Degradation of 29 per- and poly-fluoroalkyl substances (PFAS) in water using fenton-assisted electrochemical oxidation process

Abstract

Per-polyfluoroalkyl compounds (PFAS) are of widespread concern because they persist in water and resist conventional treatment processes, which may pose risks to human health and the environment. Therefore, this study for the first time focused on investigating the effectiveness of the fenton-assisted electrochemical oxidation process combined with a Pt cathode and two anodes (Ti/BDD and Ti/IrO₂) in treating 29 PFAS compounds (divided into 8 groups: PFCAs, PFOSA, Linear and branched FOSAA, PFSAs, FTSA, Gen X, NaDONA and F-53B) in a simulated wastewater model based on the surface water content evaluated and quantified by liquid chromatography-tandem mass spectrometry (LC/MS-MS). Experimental results showed that the operating parameters that directly affect the treatment process were optimized, with the Ti/BDD anode demonstrating superior degradation efficiency under optimal operating conditions: [NaCl] 2 g/L, [Fe₃O₄] 0.5 mM, pH 2.5–3, applied current density 5 mA/cm², stirring speed 200 rpm, electrolysis time 120 min removed 86.1–100 % PFAS per eight groups in water with an energy consumption of 9.0 kWh/m³. Comparatively, optimal operating conditions for the Ti/IrO₂ anode were higher than Ti/BDD: [NaCl] 2 g/L, [Fe₃O₄] 1 mM, applied current density 15 mA/cm², pH 3, stirring speed 200 rpm, electrolysis time 180 min, removing 54.5–98.1 % PFAS per eight groups with an energy consumption of 40.5 kWh/m³, respectively. Hydroxyl radicals (OH^•) generated during the process effectively degraded both long- and short-chain at 29 PFAS compounds, and the long-chain PFCAs and PFSAs groups, along with linear and branched PFAA isomers, were found to be more stable in degradation than the other groups. The hydrolysis mechanism is the proposed pathway for removing typical PFBS and intermediate compounds. This study suggested fenton-assisted electrochemical oxidation process with the Ti/BDD anode as a feasible method to reduce PFAS pollution in surface water, providing a sustainable and effective alternative to conventional treatment methods.