Removal of PFAS from groundwater using weak-base anion exchange resins

This research provides new insights on the application of weak-base (WB) anion exchange resins (AERs) for groundwater treatment of six perfluoroalkyl acids (PFAAs) with different properties. Continuous-flow column adsorption and regeneration experiments involving WB, polyacrylic, and WB, polystyrene resins were conducted considering salt-only regeneration solutions and two representative strong-base (SB)-AERs of analogous polymer composition and a third solution of methanol/salt used as baseline for comparison. The WB, polyacrylic resin was regenerated using salt-only solutions of NaOH due to deprotonation of the tertiary amine functional group at alkaline pH. However, organic cosolvent was required to weaken the hydrophobic interactions between PFAAs and the nonpolar WB, polystyrene resin. Removal was predominantly influenced by polymer composition with free-base WB-AERs exhibiting similar selectivity and higher capacity as SB resin counterparts. This work highlights WB-AER selection based on PFAA-selective removal and more sustainable regeneration strategies.