Electrochemical oxidation combined with UV irradiation for synergistic removal of perfluorooctane sulfonate (PFOS) in water

The effect of electrochemical degradation on Magnéli phase Ti 4 O 7 anode combined with UV irradiation on the removal of PFOS was systematically evaluated in the present study. A synergistic effect of electrolysis and UV irradiation rather than a simple additive effect for PFOS degradation was demonstrated experimentally and theoretically. The short wavelength irradiation within 400 nm is the main contribution to enhance the electrochemical degradation of PFOS, while the initial pH of the solution has little effect on the PFOS degradation. The increase of current density accelerates the removal of PFOS either by electrolysis treatment or the joint process. The time-dependent density functional theory (TD-DFT) calculation indicates that the synergistic effect of the electrolysis and UV irradiation is most likely due to the involvement of the excited PFOS induced under UV irradiation in the electrochemical reaction. This study provides the first mechanistic explanation for the electrochemical degradation of PFOS enhanced by UV irradiation. • PFOS degradation by electrolysis on Ti 4 O 7 anode combined with UV irradiation was studied. • A synergistic effect exists between electrolysis and UV irradiation for PFOS degradation. • TD-DFT calculation elucidates the synergistic mechanism of electrolysis and UV irradiation. • Excited PFOS induced by UV reduces the anodic potential required for electrolysis.