Interactions of Aqueous Microdroplets and Mineral Particles Drive Fluorine-First Perfluoroalkyl Mineralization

Anthropogenic perfluoroalkyl and polyfluoroalkyl substances (PFAS) are pervasive contaminants subject to increasingly stringent regulatory thresholds in water resources. Current nonthermal defluorination strategies face critical limitations, including incomplete mineralization, yielding persistent short-chain PFAS byproducts, and residual fluoride ions, thereby hindering compliance with water quality standards. Herein, we demonstrate that wollastonite-bearing microdroplets prioritize defluorination over C-C scission in perfluoroalkyl chains through liquid-solid-gas triple-phase contact electrification. This process results in complete perfluorooctanoic acid mineralization with hardly detectable shorter-chain anionic PFAS byproducts, as confirmed by Fourier transform ion cyclotron resonance mass spectrometry. Microdroplet-mediated weathering of wollastonite triggers the formation of CaF₂-SiO₂ interfacial structures through Si-F-Ca bonding interactions, thereby enabling fluoride immobilization with negligible leaching. This work reveals that atmospheric clouds containing mineral particles intrinsically exhibit a self-cleansing capacity toward PFAS contaminants, advancing cloud-inspired interfacial engineering for next-generation water purification systems.