CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Shengjun Ye,Xiao Zhou,Yanbin Xu,Weikang Lai,Kai Yan,Lu Huang,Jiayin Ling,Li Zheng
To enhance the photocatalytic performance of bismuth vanadate (BiVO 4 ) and reveal its catalytic mechanism, a multi-walled carbon nanotube photocatalyst (MWCNT/BiVO 4 ) was prepared by sol-gel preparation and an electro-spinning process. Oxytetracycline was used as the target trace persistent pollutant to research its potential degradation pathways catalyzed by MWCNT/BiVO 4 . X-ray powder diffraction spectroscopy (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM) and field emission transmission electron microscopy (FE-TEM) were used to observe the crystalline phase, morphological structure of MWCNT/BiVO 4 . The modification by MWCNTs caused changes of functional groups on the surface and a binding energy shift of Bi4f and V2p, as determined from X-ray photoelectron spectroscopy (XPS). Ultraviolet–visible diffuse reflectometry (UV–Vis DRS) revealed that the band gap became narrower and photoluminescence spectra suggested the recombination of photogenerated electron–hole pairs were inhibited after MWCNT modification. All of the characterizations showed enhancement of catalytic performance of MWCNT/BiVO 4 . The results from the high-performance liquid chromatography (HPLC) indicated that the degradation rate of oxytetracycline had increased by 42.2% and reached 88.7% within 60 min. Electron paramagnetic resonance (EPR) signals of ·OH and ·O 2 − were detected and potential photocatalytic mechanisms of the photocatalysts were put forward. Six reaction pathways were proposed based on ultra-performance liquid chromatography triple-quadrupole tandem mass spectrometry (UPLC–MS/MS) results: demethylation (−14 Da), secondary alcohol oxidation (−2 Da), dehydration (−18 Da), hydroxylation (+16 Da), decarbonylation (−28 Da) and deamination (−15 Da). The present study provides a reference for the application of photocatalytic degradation by MWCNT/BiVO 4 on hard degradable substances in aquatic environment.
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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Liwei Chen,Xiaoxin Hu,Tianming Cai,Ying Yang,Rudong Zhao,Chao Liu,Anyun Li,Canlan Jiang
As a widely used antimicrobial agent, Triclosan (TCS) may potentially enter the environment, thus invoking significant environmental concerns due to its high toxicity to organisms. The present study demonstrated that a thermally activated persulfate (PS) oxidation process could effectively degrade the TCS in various arable topsoils. Eighty percent of the TCS at 50 mg kg −1 in Zhe Jiang (ZJ) soil could be degraded after a 360 min reaction in the presence of 18.8 mM of PS. Increased PS concentrations significantly increased the efficiency of the degradation. Elevated temperatures were favorable for TCS degradation, and the apparent activation energy E a was determined to be 74.3 kJ mol −1 . The oxidation efficiency gradually decreased with the increase of the pH from 3 to 11. An electron paramagnetic resonance (EPR) experiment and radical scavenging test confirmed that both OH and SO 4 − existed during oxidation, and SO 4 − was the dominant radical species. The degradation efficiency of TCS was higher than that of Triclocarban (TCC), another widely used antimicrobial agent, which might be attributed to the electro-donating phenolic (–OH) and ether (–O–) groups in the molecular structure of TCS. The degradation of TCS in three arable topsoils indicated that the soil organic matter played a dominant role in TCS degradation. In ZJ soil, after the oxidation process, the soil’s SOM was decreased by 14%, and the breakdown of large soil aggregates into smaller ones was found. Moreover, two degradation products of TCS were identified, e.g., penta-hydroxylated and hexa-hydroxylated TCS, which may be less toxic. The degradation was induced by phenol ring hydroxylation, and the underlying oxidation mechanisms are given.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2019
·
IF 6.361
Yufeng Yao,Jia Fan,Ming Shen,Weizheng Li,Bin Du,Xue Li,Jingtao Dai
In this study, hexylresorcinol calix[4]arene (HRCA) is introduced into the reaction system, and HRCA-capped ZnO–Ag nanocomposites are prepared via a simple one-step reflux method. HRCA is used not only as a reducing agent for deoxidizing Ag + to Ag, but also as a protectant for wrapping around the microstructure of the formed ZnO–Ag. The prepared samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and water contact angle. The Ag nanoparticles and ZnO adhere to each other and HRCA molecules encapsulate on the surface of ZnO–Ag nanocomposites. HRCA-capped ZnO–Ag nanocomposites with different Ag contents are investigated for use in photodegradation of organic pollutants (rhodamine B (RhB) and levofloxacin hydrochloride). The sample with 10.20 mol% Ag, denoted as ZA3, exhibits the highest catalytic activity for photodegradation of RhB and levofloxacin hydrochloride. Moreover, ZA3 exhibits high stability during photodegradation of organic pollutants even after multiple reuses. The possible photocatalytic mechanism is discussed. We believe that O 2 − and h + are the chief active species responsible for the photocatalytic activity of HRCA-capped ZnO–Ag nanocomposite system. HRCA-capped ZnO–Ag nanocomposite is expected to be an effective photocatalyst with potential application to sewage treatment under sunlight.
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高影响因子
FREE RADICAL BIOLOGY AND MEDICINE
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2019
·
IF 5.657
Hong Huang,Xiaobing Lou,Bingwen Hu,Zhongneng Zhou,Jinquan Chen,Yang Tian
In the amyloid plaques , a signature of AD, abnormally high Cu 2+ concentrations are found bound to Aβ. Most of previous studies reported that Cu-Aβ could contribute to oxidative stress , as H 2 O 2 and •OH are catalytically generated by Cu-Aβ with the assistance of biological reductant, with only one recent report stated that free O 2 •- is also generated in the Cu-Aβ catalyzed processes, where an indirect technique was applied. To comprehensively investigate the free radicals produced during this Cu-Aβ-mediated process with a biological reductant, DNA-cleavage assay, an indirect method, and two direct methods including electron paramagnetic resonance (EPR) spectroscopy and transient absorption spectroscopy (TAS), both having qualitative and quantitative power, were employed in this work. All the experimental results obtained from the three methods demonstrated that Cu-Aβ in the biological reducing environment was not only able to catalyze the production of H 2 O 2 and •OH, but also to generate free O 2 •- . The results further indicated that O 2 •- was the precursor of H 2 O 2 and •OH. It is also important to note that the results obtained from EPR spectroscopy and TAS provided direct evidence for the presence of O 2 •- and •OH. By virtue of the direct techniques, we also found that the longest peptide fragments of Aβ 16 , Aβ 40 , and Aβ 42 produced the least radicals with a lowest rate. More interestingly, the fibrillar forms of Aβ generated less O 2 •- and •OH compared with oligomeric and monomeric forms.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Chao Liu,Liwei Chen,Dahu Ding,Tianming Cai
Efficient removal of residual metolachlor (MET), a frequently used herbicide from aquatic system is highly desirable but remains a challenge. In the present study, the emerging sulfate radical based advanced oxidation processes (SR-AOPs) is developed for the degradation of MET from aqueous solution. At the conditions of [MET] = 10 mg L −1 , [Peroxymonosulfate (PMS)] = 3 mM, [Catalyst] = 0.2 g L −1 , pH = 6.5, the degradation process could be accomplished within 40 min and the derived pseudo-first-order kinetic rate constant ( k app ) was 0.11 min −1 . The effects of reaction conditions including pH, oxidant dosage, temperature, concomitant anions and humic acid on the degradation process were comprehensively investigated. Sulfate radical was identified to be the main contributor to the degradation process through radical scavenging and electron paramagnetic resonance (EPR) analysis. The second-order rate constant for reaction of SO 4 − with MET was determined to be 2.17 × 10 9 M −1 s −1 by competition kinetic method. The degradation showed a moderate pH-tolerance. Specifically, alkaline/neutral conditions were beneficial for the MET degradation whilst acidic condition exhibited a detrimental effect on the degradation. Through LC-Q-TOF-MS analysis, eleven aromatic derivatives were detected and their molecular structures were tentatively proposed. A tentative mechanism was proposed based on the detected derivatives. The toxicity test further revealed that the degradation products performed a less toxicity than MET. The results pave an avenue toward the applications of SR-AOPs for MET elimination from aquatic environment.
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CHEMOSPHERE
·
2019
·
IF 5.108
Jingchun Yan,Yudong Chen,Weiguo Gao,Yun Chen,Linbo Qian,Lu Han,Mengfang Chen
A high catalytic system using Cu layered double hydrotalcite (Cu(II)-Mg(II)-Fe(III)LDHs) and hydrogen peroxide (H 2 O 2 ) was developed for the degradation of ethylbenzene. It was identified that the degradation efficiency of ethylbenzene (0.08 mmol L −1 ) and TOC removal were 96.1% and 39.7% respectively in the presence of 0.1 g L −1 Cu(II)-Mg(II)-Fe(III)LDHs with (Cu 2+ + Mg 2+ )/Fe 3+ molar ratio of 5.0 and 0.16 mmol L −1 H 2 O 2 in 6.0 h. Based on ESR and XPS data, hydroxyl radicals (•OH) were the predominant free radical specials generated from the catalytic decomposition of H 2 O 2 for the degradation of ethylbenzene. The redox of Cu(II)/Cu(III) on the layered Cu(II)-Mg(II)-Fe(III)LDHs surface active sites accounted for the formation of •OH radicals and the cycle of Cu(II) in the Cu(II)-Mg(II)-Fe(III)LDHs/H 2 O 2 system were proposed.
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APPLIED SURFACE SCIENCE
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2019
·
IF 5.155
Hui Li,Yanlin Zhang,Qian Zhang,Yifei Wang,Yanping Fan,Xin Gao,Jing Niu
In our work, Z -scheme Ag 3 PO 4 /NG/WO 3 composites were fabricated via a facile deposition approach, which was used in the photocatalytic degradation of indomethacin (IDM) under visible light irradiation. The as-prepared Ag 3 PO 4 -based photocatalysts were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscope , Fourier transform infrared, X-ray photoelectron spectroscopy and UV–visible diffuse reflectance spectroscopy in order to determine the chemical structure , morphological feature and optical performance. From the degradation experiments of IDM, the Ag 3 PO 4 /NG/WO 3 composite exhibited the highest photocatalytic activity and stability, and its kinetics constant was ~8 times of pure Ag 3 PO 4 . Furthermore, reactive species trapping experiment, electron spin resonance , liquid chromatography-mass spectrometry, total organic carbon , photoelectrochemical measurement and photoluminescence spectra were applied to analyze the possible degradation pathways and photocatalytic mechanism of IDM. The results indicated that the visible-light photocatalytic degradation of IDM using Ag 3 PO 4 /NG/WO 3 conformed to a Z -scheme photocatalysis mechanism, further facilitating the photoinduced charge carriers separation, and inhibiting the recombination of photoinduced electron-hole pairs. It also confirmed that the holes, OH and O 2 – radicals generated in Z -scheme system played the significant roles during the photocatalytic degradation of IDM.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Yake Xu,Lingyu Zeng,Lanqing Li,Yoon-Seok Chang,Jianyu Gong
In this study, we systematically investigated the oxidative degradation of 4-chlorophenol (4-CP) using nano zero valent iron (nZVI, Fe 0 ) cooperated with citric acid (CA), and the role of CA as well as the mechanism of oxidation were deeply evaluated. 56.2% of 4-CP was removed after 60 min under dark condition without any ventilation of oxygen in the presence of Fe 0 and CA. The addition of CA accelerated the release of ferrous ions and promoted the Fenton reaction to generate much more reactive oxygen species (ROS), which was confirmed by EPR. The MINEQL+ 4.6 soft was utilized to calculated the existent species in Fe 0 -CA system, and Fe(II)[Cit] − was found to be the key species playing an important role on the degradation of 4-CP. Fe(II)[Cit] − adsorbed on iron surface accelerated the transportation of electron from Fe 0 to O 2 to produce more OH. This study puts forward the possible mechanism of generating ROS on Fe 0 enhanced by CA and provides an application for the oxidation of pollutants.
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Journal of the Taiwan Institute of Chemical Engineers
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2019
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IF 3.834
Peng Zhou,Wenshu Li,Jing Zhang,Gucheng Zhang,Xin Cheng,Yang Liu,Xiaowei Huo,Yongli Zhang
Rhodamine B (RhB) removal in a tungsten species-catalyzed Fenton-like system using nanoscale zero valent tungsten (nZVW) was investigated. The nZVW system can effective remove RhB in oxygenated water, and the nZVW/H 2 O 2 system significantly enhances the RhB removal. Mechanism investigation shows that hydroxyl radical (·OH) is the primary reactive oxidant for removing RhB in both systems. The stepwise oxidation of nZVW can release reactive tungsten species and produce H 2 O 2 by electron transfer from W 0 or low valent tungsten species to O 2 , and ·OH was then formed via a Fenton-like reaction between low valent tungsten species and H 2 O 2 . The addition of H 2 O 2 in the nZVW/H 2 O 2 system can increase the RhB removal ratio by accelerating nZVW corrosion and enhancing the Fenton-like reaction. Moreover, higher pH inhibits the RhB removal due to the consumption of reactive tungsten species by OH − , and both higher nZVW and H 2 O 2 dosages can enhance the RhB removal. RhB degradation pathways in the nZVW/H 2 O 2 system are proposed involving N-de-ethylation, chromophore cleavage, ring open, and mineralization. In addition, the present study puts forward a new water treatment technique and contributes to understand the role of tungsten species in advanced oxidation processes.
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Journal of Environmental Sciences
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2019
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IF 3.556
Hanlu Shi,Rui He,Lei Sun,Gang Cao,Xiangjuan Yuan,Dongsheng Xia
A series of functional organic–metal AgCl-decorated graphitic carbon nitride (AgCl-CN x ) composites were synthesized and applied for the degradation of oxalic acid (OA) under visible light. The highest photocatalytic activity was achieved with AgCl decoration ratio of 1.0 (denoted as AgCl-CN 1.0 ). The pseudo-first-order constant for OA degradation was 0.0722 min −1 with the mineralization efficiency of 90.80% after 60 min reaction in the photocatalytic process with AgCl-CN 1.0 . A variety of characterization techniques including Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscope , transmission electron microscopy , X-ray photoelectron spectroscopy, Fourier transform infrared spectra , ultraviolet–visible diffuse reflectance spectra, photoluminescence , and Mott–Schottky were utilized to elucidate the physicochemical, microstructure, and optical properties contributing to the improvement of the photocatalytic performance. The results showed that AgCl-CN 1.0 had an oblate flaky erythrocyte-like structure with a moderate band gap energy of ~ 3.00 eV. In addition, the effects of the key parameters (i.e., AgCl-CN 1.0 dosage, initial OA concentration, solution pH, and presence of natural organic matter) on OA degradation were systematically investigated. Radical scavenger experiments indicated that photogenerated holes, electrons, superoxide anion radicals, and hydroxyl radicals were the dominant reactive species. Moreover, AgCl-CN 1.0 exhibited excellent stability and reusability for OA degradation without detectable Ag + release in the solution over multiple reaction cycles. The efficient OA mineralization could be mainly ascribed to the moderate specific surface area, increased numbers of active sites, and effective interfacial charge transfer of AgCl-CN 1.0 . Overall, the AgCl-CN 1.0 composite was demonstrated to be a highly efficient, stable, and recoverable photocatalyst.
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Nanoscale
·
2019
·Vol. 11
·期 19
·9444-9456
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IF 6.97
Xinyi Lian,Zhou Chen,Xiang Yu,Tingting Fan,Yunyun Dong,Hesheng Zhai,Weiping Fang,Xiaodong Yi
To solve the intrinsic deficiency inherited from the large band gap of ZnSn(OH)6 (ZSH), a gradual sulfur doping strategy is first proposed here to expand the optical absorption range, improve the separation efficiency of photogenerated electron–hole pairs, and thus enhance the photocatalytic activity. It is demonstrated that the distribution of sulfur in the flower-like ZSH (the sulfur doped sample is denoted as S-ZSH) tends to be largest on the outer most surface and becomes smaller towards the interior. The S-ZSH therefore has a gradual bandgap structure that is beneficial for transferring photogenerated charge carriers from the interior to the surface, which will greatly enhance the utilization of photoelectrons. As a result, the visible light photocurrent density of S-ZSH and the photocatalytic degradation rate of rhodamine (RhB) are about 5 and 10 times higher than with pristine ZSH, respectively.
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JOURNAL OF HAZARDOUS MATERIALS
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2019
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IF 7.65
Zhe Li,Lianying Wang,Zenghe Li,Rui Tian,Chao Lu
Fenton/Fenton-like reaction is often used as an efficient method to generate hydroxyl radicals (HO ) for bacteria inactivation in aqueous solution. However, inactivation efficiency of bacteria in aqueous solution using Fenton/Fenton-like reactions needs to further improve as a result of transient generation of HO . In this paper, we found that the formation of Tris-Co(II) complexes could decrease the redox potential of Co(III)/Co(II), facilitating the transformation of Tris-Co(III) complexes into Tris-Co(II) complexes. Therefore, HO could be generated continuously in the presence of H 2 O 2 . Especially, Tris-Co(II) complexes are apt to combine with Escherichia Coli cells by electrostatic interactions, inducing a higher utilization ratio of the generated HO . Therefore, the proposed Tris-Co(II) complex-H 2 O 2 system could be employed as a high-efficiency sterilizing reagent for inactivation of E. Coli . This work provides a promising strategy for bacterial inactivation via an economic and eco-friendly manner.
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