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Kumari P, Bahadur N, Cretin M, Kong L, O'Dell LA, Merenda A, Dumée LF. Electro-catalytic membrane reactors for the degradation of organic pollutants – a review. REACT CHEM ENG 2021. [DOI: 10.1039/d1re00091h] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electro-catalytic membrane reactor exhibiting electro-oxidation degradation of organic pollutants on anodic membrane.
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Affiliation(s)
- Priyanka Kumari
- Institute for Frontier Materials, Deakin University, Geelong, Waurn Ponds, 3216, Victoria, Australia
- TERI-Deakin Nano-Biotechnology Centre (TDNBC), Teri Gram, Gwal pahari, Gurugram 122003, Haryana, India
| | - Nupur Bahadur
- TERI-Deakin Nano-Biotechnology Centre (TDNBC), Teri Gram, Gwal pahari, Gurugram 122003, Haryana, India
- TADOX Technology Centre for Water Reuse, Water Resources Division, The Energy and Resources Institute (TERI), India Habitat Centre, Lodhi Road, New Delhi-110003, India
| | - Marc Cretin
- Institut Européen des Membranes, IEM - UMR 5635, ENSCM, CNRS, Univ Montpellier, Montpellier, France
| | - Lingxue Kong
- Institute for Frontier Materials, Deakin University, Geelong, Waurn Ponds, 3216, Victoria, Australia
| | - Luke A. O'Dell
- Institute for Frontier Materials, Deakin University, Geelong, Waurn Ponds, 3216, Victoria, Australia
| | - Andrea Merenda
- Institute for Frontier Materials, Deakin University, Geelong, Waurn Ponds, 3216, Victoria, Australia
| | - Ludovic F. Dumée
- Department of Chemical Engineering, Khalifa University, Abu Dhabi, United Arab Emirates
- Research and Innovation Center on CO2 and Hydrogen, Khalifa University, Abu Dhabi, United Arab Emirates
- Center for Membrane and Advanced Water Technology, Khalifa University, Abu Dhabi, United Arab Emirates
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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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Gayen P, Chaplin BP. Fluorination of Boron-Doped Diamond Film Electrodes for Minimization of Perchlorate Formation. ACS APPLIED MATERIALS & INTERFACES 2017; 9:27638-27648. [PMID: 28749130 DOI: 10.1021/acsami.7b06028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This research investigated the effects of surface fluorination on both rates of organic compound oxidation (phenol and terephthalic acid (TA)) and ClO4- formation at boron-doped diamond (BDD) film anodes at 22 °C. Different fluorination methods (i.e., electrochemical oxidation with perfluorooctanoic acid (PFOA), radio frequency plasma, and silanization) were used to incorporate fluorinated moieties on the BDD surface, which was confirmed by X-ray photoelectron spectroscopy (XPS). The silanization method was found to be the most effective fluorination method using a 1H,1H,2H,2H-perfluorodecyltrichlorosilane precursor to form a self-assembled monolayer (SAM) on the oxygenated BDD surface. The ClO4- formation decreased from rates of 0.45 ± 0.03 mmol m-2 min-1 during 1 mM NaClO3 oxidation and 0.28 ± 0.01 mmol m-2 min-1 during 10 mM NaCl oxidation on the BDD electrode to below detectable levels (<0.12 μmoles m-2 min-1) for the BDD electrode functionalized by a 1H,1H,2H,2H-perfluorodecyltrichlorosilane SAM. These decreases in rates corresponded to 99.94 and 99.85% decreases in selectivity for ClO4- formation during the electrolysis of 10 mM NaCl and 1 mM NaClO3 electrolytes, respectively. By contrast, the oxidation rates of phenol were reduced by only 16.3% in the NaCl electrolyte and 61% in a nonreactive 0.1 M KH2PO4 electrolyte. Cyclic voltammetry with Fe(CN)63-/4- and Fe3+/2+ redox couples indicated that the long fluorinated chains created a blocking layer on the BDD surface that inhibited charge transfer via steric hindrance and hydrophobic effects. The surface coverages and thicknesses of the fluorinated films controlled the charge transfer rates, which was confirmed by estimates of film thicknesses using XPS and density functional theory simulations. The aliphatic silanized electrode also showed very high stability during OH• production. Perchlorate formation rates were below the detection limit (<0.12 μmoles m-2 min-1) for up to 10 consecutive NaClO3 oxidation experiments.
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Affiliation(s)
- Pralay Gayen
- Department of Chemical Engineering, University of Illinois at Chicago , 810 S. Clinton Street, Chicago, Illinois 60607, United States
| | - Brian P Chaplin
- Department of Chemical Engineering, University of Illinois at Chicago , 810 S. Clinton Street, Chicago, Illinois 60607, United States
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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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5
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Guo L, Ding K, Rockne K, Duran M, Chaplin BP. Bacteria inactivation at a sub-stoichiometric titanium dioxide reactive electrochemical membrane. JOURNAL OF HAZARDOUS MATERIALS 2016; 319:137-146. [PMID: 27283345 DOI: 10.1016/j.jhazmat.2016.05.051] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 04/27/2016] [Accepted: 05/15/2016] [Indexed: 06/06/2023]
Abstract
This study investigated the use of a sub-stoichiometric TiO2 reactive electrochemical membrane (REM) for the inactivation of a model Escherichia coli (E. coli) pathogen in chloride-free solutions. The filtration system was operated in dead-end, outside-in filtration model, using the REM as anode and a stainless steel mesh as cathode. A 1-log removal of E. coli was achieved when the electrochemical cell was operated at the open circuit potential, due to a simple bacteria-sieving mechanism. At applied cell potentials of 1.3 and 3.5V neither live nor dead E. coli cells were detected in the permeate stream (detection limit of 1.0 cell mL(-1)), which was attributed to enhanced electrostatic bacteria adsorption at the REM anode. Bacteria inactivation in the retentate solution increased as a function of the applied cell potential, which was attributed to transport of E. coli to the REM and stainless steel cathode surfaces, and direct contact with the local acidic and alkaline environment produced by water oxidation at the anode and cathode, respectively. Clear evidence for an E. coli inactivation mechanism mediated by either direct or indirect oxidation was not found. The low energy requirement of the process (2.0-88Whm(-3)) makes the REM an attractive method for potable water disinfection.
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Affiliation(s)
- Lun Guo
- Department of Chemical Engineering, University of Illinois at Chicago, 810 South Clinton Street, Chicago, IL 60607, United States
| | - Kai Ding
- Department of Civil and Environmental Engineering, Villanova University, 800 Lancaster Ave., Villanova, PA, 19085 United States
| | - Karl Rockne
- Department of Civil and Materials Engineering, University of Illinois at Chicago, 842 W. Taylor St., Chicago, IL 60607, United States
| | - Metin Duran
- Department of Civil and Environmental Engineering, Villanova University, 800 Lancaster Ave., Villanova, PA, 19085 United States
| | - Brian P Chaplin
- Department of Chemical Engineering, University of Illinois at Chicago, 810 South Clinton Street, Chicago, IL 60607, United States.
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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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7
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Guo L, Jing Y, Chaplin BP. Development and Characterization of Ultrafiltration TiO2 Magnéli Phase Reactive Electrochemical Membranes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:1428-1436. [PMID: 26735740 DOI: 10.1021/acs.est.5b04366] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This research focused on the synthesis, characterization, and performance testing of a novel Magnéli phase (TinO2n-1), n = 4 to 6, reactive electrochemical membrane (REM) for water treatment. The REMs were synthesized from tubular asymmetric TiO2 ultrafiltration membranes, and optimal reactivity was achieved for REMs composed of high purity Ti4O7. Probe molecules were used to assess outer-sphere charge transfer (Fe(CN)6(4-)) and organic compound oxidation through both direct oxidation (oxalic acid) and formation of OH(•) (coumarin, terephthalic acid). High membrane fluxes (3208 L m(-2) h(-1) bar(-1) (LMH bar(-1))) were achieved and resulted in a convection-enhanced rate constant for Fe(CN)6(4-) oxidation of 1.4 × 10(-4) m s(-1), which is the highest reported in an electrochemical flow-through reactor and approached the kinetic limit. The optimal removal rate for oxalic acid was 401.5 ± 18.1 mmol h(-1) m(-2) at 793 LMH, with approximately 84% current efficiency. Experiments indicate OH(•) were produced only on the Ti4O7 REM and not on less reduced phases (e.g., Ti6O11). REMs were also tested for oxyanion separation. Approximately 67% removal of a 1 mM NO3(-) solution was achieved at 58 LMH, with energy consumption of 0.22 kWh m(-3). These results demonstrate the extreme promise of REMs for water treatment applications.
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Affiliation(s)
- Lun Guo
- Department of Chemical Engineering, University of Illinois at Chicago , 810 S. Clinton Street, Chicago, Illinois 60607
| | - Yin Jing
- Department of Chemical Engineering, University of Illinois at Chicago , 810 S. Clinton Street, Chicago, Illinois 60607
| | - Brian P Chaplin
- Department of Chemical Engineering, University of Illinois at Chicago , 810 S. Clinton Street, Chicago, Illinois 60607
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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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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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The effects of surface oxidation and fluorination of boron-doped diamond anodes on perchlorate formation and organic compound oxidation. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.06.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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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: 25] [Impact Index Per Article: 2.8] [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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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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13
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Davis J, Baygents JC, Farrell J. Understanding Persulfate Production at Boron Doped Diamond Film Anodes. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.10.104] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Bagastyo AY, Batstone DJ, Kristiana I, Escher BI, Joll C, Radjenovic J. Electrochemical treatment of reverse osmosis concentrate on boron-doped electrodes in undivided and divided cell configurations. JOURNAL OF HAZARDOUS MATERIALS 2014; 279:111-116. [PMID: 25048621 DOI: 10.1016/j.jhazmat.2014.06.060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 05/30/2014] [Accepted: 06/26/2014] [Indexed: 06/03/2023]
Abstract
An undivided electrolytic cell may offer lower electrochlorination through reduction of chlorine/hypochlorite at the cathode. This study investigated the performance of electrooxidation of reverse osmosis concentrate using boron-doped diamond electrodes in membrane-divided and undivided cells. In both cell configurations, similar extents of chemical oxygen demand and dissolved organic carbon removal were obtained. Continuous formation of chlorinated organic compounds was observed regardless of the membrane presence. However, halogenation of the organic matter did not result in a corresponding increase in toxicity (Vibrio fischeri bioassay performed on extracted samples), with toxicity decreasing slightly until 10AhL(-1), and generally remaining near the initial baseline-toxicity equivalent concentration (TEQ) of the raw concentrate (i.e., ∼2mgL(-1)). The exception was a high range toxicity measure in the undivided cell (i.e., TEQ=11mgL(-1) at 2.4AhL(-1)), which rapidly decreased to 4mgL(-1). The discrepancy between the halogenated organic matter and toxicity patterns may be a consequence of volatile and/or polar halogenated by-products formed in oxidation by OH electrogenerated at the anode. The undivided cell exhibited lower energy compared to the divided cell, 0.25kWhgCOD(-1) and 0.34kWhgCOD(-1), respectively, yet it did not demonstrate any improvement regarding by-products formation.
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Affiliation(s)
- Arseto Y Bagastyo
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia; Department of Environmental Engineering, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia
| | - Damien J Batstone
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Ina Kristiana
- Curtin Water Quality Research Centre, Resources and Chemistry Precinct, Department of Chemistry, Curtin University, Bentley, Perth, WA 6102, Australia
| | - Beate I Escher
- National Research Centre for Environmental Toxicology (Entox), The University of Queensland, Brisbane, QLD 4108, Australia
| | - Cynthia Joll
- Curtin Water Quality Research Centre, Resources and Chemistry Precinct, Department of Chemistry, Curtin University, Bentley, Perth, WA 6102, Australia
| | - Jelena Radjenovic
- Advanced Water Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia.
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15
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Zaky AM, Chaplin BP. Mechanism of p-substituted phenol oxidation at a Ti4O7 reactive electrochemical membrane. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:5857-5867. [PMID: 24766505 DOI: 10.1021/es5010472] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This research investigated the removal mechanisms of p-nitrophenol, p-methoxyphenol, and p-benzoquinone at a porous Ti4O7 reactive electrochemical membrane (REM) under anodic polarization. Cross-flow filtration experiments and density functional theory (DFT) calculations indicated that p-benzoquinone removal was primarily due to reaction with electrochemically formed OH(•), while the dominant removal mechanism of p-nitrophenol and p-methoxyphenol was a function of the anodic potential. At low anodic potentials (1.7-1.8 V/SHE), p-nitrophenol and p-methoxyphenol were removed primarily by an electrochemical adsorption/polymerization mechanism on the REM. Increasing anodic potentials (1.9-3.2 V/SHE) resulted in the electroassisted adsorption mechanism contributing far less to p-methoxyphenol removal compared to p-nitrophenol. DFT calculations indicated that an increase in anodic potential resulted in a shift in p-methoxyphenol removal from a 1e(-) direct electron transfer (DET) reaction that resulted in radical formation and significant adsorption/polymerization, to a 2e(-) DET reaction that formed nonadsorbing products (i.e., p-benzoquinone). However, the anodic potentials were too low for the 2e(-) DET reaction to be thermodynamically favorable for p-nitrophenol. The decreased COD adsorption for p-nitrophenol at higher anodic potentials was attributed to reaction of soluble/adsorbed organics with OH(•). These results provide the first mechanistic explanation for p-substituted phenolic compound removal during advanced electrochemical oxidation processes.
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Affiliation(s)
- Amr M Zaky
- Department of Chemical Engineering, University of Illinois at Chicago , 810 South Clinton Avenue, Chicago, Illinois 60607, United States
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16
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Chaplin BP. Critical review of electrochemical advanced oxidation processes for water treatment applications. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2014; 16:1182-203. [PMID: 24549240 DOI: 10.1039/c3em00679d] [Citation(s) in RCA: 250] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Electrochemical advanced oxidation processes (EAOPs) have emerged as novel water treatment technologies for the elimination of a broad-range of organic contaminants. Considerable validation of this technology has been performed at both the bench-scale and pilot-scale, which has been facilitated by the development of stable electrode materials that efficiently generate high yields of hydroxyl radicals (OH˙) (e.g., boron-doped diamond (BDD), doped-SnO2, PbO2, and substoichiometic- and doped-TiO2). Although a promising new technology, the mechanisms involved in the oxidation of organic compounds during EAOPs and the corresponding environmental impacts of their use have not been fully addressed. In order to unify the state of knowledge, identify research gaps, and stimulate new research in these areas, this review critically analyses published research pertaining to EAOPs. Specific topics covered in this review include (1) EAOP electrode types, (2) oxidation pathways of select classes of contaminants, (3) rate limitations in applied settings, and (4) long-term sustainability. Key challenges facing EAOP technologies are related to toxic byproduct formation (e.g., ClO4(-) and halogenated organic compounds) and low electro-active surface areas. These challenges must be addressed in future research in order for EAOPs to realize their full potential for water treatment.
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Affiliation(s)
- Brian P Chaplin
- Department of Chemical Engineering, University of Illinois at Chicago, 810 S. Clinton Ave., Chicago, IL 60607, USA.
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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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Zaky AM, Chaplin BP. Porous substoichiometric TiO2 anodes as reactive electrochemical membranes for water treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2013; 47:6554-6563. [PMID: 23688192 DOI: 10.1021/es401287e] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
This research investigates the characterization and testing of an anodic reactive electrochemical membrane (REM) for water treatment. The REM consists of a porous substoichiometric titanium dioxide (Ti4O7) tubular, ceramic electrode operated in cross-flow filtration mode. Advection-enhanced mass transfer rates, on the order of a 10-fold increase, are obtained when the REM is operated in filtration-mode, relative to a traditional flow-through mode. Oxidation experiments with model organic compounds showed that the REM was active for both direct oxidation reactions and formation of hydroxyl radicals (OH(•)). Electrochemical impedance spectroscopy data interpreted by transmission line modeling determined that the electro-active surface area was 619 times the nominal geometric surface area. Results from filtration-mode experiments with p-methoxyphenol indicate that compound removal occurred by electro-assisted adsorption and subsequent oxidation. Electro-assisted adsorption was the primary removal mechanism at potentials where OH(•) did not form. At higher potentials (>2.0 V), where OH(•) concentrations were significant, p-methoxyphenol removal occurred by a combination of electro-assisted adsorption and OH(•) oxidation. These removal mechanisms resulted in 99.9% p-methoxyphenol removal in the permeate, with calculated current efficiencies >73% at applied current densities of 0.5-1.0 mA cm(-2). These results illustrate the extreme promise of the REM for water treatment.
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Affiliation(s)
- Amr M Zaky
- Department of Civil and Environmental Engineering and Villanova Center for the Advancement of Sustainable Engineering, Villanova University, Villanova, Pennsylvania 19085, United States
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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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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: 69] [Impact Index Per Article: 5.8] [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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Azizi O, Hubler D, Schrader G, Farrell J, Chaplin BP. Mechanism of perchlorate formation on boron-doped diamond film anodes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:10582-90. [PMID: 22029642 DOI: 10.1021/es202534w] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This research investigated the mechanism of perchlorate (ClO(4)(-)) formation from chlorate (ClO(3)(-)) on boron-doped diamond (BDD) film anodes by use of a rotating disk electrode reactor. Rates of ClO(4)(-) formation were determined as functions of the electrode potential (2.29-2.70 V/standard hydrogen electrode, SHE) and temperature (10-40 °C). At all applied potentials and a ClO(3)(-) concentration of 1 mM, ClO(4)(-) production rates were zeroth-order with respect to ClO(4)(-) concentration. Experimental and density functional theory (DFT) results indicate that ClO(3)(-) oxidation proceeds via a combination of direct electron transfer and hydroxyl radical oxidation with a measured apparent activation energy of 6.9 ± 1.8 kJ·mol(-1) at a potential of 2.60 V/SHE. DFT simulations indicate that the ClO(4)(-) formation mechanism involves direct oxidation of ClO(3)(-) at the BDD surface to form ClO(3)(•), which becomes activationless at potentials > 0.76 V/SHE. Perchloric acid is then formed via the activationless homogeneous reaction between ClO(3)(•) and OH(•) in the diffuse layer next to the BDD surface. DFT simulations also indicate that the reduction of ClO(3)(•) can occur at radical sites on the BDD surface to form ClO(3)(-) and ClO(2), which limits the overall rate of ClO(4)(-) formation.
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Affiliation(s)
- Orchideh Azizi
- Department of Civil and Environmental Engineering and Villanova Center for the Advancement of Sustainable Engineering, Villanova University, Villanova, Pennsylvania 19085, United States
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Characterization of the performance and failure mechanisms of boron-doped ultrananocrystalline diamond electrodes. J APPL ELECTROCHEM 2011. [DOI: 10.1007/s10800-011-0351-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Mu Y, Radjenovic J, Shen J, Rozendal RA, Rabaey K, Keller J. Dehalogenation of iodinated X-ray contrast media in a bioelectrochemical system. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:782-788. [PMID: 21141818 DOI: 10.1021/es1022812] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Iodinated X-ray contrast media (ICM) are only to a limited extent removed from conventional wastewater treatment plants, due to their high recalcitrance. This work reports on the cathodic dehalogenation of the ICM iopromide in a bioelectrochemical system (BES), fed with acetate at the anode and iopromide at the cathode. When the granular graphite cathode potential was decreased from -500 to -850 mV vs standard hydrogen electrode (SHE), the iopromide removal and the iodide release rates increased from 0 to 4.62 ± 0.01 mmol m(-3) TCC d(-1) and 0 to 13.4 ± 0.16 mmol m(-3) TCC d(-1) (Total Cathodic Compartment, TCC) respectively. Correspondingly, the power consumption increased from 0.4 ± 1 to 20.5 ± 3.3 W m(-3) TCC. The Coulombic efficiency of the iopromide dehalogenation at the cathode was less than 1%, while the Coulombic efficiency of the acetate oxidation at the anode was lower than 50% at various granular graphite cathode potentials. The results suggest that iopromide could be completely dehalogenated in BESs when the granular graphite cathode potential was controlled at -800 mV vs SHE or lower. This finding was further confirmed using mass spectrometry to identify the dehalogenated intermediates and products of iopromide in BESs. Kinetic analysis indicates that iopromide dehalogenation in batch experiments can be described by a first-order model at various cathode potentials. This work demonstrates that the BESs have a potential for efficient dehalogenation of ICM from wastewater or environmental streams.
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Affiliation(s)
- Yang Mu
- Advanced Water Management Centre, The University of Queensland, St. Lucia, Queensland, Australia.
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Chaplin BP, Schrader G, Farrell J. Electrochemical destruction of N-nitrosodimethylamine in reverse osmosis concentrates using Boron-doped diamond film electrodes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:4264-4269. [PMID: 20441141 DOI: 10.1021/es903872p] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Boron-doped diamond (BDD) film electrodes were use to electrochemically destroy N-nitrosodimethylamine (NDMA) in reverse osmosis (RO) concentrates. Batch experiments were conducted ito investigate the effects of dissolved organic carbon (DOC), chloride (Cl(-)), bicarbonate (HCO(3-) and hardness on rates of NDMA destruction via both oxidation and reduction. Experimental results showed that NDMA oxidation rates were not affected by DOC, Cl(-), or HCO(3-) at concentrations present in RO concentrates. However, hydroxyl radical scavenging at 100 mM concentrations of HCO(3-) and Cl(-) shifted the reaction mechanism of NDMA oxidation from hydroxyl radical mediated to direct electron transfer oxidation. In the 100 mM Cl(-) electrolyte experimental evidence suggests that the in situ production of ClO(3)(.)also contributes to NDMA oxidation. Density functional theory calculations support a reaction mechanism between ClO(3)(.) and NDMA, with an activation barrier of 7.2 kJ/mol. Flow-through experiments with RO concentrate yielded surface area normalized first-order rate constants for NDMA (40.6 +/- 3.7 L/m(2) h) and DOC (as C) (38.3 +/- 2.2 L/m(2) h) removal that were mass transfer limited at a 2 mA/cm(2) current density. This research shows that electrochemical oxidation using BDD electrodes has an advantage over other advanced oxidation processes, as organics were readily oxidized in the presence of high HCO(3-) concentrations.
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Affiliation(s)
- Brian P Chaplin
- Department of Chemical and Environmental Engineering University of Arizona, Tucson, Arizona 85721, USA.
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Carter KE, Farrell J. Electrochemical oxidation of trichloroethylene using boron-doped diamond film electrodes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2009; 43:8350-8354. [PMID: 19924968 DOI: 10.1021/es9017738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This research investigated the oxidation of trichloroethene (TCE) at boron-doped diamond film electrodes. Flow-through experiments in gastight reactors were performed to determine trichloroethene oxidation products, and rotating disk electrode (RDE) experiments were used to determine TCE oxidation kinetics. RDE experiments were performed over a range in current densities and temperatures in order to elucidate the rate-limiting mechanisms for TCE oxidation. Density functional theory (DFT) simulations were used to investigate the activation barriers for oxidation by direct electron transfer and hydroxyl radicals. Oxidation of TCE produced formate, carbon dioxide, chlorate, and chloride. DFT simulations, experimentally measured apparent activation energies, and linear sweep voltammetry scans indicated that TCE oxidation occurred via direct electron transfer at electrode potentials <2.0 V/SHE, while at higher electrode potentials TCE oxidation also occurred via hydroxyl radicals produced from water oxidation.
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Affiliation(s)
- Kimberly E Carter
- Department of Chemical and Environmental Engineering, The University of Arizona, Tucson, Arizona 85721, USA
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