Electrochemical behaviors and influence factors of copper and copper alloys cathode for electrocatalytic nitrate removal

Abstract

The electrocatalytic activities of a series of copper alloys, Cu/Ni/Zn (Cu₆₀ Ni₁₅ Zn₂₅ ) and Cu/Zn (Cu₆₂ Zn₃₈ ), toward the reduction of nitrate were investigated, in comparison with that of pure copper. Electrochemical analysis showed that the copper alloy electrode exhibited higher electrochemical reduction rate of nitrate. The extreme difference (R) between the orthogonal experiments revealed that the ${\text{NO}}_3^{-}-\text{N}$ concentration was the main determinant of the removal percentage, followed by the current density and electrolyte concentration, while the impact of the initial pH was minimal. The conditions of the electrolysis experiments with Cu/Ni/Zn and Cu/Zn cathodes were optimized as follows: a current density of 8 mA/cm² , a NaCl concentration of 2.0 g/L, and an initial pH of 3.0. The nitrate reduction reaction process with copper alloy cathodes was confirmed by electrochemical analysis and electrolysis experiments. Therefore, copper alloyed with Zn and Ni is a feasible option for practical application to the electrocatalytic reduction of nitrate. PRACTITIONER POINTS: Alloy of Cu, Zn, and Ni improved electrochemical nitrate reduction reaction. Electrochemical reduction of nitrate was confirmed in the presence of NaCl. The optimized current density with copper alloy cathodes was 6 mA/cm² . A feasible strategy was provided for the improving nitrate removal and minimizing by-products.

Keywords: Cu/Zn alloy; Cu/Zn/Ni alloy; electrochemical reduction; nitrate.