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Membrane Water Treatment
  Volume 9, Number 3, May 2018 , pages 189-194
DOI: https://doi.org/10.12989/mwt.2018.9.3.189
 


Electrochemical nitrate reduction using a cell divided by ion-exchange membrane
Jongkeun Lee, Ho Young Cha, Kyung Jin Min, Jinwoo Cho and Ki Young Park

 
Abstract
    Electrochemical reduction of nitrate was studied using Zn, Cu and (Ir+Ru)-Ti cathodes and Pt/Ti anode in a cell divided by an ion exchange membrane. During electrolysis, effects of the different cathode types on operating parameters (i.e. voltage, temperature and pH), nitrate removal efficiency and by-products (i.e. nitrite and ammonia) formation were investigated. Ammonia oxidation rate in the presence of NaCl was also determined using the different ratios of hypochlorous acid to ammonia. The operating parameter values were similar for all types of cathode materials and were maintained relatively constant. Nitrate was well reduced and converted mostly to ammonia using Zn and Cu cathodes. Ammonia, produced as a by-product of nitrate reduction, was oxidized in the presence of NaCl in the electrochemical process and the oxidation performance was enhanced upon increasing the hypochlorous acid-to-ammonia ratio to 1.09:1. Zn and Cu cathodes promoted the nitrate reduction to ammonia and the produced ammonia was finally removed from solution by reacting with hypochlorite ions. Using Zn or Cu cathodes, instead of noble metal cathodes, in the electrochemical process can be an alternative technology for nitrate-containing wastewater treatment.
 
Key Words
    electrochemical reduction; nitrate; divided cell; ion exchange membrane
 
Address
Jongkeun Lee, Ho Young Cha and Ki Young Park: Department of Civil and Environmental Plant Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
Kyung Jin Min: AinChem Tech Co., Ltd, 33 Omokcheon-ro, Gwonseon-gu, Suwon-si, Gyunggi 16642, Republic of Korea
Jinwoo Cho: Department of Environmental and Energy, Sejong University, 209 Neungdong-ro, Gwangjin-Gu, Seoul 05006, Republic of Korea
 

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