UC Irvine

Microplastics interact with per- and polyfluoroalkyl substances (PFAS), potentially acting as vectors for these contaminants. However, little is known about how residential sources, physicochemical properties, and water chemistry influence these interactions and the subsequent fate of microplastics and PFAS. Elucidating the role of residential PFAS inputs, sorption mechanisms, and microplastics aging is critical to understand microplastic-mediated PFAS proliferation. This work aimed to address these knowledge gaps by investigating PFAS in wastewater sources, sorption to microplastics, and effect of aging (sodium sulfide treatment and natural organic matter loading) on adsorption of PFAS onto microplastics. Raw wastewater sampling at three sites revealed complex PFAS profiles, with 9 compounds detected - 5 carboxylates, 2 sulfonates, and 2 precursors. Long-chain PFAS including perfluorododecanoic acid and perfluoropentanesulfonic acid dominated, contrasting with the lower levels of legacy PFAS like PFOS. Fluorotelomer precursors, especially 6:2 FTS, were frequently detected and abundant. PFAS showed distinct variation from heavy metals, although PFOA uniquely correlated with iron. Controlled experiments found PFAS rapidly sorb to microplastics within hours, following thermodynamically favorable and spontaneous partitioning. Perfluoroalkyl sulfonic acids preferentially adsorbed over carboxylates, attributed to hydrophobicity. Water chemistry parameters like pH, salinity, and natural organic matter impacted sorption. Na2S treatment enhanced adsorption capacity by 28-95%, while NOM loading increased it by 16-42%, highlighting the impact of aging on PFAS uptake. This work advances understanding of residential PFAS inputs, microplastic interactions, and effects of MPs aging and aqueous matrices on PFAS adsorption. The results can inform source control and treatment strategies targeting these ubiquitous contaminants.