Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants whose transport, retention, and removal are governed by complex interactions with natural and engineered surfaces. Despite extensive research, key uncertainties remain regarding how PFAS molecular structure, sorbent chemistry, and environmental conditions jointly control adsorption behavior. This thesis addresses these challenges by systematically investigating PFAS interactions across a range of systems, from soil components to engineered sorbents and dynamic treatment processes. A stepwise experimental approach was applied, beginning with fundamental interactions with soil organic matter and iron (hydr)oxide, followed by competitive adsorption on granular activated carbon and ion exchange resin, and culminating in evaluation of PFAS removal under flow conditions.

The results demonstrate that PFAS sorption in soils is governed primarily by the chemical composition of soil organic matter rather than its total content. In addition, PFAS were shown to influence soil processes by mobilizing dissolved organic matter (DOM), particularly under conditions of weaker sorption. Adsorption onto ferrihydrite was strongly pH-dependent and exhibited non-linear behavior, indicating the formation of multilayer structures at higher concentrations. In engineered systems, adsorption behavior was controlled by both PFAS molecular structure and solution chemistry. Ion exchange resins showed high removal efficiency, particularly for short-chain PFAS, but were sensitive to competition from co-existing ions like phosphate, while granular activated carbon exhibited more variable performance depending on PFAS structure and DOM composition. Dynamic PFAS removal experiments further revealed that system design plays a critical role, with differences in kinetics and breakthrough behavior observed between rotating bed reactors and column systems.

Together, these findings provide a coherent framework linking molecular-scale interactions to system-scale performance. The work highlights that PFAS behavior cannot be understood or predicted based on single factors alone, but rather emerges from the interplay between sorbent properties, PFAS chemistry, and environmental conditions. This has important implications for both environmental risk assessment and the design of remediation strategies, emphasizing the need for mechanistic understanding and matrix-specific evaluation when addressing PFAS contamination.