Enhanced removal of short- and long-chain per- and poly-fluoroalkyl substances from aqueous phase using crushed grafted chitosan beads: Performance and mechanisms

Abstract

The widespread use of per- and poly-fluoroalkyl substances (PFASs), environmentally persistent halogenated hydrocarbons, in various industrial and commercial applications has caused significant concerns owing to their contamination of soil and groundwater. Chitosan is a biopolymer substance with abundant amine and hydroxyl functional groups, making it a good candidate for adsorption of PFASs. This study aimed to increase chitosan's adsorption capacity by grafting additional amine functional groups on its surface for the removal of long- and short-chain PFASs from an aqueous phase. Two types of chitosan-based sorbents were developed: crushed chitosan beads (CBs) and polyethyleneimine-grafted CBs (GCBs). Batch adsorption tests assessed the adsorption capacities of the sorbents in terms of the sorption kinetics, isotherms, selectivity, and reusability. Based on the results, the GCBs had significant potential for adsorbing PFASs. These capacities were significantly higher than those demonstrated by the CBs. The sorption kinetics data revealed that the GCBs had a fast sorption rate. Furthermore, the GCBs demonstrated a high adsorption affinity, with log Kd values ranging from 1.5 to 2.5 for PFASs at environmentally relevant concentrations (1000 ng L−1). They also demonstrated excellent selectivity sorption for these compounds, even in the presence of other organic and inorganic pollutants.