Piezoelectric Ball Milling Treatment of PFAS-Laden Spent Resins

Anion exchange resins (AERs) have been widely used for the removal of perfluoroalkyl and polyfluoroalkyl substances (PFAS) from water. However, regardless of whether AERs are regenerable or single use, the disposal of end-of-life AERs presents significant challenges. Conventional waste management strategies, such as landfill disposal and incineration, are increasingly under scrutiny and may face impending bans due to environmental concerns. This study introduces a nonthermal, solvent-free process for the effective destruction of PFAS on AERs by co-milling piezoelectric boron nitride (BN) powders with contaminated AERs and stainless steel (SS) balls. The approach achieved complete PFOS destruction in two types of AERs (PFA694E and AmberLite IRA 67), with near-quantitative (∼100%) defluorination observed in the treatment of PFA694E AER. Comprehensive targeted PFAS analysis and suspect screening analysis of transformation products (TPs) elucidated the reaction mechanisms and confirmed that the functional groups of AERs did not participate in the reaction. The process's effectiveness was further validated in treating field-collected single-use AERs (PFA694 and AmberLite PSR2 Plus) contaminated with PFAS mixtures of varying chain lengths and head groups. After treatment, PFAS levels on the AERs were reduced to below the nanogram per gram detection limits, and no PFAS release was observed in standard leaching tests.