Measuring Surface Tension of PFAS in Water and Aqueous Lioh.

Poly- and perfluoroalkyl substances (PFAS) are synthetic compounds that have been widely applied in consumer and industrial products due to their exceptional resistance to heat, oil, and water, as well as their non-stick and stain-repellent properties. They have been used in applications such as firefighting foams, food packaging, industrial surfactants, floor treatments, and textile factories. However, the same C–F bonds that give PFAS their durability also make them highly resistant to natural degradation. This chemical stability, while advantageous for product performance, results in their persistence in the environment, where they accumulate in soil and water systems, bioaccumulate in living organisms, and pose risks to human and ecological health. Because of these challenges, a variety of destruction methods have been studied, including electrochemical oxidation, thermal incineration, sonolysis, and non-thermal plasma. While effective under certain conditions, these approaches are often limited by high energy demands, substantial operating costs, and significant greenhouse gas emissions, which hinder their scalability and sustainability. In contrast, our research group has developed an ultraviolet light-assisted electrocatalytic defluorination process that utilizes non-precious materials, operates at ambient temperature and pressure, and offers a significantly more cost-effective solution. This method achieves complete degradation of PFOS, PFOA, GenX, and aqueous film-forming foams (AFFF), demonstrating a practical pathway toward large-scale PFAS remediation. In this research, we focus on understanding how adsorption phenomena at the electrode surface influence the efficiency of defluorination. To probe these effects, we employed pendant drop tensiometry to measure the surface tension of various PFAS at different concentrations in both water and aqueous LiOH, the latter being the electrolyte in our system. From these measurements, we determined critical micelle concentrations (CMC), which provide insight into PFAS aggregation behavior under reaction conditions. Establishing the relationship between CMC and defluorination efficiency is critical for optimizing catalytic performance. The results presented here, along with future investigations, will guide the rational design of more effective PFAS destruction processes that address both environmental and practical challenges.