Cationic electrospun nanofibrous membrane for PFAS sequestration from stormwater: Mechanistic insights from XDLVO Interaction energy analysis

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Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants widely detected in stormwater, yet cost-effective sorbents performing across structurally diverse PFAS remain limited. We report a cationic polyacrylonitrile–cetyltrimethylammonium chloride (PAN–CTAC) electrospun nanofibrous membrane fabricated by a single electrospinning–spraying step. In batch experiments, the PAN–CTAC membrane pieces achieved >95% removal of all ten tested PFAS, including short-chain, long-chain, and emerging alternatives, each at an initial concentration of 10 µg L −1 . Kinetics followed pseudo-second-order behavior (R 2 > 0.98). Among the four mixture-level isotherm models evaluated, the Sips model yielded the highest R 2 (0.969) and the lowest RMSE (122.2 µg g −1 ), corresponding to an apparent total adsorption capacity of 2068.5 µg g −1 for the fixed ten-PFAS mixture. Removal exceeded 95% across pH 3–11 under elevated ionic strength and natural organic matter and reached ∼85–100% in authentic stormwater at 1–10 µg L −1 . FT-IR, XPS, and XRD confirmed permanent quaternary ammonium groups within a porous fiber architecture. XDLVO analysis showed that the positively charged PAN–CTAC surface maintains attractive electrostatic double-layer interactions toward anionic PFAS, whereas pristine PAN imposes a repulsive barrier. Capture occurs through electrostatic ion-pairing and hydrophobic stabilization. After three regeneration cycles, most PFAS retained removal efficiencies of at least approximately 80%, whereas PFOS removal decreased to approximately 70%.