Electrochemical degradation of PFAS treated with synergetic oxidation system reveals structure- and dose-dependence

Given the threat posed by various legacy and novel per- and polyfluoroalkyl substances (PFAS) to the global environment and human health, it remains a priority to acquire information on associations with their structural merits for potential removal and understand their behavior in treatment processes. Herein, we investigated the effectiveness against 9 representative PFAS in a synergetic electrochemical system combining boron-doped diamond (BDD) anodic oxidation and Fe 3 O 4 -rGA cathodic Fenton-like reaction. Under optimized conditions (20 mA cm −2 , 10 mM Na 2 SO 4 , pH 6.0), this system was applicable for remediating various PFAS in water, with high destruction and removal efficiencies (>98%) and defluorination ratios (>50%), except for perfluorobutane sulfonic acid (PFBS). The results reveal that the rate and extent of degradation and defluorination have strong relationships with (i) PFAS initial concentration, (ii) fluoroalkyl chain length, and (iii) head functional groups. The coupled technology was valid over a broad initial concentration range (1–40 mg L −1 ), although the decay rate constant and defluorination decreased with increasing PFAS concentrations. Moreover, longer alkyl chain accelerated degradation and mineralization of PFAS. PFAS with different head groups exhibited varying degradation and defluorination rates and efficiencies. Degradation products were examined here to reveal the decomposition pathways of all PFAS. In conclusion, the efficient PFAS destruction and removal and the elucidated structure–reactivity relationships from this cooperative approach may provide valuable insights for developing effective strategies for combating PFAS contamination.