Epsilon Archive for Student Projects

Abstract

Per- and polyfluoroalkyl substances (PFAS) are highly persistent contaminants frequently found in the environment, including groundwater. This study investigates the sorption behavior of PFAS in colloidal activated carbon (CAC)-amended soil using batch tests with both natural and artificial groundwater. The aim was to evaluate how effectively PFAS are retained by a CAC-treated permeable reactive barrier under varying conditions, including different liquid-to-solid (L/S) ratios and water chemistries, and to assess the potential long-term performance of such barriers in in-situ remediation.
The results show that long-chain PFAS, especially PFOS and PFHpS, exhibited the strongest sorption, while short-chain compounds like PFBA showed significantly lower retention. Sorption data for natural groundwater series fit best to the Langmuir model, suggesting a finite number of sorption sites and risk of barrier saturation. The Total Oxidizable Precursor (TOP) assay also revealed precursor compounds forming PFAAs with variable sorption behavior.
Overall, the findings support CAC as a promising material for retaining long-chain PFAS in subsurface barriers, but also highlight challenges regarding short-chain mobility, precursor transformation, and long-term effectiveness.