THE INFLUENCE OF SPECIFIC ION EFFECTS ON THE DIFFUSIVITY OF LONG-CHAIN PER- AND POLYFLUOROALKYL SUBSTANCES (PFAS)

Abstract

Decades of use of per- and polyfluoroalkyl substances (PFAS) have resulted in contamination spanning the globe. Accumulation of PFAS within the environment and biota has raised concerns over their toxicity. A number of studies revealing health effects related to elevated PFAS exposure have been performed. Despite current efforts to enact more phase outs for PFAS in non-essential cases, their chemical stability will prevent the cycle of uptake and reemission into the environment for decades to come. Foam fractionation is a technique that can be used to remove PFAS from water. Some work has been done in identifying and systematically studying important physicochemical properties of PFAS, but diffusivity has not been as well represented in the prior studies. Additionally, the widespread nature of PFAS contamination necessitates further research regarding the physicochemical interactions within diverse aquatic environments, including diffusivity. The goal herein is to not only study the effect of not only charge, but also ion identity on diffusivity. Several other physicochemical characteristics are investigated, such as surface tension, solubility limits, and speciation. Modeling approaches that are novel in their application to PFAS are used in the study of speciation and aggregation. The key findings of the study were indicative that Hofmeister-like series emerge when close contact is made between anionic PFAS and cations. Different species-specific phenomena are present in the case of diffusivity, which highlights an area where trends that do not explicitly follow Hofmeister ordering necessitate other explanations.