Perfluorooctanoic acid (PFOA), with high toxicity and resistance to degradation, has been widely detected in various wastewaters, posing a potential threat to environmental health. This study found that far-ultraviolet light (UV222) markedly enhanced the mineralization rates of PFOA in secondary effluent by driving the silver oxide (Ag2O)/peroxymonosulfate (PMS) system. The photocatalysis in Ag2O, radiation activation of PMS by the high photon energy of UV222, activation of PMS by Ag2O, and Ag2+ formation by electron transfer formed multiple pathways for radical generation. Characterization results indicated that UV222 inhibited the transformation of Ag+ crystal structures, enabling stable cycling between Ag/Ag+/Ag2+ states. Degradation product analysis and ECOSAR assessment revealed that the majority of PFOA was degraded into small-molecule products, thereby reducing the ecological toxicity risk. The free radical pathway, primarily utilizing sulfate radicals as the active species, serves as the main mechanism for defluorinating PFOA. This system successfully overcame the limitations associated with the Fenton-like process, including pH constraints, elevated oxidant doses, and ionic interference, while also demonstrating notable antibacterial performance and detoxification capabilities. These findings enhance the understanding of UV222-driven technologies and offer an efficient and sustainable strategy for the treatment of PFASs.
Mao et al. (Thu,) studied this question.