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Effects of Anodic Potential and Chloride Ion on Overall Reactivity in Electrochemical Reactors Designed for Solar-Powered Wastewater Treatment

Cho, Kangwoo and Qu, Yan and Kwon, Daejung and Zhang, Hao and Cid, Clément A. and Aryanfar, Asghar and Hoffmann, Michael R. (2014) Effects of Anodic Potential and Chloride Ion on Overall Reactivity in Electrochemical Reactors Designed for Solar-Powered Wastewater Treatment. Environmental Science and Technology, 48 (4). pp. 2377-2384. ISSN 0013-936X. http://resolver.caltech.edu/CaltechAUTHORS:20140204-111726022

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Abstract

We have investigated electrochemical treatment of real domestic wastewater coupled with simultaneous production of molecular H2 as useful byproduct. The electrolysis cells employ multilayer semiconductor anodes with electroactive bismuth-doped TiO_2 functionalities and stainless steel cathodes. DC-powered laboratory-scale electrolysis experiments were performed under static anodic potentials (+2.2 or +3.0 V NHE) using domestic wastewater samples, with added chloride ion in variable concentrations. Greater than 95% reductions in chemical oxygen demand (COD) and ammonium ion were achieved within 6 h. In addition, we experimentally determined a decreasing overall reactivity of reactive chlorine species toward COD with an increasing chloride ion concentration under chlorine radicals (Cl·, Cl2–·) generation at +3.0 V NHE. The current efficiency for COD removal was 12% with the lowest specific energy consumption of 96 kWh kgCOD–1 at the cell voltage of near 4 V in 50 mM chloride. The current efficiency and energy efficiency for H2 generation were calculated to range from 34 to 84% and 14 to 26%, respectively. The hydrogen comprised 35 to 60% by volume of evolved gases. The efficacy of our electrolysis cell was further demonstrated by a 20 L prototype reactor totally powered by a photovoltaic (PV) panel, which was shown to eliminate COD and total coliform bacteria in less than 4 h of treatment.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/es404137uDOIArticle
http://pubs.acs.org/doi/abs/10.1021/es404137uPublisherArticle
ORCID:
AuthorORCID
Cid, Clément A.0000-0002-7293-035X
Aryanfar, Asghar0000-0002-8890-077X
Hoffmann, Michael R.0000-0002-0432-6564
Additional Information:© 2014 American Chemical Society. Received: September 30, 2013; revised: December 16, 2013; Accepted: January 14, 2014. Publication Date (Web): January 14, 2014. The authors would like to acknowledge the financial support of the Bill and Melinda Gates Foundation (BMGF RTTC Grant OPP1037491 and BMGF RTTC Grant OPP109500C) and the Korea Institute of Science and Technology for support provided for the graduate study of Kangwoo Cho. This project benefited from the use of instrumentation made available by the Caltech Environmental Analysis Center.
Funders:
Funding AgencyGrant Number
Bill and Melinda Gates FoundationOPP1037491
Bill and Melinda Gates FoundationOPP109500C
Korea Institute of Science and Technology (KIST)UNSPECIFIED
Record Number:CaltechAUTHORS:20140204-111726022
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20140204-111726022
Official Citation:Effects of Anodic Potential and Chloride Ion on Overall Reactivity in Electrochemical Reactors Designed for Solar-Powered Wastewater Treatment Kangwoo Cho, Yan Qu, Daejung Kwon, Hao Zhang, Clément A. Cid, Asghar Aryanfar, and Michael R. Hoffmann Environmental Science & Technology 2014 48 (4), 2377-2384
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43647
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:04 Feb 2014 22:19
Last Modified:15 Sep 2017 22:35

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