Wu, Jhen-CihJhen-CihWuTsai, Chun-WeiChun-WeiTsaiCHIA-HUNG HOU2025-09-092025-09-092025-10https://www.scopus.com/record/display.uri?eid=2-s2.0-105013093618&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/731954The widespread use of cobalt and its interaction with chelating agents such as ethylenediaminetetraacetic acid (EDTA) across various industries have raised concerns about cobalt-complex contamination in wastewater. The distinct oxidation states of cobalt (Co(II)/Co(III)) further complicate its degradation pathways, leaving the decomplexation mechanisms inadequately understood. This study investigates the potential of electrochemical advanced oxidation processes (EAOPs) for degrading Co(II)-EDTA complexes while simultaneously enabling cobalt recovery. Under the most effective tested conditions (200 mM Na2SO4 electrolyte, 5 V vs. Ag/AgCl), the process demonstrated a remarkable 99.8 % decomplexation efficiency, along with a 96 % conversion of inorganic nitrogen, indicative of the breakdown of nitrogen-containing functional groups in EDTA. Additionally, TOC removal reached 71.5 %, confirming the significant mineralization of organic content. We closely monitored the transition from Co(II)-EDTA to Co(III)-EDTA, followed by its degradation into ammonium and nitrate, offering unprecedented insights into cobalt-EDTA oxidation pathways and decomplexation mechanisms. Notably, cobalt recovery at the cathode reached 97 %, with cobalt being deposited in multiple forms, including metallic cobalt (Co0), cobalt hydroxide (Co(OH)2), and cobalt oxide (CoO). The decomplexation process is primarily driven by an indirect oxidation mechanism, facilitated by hydroxyl radical (•OH) production. These findings highlight the potential of EAOP as an effective strategy for remediating Co-EDTA-contaminated wastewater while promoting cobalt recovery, thereby mitigating environmental impact and advancing resource sustainability.Chelated cobaltCobalt species conversionDecomplexationElectrochemical advanced oxidation processResource recovery[SDGs]SDG6journal article10.1016/j.cej.2025.167014