Recycling of PFAS using magnesium through mechanochemical process

Per- and polyfluoroalkyl substances (PFAS) are widely used a class of organofluorine compounds whose high chemical and thermal stability has motivated the development of strategies for their chemical conversion and fluorine recovery from the perspective of effective fluorine resource utilization. Herein, we report a mechanochemical strategy for the recovery and utilization of fluorine using alkaline-earth metals. Mechanochemical treatment of polytetrafluoroethylene (PTFE) with Mg rapidly converted the fluoropolymer into MgF2, and the method was extended to various PFAS. We further established a method for converting poorly soluble MgF2 into water-soluble NaF by ball milling with NaOH. The poorly water soluble Mg(OH)2 formed during this conversion, which enabled the selective recovery of NaF without additional metal oxide additives. These two transformations were subsequently integrated into a single-step process, enabling the direct conversion of fluoropolymers and perfluoroalkanes into water-soluble and reaildy usable NaF under mechanochemical conditions. The recovered NaF was directly utilized as a fluoride source for one-pot fluorination reactions of sulfonyl chlorides and acyl chlorides, affording the corresponding fluorinated products. This protocol was also scaled up, highlighting important considerations for reaction scale and operational safety. This study provides a useful approach to recovering PFASderived fluorine as a reusable fluoride source and demonstrates its potential for the circular utilization of fluorine resources.