Removal of nitrate from water by the electrocatalytic denitrification on the Cu-Bi electrode

The Cu-Bi cathode was a new type of electrode in the field of electrocatalytic denitrification. The Cu-Bi electrode prepared by electrodeposition at the current density of 6 mA cm−2 was better. The Cu-Bi coating was compact and crystalline by the characterization of SEM, EDS and XRD. Reduction of nitrate was investigated on Cu-Bi cathodes and Ti/Ru-IrO2 anodes. For 100 mg L−1 NO3−-N, the highest NO3−-N removal rate of 87.5% was obtained at the current density of 6 mA cm−2 and in neutral electrolyte at 4 h. The removal of nitrate on Cu-Bi electrodes was better in neutral electrolyte, which didn't require additional acid or alkali to adjust pH. When the initial concentration of NO3−-N was 50 mg L−1, the effluent concentration of NO3−-N at 4 h was 7.175 mg L−1 lower than the level of drinking water on the standard of the World Health Organization (WHO, 10 mg L−1). The kinetic investigation showed that the reduction of nitrate on Cu-Bi displayed pseudo first-order kinetic behavior. The results of Cyclic Voltammetric (CV) measurements indicated that nitrate was reduced on the Cu-Bi electrode with the occurrence of the hydrogen evolution.