Interactions of PFAS with Common Surfactants and Dissolved Solids

As a result of their use in a variety of consumer products and industrial processes, the widespread contamination of per- and polyfluoroalkyl substances (PFAS) in the water supply has been linked to adverse impacts on both human health and the environment. This has necessitated the development of rapid and on-site detection and remediation efforts. In the context of environmentally relevant systems, contaminant PFAS molecules exist in tandem with a variety of other pollutants, some of which may also be surface active or involved in electrostatic interactions. In this project, we sought to characterize how the interactions between PFAS molecules and other environmental contaminants, particularly surfactant molecules and metal ions, alter the interfacial behavior of PFAS. Disentangling the interactions within these systems is necessary for the development of a sensing device which can accurately distinguish and quantify PFAS contamination. We observe that the interactions follow either synergistic or antagonistic behaviors, depending on the structural factors of the compounds involved. We identify several key factors that dictate such behaviors, including (1) headgroup charges, (2) length of the hydrophobic tail group, and (3) chemical identity of the hydrophobic tail group. Our results demonstrate how structural characteristics dictate the interaction of PFAS with other compounds and brings into focus potential challenges sensors may have in accurately differentiating between PFAS and other contaminants.