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Application of Heterojunction Ni–Sb–SnO₂ Anodes for Electrochemical Water Treatment

Zhang, Yi and Yang, Yang and Yang, Shasha and Quispe-Cardenas, Estefanny and Hoffmann, Michael R. (2021) Application of Heterojunction Ni–Sb–SnO₂ Anodes for Electrochemical Water Treatment. ACS ES&T Engineering, 1 (8). pp. 1236-1245. ISSN 2690-0645. doi:10.1021/acsestengg.1c00122.

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Electrochemical oxidation can be used for decentralized wastewater treatment without the addition of chemicals. Antimony-doped tin oxide (Sb-SnO₂: AT) provides a catalytic anode coating that is easily prepared at a relatively low cost. However, there is the potential of Sb leaching during use. To overcome this problem, a heterojunction anode is developed that uses an AT oxide layer as an ohmic contact and a nickel-doped AT oxide layer (NAT) with a substantially lower Sb content as an outer catalytic layer (NAT/AT). The two-layer NAT/AT anode has significantly longer operational lifetimes, lower Sb leaching potential, and higher activities for free radical generation and ozone production than either layer when used alone. Based on experimental results in combination with theory, an anodic ozone activation pathway at the acidic electrode/electrolyte interface is identified as a key •OH source coupled with direct •OH production via water electrolysis. The NAT/AT anode outperforms commercial anodes (e.g., boron-doped diamond and IrO₂) for organic compound destruction and for microbial disinfection. The 1-log removal of carbamazepine (surface area-normalized first-order rate constant k_(CBZ,SA) = 1.13 × 10⁻³ m/s) and 5-log inactivation of E. coli and MS2 virus are achieved within 60 s in synthetic electrolytes. Even though the electrochemical efficiency is lower in the case of latrine wastewater treatment, the energy consumption (e.g., 3.9–14.0 kWh/m³) is low compared to previously reported values.

Item Type:Article
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URLURL TypeDescription
Yang, Yang0000-0003-3767-8029
Yang, Shasha0000-0002-6646-5332
Hoffmann, Michael R.0000-0001-6495-1946
Alternate Title:Application of Heterojunction Ni–Sb–SnO2 Anodes for Electrochemical Water Treatment
Additional Information:© 2021 American Chemical Society. Received: March 29, 2021; Revised: May 10, 2021; Accepted: May 14, 2021; Published: June 2, 2021. This research was supported by an investment grant made by the Bill and Melinda Gates Foundation (INV-003227). We are grateful to our program officers, Dr. Carl Hensman and Dr. Doulaye Kone, for their suggestions and guidance. We also thank Dr. Yuanlong Huang for help with headspace ozone measurements and Dr. Nathan Dalleska for help on sample analysis. Author Contributions. (Y.Z. and Y.Y.) These authors contributed equally. The authors declare the following competing financial interest(s): Y.Y. and M.R.H. are inventors on U.S. patent application 16/911,912 (Caltech, filed 06/25/2020) partially based on this work. All other authors declare that they have no competing interests.
Funding AgencyGrant Number
Bill and Melinda Gates FoundationINV-003227
Subject Keywords:Double-layer Ni−Sb−SnO₂ anodes, Anodic ozone activation, Organic compound degradation, Microbial disinfection, Wastewater treatment
Issue or Number:8
Record Number:CaltechAUTHORS:20210604-111534211
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Official Citation:Application of Heterojunction Ni–Sb–SnO2 Anodes for Electrochemical Water Treatment. Yi Zhang, Yang Yang, Shasha Yang, Estefanny Quispe-Cardenas, and Michael R. Hoffmann. ACS ES&T Engineering 2021 1 (8), 1236-1245; DOI: 10.1021/acsestengg.1c00122
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109379
Deposited By: George Porter
Deposited On:07 Jun 2021 14:52
Last Modified:16 Nov 2021 19:35

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