# Effect of Hydrophobic Cross-Linkers in Strong Base Gel-Type Resins on the Adsorption Kinetics and Capacity for Perfluoroalkyl Substances

## TL;DR

This study explores how hydrophobic cross-linkers in ion exchange resins improve the removal of harmful perfluoroalkyl substances from water.

## Contribution

Novel cationic resins with hydrophobic cross-linkers were developed, showing faster PFAS removal and comparable adsorption capacity.

## Key findings

- New cationic resins achieved significantly faster removal of both long- and short-chain PFAS.
- Fluorous cationic adsorbent reached equilibrium loadings comparable to existing resins for PFAS with five or more perfluorinated carbon atoms.

## Abstract

The persistence and water mobility of per- and polyfluoroalkyl
substances (PFAS) have led authorities worldwide to lower regulatory
limits to prevent adverse health effects. Removal via adsorption on
activated carbon can be inefficient due to the unspecific surface
interaction, while ion exchange resins with positive charges and hydrophobic
chains can offer faster kinetics and improved removal. In here, novel
cationic resins were synthesized by cross-linking polyethylenimine,
followed by methylation. To obtain cross-linked particles and introduce
hydrophobic interacting moieties in one single synthetic step, aliphatic,
fluorous, and silicone-based oligoethers were used as cross-linkers.
These cationic adsorbents were compared with two state-of-the-art
strong base gel-type ion exchange resins and granular activated carbon
in isotherm and kinetic studies. The newly developed adsorbents showed
significantly faster removals of all tested long- and short-chain
PFAS. The fluorous cationic adsorbent achieved equilibrium loadings
that were comparable to those of the state-of-the-art adsorbents for
all PFAS with five or more perfluorinated carbon atoms.