Alcohol regeneration of anion exchange resin loaded with per- and polyfluoroalkyl substances and organic contaminants

Abstract

Hydrophobic ionizable organic compounds (HIOCs) like per- and polyfluoroalkyl substances (PFAS), pharmaceuticals, and surfactants have been detected in water supplies. Anion exchange is an effective process for the removal of HIOCs from water. Regeneration solution comprising methanol (ca. 75% v/v) and brine is used to effectively desorb HIOCs from resins to overcome the combination of electrostatic and non-electrostatic interactions. This research investigated different mono- and polyhydroxy alcohol cosolvents with brine to regenerate resins saturated with HIOCs to understand the effects of cosolvent properties on regeneration. For PFAS desorption using 25% v/v alcohol in 5% NaCl solution, regeneration efficiency increased in the order methanol < ethanol < 1-propanol. Experiments with the pharmaceutical diclofenac and surfactant dodecylbenzene sulfonate showed similar regeneration efficiency using 75% v/v methanol in 5% NaCl solution and 25% v/v 1-propanol in 5% NaCl solution and higher regeneration efficiency using 1-propanol than ethanol or methanol at the same volume fraction.