Technologies and materials for the removal of perfluorinated surfactants (PFCs) from the environment are greatly needed. Cyclodextrins, cyclic sugars composed of glucose monomers, have shown promise as a potential remediation strategy. The association constants between α-, β-, and γ-cyclodextrin and various PFCs were elucidated via 19F NMR spectroscopy. β-Cyclodextrin (β-CD) exhibited the strongest association with all PFCs, up to 104-107 M-1 for the 1:1 association constants. Both 1:1 and 2:1 CD:PFC interactions were observed. Furthermore, various effects on association were studied, including pH, ionic strength, and presence of competitive species. Association between perfluorooctanoic acid (PFOA) and β-CD were studied at pH 2, 4, 7, and 10. Both 1:1 and 2:1 associations are strongest at pH 7. 1:1 association did not vary with pH, whereas 2:1 association relatively increased with pH, with highest values at pH 7 and 10. PFOA-β-CD association was also studied with sodium chloride concentrations of 0.01M, 0.1M, and 1.0M. Presence of salt did not affect the association constants significantly, but seemed to affect the dynamics of the system. Competition studies between PFOA and PFBA or PFOS were also performed. The findings agreed with the calculated association constants, namely that PFOA is more likely to be encapsulated by β-CD than PFBA, and that PFOA and PFOS successfully compete with each other for the β-CD cavity.

Effects of environmental factors on β-cyclodextrin-perfluorinated surfactant host-guest interactions

251st National Meeting (2016)

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