Hydrated Electron Degradation of PFOA Laden on Ion-Exchange Resins in the Presence of Natural Organic Matter

Abstract

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.