Per- and polyfluoroalkyl substances (PFAS) are found in a wide range of environmental matrixes including groundwater, stormwater, and landfill leachate. The persistence of PFAS compounds, due to their high chemical and biological stability, has limited current water purification options to primarily the use of adsorbents. The hypothesis that selective adsorbents could be used to remove PFAS compounds from aqueous matrixes with a diversity of other solutes was tested.  Organosilica absorbents prepared by the sol-gel method were systematically tailored to have hydrophobic, fluorophilic, and/or ion exchange (cationic) groups through the selection of sol-gel precursors and post-gelation chemical modification. Separate testing showed that adsorbents having both hydrophobic and cationic groups had improved affinity and 2-5X capacity for a PFAS compounds compared to granular activated carbon. Mixed-mode organosilica materials were evaluated to remove perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and perfluorobutanesulfonic acid (PFBS) from groundwater, water containing ppm-levels hydrocarbon co-solutes, and water containing humic acid using column breakthrough measurements. Measurements using groundwater show that PFOA, PFOS, and PFBS concentrations could be decreased from μg/L levels to less than 10 ng/L. Regeneration of adsorbents by methanol rinse was evaluated to determine if the resins could be reused. Data from commercial scale-up was used to generate a cost model for the potential use of the organosilica resins in a pump-and-treat system compared to activated carbon. The model shows economic feasibility is dependent on adsorption capacity and factors related to the processing of spent media and ultimate PFAS disposal.<br/>

Organosilica-based adsorbents for treatment PFAS impacted groundwater

2019 Fall National Meeting

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