Achieving bulk defluorination (i.e., all TOF broken down to F -) of AFFF is more challenging than destroying target PFAS due to the complexity of the AFFF solution. Surprisingly, after 6 h of BM treatment, >99% defluorination of AFFF was achieved (Figure ; see Table for fluorine balance data). This is the very first proof-of-concept demonstrating the near complete defluorination of AFFF via a novel piezoelectric BM route.