Removal characteristics for nine species of per-and poly-fluoroalkyl substances using different types of anion exchange

Objectives : This study aims to compare the removal characteristics of nine PFAS species using two commercial anion exchanges(AIXs) with different matrices and their Cu-modified derivatives.Methods : IRA900-Cu and A860-Cu were synthesized from two commercial AIXs(IRA900 and A860) using a 1% CuCl2·2H2O solution. SEM-EDS analysis and Cu2+ extraction experiments were conducted to evaluate surface characteristics under different matrices and their modification. Batch removal tests, pH effect tests ranging from 4 to 8.5, and isotherm tests(Langmuir and Freundlich) were performed.Results and Discussion : According to SEM-EDS analysis, the (O+N)/C ratio for A860(polyacrylic) was found to be 2.57 times higher than that of IRA900(polystyrene), indicating A860 is more hydrophilic than IRA900. In addition, no significant changes in surface properties, including Cu and Cl elements, were observed after modification. The total uptake of the nine PFAS species by IRA900 was 2.21 times higher than that of A860, due to the greater hydrophobicity of IRA900. The effect of Cu modification on both AIXs was not significant due to the low amount of Cu on the surface, except for the short-chain species(PFBA and PFPeA) in IRA900. While the total uptake was not influenced by pH in IRA900 and IRA900-Cu, it decreased rapidly in A860 at pH 7.0 and 8.5, likely due to its relatively low basicity and hydrophilic matrix. Based on Langmuir and Freundlich isotherm models, the total uptake and KF for IRA900 were 2.97 and 16.7 times higher than those of A860, respectively. Comparing the uptake for each species, higher capacity was generally observed for sulfonic functional groups(PFSA) than for carboxylic functional groups (PFCA) at the same chain length, and the capacity increased with increasing chain length.Conclusion : Higher hydrophobicity of IRA900 plays a key role in PFAS adsorption, regardless of the species, and is less sensitive to basic solution conditions.