
Co-reporter:Dan Wu, Bo Wang, Wei Wang, Taicheng An, Guiying Li, Tsz Wai Ng, Ho Yin Yip, Chunmei Xiong, Hung Kay Lee and Po Keung Wong
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN15155-15155
Publication Date(Web):2015/06/11
DOI:10.1039/C5TA02757H
Bismuth oxybromide (BiOBr) nanosheets with fully exposed {001} and {010} facets are synthesized via a facile hydrothermal method. Significant differences in photocatalytic inactivation towards Escherichia coli K-12 under visible light irradiation are found to be highly dependent on the dominantly exposed facets. In comparison with BiOBr with dominant {010}-facet (B010) nanosheets, BiOBr with dominant {001}-facet (B001) nanosheets exhibit remarkably higher photocatalytic activity in bacterial inactivation. This superior activity is ascribed to the more favorable separation and transfer of photogenerated electron–hole pairs as well as more oxygen vacancies of B001 nanosheets. Due to the faster production and further accumulation of ˙O2− and h+ within a short time, the VLD photocatalyst of B001 nanosheets can completely inactivate 107 colony forming unit (CFU) mL−1 (i.e. 7-log reduction) bacterial cells within 2 h; while only 1- and 6.5-log reductions of bacterial cells can be achieved within 2 and 6 h, respectively, by B010 nanosheets due to limited amounts of h+ and ˙O2− generated.
![Ferrate(2-),[[N,N'-1,2-ethanediylbis[N-[(carboxy-kO)methyl]glycinato-kN,kO]](4-)]-, hydrogen (1:2), (OC-6-21)-](http://img.cochemist.com/ccimg/21400/21393-59-9.png)
![Ferrate(2-),[[N,N'-1,2-ethanediylbis[N-[(carboxy-kO)methyl]glycinato-kN,kO]](4-)]-, hydrogen (1:2), (OC-6-21)-](http://img.cochemist.com/ccimg/21400/21393-59-9_b.png)
