(38i) Equilibrium and Dynamic Surface Tension of per- and Polyfluoroalkyl Substances at Air-Water Interface

Per- and polyfluoroalkyl substances known as PFAS containing a hydrophobic fluorinated tail and a hydrophilic head group have unique properties such as high thermal and chemical stability and lowering the surface tension. Therefore, they are used in widespread applications in different processes and products such as firefighting foams, coatings, paints, electroplating, waxes, and photographic emulsifiers. However, PFAS are toxic, bio-accumulative, and persistent in the environment. Therefore, the wide distribution of PFAS in the environment, particularly in soil and water resources, has become a matter of concern during recent years. In the present study, the kinetics and equilibrium of PFAS adsorption at air-water interface is investigated by measuring the dynamic surface tension. Study of these properties is of great importance as the air-water interface is a retention source of these toxic components for transport to the environment. In this work, we present the effect of fluorinated chain length, surfactant concentration, and presence of salt on the surface tension of fluorinated surfactants and their diffusion to the interface.