Perfluoroalkyl substances (PFASs) are highly fluorinated alkyl chemicals where most H substituents have been replaced by F. Surfactants and polymers comprised of PFASs have been used in industrial and commercial applications such as fire fighting foams. The widespread use of PFASs and the recalcitrant nature of these compounds, due to the stability of a C-F bond, has resulted in a long-term presence in the environment. Recently, it was found that drinking water for 6 million U.S. residents exceed US EPA’s lifetime health advisory (70 ng/L) for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)<sup>1</sup>. Microporous organosilica coatings were designed with pore structures optimized to adsorb PFASs by hydrophobic interactions. The coatings were covalently attached to standard sand filtration media and porous silica media to create low cost sorbents. Use of porous coating layers allows for fast kinetics of adsorption needed for continuous flow media beds. Careful choice of the surface chemistry led to high affinity interactions. Adsorption isotherms for PFOS, PFOS, and perfluorobutanoic (PFBA) were measured in addition to breakthrough curves. The coating layer have adsorption capacities exceeding 3.0 mg/g. Adsorption is reversible with methanol rinse. In addition, the presentation will explain how similar approaches to coating design can be used to selectively remove other challenging water contaminants such as microcystins.

Removal of perfluoroalkyl substances from water using molecularly engineered coatings on sand and silica

253rd National Meeting (2017)

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