LAUSR

Short chain perfluoroalkyl substances (PFAS), replacements for long chain legacy PFAS such as perfluorooctanoic acid (PFOA), have similar toxicity, negative health effects, and exceptional persistence as long chain PFAS. β-Cyclodextrin (β-CD) is a powerful host–guest complexing agent for a number of legacy PFAS, suggesting potential β-CD-based remediation processes. We report herein that the addition of charged functional groups at the perimeter of β-CD has a pronounced influence on the strength of the β-CD:PFAS complex. The presence of a positively charged amine functionality on the perimeter of β-CD significantly increases the complexation of legacy and short chain PFAS. We assigned the enhanced complexation to electrostatic attraction between the negatively charged PFAS head group and the positively charged β-CD derivative. In comparison to neutral β-CD, addition of a negative charge to β-CD decreases complexation to PFAS due to electrostatic repulsion between the negatively charged polar head group of PFAS and the negatively charged β-CD. 19F NMR titration experiments illustrate the complexation of short chain PFAS by positive charged β-CDs over neutral β-CD, with increases up to 20 times depending on the PFAS guest. The results give further understanding to the nature of the β-CD:PFAS host–guest complex and the various intermolecular forces that drive complexation. Positively charged β-CDs appear to be potential complexing agents for remediation of short chain PFAS.