The mechanochemical process may generate transient high temperatures at the point of collision or friction. However, the possibility of PFAS pyrolysis in our system was excluded as the milling of PFAS in the absence of BN did not lead to destruction. The ball surface temperature measured immediately after different durations of BM using an infrared thermometer was 60 ± 4 °C. This value is far below the minimum criteria (> 200 °C) of thermal decomposition of PFAS, but it might be sufficient to vaporize co-solvents in AFFF. Since it is impossible to study the solvent vaporization process when AFFF was blended with co-milling reagents in a fast-moving jar, we placed AFFF samples in a water bath held at a constant 60°C to simulate heat-induced solvent loss. The heating led to volume reduction linearly correlated with heating time (Figure ). The 4 h heating resulted in a 38% volume reduction, and the sum of target PFAS concentrations in the remaining AFFF solution increased by 37% correspondingly (Figure ).