(297a) Fate and Transport of Perfluorooctanesulphonic Acid (PFOS) and Microplastics in Water: Insights for Their Removal By Adsorption

Microplastics are becoming a concern for the environment and are gaining significant attention due to their challenging removal process and ability to transport coexisting pollutants. Because of their mobility, small size, and accumulation tendency, microplastics are toxic for terrestrial and aquatic living organisms and humans, causing inflammation and oxidative stress. In addition, the presence of per- and polyfluoroalkyl substances (PFAS) in water causes health effects on humans and animals over time. In this work, we investigated the interaction between these two emerging water contaminates at different conditions (pH, temperature, ionic strength, etc). The interaction of perfluorooctanesulphonic (PFOS) acid and micron size polyethylene (PE) (20 microns) and polypropylene (PP) (17 microns) were investigated via experiment and modeling. The isothermal adsorption of PFOS on the microplastics was measured at different conditions (time, pH, concentration). The results showed that PFOS adsorption on PE and PP was 9% and 13.95% after 24 hours, respectively, and 43.11 ± 0.18% and 35.90 ± 20.94% after one week of contact time. However the extension of contact time from a week to two weeks resulted in lower adsorption (36.17% for PE and 22.62% for PP) which implied desorption of PFOS from these microplastics. In addition, molecular dynamics simulations were employed to model the adsorption mechanism of four different perfluorooctyl PFAS molecules on PE, PP, and PVC microplastic particles by inspecting the potential-of-mean-force of pulling the PFAS molecules from the aqueous bulk phase to the plastic-water interfacial region. The molecular simulation results suggest a pronounced dispersive interaction between the polymer and PFAS molecules for PE and PP; while the dispersive interaction dominates the PVC systems, as compared to PE and PP, a much stronger coulombic PFAS-PVC interaction is found.