PFAS Surrogates for Monitoring Adsorption Column Saturation in GACs and Ion‐Exchange Resins

This study identified per‐ and polyfluoroalkyl substances (PFAS) surrogates to benchmark granular activated carbons (GACs) and ion‐exchange resins (IXRs) for drinking water treatment. Three GACs and two IXRs were evaluated using isotherm, kinetic, and rapid small‐scale column tests with 16 PFAS (C3–C8) across five classes. IXRs outperformed GACs in adsorption affinity (Freundlich constant, K F = 50.0 vs. 11.8), maximum adsorption capacity (qmax = 116.3 vs. 30.0 μg/g), and kinetics (pseudo‐first‐order kinetic constant, k1 = 0.0019 vs. 0.0008 min −1 ) due to combined hydrophobic and electrostatic interactions. IXRs exhibited substantially greater PFAS adsorption, with saturation occurring beyond ~130,000 BVs, compared with < 40,000 BVs for GACs. PFBA exhibited the earliest breakthrough; PFOA also broke through early among regulated PFAS. Average BV50 followed FASAs>FTSAs>PFSAs>>PFECAs>PFCAs for GACs and PFSAs>FASAs>PFECAs≈FTSAs>PFCAs for IXRs. Elevated DOC reduced GAC BV50 by 17% but had < 8% impact on IXRs. Inorganic anions reduced IXR BV50 by up to 52%.