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Perfluorooctanoic acid (PFOA) is one of the most persistent per- and polyfluoroalkyl substances (PFAS), requiring advanced treatment technologies and reliable analytical approaches to elucidate transformation mechanisms. In this study, photocatalytic degradation using immobilized rGO-doped TiO₂ coatings and long-term bioelectrochemical treatment in sediment microbial fuel cells (MFCs) were comparatively investigated.
Targeted LC-MS/MS analysis revealed progressive chain shortening of PFOA and formation of shorter-chain perfluoroalkyl carboxylic acids in both systems. Photocatalytic treatment produced perfluoroheptanoic acid (PFHpA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), accompanied by fluoride release, while high-resolution mass spectrometry confirmed additional intermediates.1 Ten months of MFC operation resulted in a 94.9 % decrease in extractable PFOA, with PFHpA and PFHxA detected as major products.2
The results demonstrate that both abiotic and bioelectrochemical systems promote stepwise shortening of the fluorinated carbon chain, whereas complete mineralization could not be confirmed. The study highlights the importance of combining targeted and non-target analytical approaches to distinguish apparent removal from actual degradation and improve understanding of PFAS transformation pathways.