In Situ Remediation Method for Enhanced Sorption of Perfluoro-Alkyl Substances onto Ottawa Sand

Perfluoro-alkyl substances (PFAS) have drawn increased concern in recent years. Due to resistance to many remediation methods and potential for long-range transport, there is need for continued in situ remediation technique development. One such method is enhanced sorption onto aquifer material, thereby sequestering a plume and preventing long-range migration. Batch tests and column studies were carried out to evaluate the ability of polydiallyldimethylammonium chloride (PDM) and polyamine (PA) to enhance the adsorption of six PFAS onto Ottawa sand. At a dosage of 2,000 mg/L of either PDM or PA, results show increases of adsorption of the tested PFAS in all batches by factors of 3.6-45. Column studies showed retention capacity increasing up to six times for perfluorooctanoic acid (PFOA) and 10 times for perfluorooctane sulfonic acid (PFOS). Normalizing partitioning coefficients from batch tests to fraction of organic carbon suggest that an interaction other than PFAS associating with organic matter may be the main driving force behind sorption enhancement. These results suggest that this method shows promise for in situ remediation of PFAS-contaminated groundwater.