This study aimed to probe the interactions of hydrated electrons (eaq-) and perfluorooctanoic acid (PFOA)-laden ion-exchange (IX) resins in the presence of natural organic matter (NOM). PFOA and Suwannee River NOM-loaded resins were prepared through the removal of PFOA in simulated natural water with weak-base anion (WBA) resins (IRA67). Adsorption tests reveal that sorbed NOM was much more abundant than cosorbed PFOA, highlighting the role of NOM in resin saturation. Ensuing UV/SO32- treatment of PFOA/NOM-laden resins (pH 10.0) under a dissolved oxygen-free condition indicates that eaq- generated could effectively degrade sorbed and aqueous PFOA, the latter of which derived from desorption of PFOA due to pH increase. Finally, cyclic adsorption-UV/SO32- treatment tests demonstrate that the PFOA sorbed on the WBA resins could be mostly degraded over six cycles. However, eaq- could not effectively decompose cosorbed NOM, resulting in a gradual decrease in the recovered PFOA adsorption capability with the cycle number. This study spotlights that eaq- can decompose PFOA sorbed on the WBA resins in the presence of NOM. The UV/SO32- process, when jointly used with appropriate strategies for mitigating cosorbed NOM, can enable a promising on-site resin regeneration process with PFOA degradation while producing a relatively small volume of regenerant waste.
- hydrated electrons
- ion-exchange resins
- natural organic matter (NOM)
- per- and polyfluoroalkyl substances (PFAS)