Adsorption is an effective method for removal of per- and polyfluoroalkyl substances (PFASs) from water, and the limitation of adsorption rate and capacities of existing adsorbents motivates efforts to develop novel adsorbents. In this study, various covalent organic frameworks (COFs) were developed via an imine condensation reaction for efficient removal of different PFASs from aqueous solution. The cationic COF with quaternary ammonium showed high adsorption capacity for hexafluoropropylene oxide dimer acid (2.06 mmol/g) and hexafluoropropylene oxide trimer acid (2.16 mmol/g), which is more efficient than conventional activated carbons and resins. β cyclodextrin covalent organic frameworks (β-CD-COFs) with rapid removal rate and high adsorption capacity were developed for four PFASs in water including perfluorooctane sulfonate (PFOS), perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), and chlorinated polyfluorinated ether sulfonate (F53B). All β-CD-COFs exhibited extremely fast adsorption (adsorption equilibrium &lt; 2 min) for PFSAs with high adsorption capacities (0.33-1.51 mmol/g), which were significantly better than traditional resins and activated carbons, probably due to the ordered pores of β-CD-COFs and the electron-deficient cavity β-CD. The underlying competitive mechanism was further clarified by performing a density functional theory calculation. This study highlights the exceptional potential of COFs through topology structural design for the efficient removal of PFASs from aqueous solution.

Efficient removal of typical PFASs from water by covalent organic frameworks

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.