Enhanced degradation of bisphenol AF (BPAF) by visible light irradiated zero valent iron activated persulfate system

In this study, we conducted a systematic study of bisphenol AF (BPAF) removal by visible light coupled zero valent iron activated persulfate (Vis/Fe0/PS) system. The results showed that in Fe0/PS system, the removal rate of BPAF increased by 46.4% with the addition of Vis. New mechanisms were proposed: that PS became excited under Vis irradiation, which favored its reaction with Fe2+ to produce more free radicals. Moreover, Fe3+ could form complex with mono-hydroxylated and mono-carboxylated intermediate of BPAF, and the photoinduced ligand-metal charge transfer (LMCT) process could effectively transfer the charge to the metal ion, accelerating the reduction of Fe3+ to Fe2+ to enhance the generation of free radicals. The generation of hydroxylation products of bisphenol AF in the Vis/Fe0/PS system was greatly increased compared to the Fe0/PS system. The Vis/Fe0/PS system had a great application prospect, as it reduced the economic cost of treating bisphenol AF by at least 49.5% compared to other methods. Moreover, 99.6% of bisphenol AF was degraded after 45 min of reaction under natural light. Findings of this study provides new insights into the synergistic role of Vis in Fe0/PS systems and may advance the practical application of Vis/Fe0/PS system in water and wastewater treatment.