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Botti A, Musmeci E, Matturro B, Vanzetto G, Bosticco C, Negroni A, Rossetti S, Fava F, Biagi E, Zanaroli G. Chemical-physical parameters and microbial community changes induced by electrodes polarization inhibit PCB dechlorination in a marine sediment. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:133878. [PMID: 38447365 DOI: 10.1016/j.jhazmat.2024.133878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/30/2024] [Accepted: 02/22/2024] [Indexed: 03/08/2024]
Abstract
Microbial reductive dechlorination of organohalogenated pollutants is often limited by the scarcity of electron donors, that can be overcome with microbial electrochemical technologies (METs). In this study, polarized electrodes buried in marine sediment microcosms were investigated to stimulate PCB reductive dechlorination under potentiostatic (-0.7 V vs Ag/AgCl) and galvanostatic conditions (0.025 mA·cm-2-0.05 mA·cm-2), using graphite rod as cathode and iron plate as sacrificial anode. A single circuit and a novel two antiparallel circuits configuration (2AP) were investigated. Single circuit polarization impacted the sediment pH and redox potential (ORP) proportionally to the intensity of the electrical input and inhibited PCB reductive dechlorination. The effects on the sediment's pH and ORP, along with the inhibition of PCB reductive dechlorination, were mitigated in the 2AP system. Electrodes polarization stimulated sulfate-reduction and promoted the enrichment of bacterial clades potentially involved in sulfate-reduction as well as in sulfur oxidation. This suggested the electrons provided were consumed by competitors of organohalide respiring bacteria and specifically sequestered by sulfur cycling, which may represent the main factor limiting the applicability of METs for stimulating PCB reductive dechlorination in marine sediments.
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Affiliation(s)
- Alberto Botti
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Eliana Musmeci
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Bruna Matturro
- Water Research Institute (IRSA), National Research Council (CNR), 00010 Montelibretti, Italy; National Biodiversity Future Center, 90133 Palermo, Italy
| | - Giampietro Vanzetto
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Caterina Bosticco
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Andrea Negroni
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Simona Rossetti
- Water Research Institute (IRSA), National Research Council (CNR), 00010 Montelibretti, Italy
| | - Fabio Fava
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Elena Biagi
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy
| | - Giulio Zanaroli
- Dept. of Civil, Chemical, Environmental and Materials Engineering (DICAM), Alma Mater Studiorum University of Bologna, Via Terracini 28, 40131 Bologna, Italy.
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2
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Choi C, Wang X, Kwon S, Hart JL, Rooney CL, Harmon NJ, Sam QP, Cha JJ, Goddard WA, Elimelech M, Wang H. Efficient electrocatalytic valorization of chlorinated organic water pollutant to ethylene. NATURE NANOTECHNOLOGY 2023; 18:160-167. [PMID: 36536043 DOI: 10.1038/s41565-022-01277-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Electrochemistry can provide an efficient and sustainable way to treat environmental waters polluted by chlorinated organic compounds. However, the electrochemical valorization of 1,2-dichloroethane (DCA) is currently challenged by the lack of a catalyst that can selectively convert DCA in aqueous solutions into ethylene. Here we report a catalyst comprising cobalt phthalocyanine molecules assembled on multiwalled carbon nanotubes that can electrochemically decompose aqueous DCA with high current and energy efficiencies. Ethylene is produced at high rates with unprecedented ~100% Faradaic efficiency across wide electrode potential and reactant concentration ranges. Kinetic studies and density functional theory calculations reveal that the rate-determining step is the first C-Cl bond breaking, which does not involve protons-a key mechanistic feature that enables cobalt phthalocyanine/carbon nanotube to efficiently catalyse DCA dechlorination and suppress the hydrogen evolution reaction. The nanotubular structure of the catalyst enables us to shape it into a flow-through electrified membrane, which we have used to demonstrate >95% DCA removal from simulated water samples with environmentally relevant DCA and electrolyte concentrations.
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Affiliation(s)
- Chungseok Choi
- Department of Chemistry, Yale University, New Haven, CT, USA
- Energy Sciences Institute, Yale University, West Haven, CT, USA
| | - Xiaoxiong Wang
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA
| | - Soonho Kwon
- Materials and Process Simulation Center (MSC), California Institute of Technology, Pasadena, CA, USA
| | - James L Hart
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
| | - Conor L Rooney
- Department of Chemistry, Yale University, New Haven, CT, USA
- Energy Sciences Institute, Yale University, West Haven, CT, USA
| | - Nia J Harmon
- Department of Chemistry, Yale University, New Haven, CT, USA
- Energy Sciences Institute, Yale University, West Haven, CT, USA
| | - Quynh P Sam
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
| | - Judy J Cha
- Energy Sciences Institute, Yale University, West Haven, CT, USA
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA
- Department of Mechanical Engineering and Materials Science, Yale University, West Haven, CT, USA
| | - William A Goddard
- Materials and Process Simulation Center (MSC), California Institute of Technology, Pasadena, CA, USA.
| | - Menachem Elimelech
- Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA.
| | - Hailiang Wang
- Department of Chemistry, Yale University, New Haven, CT, USA.
- Energy Sciences Institute, Yale University, West Haven, CT, USA.
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3
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Peng YP, Zhang EX, Chen CH, Chen WX. Photoelectrochemical degradation of trichloroethylene by iron modified TiO 2 nanotube arrays. CHEMOSPHERE 2022; 308:136217. [PMID: 36075360 DOI: 10.1016/j.chemosphere.2022.136217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 08/18/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
In this study, iron was deposited to titanium dioxide nanotube arrays (TNAs) by impregnation method to enhance its photocatalytic ability. The as-synthesized iron-modified TNAs (Fe-TNAs) was employed in a photoelectrochemical (PEC) system to degrade trichloroethylene (TCE). Results of AFE-SEM analysis showed that the iron nanoparticles (NPs) were successfully attached evenly to the nozzle of Fe-TNAs. Results of XRD analysis confirmed the findings of EDS and XPS, indicating the success of iron modification. The absorption wavelength of Fe-TNAs-27 mL red-shifts to 543 nm which corresponds to the band gap of 2.54 eV after iron modification. Mott-Schottky analysis yielded a donor density of 7.21 × 1020 and 2.30 × 1020/cm3 for TNAs and Fe-TNAs-27 mL, respectively. The photo-generated electrons had a lifetime (τel) of 21.49 and 39.19 ms for TNAs and Fe-TNAs-27 mL, respectively, illustrating the reduce of recombination of photo-generated electron-hole pairs. process. PEC methods performed the most effective way to degrade TCE with a rate constant of 0.079 min-1 in Fe-TNAs PEC system. Mechanism of Fe-TNAs PEC system was proposed in detail.
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Affiliation(s)
- Yen-Ping Peng
- Institute of Environmental Engineering, National Sun Yat-sen University, Kaoshiung, 804, Taiwan.
| | - En-Xian Zhang
- Institute of Environmental Engineering, National Sun Yat-sen University, Kaoshiung, 804, Taiwan
| | - Chia-Hung Chen
- Institute of Environmental Engineering, National Sun Yat-sen University, Kaoshiung, 804, Taiwan
| | - Wu-Xing Chen
- Institute of Environmental Engineering, National Sun Yat-sen University, Kaoshiung, 804, Taiwan
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4
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Pavelková A, Cencerová V, Zeman J, Antos V, Nosek J. Reduction of chlorinated hydrocarbons using nano zero-valent iron supported with an electric field. Characterization of electrochemical processes and thermodynamic stability. CHEMOSPHERE 2021; 265:128764. [PMID: 33183783 DOI: 10.1016/j.chemosphere.2020.128764] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/23/2020] [Accepted: 10/25/2020] [Indexed: 06/11/2023]
Abstract
Electric field assisted remediation using nano iron has shown outstanding results as well as economic benefits during pilot applications (Černíková et al., 2020). This method is based on donating electrons to the zero-valent iron that possess an inherently strong reductive capacity. The reduction of chlorinated hydrocarbons may be characterized by a decrease in contaminants or better still by the evolution of ethene and ethane originating from the reduction of chlorinated ethenes. The evolution of ethene and ethane was observed predominantly in the vicinity of the anode despite reduction processes being expected near the cathode - the electron donor. The reduction near the anode occurred due to dissolved Fe2+ ions, whose presence was suggested by a Pourbaix diagram that combines Eh/pH values to characterize electrochemical stabilities between different species. No products of dechlorination were observed in the area of the cathode due to presence of oxidized Fe in the form of Fe3+ or Fe(OH)4-. The experimental work described in this research provides a deeper view of the processes of electrochemical reductive dechlorination using zero-valent iron and DC. It also showed an increase in the efficiency compared to the method using zero-valent iron only.
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Affiliation(s)
- Alena Pavelková
- Institute for Nanomaterials, Advanced Technologies and Innovation, Technical University of Liberec, Bendlova 7, CZ-46117, Liberec, Czech Republic.
| | | | - Josef Zeman
- Institute of Geological Sciences, Faculty of Science, Masaryk University in Brno, Kotláská 2, CZ-611 37, Brno, Czech Republic.
| | - Vojtech Antos
- Institute for Nanomaterials, Advanced Technologies and Innovation, Technical University of Liberec, Bendlova 7, CZ-46117, Liberec, Czech Republic
| | - Jaroslav Nosek
- Institute for Nanomaterials, Advanced Technologies and Innovation, Technical University of Liberec, Bendlova 7, CZ-46117, Liberec, Czech Republic.
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5
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Xie S, Shao W, Zhan H, Wang Z, Ge C, Li Q, Fu W. Cu(II)-EDTA removal by a two-step Fe(0) electrocoagulation in near natural water: Sequent transformation and oxidation of EDTA complexes. JOURNAL OF HAZARDOUS MATERIALS 2020; 392:122473. [PMID: 32193116 DOI: 10.1016/j.jhazmat.2020.122473] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/01/2020] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
The widely usage of ethylenediaminetetraacetic acid (EDTA) arises environmental concerns on toxic metal mobilization, and challenges the conventional processes in water treatment. In the study Cu(II)-EDTA in near natural water was efficiently removed during a two-step electrocoagulation using Fe(0) anode (Fe-EC), including a transformation to Fe(III)-EDTA induced mainly by structural Fe(II) in anoxic Fe-EC and further degradation in oxic Fe-EC. The degradation of Fe(III)-EDTA was mostly attributed to an oxygen activation mechanism that involving O2- and hydroxyl radical (OH) generation, as validated by the quenching experiments and electron spin resonance. Furthermore, O2- generated during Fe(II) oxidation took a dominant role on Fe(III)/Fe(II)-EDTA transformation instead of electrochemical reduction. Six intermediates during the Fe(III)-EDTA degradation were identified by LC-Q-TOF, indicating a pathway of stepwise breakage of NC bonds. The results revealed in this work is helpful to understand the contribution and fate of EDTA during Fe-EC treatment of metal-EDTA polluted water.
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Affiliation(s)
- Shiwei Xie
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China.
| | - Wei Shao
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China
| | - Hui Zhan
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China
| | - Zheng Wang
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China
| | - Chengcheng Ge
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China
| | - Qingjie Li
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China
| | - Wenjing Fu
- School of Urban Construction, Wuhan University of Science and Technology, Wuhan, 430065, PR China
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6
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Yin H, Cao X, Lei C, Chen W, Huang B. Insights into Electroreductive Dehalogenation Mechanisms of Chlorinated Environmental Pollutants. ChemElectroChem 2020. [DOI: 10.1002/celc.202000067] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Hanshuang Yin
- College of Environmental Science and Engineering, Hunan University Key Laboratory of Environmental Biology and Pollution ControlHunan University, Ministry of Education Changsha 410082 China
| | - Xingkai Cao
- College of Environmental Science and Engineering, Hunan University Key Laboratory of Environmental Biology and Pollution ControlHunan University, Ministry of Education Changsha 410082 China
| | - Chao Lei
- School of Hydraulic EngineeringChangsha University of Science & Technology Changsha 410114 China
| | - Wenqian Chen
- Department of Chemical Engineering and TechnologyImperial College London Exhibition Road London SW7 2AZ UK
| | - Binbin Huang
- College of Environmental Science and Engineering, Hunan University Key Laboratory of Environmental Biology and Pollution ControlHunan University, Ministry of Education Changsha 410082 China
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7
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Hyldegaard BH, Ottosen LM, Alshawabkeh AN. Transformation of tetrachloroethylene in a flow-through electrochemical reactor. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 707:135566. [PMID: 31767295 PMCID: PMC6980996 DOI: 10.1016/j.scitotenv.2019.135566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 11/04/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
Electrochemical transformation of harmful tetrachloroethylene (PCE) is evaluated as a method for management of groundwater plumes to protect the drinking water resource, its consumers and the environment. In contrast to previous work that reported transformation of trichloroethylene, a byproduct of PCE, this work focuses on transformation of PCE in a saturated porous matrix and the influence of design parameters on the removal performance. Design parameters investigated were electrode configuration, catalyst load, electrode spacing, current intensity, orientation of reactor and flow through a porous matrix. A removal of 86% was reached in the fully liquid-filled, horizontally oriented reactor at a current of 120 mA across a cathode → bipolar electrode → anode arrangement with a Darcy velocity of 0.03 cm/min (150 m/yr). The palladium load on the cathode significantly influenced the removal. Enhanced removal was observed with increased electrode spacing. Presence of an inert porous matrix improved PCE removal by 9%-point compared to a completely liquid-filled reactor. Normalization of the data indicated, that a higher charge transfer per contaminant mass is required for removal of low PCE concentrations. No chlorinated intermediates were formed. The results suggest, that PCE can be electrochemically transformed in reactor designs replicating that of a potential field-implementation. Further work is required to better understand the reduction and oxidation processes established and the parameters influencing such. This knowledge is essential for optimization towards testing in complex conditions and variations of contaminated sites.
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Affiliation(s)
- Bente H Hyldegaard
- Department of Waste & Contaminated Sites, COWI, Parallelvej 2, 2800 Kgs. Lyngby, Denmark; Department of Civil Engineering, Brovej, Building 118, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark; Department of Civil & Environmental Engineering, 501 Stearns, 360 Huntington Avenue, Boston, MA 02115, United States of America.
| | - Lisbeth M Ottosen
- Department of Civil Engineering, Brovej, Building 118, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Akram N Alshawabkeh
- Department of Civil & Environmental Engineering, 501 Stearns, 360 Huntington Avenue, Boston, MA 02115, United States of America
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8
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Hyldegaard BH, Jakobsen R, Ottosen LM. Electrochemical transformation of an aged tetrachloroethylene contamination in realistic aquifer settings. CHEMOSPHERE 2020; 243:125340. [PMID: 31760284 DOI: 10.1016/j.chemosphere.2019.125340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/06/2019] [Accepted: 11/07/2019] [Indexed: 06/10/2023]
Abstract
Electrochemical removal of chlorinated ethenes in groundwater plumes may potentially overcome some of the challenges faced by current remediation technologies. So far, studies have been conducted in simplified settings of synthetic groundwater and inert porous matrices. This study is a stepwise investigation of the influence of field-extracted groundwater, sandy sediment and groundwater aquifer temperatures on the removal of an aged partially degraded contamination of tetrachloroethylene (PCE) at a typical groundwater flow rate. The aim is to assess the potential for applying electrochemistry at contaminated sites. At a constant current of 120 mA, pH and conductivity were unaffected downgradient the electrochemical zone. Major groundwater species were reduced and oxidized. Some minerals deposited, others dissolved. Hydrogen peroxide, a strong oxidant, was formed in levels up to 5 mg L-1 with a limited distribution into the sandy sediment. Trichloromethane was formed, supposedly by oxidation of organic matter in the sandy sediment in the presence of chloride. The more realistic the settings, the higher the PCE removal, bringing concentrations down to 7.8 ± 2.3 μg L-1. A complete removal of trichloroethylene and cis-1,2-dichloroethylene was obtained. The results suggest that competing reactions related to the natural complex hydrogeochemistry are insignificant in terms of affecting the electrochemical degradation of PCE and chlorinated intermediates.
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Affiliation(s)
- Bente H Hyldegaard
- Department of Waste & Contaminated Sites, COWI A/S, Parallelvej 2, 2800, Kgs. Lyngby, Denmark; Department of Civil Engineering, Brovej, Building 118, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark.
| | - Rasmus Jakobsen
- Department of Geochemistry, Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350, København K, Denmark
| | - Lisbeth M Ottosen
- Department of Civil Engineering, Brovej, Building 118, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
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9
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Wu S, Liang G, Guan X, Qian G, He Z. Precise control of iron activating persulfate by current generation in an electrochemical membrane reactor. ENVIRONMENT INTERNATIONAL 2019; 131:105024. [PMID: 31357090 DOI: 10.1016/j.envint.2019.105024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/14/2019] [Accepted: 07/15/2019] [Indexed: 06/10/2023]
Abstract
Activated persulfate (PS) oxidation is promising for contaminant removal but a lack of controllable activation can lead to a loss of reagents and thus low contamination degradation. Herein, we have proposed and investigated an innovative method to control PS activation by introducing ion exchange membrane into electrochemically activated PS. This electrochemical membrane reactor (EMR) could precisely control PS activation by adjusting electrical current for slow release of Fe2+, and also avoid direct contact between PS and a sacrificial anode electrode (iron electrode)/an alkaline cathode solution. It was found that the PS decomposition rate constant was linearly increased by increasing the applied current (R2 = 0.988). The rate of the released Fe2+ also exhibited a linear relationship with the applied current (R2 = 0.995). Compared to one-time dosage of Fe2+, the EMR-based slow-release process had higher contamination degradation and better PS utilization (molar ratio of the decomposed PS to the migrated Fe, 1.04 ± 0.01:1), thereby minimizing the waste of both reaction reagents and generated radicals. The EMR was also employed to degrade a representative dye contaminant in a controllable manner and achieved 95.7 ± 0.7% removal percentage with PS dosage of 3.0 g L-1 within 20 min. This study is among the earliest to explore effective approaches for precisely controlling PS activation and subsequent oxidation of contaminants.
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Affiliation(s)
- Simiao Wu
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China; Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Guannan Liang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Xiaohong Guan
- College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
| | - Guangren Qian
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, PR China
| | - Zhen He
- Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
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10
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Hu Y, Mao X, Cui J, Xiong L, Yin P, Zhou S, Wang X. Electrochemical Processes with a Chambered Dual‐Anode Design for Enhanced Removal of Dichlorophenol in Aqueous Solutions. ChemistrySelect 2019. [DOI: 10.1002/slct.201803863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yue Hu
- School of Resources and Environmental ScienceHubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University Wuhan 430079 China
| | - Xuhui Mao
- School of Resources and Environmental ScienceHubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University Wuhan 430079 China
- Hubei Biomass-Resource Chemistry and Environmental Biotechnology Key LaboratoryWuhan University Wuhan 430072 China
| | - Jiaxin Cui
- School of Resources and Environmental ScienceHubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University Wuhan 430079 China
| | - Lili Xiong
- School of Resources and Environmental ScienceHubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University Wuhan 430079 China
| | - Panji Yin
- School of Resources and Environmental ScienceHubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University Wuhan 430079 China
| | - Shoubin Zhou
- Jiangsu Huafu Energy Storage Company Ltd. Yangzhou City 215316 China
| | - Xu Wang
- School of Resources and Environmental ScienceHubei International Scientific and Technological Cooperation Base of Sustainable Resource and EnergyWuhan University Wuhan 430079 China
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11
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Zhang Y, Zhao Y, Chen Z, Wang L, Wu P, Wang F. Electrochemical reduction of nitrate via Cu/Ni composite cathode paired with Ir-Ru/Ti anode: High efficiency and N2 selectivity. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.08.154] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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12
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Hojabri S, Rajic L, Alshawabkeh AN. Transient reactive transport model for physico-chemical transformation by electrochemical reactive barriers. JOURNAL OF HAZARDOUS MATERIALS 2018; 358:171-177. [PMID: 29990804 PMCID: PMC6247793 DOI: 10.1016/j.jhazmat.2018.06.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 06/22/2018] [Accepted: 06/23/2018] [Indexed: 05/12/2023]
Abstract
A comprehensive model that integrates coupled effects of chemical, physical, and electrochemical processes, is necessary for design, analysis, and implementation of the electro-remediation of groundwater under flow conditions. A coupled system of equations to solve for transport and multiple reactions in an electrochemical reactor is numerically intensive due to highly stiff nature of reaction model formulation. In this study, the focus is to develop an efficient model for reactions associated with the transport and physico-chemical transformation in an electrochemical reactor. The model incorporates effects of transport mechanisms as well as chemical and electrochemical reactions. Model verification is provided for pH profiles under different electrolyte compositions in two sets of reactors; a batch and a flow-through reactor. The model is able to predict the concentration of species during the electrochemical remediation process with a close correlation to experimental data (R2 = 0.99 for batch and R2 = 0.78 for flow-through reactor.) Imposing polarity reversal to the system will cause fluctuation of pH, however, the trend stays the same as if no polarity were applied. Ultimately, volumetric charge flow is introduced as a unique parameter characterizing the electroremediation reactor for operating purposes.
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Affiliation(s)
- Shirin Hojabri
- Civil and Environmental Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Ljiljana Rajic
- Civil and Environmental Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Akram N Alshawabkeh
- Civil and Environmental Engineering, Northeastern University, Boston, MA, 02115, USA.
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13
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Liu B, Zhang H, Lu Q, Li G, Zhang F. A CuNi bimetallic cathode with nanostructured copper array for enhanced hydrodechlorination of trichloroethylene (TCE). THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 635:1417-1425. [PMID: 29710594 DOI: 10.1016/j.scitotenv.2018.04.238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 04/01/2018] [Accepted: 04/17/2018] [Indexed: 06/08/2023]
Abstract
To address the challenges of low hydrodechlorination efficiency by non-noble metals, a CuNi bimetallic cathode with nanostructured copper array film was fabricated for effective electrochemical dechlorination of trichloroethylene (TCE) in aqueous solution. The CuNi bimetallic cathodes were prepared by a simple one-step electrodeposition of copper onto the Ni foam substrate, with various electrodeposition time of 5/10/15/20 min. The optimum electrodeposition time was 10 min when copper was coated as a uniform nanosheet array on the nickel foam substrate surface. This cathode exhibited the highest TCE removal, which was twice higher compared to that of the nickel foam cathode. At the same passed charge of 1080C, TCE removal increased from 33.9 ± 3.3% to 99.7 ± 0.1% with the increasing operation current from 5 to 20 mA cm-2, while the normalized energy consumption decreased from 15.1 ± 1.0 to 2.6 ± 0.01 kWh log-1 m-3. The decreased normalized energy consumption at a higher current density was due to the much higher removal efficiency at a higher current. These results suggest that CuNi cathodes prepared by simple electrodeposition method represent a promising and cost-effective approach for enhanced electrochemical dechlorination.
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Affiliation(s)
- Bo Liu
- School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China.
| | - Hao Zhang
- School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China
| | - Qi Lu
- Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
| | - Guanghe Li
- School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China.
| | - Fang Zhang
- School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China.
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14
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Electrolytic control of hydrogen peroxide release from calcium peroxide in aqueous solution. Electrochem commun 2018; 93:81-85. [PMID: 30542246 DOI: 10.1016/j.elecom.2018.06.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The in situ generation of hydrogen peroxide (H2O2) for water treatment is more practical than the use of liquid H2O2, which is costly to store and transport. Calcium peroxide (CaO2), a solid carrier of H2O2, can release H2O2 on dissolution in water. However, the constant H2O2 release rate of CaO2 has been a bottleneck constraining its wider application. In this study, a practical electrochemical method using a divided cell is developed to control the rate of release of H2O2 from CaO2. The results show that the rate of H2O2 release from CaO2 is enhanced in the anolyte. The increase in H2O2 release is positively correlated with the current. Under a current of 100 mA, the H2O2 concentration was 2.5 times higher after 30 min of electrolysis than in the control experiment in which no current was applied. Water electrolysis in the anodic compartment generates protons that not only: (i) en-hance dissolution of CaO2 and release of H2O2, but also (ii) neutralize the alkaline pH resulting from CaO2 dissolution, thus providing new advantages for the use of CaO2. This effective technique may be suitable for the sophisticated control of H2O2 release in environmental applications.
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15
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Dai C, Zhou Y, Peng H, Huang S, Qin P, Zhang J, Yang Y, Luo L, Zhang X. Current progress in remediation of chlorinated volatile organic compounds: A review. J IND ENG CHEM 2018. [DOI: 10.1016/j.jiec.2017.12.049] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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16
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Fallgren PH, Eisenbeis JJ, Jin S. In situ electrochemical manipulation of oxidation-reduction potential in saturated subsurface matrices. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2018; 53:517-523. [PMID: 29346016 DOI: 10.1080/10934529.2017.1422951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Application of a low-intensity electric field is known to influence oxidation-reduction (redox) potential in a saturated matrix. In this study, such redox manipulation was attempted in at a site with contaminated aquifer. At the experiment field site, electrodes connected to a direct current (DC) source provided an electric field with an intensity of 1.82 V m-1. Redox potentials at locations 3.0 m and 7.9 m from the cathode decreased by 111 mV and 33 mV within a few hours, respectively, indicating that reducing conditions in the aquifer may be established within the electric field. Overall, it is possible to manipulate in situ redox potential in saturated subsurface matrices by applying low-intensity electric fields.
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Affiliation(s)
- Paul H Fallgren
- a Advanced Environmental Technologies, LLC , Fort Collins , Colorado , USA
| | | | - Song Jin
- a Advanced Environmental Technologies, LLC , Fort Collins , Colorado , USA
- c Department of Civil and Architectural Engineering , University of Wyoming , Laramie , Wyoming , USA
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17
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Liang X, Li M, Mack J, Lobb K, Zhu W. Iron( iii)porphyrin electrocatalyzed enantioselective carbon-chloride bond cleavage of hexachlorocyclohexanes (HCHs): combined experimental investigation and theoretical calculations. Dalton Trans 2018; 47:11470-11476. [DOI: 10.1039/c8dt02510j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Enantioselective electrocatalysis of α-, β-, γ- and δ-hexachlorocyclohexanes (HCHs) by tetrakis-pentafluorophenyl-Fe(iii)porphyrin is described.
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Affiliation(s)
- Xu Liang
- School of Chemistry and Chemical Engineering
- Jiangsu University
- Zhenjiang 212013
- P. R. China
- State Key Laboratory of Coordination Chemistry
| | - Minzhi Li
- School of Chemistry and Chemical Engineering
- Jiangsu University
- Zhenjiang 212013
- P. R. China
| | - John Mack
- Department of Chemistry
- Rhodes University
- South Africa
| | - Kevin Lobb
- Department of Chemistry
- Rhodes University
- South Africa
| | - Weihua Zhu
- School of Chemistry and Chemical Engineering
- Jiangsu University
- Zhenjiang 212013
- P. R. China
- State Key Laboratory of Coordination Chemistry
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18
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Uncovering the intrinsic relationship of electrocatalysis and molecular electrochemistry for dissociative electron transfer to polychloroethanes at silver cathode. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.02.055] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Ionic Liquid Induced Enhancement in the Stickiness of Sticky Dissociative Electroreductive C Cl Bond Cleavage: A Key to Eco-Green Detoxification of Chloroacetonitrile. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.11.084] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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20
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Lan H, Mao R, Tong Y, Liu Y, Liu H, An X, Liu R. Enhanced Electroreductive Removal of Bromate by a Supported Pd-In Bimetallic Catalyst: Kinetics and Mechanism Investigation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:11872-11878. [PMID: 27689240 DOI: 10.1021/acs.est.6b02822] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this work, the electroreductive removal of bromate by a Pd1-In4/Al2O3 catalyst in a three-dimensional electrochemical reactor was investigated. A total of 96.4% of bromate could be efficiently reduced and completely converted into bromide within 30 min under optimized conditions. On the basis of the characterization results and kinetics analysis, a synergistic effect of Pd and In was observed, and Pd1-In4/Al2O3 had the highest reaction rate constant of 0.1275 min-1 (vs 0.0413, 0.0328, and 0.0253 min-1 for In/Al2O3, Pd/Al2O3, and Al2O3). The results of electron spin resonance and scavenger experiments confirmed that both direct electron transfer and indirect reduction by atomic H* were involved in the bromate removal process, while the direct reduction played a more important role. Moreover, the introduction of In could increase the zeta potential of Pd1-In4/Al2O3, facilitating bromate adsorption and its subsequent reduction on the catalyst. Finally, a reaction mechanism for bromate reduction by Pd1-In4/Al2O3 was proposed based on all the experimental results.
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Affiliation(s)
- Huachun Lan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Ran Mao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Yating Tong
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Yanzhen Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Huijuan Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Xiaoqiang An
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
| | - Ruiping Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085, China
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21
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Mao R, Li N, Lan H, Zhao X, Liu H, Qu J, Sun M. Dechlorination of Trichloroacetic Acid Using a Noble Metal-Free Graphene-Cu Foam Electrode via Direct Cathodic Reduction and Atomic H. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:3829-37. [PMID: 26977556 DOI: 10.1021/acs.est.5b05006] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A three-dimensional graphene-copper (3D GR-Cu) foam electrode prepared by chemical vapor deposition method exhibited superior electrocatalytic activity toward the dechlorination of trichloroacetic acid (TCAA) as compared to the Cu foam electrode. The cyclic voltammetry and electrochemical impedance spectra analysis confirmed that GR accelerated the electron transfer from the cathode surface to TCAA. With the applied cathode potential of -1.2 V (vs SCE), 95.3% of TCAA (500 μg/L) was removed within 20 min at pH 6.8. TCAA dechlorination at the Cu foam electrode was enhanced at acidic pH, while a slight pH effect was observed at the GR-Cu foam electrode with a significant inhibition for Cu leaching. The electrocatalytic dechlorination of TCAA was accomplished via a combined stepwise and concerted pathway on both electrodes, whereas the concerted pathway was efficiently promoted on the GR-Cu foam electrode. The direct reduction by electrons was responsible for TCAA dechlorination at Cu foam electrode, while at GR-Cu foam electrode, the surface-adsorbed atomic H* also contributed to TCAA dechlorination owing to the chemical storage of hydrogen in the GR structure. Finally, the potential applicability of GR-Cu foam was revealed by its stability in the electrocatalytic dechlorination over 25 cycles.
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Affiliation(s)
- Ran Mao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
- University of Chinese Academy of Sciences , Beijing, 100049, P. R. China
| | - Ning Li
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
- University of Chinese Academy of Sciences , Beijing, 100049, P. R. China
| | - Huachun Lan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
| | - Xu Zhao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
| | - Huijuan Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
| | - Jiuhui Qu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
| | - Meng Sun
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, P. R. China
- University of Chinese Academy of Sciences , Beijing, 100049, P. R. China
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22
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Yang N, Cui J, Zhang L, Xiao W, Alshawabkeh AN, Mao X. Iron electrolysis-assisted peroxymonosulfate chemical oxidation for the remediation of chlorophenol-contaminated groundwater. JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY (OXFORD, OXFORDSHIRE : 1986) 2016; 91:938-947. [PMID: 30473593 PMCID: PMC6247945 DOI: 10.1002/jctb.4659] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 01/29/2015] [Indexed: 05/23/2023]
Abstract
BACKGROUND Electrolysis with an iron anode is a novel way to provide ferrous activators for chemical oxidation. The objective of this study is to evaluate the performance of peroxymonosulfate (PMS) for chlorophenol destruction when compared with H2O2 and persulfate (PS), and to see whether the electrolysis mode facilitates the buildup of conditions that favor the activation of PMS and removal of chlorophenols. RESULTS Ferrous species can effectively activate the PMS over a wide pH range. In comparison with H2O2 and PS, PMS is less sensitive to the solution's pH and possesses stronger oxidation capability at alkaline pHs. The optimal molar ratio of PMS to Fe(II) activator is 1:1 for the destruction of 2,4-dichlorophenol (2,4-DCP). The column experiments show that an acidic zone developed downstream from the anode is favorable to maintain ferrous ions and subsequent activation of PMS. The reactivity of the PMS can be manipulated by varying the electrical currents, and the process demonstrates effectiveness for treating organic contaminants. 2,4-DCP contaminated groundwater shows decreased biotoxicity after the chemical oxidation process without considering the residual PMS. CONCLUSIONS Iron electrolysis-assisted peroxymonosulfate chemical oxidation can effectively treat the 2,4-dichlorophenol and mixtures of organic contaminants. This process can be engineered as an in situ chemical oxidation method for groundwater remediation.
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Affiliation(s)
- Nuo Yang
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Jiaxin Cui
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Lieyu Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Wei Xiao
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Akram N. Alshawabkeh
- Civil and environmental engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Xuhui Mao
- State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
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Rajic L, Nazari R, Fallahpour N, Alshawabkeh AN. Electrochemical degradation of trichloroethylene in aqueous solution by bipolar graphite electrodes. JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 2016; 4:197-202. [PMID: 26955517 PMCID: PMC4778262 DOI: 10.1016/j.jece.2015.10.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
In this study, we tested the use of the bipolar electrodes to enhance electrochemical degradation of trichloroethylene (TCE) in an undivided, flow-through electrochemical reactor. The bipolar electrode forms when an electrically conductive material polarizes between feeder electrodes that are connected to a direct current source and, therefore, creates an additional anode/cathode pair in the system. We hypothesize that bipolar electrodes will generate additional oxidation/reduction zones to enhance TCE degradation. The graphite cathode followed by graphite anode sequence were operated without a bipolar electrode as well as with one and two bipolar graphite electrodes. The system without bipolar electrodes degraded 29% of TCE while the system with one and two bipolar electrodes degraded 38% and 66% of TCE, respectively. It was found that the removal mechanism for TCE in bipolar mode includes hydrodechlorination at the feeder cathode, and oxidation through reaction with peroxide. The results show that the bipolar electrodes presence enhance TCE removal efficiency and rate and imply that they can be used to improve electrochemical treatment of contaminated groundwater.
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Rajic L, Fallahpour N, Podlaha E, Alshawabkeh A. The influence of cathode material on electrochemical degradation of trichloroethylene in aqueous solution. CHEMOSPHERE 2016; 147:98-104. [PMID: 26761603 PMCID: PMC4742380 DOI: 10.1016/j.chemosphere.2015.12.095] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 12/22/2015] [Accepted: 12/23/2015] [Indexed: 05/11/2023]
Abstract
In this study, different cathode materials were evaluated for electrochemical degradation of aqueous phase trichloroethylene (TCE). A cathode followed by an anode electrode sequence was used to support reduction of TCE at the cathode via hydrodechlorination (HDC). The performance of iron (Fe), copper (Cu), nickel (Ni), aluminum (Al) and carbon (C) foam cathodes was evaluated. We tested commercially available foam materials, which provide large electrode surface area and important properties for field application of the technology. Ni foam cathode produced the highest TCE removal (68.4%) due to its high electrocatalytic activity for hydrogen generation and promotion of HDC. Different performances of the cathode materials originate from differences in the bond strength between atomic hydrogen and the material. With a higher electrocatalytic activity than Ni, Pd catalyst (used as cathode coating) increased TCE removal from 43.5% to 99.8% for Fe, from 56.2% to 79.6% for Cu, from 68.4% to 78.4% for Ni, from 42.0% to 63.6% for Al and from 64.9% to 86.2% for C cathode. The performance of the palladized Fe foam cathode was tested for degradation of TCE in the presence of nitrates, as another commonly found groundwater species. TCE removal decreased from 99% to 41.2% in presence of 100 mg L(-1) of nitrates due to the competition with TCE for HDC at the cathode. The results indicate that the cathode material affects TCE removal rate while the Pd catalyst significantly enhances cathode activity to degrade TCE via HDC.
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Affiliation(s)
- Ljiljana Rajic
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA
| | - Noushin Fallahpour
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA
| | - Elizabeth Podlaha
- Department of Chemical Engineering, Northeastern University, Boston, MA 02115, USA
| | - Akram Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA.
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25
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Fallahpour N, Yuan S, Rajic L, Alshawabkeh AN. Hydrodechlorination of TCE in a circulated electrolytic column at high flow rate. CHEMOSPHERE 2016; 144:59-64. [PMID: 26344148 PMCID: PMC4695317 DOI: 10.1016/j.chemosphere.2015.08.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 08/07/2015] [Accepted: 08/10/2015] [Indexed: 05/31/2023]
Abstract
Palladium-catalytic hydrodechlorination of trichloroethylene (TCE) by cathodic H2 produced from water electrolysis has been tested. For a field in-well application, the flow rate is generally high. In this study, the performance of Pd-catalytic hydrodechlorination of TCE using cathodic H2 is evaluated under high flow rate (1 L min(-1)) in a circulated column system, as expected to occur in practice. An iron anode supports reduction conditions and it is used to enhance TCE hydrodechlorination. However, the precipitation occurs and high flow rate was evaluated to minimize its adverse effects on the process (electrode coverage, clogging, etc.). Under the conditions of 1 L min(-1) flow, 500 mA current, and 5 mg L(-1) initial TCE concentration, removal efficacy using iron anodes (96%) is significantly higher than by mixed metal oxide (MMO) anodes (66%). Two types of cathodes (MMO and copper foam) in the presence of Pd/Al2O3 catalyst under various currents (250, 125, and 62 mA) were used to evaluate the effect of cathode materials on TCE removal efficacy. The similar removal efficiencies were achieved for both cathodes, but more precipitation generated with copper foam cathode (based on the experiments done by authors). In addition to the well-known parameters such as current density, electrode materials, and initial TCE concentration, the high velocities of groundwater flow can have important implications, practically in relation to the flush out of precipitates. For potential field application, a cost-effective and sustainable in situ electrochemical process using a solar panel as power supply is being evaluated.
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Affiliation(s)
- Noushin Fallahpour
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Songhu Yuan
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA; State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, PR China
| | - Ljiljana Rajic
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Akram N Alshawabkeh
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA.
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Martínez-Huitle CA, Rodrigo MA, Sirés I, Scialdone O. Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review. Chem Rev 2015; 115:13362-407. [PMID: 26654466 DOI: 10.1021/acs.chemrev.5b00361] [Citation(s) in RCA: 761] [Impact Index Per Article: 84.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Traditional physicochemical and biological techniques, as well as advanced oxidation processes (AOPs), are often inadequate, ineffective, or expensive for industrial water reclamation. Within this context, the electrochemical technologies have found a niche where they can become dominant in the near future, especially for the abatement of biorefractory substances. In this critical review, some of the most promising electrochemical tools for the treatment of wastewater contaminated by organic pollutants are discussed in detail with the following goals: (1) to present the fundamental aspects of the selected processes; (2) to discuss the effect of both the main operating parameters and the reactor design on their performance; (3) to critically evaluate their advantages and disadvantages; and (4) to forecast the prospect of their utilization on an applicable scale by identifying the key points to be further investigated. The review is focused on the direct electrochemical oxidation, the indirect electrochemical oxidation mediated by electrogenerated active chlorine, and the coupling between anodic and cathodic processes. The last part of the review is devoted to the critical assessment of the reactors that can be used to put these technologies into practice.
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Affiliation(s)
- Carlos A Martínez-Huitle
- Instituto de Química, Campus Universitário, Universidade Federal do Rio Grande do Norte , Av. Salgado Filho 3000 Campus Universitário Lagoa-Nova CEP 59078-970 Natal, RN, Brazil
| | - Manuel A Rodrigo
- Department of Chemical Engineering, Faculty of Chemical Sciences & Technologies, Ciudad Real, Universidad de Castilla-La Mancha , Ciudad Real 13071, Spain
| | - Ignasi Sirés
- Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona , Martí i Franquès 1-11, 08028 Barcelona, Spain
| | - Onofrio Scialdone
- Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, Università degli Studi di Palermo , Palermo 90128, Italy
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Mao X, Baek K, Alshawabkeh AN. IRON ELECTROCOAGULATION WITH ENHANCED CATHODIC REDUCTION FOR THE REMOVAL OF AQUEOUS CONTAMINANT MIXTURES. ENVIRONMENTAL ENGINEERING AND MANAGEMENT JOURNAL 2015; 14:2905-2911. [PMID: 31435204 PMCID: PMC6703562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This study presents enhanced reduction of soluble contaminants in a modified electrocoagulation process that is capable of treating a mixture of aqueous contaminants. By incorporating an iron foam cathode, the process can remove aqueous trichloroethylene (TCE) by 99.1% and nitrate ions by 98.2%, which represents 58.1 and 20 percent higher than the removal rates achieved by iron plate cathode, respectively. pH and ORP measurements indicate the development of a reducing electrolyte condition due to the ferrous generation from an iron anode, which facilitates the reduction of soluble contaminants because the competition from O2 reduction is eliminated in the system. Both iron foam and vitreous carbon foam electrodes are compatible with polarity reversal, without any deterioration in the efficiency of electroreduction of TCE and nitrate. The modified iron electrolysis process demonstrates versatility for the treatment of mixtures of contaminants, including a binary mixture of TCE and dichromate, a mixture of selenate and nitrate and a mixture of phosphate and nitrate. The ferrous species generated from the iron anode can reduce and (or) co-precipitate certain aqueous contaminants such as dichromate, selenate and phosphate, while the cathodic process can directly reduce contaminants like TCE and nitrate. Compared with the conventional electrocoagulation system that consists of two planar electrodes, the proposed process is not only more effective, but also suitable for the development of integrated and versatile process for the treatment of co-contaminated wastewater or groundwater.
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Affiliation(s)
- Xuhui Mao
- School of Resources and Environmental Science, Wuhan University, Wuhan, P.R. China, 430079
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
| | - Kitae Baek
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
- Department of Environmental Engineering, Chonbuk National University, Jeonju, Republic of Korea, 561756
| | - Akram N. Alshawabkeh
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
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Rajic L, Fallahpour N, Oguzie E, Alshawabkeh A. Electrochemical transformation of thichloroethylene in groundwater by Ni-containing cathodes. Electrochim Acta 2015; 181:118-122. [PMID: 26538681 DOI: 10.1016/j.electacta.2015.03.112] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this study, we evaluate the use of different stainless steel (SS) materials as cost-effective cathode materials for electrochemical transformation of trichloroethylene (TCE) in contaminated groundwater. Ni, which is present in certain SS, has low hydrogen overpotential that promotes fast formation of atomic hydrogen and, therefore, its content can enhance hydrodechlorination (HDC). We a flow-through electrochemical reactor with a SS cathode followed by an anode. The performance of Ni containing foam cathodes (Fe/Ni and Ni foam) was also evaluated for electrochemical transformation of TCE in groundwater. SS type 316 (12% Ni) removed 61.7% of TCE compared to 52.6% removed by SS 304 (9.25% Ni) and 37.5% removed by SS 430 (0.75% Ni). Ni foam cathode produced the highest TCE removal rate (68.4%) compared with other cathodes. The slightly lower performance of SS type 316 mesh is balanced by the reduction in treatment costs for larger-scale systems. The results prove that Ni content in SS highly influences TCE removal rate.
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Affiliation(s)
- Ljiljana Rajic
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Noushin Fallahpour
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Emeka Oguzie
- Electrochemistry and Material Science Research Laboratory, Department of Chemistry, Federal University of Technology, PM B 1526, Owerri, Nigeria
| | - Akram Alshawabkeh
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
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Influence of humic substances on electrochemical degradation of trichloroethylene in limestone aquifers. Electrochim Acta 2015; 181:123-129. [PMID: 26549889 DOI: 10.1016/j.electacta.2015.03.121] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study we investigate the influence of humic substances (HS) on electrochemical transformation of trichloroethylene (TCE) in groundwater from limestone aquifers. A laboratory flow-through column with an electrochemical reactor that consists of a palladized iron foam cathode followed by a MMO anode was used to induce TCE electro-reduction in groundwater. Up to 82.9% TCE removal was achieved in the absence of HS. Presence of 1, 2, 5, and 10 mgTOC L-1 reduced TCE removal to 70.9%, 61.4%, 51.8% and 19.5%, respectively. The inverse correlation between HS content and TCE removal was linear. Total organic carbon (TOC), dissolved organic carbon (DOC) and absorption properties (A=254 nm, 365 nm and 436 nm) normalized to DOC, were monitored during treatment to understand the behavior and impacts of HS under electrochemical processes. Changes in all parameters occurred mainly after contact with the cathode, which implies that the HS are reacting either directly with electrons from the cathode or with H2 formed at the cathode surface. Since hydrodechlorination is the primary TCE reduction mechanism in this setup, reactions of the HS with the cathode limit transformation of TCE. The presence of limestone gravel reduced the impact of HS on TCE removal. The study concludes that presence of humic substances adversely affects TCE removal from contaminated groundwater by electrochemical reduction using palladized cathodes.
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Rajic L, Fallahpour N, Alshawabkeh AN. Impact of electrode sequence on electrochemical removal of trichloroethylene from aqueous solution. APPLIED CATALYSIS. B, ENVIRONMENTAL 2015; 174-175:427-434. [PMID: 25931774 PMCID: PMC4410430 DOI: 10.1016/j.apcatb.2015.03.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The electrode sequence in a mixed flow-through electrochemical cell is evaluated to improve the hydrodechlorination (HDC) of trichloroethylene (TCE) in aqueous solutions. In a mixed (undivided) electrochemical cell, oxygen generated at the anode competes with the transformation of target contaminants at the cathode. In this study, we evaluate the effect of placing the anode downstream from the cathode and using multiple electrodes to promote TCE reduction. Experiments with a cathode followed by an anode (C→A) and an anode followed by a cathode (A→C) were conducted using mixed metal oxide (MMO) and iron as electrode materials. The TCE removal rates when the anode is placed downstream of the cathode (C→A) were 54% by MMO→MMO, 64% by MMO→Fe and 87% by Fe→MMO sequence. Removal rates when the anode is placed upstream of the cathode (A→C) were 38% by MMO→MMO, 58% by Fe→MMO and 69% by MMO→Fe sequence. Placing the anode downstream of the cathode positively improves (by 26%) the degradation of aqueous TCE in a mixed flow-through cell as it minimizes the influence of oxygen generated at the MMO anode on TCE reduction at the cathode. Furthermore, placing the MMO anode downstream of the cathode neutralizes pH and redox potential of the treated solution. Higher flow velocity under the C→A setup increases TCE mass flux reduction rate. Using multiple cathodes and an iron foam cathode up stream of the anode increase the removal rate by 1.6 and 2.4 times, respectively. More than 99% of TCE was removed in the presence of Pd catalyst on carbon and as an iron foam coating. Enhanced reaction rates found in this study imply that a mixed flow-through electrochemical cell with multiple cathodes up stream of an anode is an effective method to promote the reduction of TCE in groundwater.
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Affiliation(s)
- Ljiljana Rajic
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, United States
| | - Noushin Fallahpour
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, United States
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, United States
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Mao R, Zhao X, Lan H, Liu H, Qu J. Graphene-modified Pd/C cathode and Pd/GAC particles for enhanced electrocatalytic removal of bromate in a continuous three-dimensional electrochemical reactor. WATER RESEARCH 2015; 77:1-12. [PMID: 25834955 DOI: 10.1016/j.watres.2015.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 03/04/2015] [Accepted: 03/04/2015] [Indexed: 06/04/2023]
Abstract
Bromate (BrO3(-)) is a carcinogenic and genotoxic contaminant commonly generated during ozonation of bromide-containing water. In this work, the reductive removal of BrO3(-) in a continuous three-dimensional electrochemical reactor with palladium-reduced graphene oxide modified carbon paper (Pd-rGO/C) cathode and Pd-rGO modified granular activated carbon (Pd-rGO/GAC) particles was investigated. The results indicated that the rGO sheets significantly promoted the electrochemical reduction of BrO3(-). With the enhanced electron transfer by rGO sheets, the electroreduction of H2O to atomic H* on the polarized Pd particles could be significantly accelerated, leading to a faster reaction rate of BrO3(-) with atomic H*. The synergistic effect of the Pd-rGO/C cathode and Pd-rGO/GAC particles were also exhibited. The atomic H* involved in various electroreduction processes was detected by electron spin resonance spectroscopy and its role for BrO3(-) reduction was determined. The performance of the reactor was evaluated in terms of the removal of BrO3(-) and the yield of Br(-) as a function of the GO concentration, Pd loading amount, current density, hydraulic residence time (HRT), and initial BrO3(-) concentration. Under the current density of 0.9 mA/cm(2), BrO3(-) with the initial concentration of 20 μg/L was reduced to be less than 6.6 μg/L at the HRT of 20 min. The BrO3(-) reduction was inhibited in the presence of dissolved organic matter. Although the precipitates generated from Ca(2+) and Mg(2+) in the tap water would cover the Pd catalysts, a long-lasting electrocatalytic activity could be maintained for the 30 d treatment. SEM and XPS analysis demonstrated that the precipitates were predominantly deposited onto the Pd-rGO/C cathode rather than the Pd-rGO/GAC particles.
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Affiliation(s)
- Ran Mao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Xu Zhao
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China
| | - Huachun Lan
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China
| | - Huijuan Liu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China
| | - Jiuhui Qu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China.
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Liu Y, Liu L, Shan J, Zhang J. Electrodeposition of palladium and reduced graphene oxide nanocomposites on foam-nickel electrode for electrocatalytic hydrodechlorination of 4-chlorophenol. JOURNAL OF HAZARDOUS MATERIALS 2015; 290:1-8. [PMID: 25731146 DOI: 10.1016/j.jhazmat.2015.02.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 02/04/2015] [Accepted: 02/06/2015] [Indexed: 06/04/2023]
Abstract
A high-performance palladium (Pd) and reduced graphene oxide (RGO) composite electrode was prepared on foam-nickel (foam-Ni) via two-step electrodeposition processes. The scanning electron microscopic (SEM) observation showed that the obtained Pd/RGO/foam-Ni composite electrode displayed a uniform and compact morphology. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopic (XPS) analysis confirmed the successful deposition of Pd and RGO on nickel substrate. The cyclic voltammetric (CV) measurements indicated that the presence of RGO greatly enhanced the active surface area of Pd particles deposited on foam-Ni. The as-deposited Pd/RGO/foam-Ni electrode was applied to electrocatalytic hydrodechlorination (ECH) of 4-chlorophenol (4-CP). Various factors influencing the dechlorination of 4-CP such as dechlorination current, initial concentration of 4-CP, Na2SO4 concentration and initial pH were systematically investigated. The thermodynamic analysis showed that the dechlorination reaction of 4-CP at different temperatures followed the first-order kinetics and the activation energy for 4-CP dechlorination on Pd/RGO/foam-Ni electrode was calculated to be 51.96 kJ mol(-1). Under the optimum conditions, the dechlorination efficiency of 4-CP could reach 100% after 60-min ECH treatment. Moreover, the prepared Pd/RGO/foam-Ni composite electrode showed good stability for recycling utilization in ECH of 4-CP.
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Affiliation(s)
- Yong Liu
- Key Laboratory for Large-Format Battery Materials and System (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074, PR China
| | - Lan Liu
- Key Laboratory for Large-Format Battery Materials and System (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074, PR China
| | - Jun Shan
- Key Laboratory for Large-Format Battery Materials and System (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074, PR China
| | - Jingdong Zhang
- Key Laboratory for Large-Format Battery Materials and System (Ministry of Education), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Luoyu Road 1037, Wuhan 430074, PR China.
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Qian A, Yuan S, Zhang P, Tong M. A New Mechanism in Electrochemical Process for Arsenic Oxidation: Production of H2O2 from Anodic O2 Reduction on the Cathode under Automatically Developed Alkaline Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:5689-5696. [PMID: 25853500 DOI: 10.1021/acs.est.5b00808] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Electrochemical cathodes are often used to reduce contaminants or produce oxidizing substances (i.e., H2O2). Alkaline conditions develop automatically around the cathode in electrochemical processes, and O2 diffuses onto the cathode easily. However, limited attention is paid to contaminant transformation by the reactive species produced on the cathode under oxic and alkaline conditions due to the inapplicability of pH for Fenton reaction. In this study, a new oxidation mechanism on the cathode is presented for contaminant transformation under automatically developed alkaline conditions. In an electrochemical sand column, 6.67 μM As(III) was oxidized by 36% when it passed through the cathode under the conditions of 30 mA current, an initial pH of 7.5 and a flow rate of 2 mL/min. Under the alkaline conditions (pH 10.0-11.0) that developed automatically around the cathode, the reduction potential of As(III) decreased greatly, allowing a pronounced oxidation by the small quantities of H2O2 produced from O2 reduction on the cathode. As(III) oxidation was further increased by the presence of soil pore water and groundwater solutes of HCO3-, Ca2+, Mg2+ and humic acid. The new oxidation mechanism found for the cathode under localized alkaline conditions supplements the fundamentals of contaminant transformation in electrochemical processes.
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Affiliation(s)
- Ao Qian
- †State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- ‡School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Songhu Yuan
- †State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- ‡School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Peng Zhang
- †State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Man Tong
- †State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- ‡School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
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Liao P, Al-Ani Y, Malik Ismael Z, Wu X. Insights into the role of humic acid on Pd-catalytic electro-Fenton transformation of toluene in groundwater. Sci Rep 2015; 5:9239. [PMID: 25783864 DOI: 10.1038/srep09239] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 02/16/2015] [Indexed: 11/09/2022] Open
Abstract
A recently developed Pd-based electro-Fenton (E-Fenton) process enables efficient in situ remediation of organic contaminants in groundwater. In the process, H₂O₂, Fe(II), and acidic conditions (~pH 3) are produced in situ to facilitate the decontamination, but the role of ubiquitous natural organic matters (NOM) remain unclear. This study investigated the effect of Aldrich humic acid (HA) on the transformation of toluene by the Pd-based E-Fenton process. At pH 3 with 50 mA current, the presence of HA promoted the efficiency of toluene transformation, with pseudo-first-order rate constants increase from 0.01 to 0.016 as the HA concentration increases from 0 to 20 mg/L. The HA-enhanced toluene transformation was attributed to the accelerated thermal reduction of Fe(III) to Fe(II), which led to production of more hydroxyl radicals. The correlation of the rate constants of toluene transformation and HA decomposition validated hydroxyl radical (·OH) as the predominant reactive species for HA decomposition. The finding of this study highlighted that application of the novel Pd-based E-Fenton process in groundwater remediation may not be concerned by the fouling from humic substances.
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Affiliation(s)
- Peng Liao
- 1] School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, P.R. China [2] State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, Wuhan. 430074, P. R. China
| | - Yasir Al-Ani
- 1] State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, Wuhan. 430074, P. R. China [2] Faculty of Engineering, University of AL-Anbar, Al-Anbar Governorate, Iraq
| | - Zainab Malik Ismael
- 1] State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, Wuhan. 430074, P. R. China [2] Faculty of Engineering, University of AL-Anbar, Al-Anbar Governorate, Iraq
| | - Xiaohui Wu
- School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, P.R. China
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Rajic L, Fallahpour N, Yuan S, Alshawabkeh AN. Electrochemical transformation of trichloroethylene in aqueous solution by electrode polarity reversal. WATER RESEARCH 2014; 67:267-75. [PMID: 25282093 PMCID: PMC4262522 DOI: 10.1016/j.watres.2014.09.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 05/12/2023]
Abstract
Electrode polarity reversal is evaluated for electrochemical transformation of trichloroethylene (TCE) in aqueous solution using flow-through reactors with mixed metal oxide electrodes and Pd catalyst. The study tests the hypothesis that optimizing electrode polarity reversal will generate H2O2 in Pd presence in the system. The effect of polarity reversal frequency, duration of the polarity reversal intervals, current intensity and TCE concentration on TCE removal rate and removal mechanism were evaluated. TCE removal efficiencies under 6 cycles h(-1) were similar in the presence of Pd catalyst (50.3%) and without Pd catalyst (49.8%), indicating that Pd has limited impact on TCE degradation under these conditions. The overall removal efficacies after 60 min treatment under polarity reversal frequencies of 6, 10, 15, 30 and 90 cycles h(-1) were 50.3%, 56.3%, 69.3%, 34.7% and 23.4%, respectively. Increasing the frequency of polarity reversal increases TCE removal as long as sufficient charge is produced during each cycle for the reaction at the electrode. Electrode polarity reversal shifts oxidation/reduction and reduction/oxidation sequences in the system. The optimized polarity reversal frequency (15 cycles h(-1) at 60 mA) enables two reaction zones formation where reduction/oxidation occurs at each electrode surface.
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Affiliation(s)
- Ljiljana Rajic
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115, USA
| | - Noushin Fallahpour
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115, USA
| | - Songhu Yuan
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115, USA; State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China
| | - Akram N Alshawabkeh
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA 02115, USA.
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36
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Electrochemical processes in macro and microfluidic cells for the abatement of chloroacetic acid from water. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.03.127] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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37
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Yuan S, Liao P, Alshawabkeh AN. Electrolytic manipulation of persulfate reactivity by iron electrodes for trichloroethylene degradation in groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:656-63. [PMID: 24328192 PMCID: PMC3916217 DOI: 10.1021/es404535q] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Activated persulfate oxidation is an effective in situ chemical oxidation process for groundwater remediation. However, reactivity of persulfate is difficult to manipulate or control in the subsurface causing activation before reaching the contaminated zone and leading to a loss of chemicals. Furthermore, mobilization of heavy metals by the process is a potential risk. An effective approach using iron electrodes is thus developed to manipulate the reactivity of persulfate in situ for trichloroethylene (TCE) degradation in groundwater and to limit heavy metals mobilization. TCE degradation is quantitatively accelerated or inhibited by adjusting the current applied to the iron electrode, following k1 = 0.00053·Iv + 0.059 (-122 A/m(3) ≤ Iv ≤ 244 A/m(3)) where k1 and Iv are the pseudo first-order rate constant (min(-1)) and volume normalized current (A/m(3)), respectively. Persulfate is mainly decomposed by Fe(2+) produced from the electrochemical and chemical corrosion of iron followed by the regeneration via Fe(3+) reduction on the cathode. SO4(•-) and ·OH cocontribute to TCE degradation, but ·OH contribution is more significant. Groundwater pH and oxidation-reduction potential can be restored to natural levels by the continuation of electrolysis after the disappearance of contaminants and persulfate, thus decreasing adverse impacts such as the mobility of heavy metals in the subsurface.
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Affiliation(s)
- Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- To whom correspondence should be addressed: (S. Yuan), Phone: +86-27-67848629. Fax: +86-27-67883456; (A. Alshawabkeh), Phone: 617 373 3994. Fax: 617 373 4419
| | - Peng Liao
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- To whom correspondence should be addressed: (S. Yuan), Phone: +86-27-67848629. Fax: +86-27-67883456; (A. Alshawabkeh), Phone: 617 373 3994. Fax: 617 373 4419
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38
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Baek K, Ciblak A, Mao X, Kim EJ, Alshawabkeh A. Iron anode mediated transformation of selenate in sand columns. WATER RESEARCH 2013; 47:6538-45. [PMID: 24035677 PMCID: PMC6886739 DOI: 10.1016/j.watres.2013.08.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 08/09/2013] [Accepted: 08/22/2013] [Indexed: 05/13/2023]
Abstract
Removal of aqueous selenate by iron electrolysis is investigated using sand-packed column experiments under a flowing condition. An iron anode generates ferrous ions, while cathode produces hydroxide, thus producing ferrous hydroxide capable of reducing selenate to elemental selenium. Additionally, siderite could reduce selenate or selenite to elemental selenium. The removal rate of selenate is proportional to the contact time and the yield of ferrous hydroxide or ferrous carbonate. At a sequence of anode-cathode, the transformation of selenate mostly occurs in the zone after cathode. An operation of 48 h electrolysis finally transforms 82.2% of selenate at 0.2 mM of initial concentration, 1.8 m/day of seepage velocity and 1.26 mA/cm(2) of current density. A longer reactive zone after cathode slightly increases the reduction of selenate to 84.1%, in comparison with 82.2% of a shorter residence time in the reactive zone after cathode. With shorter electrode spacing (approximately 27% shorter), the transformation rate of selenate decreased to 73.5%; however, the specific electrical energy consumption was saved by 78%. A sequence of cathode-anode was ineffective in removing selenate because of the lack of reducing agent in the column. The results indicate that the electrochemical system might be effective in removing selenate in a single well.
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Affiliation(s)
- Kitae Baek
- Department of Environmental Engineering, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju, Republic of Korea.
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Cui X, Quicksall AN, Blake AB, Talley JW. Electrochemical disinfection of Escherichia coli in the presence and absence of primary sludge particulates. WATER RESEARCH 2013; 47:4383-90. [PMID: 23764589 DOI: 10.1016/j.watres.2013.04.039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 04/19/2013] [Accepted: 04/21/2013] [Indexed: 05/15/2023]
Abstract
Electrochemical (EC) residual disinfection of Escherichia coli (E. coli) in the presence and absence of primary sludge particulates (PSPs) was studied. The kinetics followed a first-order rate law. When PSPs were absent, the EC residual disinfection rate coefficient (k) increased linearly with EC pretreatment energy (EC, 0-0.63 kWh/m(3)). However, with 143 mg PSPs/L, k first increased linearly with EC (0-0.28 kWh/m(3)) and then decreased linearly with EC (0.28-0.42 kWh/m(3)). H2O2 was detected during EC pretreatment in PSPs-free samples and the H2O2 concentration (CH) increased with EC (0-0.83 kWh/m(3)) linearly. Chloride was detected in PSPs aqueous samples (143 mg PSPs/L) and its concentration (CC) changed during EC pretreatment: initially, a decrease of CC was observed when EC increased from 0 to 0.28 kWh/m(3), followed by an increase of CC when EC increased 0.28-0.42 kWh/m(3). In both cases, k correlated to the initial post-EC chloride concentration (CCI) in an inverse linear relationship. This two-stage change of CC and k was caused by a combination of two reactions: anodic oxidation of chloride and the reaction of chloramines with excess chlorine. This paper explains the mechanisms underlying EC residual disinfection in the presence and absence of PSPs, and proposes a feasible strategy for EC disinfection when PSPs are present, an approach that could be useful in the treatment of combined sewage overflow (CSO).
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Affiliation(s)
- Xiaofei Cui
- Department of Civil and Environmental Engineering, Southern Methodist University, Room 203, 3101 Dyer Street, Dallas, TX 75205, USA
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40
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Liao P, Yuan S, Chen M, Tong M, Xie W, Zhang P. Regulation of electrochemically generated ferrous ions from an iron cathode for Pd-catalytic transformation of MTBE in groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:7918-7926. [PMID: 23768068 DOI: 10.1021/es401730s] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A novel Pd-based electro-Fenton (E-Fenton) process has recently been developed to transform organic contaminants in groundwater. However, it only produces H2O2 and requires addition of Fe(2+). In this study, an innovative approach is developed to effectively regulate the generation of Fe(2+) from an iron cathode in a three-electrode system in addition to H2O2 production. The Fe(2+) is then used for the Pd-catalytic transformation of methyl tert-butyl ether (MTBE) in groundwater. Results from batch experiments suggest Fe(2+) accumulation follows pseudo-first-order kinetics with rate quantitatively regulated by current and pH, and MTBE can be completely transformed. In a specially configured three-electrode column using iron as the first cathode, the localized acidic conditions develop automatically in the iron cathode and Pd zone by partitioning the current between the two cathodes, leading to controllable generation of Fe(2+) and H2O2. Effects of electrolyte concentrations and types as well as humic acid on MTBE transformation are slight. The stable transformation (~70%) in a long-term study (20 days) suggests this improved Pd-based E-Fenton process is sustainable to produce Fe(2+), H2O2, and appropriate pH conditions simultaneously for transforming organic contaminants. This study presents a new concept of generating Fe(2+) from an iron cathode for the processes requiring Fe(2+).
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Affiliation(s)
- Peng Liao
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences , 388 Lumo Road, Wuhan 430074, P R China
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41
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Xie W, Yuan S, Mao X, Hu W, Liao P, Tong M, Alshawabkeh AN. Electrocatalytic activity of Pd-loaded Ti/TiO2 nanotubes cathode for TCE reduction in groundwater. WATER RESEARCH 2013; 47:3573-82. [PMID: 23726693 PMCID: PMC6321742 DOI: 10.1016/j.watres.2013.04.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 03/29/2013] [Accepted: 04/01/2013] [Indexed: 05/11/2023]
Abstract
A novel cathode, Pd loaded Ti/TiO2 nanotubes (Pd-Ti/TiO2NTs), is synthesized for the electrocatalytic reduction of trichloroethylene (TCE) in groundwater. Pd nanoparticles are successfully loaded on TiO2 nanotubes which grow on Ti plate via anodization. Using Pd-Ti/TiO2NTs as the cathode in an undivided electrolytic cell, TCE is efficiently and quantitatively transformed to ethane. Under conditions of 100 mA and pH 7, the removal efficiency of TCE (21 mg/L) is up to 91% within 120 min, following pseudo-first-order kinetics with the rate constant of 0.019 min(-1). Reduction rates increase from 0.007 to 0.019 min(-1) with increasing the current from 20 to 100 mA, slightly decrease in the presence of 10 mM chloride or bicarbonate, and decline with increasing the concentrations of sulfite or sulfide. O2 generated at the anode slightly influences TCE reduction. At low currents, TCE is mainly reduced by direct electron transfer on the Pd-Ti/TiO2NT cathode. However, the contribution of Pd-catalytic hydrodechlorination, an indirect reduction mechanism, becomes significant with increasing the current. Compared with other common cathodes, i.e., Ti-based mixed metal oxides, graphite and Pd/Ti, Pd-Ti/TiO2NTs cathode shows superior performance for TCE reduction.
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Affiliation(s)
- Wenjing Xie
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
- Corresponding author. Tel.: +86 18971623175., , (S. Yuan)
| | - Xuhui Mao
- School of resource and Environmental Science, Wuhan University, 129 Luoyu Road, Wuhan 430079, PR China
| | - Wei Hu
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Peng Liao
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Man Tong
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, MA 02115, United States
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42
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Baek K, Kasem N, Ciblak A, Vesper D, Padilla I, Alshawabkeh AN. Electrochemical Removal Of Selenate From Aqueous Solutions. CHEMICAL ENGINEERING JOURNAL (LAUSANNE, SWITZERLAND : 1996) 2013; 215-216:678-684. [PMID: 23378820 PMCID: PMC3559022 DOI: 10.1016/j.cej.2012.09.135] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Removal of selenate from solution is investigated in batch electrochemical systems using reactive iron anodes and copper plate cathode in a bicarbonate medium. Iron anodes produce ferrous hydroxide, which is a major factor in the removal of selenate from solution. Iron anodes also generate a significant decrease in the oxidation-reduction potential (ORP) of the solution because it prevents generation of oxygen gas at the anode by electrolysis. The removal rates varied from 45.1 to 97.4%, depending on current density and selenate concentration. The transformation of selenate by the process is modeled based on a heterogeneous reaction coupled with electrochemical generation of ferrous and hydroxide. The rates are optimized at lower initial concentrations, higher electrical currents, and the presence of anions. Presence of dissolved oxygen does not cause any significant effects the removal of selenate.
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Affiliation(s)
- Kitae Baek
- Department of Environmental Engineering, Chonbuk National University, 567 Baekje-daero, Jeonju, Jeollabukdo, Republic of Korea
- Co-corresponding author: (Kitae Baek), Tel.:+ 82-63-270-2437; Fax:+ 82-63-270-2449;
| | - Naji Kasem
- Department of Civil and Environmental Engineering, Northeastern University, 360 Huntington Ave, Boston, MA 02115, USA
| | - Ali Ciblak
- Department of Civil and Environmental Engineering, Northeastern University, 360 Huntington Ave, Boston, MA 02115, USA
| | - Dorothy Vesper
- Department of Geology and Geography, West Virginia University, 98 Beechurst Ave, 330 Brooks Hall, Morgantown, WV 26506, USA
| | - Ingrid Padilla
- Department of Civil Engineering and Surveying, University of Puerto Rico, Mayaguez, Puerto Rico 00681
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 360 Huntington Ave, Boston, MA 02115, USA
- Corresponding author: (Akram Alshawabkeh), Tel.: + 1-617-373-3994; Fax:+ 1-617-373-4419;
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Yuan S, Chen M, Mao X, Alshawabkeh AN. A three-electrode column for Pd-catalytic oxidation of TCE in groundwater with automatic pH-regulation and resistance to reduced sulfur compound foiling. WATER RESEARCH 2013; 47:269-78. [PMID: 23121896 PMCID: PMC3581803 DOI: 10.1016/j.watres.2012.10.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2012] [Revised: 09/13/2012] [Accepted: 10/04/2012] [Indexed: 05/11/2023]
Abstract
A hybrid electrolysis and Pd-catalytic oxidation process is evaluated for degradation of trichloroethylene (TCE) in groundwater. A three-electrode, one anode and two cathodes, column is employed to automatically develop a low pH condition in the Pd vicinity and a neutral effluent. Simulated groundwater containing up to 5 mM bicarbonate can be acidified to below pH 4 in the Pd vicinity using a total of 60 mA with 20 mA passing through the third electrode. By packing 2 g of Pd/Al(2)O(3) pellets in the developed acidic region, the column efficiency for TCE oxidation in simulated groundwater (5.3 mg/L TCE) increases from 44 to 59 and 68% with increasing Fe(II) concentration from 0 to 5 and 10 mg/L, respectively. Different from Pd-catalytic hydrodechlorination under reducing conditions, this hybrid electrolysis and Pd-catalytic oxidation process is advantageous in controlling the fouling caused by reduced sulfur compounds (RSCs) because the in situ generated reactive oxidizing species, i.e., O(2), H(2)O(2) and OH, can oxidize RSCs to some extent. In particular, sulfite at concentrations less than 1 mM even greatly increases TCE oxidation by the production of SO(4)(•-), a strong oxidizing radical, and more OH.
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Affiliation(s)
- Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- Corresponding author. (S. Yuan), (A. Alshawabkeh)
| | - Mingjie Chen
- Atmospheric, Earth and Energy Division, Lawrence Livermore National Laboratory, P.O. Box 808, L-184, Livermore, CA 94550, United States
| | - Xuhui Mao
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- Corresponding author. (S. Yuan), (A. Alshawabkeh)
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Ntsendwana B, Mamba BB, Sampath S, Arotiba OA. Synthesis, characterisation and application of an exfoliated graphite–diamond composite electrode in the electrochemical degradation of trichloroethylene. RSC Adv 2013. [DOI: 10.1039/c3ra44977g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Mao X, Yuan S, Fallahpour N, Ciblak A, Howard J, Padilla I, Loch-Caruso R, Alshawabkeh AN. Electrochemically induced dual reactive barriers for transformation of TCE and mixture of contaminants in groundwater. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:12003-11. [PMID: 23067023 PMCID: PMC3493133 DOI: 10.1021/es301711a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
A novel reactive electrochemical flow system consisting of an iron anode and a porous cathode is proposed for the remediation of mixture of contaminants in groundwater. The system consists of a series of sequentially arranged electrodes, a perforated iron anode, a porous copper cathode followed by a mesh-type mixed metal oxide anode. The iron anode generates ferrous species and a chemically reducing environment, the porous cathode provides a reactive electrochemically reducing barrier, and the inert anode provides protons and oxygen to neutralize the system. The redox conditions of the electrolyte flowing through this system can be regulated by controlling the distribution of the electric current. Column experiments are conducted to evaluate the process and study the variables. The electrochemical reduction on a copper foam cathode produced an electrode-based reductive potential capable of reducing TCE and nitrate. Rational electrodes arrangement, longer residence time of electrolytes and higher surface area of the foam electrode improve the reductive transformation of TCE. More than 82.2% TCE removal efficiency is achieved for the case of low influent concentration (<7.5 mg/L) and high current (>45 mA). The ferrous species produced from the iron anode not only enhance the transformation of TCE on the cathode, but also facilitates transformation of other contaminants including dichromate, selenate and arsenite. Removal efficiencies greater than 80% are achieved for these contaminants in flowing contaminated water. The overall system, comprising the electrode-based and electrolyte-based barriers, can be engineered as a versatile and integrated remedial method for a relatively wide spectrum of contaminants and their mixtures.
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Affiliation(s)
- Xuhui Mao
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
- School of Resources and Environmental Science, Wuhan University, Wuhan 430079, P. R. China
| | - Songhu Yuan
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, P. R. China
| | - Noushin Fallahpour
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Ali Ciblak
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
| | - Joniqua Howard
- Department of Civil Engineering and Surveying, University of Puerto Rico, Mayaguez, Puerto Rico, 00681
| | - Ingrid Padilla
- Department of Civil Engineering and Surveying, University of Puerto Rico, Mayaguez, Puerto Rico, 00681
| | - Rita Loch-Caruso
- Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan 48109
| | - Akram N. Alshawabkeh
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115, USA
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Mao X, Ciblak A, Baek K, Amiri M, Loch-Caruso R, Alshawabkeh AN. Optimization of electrochemical dechlorination of trichloroethylene in reducing electrolytes. WATER RESEARCH 2012; 46:1847-57. [PMID: 22264798 PMCID: PMC3288245 DOI: 10.1016/j.watres.2012.01.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 12/18/2011] [Accepted: 01/02/2012] [Indexed: 05/25/2023]
Abstract
Electrochemical dechlorination of trichloroethylene (TCE) in aqueous solution is investigated in a closed, liquid-recirculation system. The anodic reaction of cast iron generates ferrous species, creating a chemically reducing electrolyte (negative ORP value). The reduction of TCE on the cathode surface is enhanced under this reducing electrolyte because of the absence of electron competition. In the presence of the iron anode, the performances of different cathodes are compared in a recirculated electrolysis system. The copper foam shows superior capability for dechlorination of aqueous TCE. Electrolysis by cast iron anode and copper foam cathode is further optimized though a multivariable experimental design and analysis. The conductivity of the electrolyte is identified as an important factor for both final elimination efficiency (FEE) of TCE and specific energy consumption. The copper foam electrode exhibits high TCE elimination efficiency in a wide range of initial TCE concentration. Under coulostatic conditions, the optimal conditions to achieve the highest FEE are 9.525 mm thick copper foam electrode, 40 mA current and 0.042 mol L(-1) Na(2)SO(4). This novel electrolysis system is proposed to remediate groundwater contaminated by chlorinated organic solvents, or as an improved iron electrocoagulation process capable of treating the wastewater co-contaminated with chlorinated compounds.
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Affiliation(s)
- Xuhui Mao
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
| | - Ali Ciblak
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
| | - Kitae Baek
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
- Environmental Engineering Department, Kumoh National Institute of Technology, Republic of Korea
| | - Mohammad Amiri
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
| | - Rita Loch-Caruso
- Environmental Health Sciences Department, School of Public Health, University of Michigan, Ann Arbor, MI 48109-2029
| | - Akram N. Alshawabkeh
- Civil and Environmental Engineering Department, Northeastern University, Boston, MA, 02115
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47
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Yuan S, Mao X, Alshawabkeh AN. Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:3398-405. [PMID: 22315993 PMCID: PMC3319670 DOI: 10.1021/es204546u] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H(2) and O(2) is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H(2)O(2) up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radicals are detected due to decomposition of H(2)O(2), slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 μM improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 μM/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na(2)SO(4), NaCl, NaNO(3), NaHCO(3), K(2)SO(4), CaSO(4), and MgSO(4) does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppress degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation.
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Affiliation(s)
- Songhu Yuan
- State Key Lab of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan, 430074, P. R. China
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Xuhui Mao
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, 400 Snell Engineering, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
- To whom correspondence should be addressed. . Phone: (617) 373-3994
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Ciblak A, Mao X, Padilla I, Vesper D, Alshawabkeh I, Alshawabkeh AN. Electrode effects on temporal changes in electrolyte pH and redox potential for water treatment. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2012; 47:718-26. [PMID: 22416866 PMCID: PMC3329560 DOI: 10.1080/10934529.2012.660088] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The performance of electrochemical remediation methods could be optimized by controlling the physicochemical conditions of the electrochemical redox system. The effects of anode type (reactive or inert), current density and electrolyte composition on the temporal changes in pH and redox potential of the electrolyte were evaluated in divided and mixed electrolytes. Two types of electrodes were used: iron as a reactive electrode and mixed metal oxide coated titanium (MMO) as an inert electrode. Electric currents of 15, 30, 45 and 60 mA (37.5 mA L(-1), 75 mA L(-1), 112.5 mA L(-1) and 150 mA L(-1)) were applied. Solutions of NaCl, Na(2)SO(4) and NaHCO(3) were selected to mimic different wastewater or groundwater compositions. Iron anodes resulted in highly reducing electrolyte conditions compared to inert anodes. Electrolyte pH was dependent on electrode type, electrolyte composition and current density. The pH of mixed-electrolyte was stable when MMO electrodes were used. When iron electrodes were used, the pH of electrolyte with relatively low current density (37.5 mA L(-1)) did not show significant changes but the pH increased sharply for relatively high current density (150 mA L(-1)). Sulfate solution showed more basic and relatively more reducing electrolyte conditions compared to bicarbonate and chloride solution. The study shows that a highly reducing environment could be achieved using iron anodes in divided or mixed electrolytes and the pH and redox potential could be optimized using appropriate current and polarity reversal.
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Affiliation(s)
- Ali Ciblak
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, USA
| | - Xuhui Mao
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, USA
| | - Ingrid Padilla
- Department of Civil Engineering and Surveying, University of Puerto Rico, Mayaguez, PR
| | - Dorothy Vesper
- Department of Geology and Geography, West Virginia University, Morgantown, WV, USA
| | | | - Akram N. Alshawabkeh
- Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, USA
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