AFFF was treated as received without dilution. Milling 0.5 g BN with 100 μL of AFFF (TOF=47.8 μmol) led to the destruction of FTS, accompanied by the generation and decay of PFCAs (Figures and). A series of n=6-7 PFAS surfactant precursors were detected by Q-ToF-HRMS following the literature (Figure ). The destruction of 6:2 FTS, 8:2 FTS, and precursors via the cleavage of -CF2-CH2-or -CF2-SO2-followed by the hydrolysis of the terminal -CF2• to -COOH may explain the formation of PFHxA and PFOA as intermediates.