Electrochemical mineralization of perfluorooctane sulfonate by novel F and Sb co-doped Ti/SnO2 electrode containing Sn-Sb interlayer

The F and Sb co-doped Ti/SnO2 electrode containing Sn-Sb interlayer was innovatively synthesized for electro-oxidation (EO) removal of perfluorooctane sulfonate (PFOS) in water. Stronger oxidation capability and remarkably longer lifetime were performed for Ti/Sn-Sb/SnO2-F-Sb electrode than these similar electrodes in this study without Sn-Sb interlayer and F/Sb doping, which could removed more than 99% of PFOS (C0 = 100 mg L−1) after 120-min electrolysis. The attribute of Ti/Sn-Sb/SnO2-F-Sb anode and its EO mechanism were surveyed by XRD, XPS, SEM, and LSV. F and Sb co-doping could improve the stability and EO capability of the electrode, which resulted from that the smooth surface was formed conveniently to produce physically adsorbed hydroxyl radical and lead to relatively high OEP. The operating parameters of EO process were also investigated including current density, pH value, and stirring speed, which revealed the effect of these parameters on PFOS decomposition. Additionally, the mineralization parameters, TOC and F− concentration, as well as short-chain perfluorocarboxylic acids were analyzed in solution during the electrolysis. Consequently, the EO pathway of PFOS was proposed through the detection of intermediates. These results manifest that Ti/Sn-Sb/SnO2-F-Sb anode is prospective to effectively decompose PFOS in wastewater.