UV/Fe?NTA as a novel photoreductive system for the degradation of perfluorooctane sulfonate (PFOS) via a photoinduced intramolecular electron transfer mechanism

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that toxic and bio-accumulative. Previously, we used hydrated electrons (eaq–) generated by the UV photolysis of nitrilotriacetic acid (NTA) to initiate photoreductive decomposition PFOS. However, due protonation NTA scavenging effect H+ on eaq–, this process relies highly alkaline conditions. Herein, report an enhanced system based Fe?NTA, which results in PFOS at pH 8.0 under anoxic After 10 h photolysis, degradation defluorination efficiencies UV/Fe?NTA were ~ 60% 29.5%, respectively, with pseudo first-order rate constant kobs = 0.081 h?1. Laser flash combined time-dependent density functional theory (TDDFT) calculations indicate PFOS, Fe(H2O)62+, form penta-coordinated metal–ligand complex undergoes UV-induced directional electron transfer from Fe?NTA decomposes via mechanism proceeds through concerted photoinduced intramolecular charge instead direct attack eaq–. Model chelate studies show inherent properties transition metal ion electron-donating capabilities complexing ligands determine efficiency for transfer. A low apparent activation energy 4.74 kJ/mol over broad range higher compared initiated un-complexed NTA.