Effect of Ionic Strength on Foaming Behaviors of Per- and Polyfluoroalkyl Substances (PFAS) Solutions

Per- and polyfluoroalkyl substances (PFAS), a group of partially or fully fluorinated organic chemicals, have been widely used in many fields, such as non-stick cookware, aqueous film-forming foams (AFFFs), and food packaging. However, the main concern associated with using PFAS is their toxicity and accumulation in the human body. The PFAS are mainly transported through the air-water interfaces in water resources owing to surfactancy of PFAS molecules. Foam fractionation is one of the promising remediations to remove surfactants and colloids from water resources. Nevertheless, the foam fractionation at present is not viable for PFAS removal. Therefore, with the aim of making the foam fractionation viable and practical for PFAS remediation with improved removal efficiency, we conduct fundamental studies on the interfacial properties of long-chain and short-chain PFAS aqueous solutions. We use electrolytes with different ionic strengths to improve the PFAS foaming capacity and foam stability. Additionally, the correlations of PFAS air-water interfacial properties and their foaming properties are discussed.