Fast Adsorption of Short and Long-Chain Per- and Polyfluoroalkyl Substances from Water by Chemically Modified Sawdust

To remove per- and polyfluoroalkyl substances (PFAS) from water, this study focused on synthesizing a sawdust-based adsorbent through KMnO₄ oxidation and coating m-phenylenediamine (mPD) onto the sawdust's surface. The resulting sawdust/MnO₂/PmPD was able to remove >90% of nine target PFAS and >80% of GenX spiked at 10 ppb in deionized water. When added to river water samples, the capture of long-chain PFAS remained basically the same. This was in line with the observations that environmental factors, such as a change of pH between 4.0 and 11.0, the presence of natural organic matter in the range of 0 and 100 mg L^-1, and the presence of bicarbonate, nitrate, and chloride, each at 1 mM, did not affect the removal of long-chain PFAS significantly. The low-cost nature of this sorbent was further strengthened by its regenerability and reusability for at least five cycles. To improve the sorption performance, especially for short-chain PFAS, further modification of the sawdust/MnO₂/PmPD will need to be performed based on the revealed mechanisms underlying PFAS capture. Overall, at this stage, the sawdust/MnO₂/PmPD material is ready to be used for removing PFAS from surface water.