Electrochemical advanced oxidation combined to electro-Fenton for effective treatment of perfluoroalkyl substances “PFAS” in water using a Magnéli phase-based anode

Abstract

Per-and polyfluoroalkyl substances (PFAS), known as “forever chemicals”, are posing a considerable threat to human health and the environment, that conventional treatment methods are unable to treat. In recent years, electrochemical advanced oxidation emerged as a promising technology for the degradation of recalcitrant pollutants such as PFAS. This work reports the degradation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), using a Magnéli phase-based anode type Ti₄O₇ by electro-oxidation and electro-oxidation combined with electro-Fenton. First the Ti₄O₇ anode was prepared from Rutile TiO₂ powder and characterized, the results showed that the Ti_nO_2n−1 phase is the dominant phase. Afterward, the degradation of PFOA and PFOS was evaluated on the developed anode. After 5 hours of treatment, 52% and 82% of PFOA and PFOS were removed respectively. To improve this results electro-oxidation was combined with electro-Fenton, the degradation of both pollutants increased, 92% of PFOA was degraded and PFOS was totally removed after 5 hours of treatment. The energy consumption was also evaluated at t_1/2 which is defined as the time when half of the initial concentration of PFOA and PFOS was degraded. Combining the two degradation approaches showed promising results that need to be further optimized for potential application at large volumes.