Performance of a 3D-particle electrode for PFOA degradation by persulfate-activated electrochemical advanced oxidation processes

Perfluorooctanoic acid (PFOA), a representative perfluoroalkyl substance (PFAS), is a highly persistent contaminant in aquatic environments. Its resistance to degradation and potential health risk demands the development of effective and sustainable treatment methods. In this study, a novel Fe 3 O 4 @mesoporous hollow carbon (Fe 3 O 4 @MHCS) was synthesized and used as a three-dimensional (3D) particle electrode for PFOA degradation through a persulfate-activated electrooxidation process. Spectroscopic analyses confirmed the successful incorporation of Fe within the hollow carbon spheres. The maximum adsorption capacity ( Q ₘₐₓ) of PFOA on Fe 3 O 4 @MHCS was 109 µg/mg. While the PDS/Fe 3 O 4 @MHCS system alone achieved only a 35% removal rate, the 3D electrochemical advanced oxidation process (3D-EAP) reached >96% PFOA removal within 120 min, accompanied by nearly 98% defluorination. Chemical scavenging experiments demonstrated that hydroxyl radicals (HO·) and electrons (e – ) were the main reactive species generated during the 3D-EAP process. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identified four short-chain perfluorocarboxylic acid (PFCA) intermediates, which peaked at 15 min and diminished by 120 min, except for perfluoropropanoic acid (PFPeA) and perfluorobutanoic acid (PFBA). These findings demonstrate that the 3D-EAP system effectively mineralizes PFOA and provides a promising, sustainable approach to mitigating PFAS contamination in surface water. • Novel Fe 3 O 4 -Mesoporous hollow carbon sphere (Fe 3 O 4 @MHCS) functionalized carbon was synthesized. • The 3D-EAP system (Fe 3 O 4 @MHCS/PDS/EO) is exhibited to achieve excellent PFOA degradation efficiency. • >96% PFOA degradation was achieved within 120 min of 3D-EAP with 98% defluorination. • Complete removal of intermediate byproducts from PFOA in the 3D-EAP system.