Stacked electrode configuration for accelerated degradation of perfluorooctanoic acid via electrochemical and peroxymonosulfate oxidation

This work introduces an innovative stacked iron mesh electrode configuration to achieve accelerated degradation of perfluorooctanoic acid (PFOA) by synergistically coupling electrochemical oxidation with peroxymonosulfate (PMS) activation. The system was systematically evaluated through electrochemical measurements, free radical quenching, and electron paramagnetic resonance spectroscopy, complemented by density functional theory calculations. The optimized triple-layer Fe electrode demonstrated outstanding performance, attaining nearly complete PFOA removal (100 %) within 12 min and a high kinetic rate constant of 0.218 min –1 . DFT analysis revealed that the Fe mesh possessed the strongest PMS adsorption energy (–2.68 eV) and the shortest Fe–O bond length (2.24 Å), confirming its superior activation capability. Mechanistic studies confirm the effectiveness of the electron transfer coupled with the hydroxyl radicals in defluorination and decarbonization during PFOA degradation. In addition, the system exhibited high cycle stability and strong tolerance to various background ion under continuous operations in the amplification experiment. The system also exhibited superior performance and low leaching of metal ions in treating various organic pollutants of practical wastewater (fluoride wastewater and landfill leachate). These findings present an effective and practical strategy for the remediation of persistent per- and polyfluoroalkyl substances in contaminated water sources.