Novel degradation mechanism for rapid photochemical PFAS defluorination

Per- and polyfluoroalkyl substances (PFAS) represent a broad class of chemicals critical to industrial processes and consumer products due to their unique chemical and physical properties. However, their recalcitrance and detrimental effects to organisms pose a serious threat to human health and the environment necessitating their removal and destruction. In this study, we reveal a novel PFAS degradation mechanism within the aqueous UV/sulfite photochemical system. Under mild reaction conditions (pH<10, 20 °C), the mechanism enabled rapid (<1 h) and deep defluorination (>80%). The minor transformation products with residual C–F bonds are susceptible to further defluorination (>95% in total) by oxidation. The findings will contribute to the comprehensive elucidation of C–F bond cleavage mechanisms, filling major knowledge gaps in both environmental science and fluorine chemistry.