Electrochemical nitrate reduction by using a novel Co3O4/Ti cathode

Liuhua Su; Kan Li; Hongbo Zhang; Maohong Fan; Diwen Ying; Tonghua Sun; Yalin Wang; Jinping Jia

doi:10.1016/j.watres.2017.04.069

Electrochemical nitrate reduction by using a novel Co₃O₄/Ti cathode

Water Res. 2017 Sep 1:120:1-11. doi: 10.1016/j.watres.2017.04.069. Epub 2017 Apr 29.

Authors

Liuhua Su¹, Kan Li², Hongbo Zhang³, Maohong Fan⁴, Diwen Ying¹, Tonghua Sun¹, Yalin Wang¹, Jinping Jia⁵

Affiliations

¹ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China.
² School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China; School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China; School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA; Department of Chemical & Petroleum Engineering, University of Wyoming, Laramie, WY, 82071, USA.
³ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China; School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China; Department of Chemical & Petroleum Engineering, University of Wyoming, Laramie, WY, 82071, USA.
⁴ School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA; Department of Chemical & Petroleum Engineering, University of Wyoming, Laramie, WY, 82071, USA; School of Energy Resources, University of Wyoming, Laramie, WY, 82071, USA.
⁵ School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China. Electronic address: jpjia@sjtu.edu.cn.

PMID: 28478288
DOI: 10.1016/j.watres.2017.04.069

Abstract

Co₃O₄ film coated on Ti substrate is prepared using sol-gel method and applied as cathode material for electrochemical denitrification in this research. Preparation conditions including precursor coating times and calcination temperature are optimized based on NO₃^--N removal, NO₂^--N generation, NH₄⁺-N generation and total nitrogen (TN) removal efficiencies. The influences of electrolysis parameters such as current density and NO₃^--N initial concentration are also investigated. In comparison with other common researched cathodes (Ti, Cu and Fe₂O₃/Ti), Co₃O₄/Ti exhibits better NO₃^--N removal and NH₄⁺-N generation efficiencies. In order to remove NO₃^--N completely from water, Cl^- is added to help further oxidize NH₄⁺-N to N₂. TN removal after 3 h treatment increases from 65% to 80%, 90% and 96% with the increase of Cl^- from 0 mg L^-1 to 500, 1000 and 1500 mg L^-1, respectively. The mechanisms of NO₃^--N reduction on cathode and NH₄⁺-N oxidation on anode in the absence and presence of Cl^- are investigated in a double-cell reactor. Actual textile wastewater containing both NO₃^- and Cl^- is also treated and the Co₃O₄/Ti cathode exhibits excellent stability and reliability. It is interesting to find out that FeCl₂-H₂O₂ Fenton pretreatment is needed to remove extra COD and provide more Cl^- to help oxidize NH₄⁺-N to N₂ at the same time.

Keywords: Actual textile wastewater; ClO(−) oxidation; Co(3)O(4)/Ti cathode; Electrochemical denitrification; Total nitrogen removal.

MeSH terms

Electrodes*
Ferric Compounds
Hydrogen Peroxide*
Nitrates*
Reproducibility of Results

Substances

Ferric Compounds
Nitrates
Hydrogen Peroxide