Removal of PFAS from Water Using Zeolites

Per- and Polyfluoroalkyl Substances (PFAS) are man-made chemicals, found in almost all water sources around the world: including drinking water, and are detrimental to our health. Accurate PFAS analysis is challenging due to contamination from their prevalence in most products. The latest EPA regulations (April 10, 2024) require all public water facilities to remove PFAS to a specified level by 2029. PFOA and PFOS need to be below 4.0 ppt, while PFHxS, PFNA, and GenX need to be below 10 ppt, and PFHxS, PFNA, HFPO-DA, and PFBS mixtures need to have a hazard index below 1. Their removal from water using an effective and sustainable method is currently unavailable. Project DISCOVER focuses on PFAS removal using zeolites. Zeolites are alumina-silica structures that have molecular selectivity through diffusion. Compared to other methods such as granular activated carbon, ion-exchange resins, and membranes, zeolites are easily reusable. In this study, zeolite beta CP814E* was tested to see its effectiveness at PFAS removal, as well as CP814E* modified for ion-exchange of the hydrogen with sodium and potassium. All materials were HDPE or PP to ensure no PFAS contamination and the reusable materials were washed with methanolic ammonium hydroxide. Zeolites were placed in water, spiked with varying concentrations of PFAS; K-PFOS, PFOA, 6:2 FTS, PFHxS, PFHxA, PFBS, and PFBA. The samples were vortexed, shaken for at least 24 hours, and centrifuged followed by a 50% dilution with methanol. After centrifugation, a final sample was spiked with internal standards. PFAS identification/quantification used LC/MS-QQQ. This was repeated for kinetic data collection, using syringe and syringe filters to sample in under 30 seconds. The study showed that zeolite BEA can adsorb K-PFOS and PFOA, with more than 90% removal. However, PFBA is most challenging to adsorb, with less than 5% removal. The kinetic data shows the adsorption process goes to its equilibrium concentration in under 30 seconds for K-PFOS and PFOA. The porous material identified could be scaled up for large scale pump/column separation.