Novel Modified Natural Clinoptilolite for Perfluorooctane Sulfonate (PFOS) Removal from Aqueous Solutions

Perfluorooctane Sulfonate (PFOS) is widely used in various commercial applications, including food packaging, fabrics, and fire-fighting foams. This toxic and carcinogenic compound could be present in water and food products, which could be fatal to living beings. Zeolite-based materials are promising PFOS sorbents due to their high anion exchange capacity and specific surface area. In this study, a natural Clinoptilolite-type zeolite was modified with Hexadecyl Trimetilammonium Bromide (HDTMA) for PFOS remediation in aqueous solutions. The modification introduced an inversion of Clinoptilolite's natural surface net charge, i.e., from negative to positive, making it effective in capturing PFOS. At pH 7, the modified material (Clinop_HDTMA) showed ~ 96–98% removal of PFOS at a low concentration range of 0.5–1 mg L⁻¹. The adsorption isotherm and kinetic data followed the Freundlich and pseudo second-order model, respectively, which suggested the involvement of physicochemical forces in the adsorption process. Thus, this study demonstrates a viable and cost-effective solution to remove PFOS ions from wastewater.