Cyclodextrin Polymers with Nitrogen-Containing Tripodal Crosslinkers for Efficient PFAS Adsorption

Anna Yang, Casey Ching, Maeghan Easler, Damian E. Helbling, William R. Dichtel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Per- and polyfluoroalkyl substances (PFAS) are widely used industrial chemicals that are of a great concern because of their pervasive presence in water resources and association with negative health effects. Crosslinked β-cyclodextrin-containing (β-CD) polymer adsorbents have shown promising performances for sequestering PFAS. Recently, installing amino groups into the crosslinkers of a β-CD polymer network improved the binding of many anionic PFAS, including short-chain and branched derivatives. However, the relative importance of the electrostatic interactions from the amino groups and the host-guest interactions within the cavity of the β-CD for PFAS binding are unclear. Herein, β-CD-based adsorbents crosslinked with tripodal crosslinkers containing three amino or amido groups are prepared with comparable physicochemical properties to investigate the respective roles of the crosslinker and β-CD in binding affinity and capacity for anionic PFAS. β-CD polymers containing amines showed superior removal for ten anionic PFAS compared to polymers containing amido groups. Both β-CD polymers have superior performance for perfluorooctanoic acid (PFOA) removal compared to activated carbons (ACs), consistent with β-CD:PFOA inclusion complexes playing an important role. Adsorbents containing amido groups showed low binding affinity and capacity for GenX, whereas the amine-functionalized polymer had outstanding affinity and capacity for GenX (KL = 8.8 × 104 M-1, QM = 222 mg g-1), underscoring the essential role of electrostatic interactions for removing short-chain and branched PFAS. The amine-containing β-CD polymer exhibited 100-fold higher affinity and twice the capacity (KL = 1.8 × 106 M-1, QM = 457 mg g-1) for PFOA compared to GenX, which are the highest reported values for β-CD polymers. These results highlight the synergistic effects of electrostatic interactions and host-guest interactions in β-CD polymers as important design criteria for efficient removal of anionic PFAS from water. This study further demonstrates broad tunability of crosslinked β-CD polymers and their promise as adsorbents for PFAS remediation.

Original languageEnglish (US)
Pages (from-to)1240-1245
Number of pages6
JournalACS Materials Letters
Volume2
Issue number9
DOIs
StatePublished - Sep 8 2020

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)
  • Biomedical Engineering

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