Efficient removal of GenX (HFPO-DA) and other perfluorinated ether acids from drinking and recycled waters using anion exchange resins

Abstract

Carcinogenic GenX chemicals, heptafluoropropylene-oxide-dimer-acid (HFPO-DA), have been recently detected in surface, ground and recycled water sources worldwide. However, GenX removals under the influence of variable characteristics of the organic and inorganic compounds present in the natural water sources, have often been overlooked in scientific literature. This is critically important given that the ionic composition and characteristics of organic matter in natural waters are spatially and seasonally variable. A strongly basic anion exchange (IX) resin was used to remove GenX and two other perfluorinated ether acids (PFEAS) from natural surface and recycled water sources. Factors influencing the uptake behavior included the PFEAS concentrations, resin dosage, and background anion characteristics. The equivalent background compound was employed to evaluate the competitive uptake between natural organic matter (NOM), inorganic ions and PFEAS in natural water matrices. Experimental data were compared with different mathematical and physical models and it was depicted that approximately 4–6% of the initial NOM competed with PFEAS for active exchange sites. Further, IX was able to achieve complete PFEAS removal (Cfinal<10 ng/L) with simultaneous removal of>60% NOM and >80% inorganic ions. Results of this study indicate that IX exhibits great potential for PFEAS removal from natural drinking water sources.