Amidoxime-Functionalized Interfacial Microenvironment Reconstruction Promotes Cathodic Nickel Recovery from Ni–EDTA

The presence of metals and complexing agents in wastewater poses serious threats to public health and aquatic ecosystems. Electrochemically advanced oxidation processes can break down heavy metal compounds, but recovering these metals at the cathode presents challenges. To address this concern, we explore amidoxime, known for its high complexation capacity and hydrophilicity, as a cathodic microenvironment modifier to enhance heavy metal adsorption and immobilization. We develop a novel carbon felt (CF) amidoxime-functionalized group (CFAG) cathode for cathodic nickel recovery from Ni–EDTA. Experimental results show a significant improvement in nickel recovery efficiency with amidoxime functionalization. Specifically, CFAG outperforms CF by 2 times, driven by nickel recovery reaction kinetic constants of 0.0202 min –1 for CFAG and 0.0101 min –1 for CF. Furthermore, cycling and desorption experimental results have validated the enduring stability and regenerative attributes of the CFAG electrode, and the density functional theory calculations confirm that nickel binds more effectively to amidoxime groups than conventional polymer groups on CF. This study presents a promising electrochemical approach for recycling metals in complex heavy metal wastewater, making metal resource recovery more economical and efficient.