Toward systematic understanding of adsorptive removal of legacy and emerging per-and polyfluoroalkyl substances (PFASs) by various activated carbons (ACs)

Per-and polyfluoroalkyl substances (PFASs) have received great attention due to their persistence, bioaccumulation and toxicity. Various activated carbons (ACs) exhibit wide variability in adsorptive performance towards PFASs. In order to gain a systematic understanding of adsorptive removal of legacy and emerging PFASs by ACs, the adsorption of ten PFASs on various ACs was comprehensively investigated. Results showed that granular activated carbon-1 (GAC-1) and powdered activated carbon-1 (PAC-1) removed more than 90% of all target PFASs. Particle size, surface charge, and micropores quantity of ACs were closely related to their performance for PFASs removal. Electrostatic interaction, hydrophobic interaction, surface complexation and hydrogen bonding were the adsorption mechanisms, with hydrophobic interaction being the predominant adsorptive force. Physical and chemical adsorption were both involved in PFAS adsorption. The removal rates of PFASs by GAC-1 decreased from 93%–100% to 15%–66% in the presence of 5 mg/L fulvic acid (FA). GAC was able to remove more PFASs under acidic medium, whereas PAC removed hydrophobic PFASs better under the neutral medium. The removal rates of PFASs by GAC-3 increased significantly from 0%–21% to 52%–97% after being impregnated with benzalkonium chlorides (BACs), demonstrating the superiority of this modification method. Overall, this study provided theoretical support for removing PFASs from water phase with ACs. •Particle size and surface properties of ACs affect their efficiency for PFAS removal.•Removal of PFASs by GAC was probably homogenous physical adsorption.•Neutral medium was favorable for the removal of long-chain PFASs by PAC.•Adsorption of PFASs by GAC was enhanced significantly by BACs impregnation.