Porous organosilicas with specific surface chemistries were developed as adsorbents for perfluoroalkyl surfactants (PFASs). Swellable organically modified silica (SOMS) materials were created that incorporated cationic and fluoroalkyl groups with the hypothesis that intermolecular interactions specific to PFASs would improve adsorption affinity and capacity. SOMS materials were chosen due to: i) the ability to swell creating a continuous mesoporous structure, ii) a surface chemistry that could be tailored through synthesis or incorporation of polymer coatings to the pores, and iii) chemical stability to allow for regeneration.  Adsorption kinetics, adsorption isotherms, and column breakthrough experiments were used to measure performance for a range of PFASs with variable chain length and chemical identity (PFDA, PFNA, PFOA, PFHpA, PFHxA, PFPeA, PFBA, PFOSA, PFHxS, PFOSA, and PFOSaAm). Unmodified hydrophobic SOMS was found to remove PFASs with fluoroalkyl chains &gt;C6 from DI water, which was enhanced at higher ionic strength (50 mM). Addition of fluoroalkyl groups improved adsorption affinity at lower ionic strength. Addition of cationic groups yielded adsorbents that could remove all PFASs from water including short chain PFASs (ex. PFBA).  Adsorption was compared to GAC where SOMS materials were found to have faster adsorption kinetics than GAC. Under conditions of 50 mM ionic strength the equilibrium time for SOMS was &lt;0.2 hr whereas the equilibrium time for GAC exceeded 18 hr. Column breakthrough measurements showed fluoroalkyl modified SOMS had a capacity 17.2 mg/g for PFOS given an influent concentration of 200 ug/L. Adsorption mechanisms will be discussed. Organosilica materials show promise for allowing rational design of adsorbents used for remediation of PFAS impacted water.<br/>

Removal of short-chain to long-chain perfluoroalkyl substances from water using organosilica adsorbents

2019 Spring National Meeting

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