Per- and Polyfluoroalkyl Substances (PFAS) Foams: Effect of Interfacial Properties

Per- and polyfluoroalkyl substances (PFAS) are a group of partially or fully fluorinated organic compounds. They have been widely used in many applications, such as non-stick cookware, aqueous film-forming foams (AFFFs), coating materials, and surfactants, due to their excellent thermal and chemical stability. However, PFAS are toxic and accumulative in organisms and the environment. Water resources have been contaminated by PFAS owing to their surfactancy and tendency of being transported through the air-water interfaces. While foam fractionation is one of the promising remediations to remove surfactants and colloids from water resources, it is currently not viable for PFAS removal. Therefore, fundamental studies on the correlations between the properties of PFAS aqueous foams and their interfacial properties, such as dilatational rheological properties, are required and necessary for improving the effectiveness of the foam fractionation process. In the present work, the foaming capacity of long-chain and short-chain PFAS in the presence of electrolytes is studied. In addition, the PFAS foam properties in terms of liquid drainage and bubble coarsening are analyzed. Then, the air-water interfacial properties of PFAS are studied by performing dilatational rheology and measuring dynamic surface tension to further evaluate their effects on the PFAS aqueous foam properties.