Persulfate-based degradation of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in aqueous solution: Review on influences, mechanisms and prospective

[Display omitted] •The present activation methods of persulfate oxidation of PFOA and PFOS are reviewed.•Operational factors influencing the removal efficiency are discussed and summarized.•Reaction mechanisms and practical feasibility of PFOS and PFOA are evaluated and outlined.•Knowledge gaps and research needs of PFOS and PFOA degradation are proposed. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) have attracted global attention due to their chemical durability, wide distribution, biotoxicity and bioaccumulative properties. Persulfate is a promising alternative to H2O2 for advanced oxidation processes and effective for organic removal. In this review, persulfate activation methods and operational factors in persulfate-based PFOA / PFOS degradation are analyzed and summarized. Moreover, the decomposing mechanisms of PFOA and PFOS are outlined in terms of molecular structures based a series of proposed pathways. PFOS could be converted to PFOA with the attack of SO4− and OH. And then PFOA defluorination occurs with one CF2 unit missing in each round and the similar procedure would occur continuously with sufficient SO4− and OH until entire decomposition. In addition, several knowledge gaps and research needs for further in-depth studies are identified. This review provides an overview for better understanding of the mechanisms and prospects in persulfate-based degradation of PFOA and PFOS.