Design and syntheses of Cu–Fe3O4@Fe electrode with needle-like structure and electric field potential: Remediation of nitrate contamination and action in protein wastewater

As nitrate is highly stabilised in solution, its removal is a constant challenge. Electrochemical reduction of nitrate is considered a promising treatment, but most strategies only concern reduction rate without current efficiency and practical application prospects. In this work,a binary non-precious metal needle-like Cu–Fe3O4@Fe electrode was synthesized from by a two-step in situ growth method using Fe foam as raw material, and its feasibility for nitrate reduction was investigated. The Cu–Fe3O4@Fe electrode exhibits 92.01% nitrate removal and 50.3% current efficiency in 150 min electrocatalysis, which is 2.82 and 2.18 times more effective than Fe foam, respectively. The excellent nitrate removal performance of Cu–Fe3O4@Fe is credited to the electricity field and the needle-like structure. The needle-like structure improves mass transfer, while the electricity field enhances the efficiency of electron transfer. The electrode Cu–Fe3O4@Fe maintains excellent stability over six cycles and the leaching rates of Cu and Fe are far less than the electrodes Fe and Cu@Fe. The electrode was used to treat protein wastewater with significant removal of nitrate, total nitrogen (TN) and Chemical oxygen demand (COD). All the results have proved that the binary non-precious metal needle-like Cu–Fe3O4@Fe electrode is a cost-effective, efficient and stable, environmentally friendly electrode material for the deep purification of protein wastewater.