Dynamic Column Studies of Multicomponent PFAS Sequestration Facilitated by Four Contrasting Injectable Adsorbent Suspensions and Associated PFAS Release in Simulated Groundwater

Abstract

There is limited information on the effectiveness of injectable adsorbent suspensions (IASs) for in situ sequestration of perand polyfluoroalkyl substance (PFAS)-contaminated groundwater, especially regarding potential PFAS release in the presence of coexisting anions. In this study, four IASs were injected into water-saturated sand columns. The IAS mobility and retention and the sequestration of 3 perfluoroalkyl sulfonates and 6 perfluoroalkyl carboxylic acids (PFCAs) and their release were investigated, following two designs. The IAS retention (95%) was evaluated by using organic carbon measurements and scanning electron microscopy. The anion exchange resin (A-IXR) IAS facilitated the largest (76 to 99% or 239−291 mg) PFAS sequestration, with the extent of short chain PFAS sequestration affected by competitive effects. Total PFAS released ranged from 11 to 54%, with the A-IXR columns also exhibiting the largest (44% to 52%) release of short chain PFAS (especially PFCA) in simulated groundwater, as influenced by anion exchange. Mass balance of PFAS ranged from 18 to 129%, with the longer chain PFAS showing the lowest recoveries, indicating their stronger sequestration. Overall, a complete picture regarding the effectiveness of IAS for in situ PFAS sequestration must consider the potential release of previously sequestered PFAS, given the influence of the variable groundwater chemistry.