PFAS Removal from Aqueous Media by Novel Adsorbents

Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants of drinking water, and perfluorooctanoic acid (PFOA) is one of the four PFAS covered by the upcoming German PFAS-4 limit. Anion-exchange resins are among the most practical options for removing these compounds at full scale. This thesis investigated Puromet MTS9850, a commercial polyamine-functionalised resin designed for heavy-metal recovery, as an adsorbent for PFOA, comparing the resin as received with a modified version carrying a fluorinated azoimidazolium group. The resins were characterised by FTIR, SEM/EDX and laser diffraction. Pre-treatment trials were then carried out to find how the conditioning agent and handling affect PFOA uptake, followed by batch adsorption isotherms and rapid small-scale column tests (RSSCT). Results were evaluated statistically with t-tests, ANOVA with Tukey HSD and Kruskal-Wallis tests. Characterisation showed that treatment alters both the surface chemistry and the morphology of the resin. Among all pre-treatments, conditioning with HCl gave by far the highest PFOA uptake (ANOVA, p < 0.0001). Langmuir fitting gave maximum capacities of 149.5 mg/g for the modified and 157.6 mg/g for the unmodified resin; the difference between the two materials was not statistically significant. In column tests with a mixture of PFOA, GenX and PFBA, the modified resin retained PFOA and GenX with regular breakthrough behaviour, while the short-chain PFBA was displaced by the longer-chain compounds. In a single-solute column comparison the unmodified resin performed better, so batch and column tests did not rank the two materials in the same way. Overall, MTS9850 shows high capacity for PFOA, and HCl conditioning is a simple step to improve its uptake.