Understanding the Static and Dynamic Interfacial Behavior of PFAS at Complex Liquid Interfaces

Abstract

The widespread use of per- and polyfluoroalkyl substances (PFAS) in various anthropogenic and industrial processes has led to an urgent demand for the advancement of reliable sensing and remediation technologies for mitigating the adverse effects associated with PFAS contamination. Within water systems, a plethora of residual toxins and pollutants, including surface-active compounds, contribute to the complexity of the matrices. The complexity of these matrices has made sensing and remediation challenging and cost intensive. Therefore, acquiring a comprehensive understanding of PFAS interactions with other surface-active agents within these matrices is essential to safeguarding environmental and human well-being. This thesis explores the intricate equilibrium and dynamic behavior of PFAS at air/water and oil/water interfaces, aiming to deepen our understanding of their interfacial behavior and interactions with other surface-active compounds in aqueous systems. Chapter 1 lays the theoretical foundation by discussing the behavior of surfactant mixtures and surfactant adsorption kinetics, with a particular focus on surface-active PFAS. Chapter 2 and Appendix A elucidate the mechanisms underlying the interaction of PFAS with interfering compounds in aqueous environments, revealing three key characteristics of molecularchemistry that dictate synergistic or antagonistic behavior of PFAS mixtures. These insights provide valuable guidance for enhancing current PFAS sensing and remediation technologies through the formulation of design rules. Furthermore, Chapter 3 and Appendix B investigate the transport mechanisms of PFAS with varying chain lengths to oil/water interfaces. This study provides a predictive kinetic model for classifying different PFAS and distinguishing them from cationic interfering compounds, both individually and in binary mixtures at unknown concentrations. By leveraging both equilibrium and dynamic features extracted from PFAS adsorption data, this study points towards promising avenues for improving PFAS sensing and remediation, ultimately contributing to the protection of environmental and public health.