Nucleophilic defluorination of PFAS under mild conditions

Per- and polyfluoroalkyl substances (PFAS) are globally significant water contaminants because of their persistence and associated environmental and health risks. Because PFAS stability and toxicity are closely linked to their fluorinated structures, complete defluorination represents a critical strategy for detoxification. Yet near-complete defluorination of structurally diverse PFAS, particularly short-chain compounds, under mild conditions remains challenging. Here, we report a nucleophile-driven approach for effective PFAS defluorination in DMSO at relatively mild temperatures around 100 °C, yielding free fluoride ions. Five nucleophiles, methanethiolate, ethanethiolate, methoxide, ethoxide, and amide, were evaluated. Under optimized conditions, complete defluorination, as verified by nearly quantitative fluoride recovery, was achieved for a broad range of perfluoroalkyl carboxylic acids and fluoropolymers, including short- and ultrashort-chain compounds such as PFPrA and TFA, which are typically resistant to other defluorination methods. Partial degradation of PFOS was also achieved under the same conditions. This approach provides an effective route to PFAS defluorination under comparatively mild reaction conditions.