Removing per‐ and polyfluoroalkyl substances from groundwaters using activated carbon and ion exchange resin packed columns

Abstract

Human exposure to per‐ and polyfluoroalkyl substances (PFAS) in drinking water is of growing concern as a result of increasing reports of occurrence and potential regulation. Adsorption of PFAS by granular activated carbon (GAC) or ion exchange (IX) resin is a suitable treatment technique. However, few studies compare PFAS removal in continuous flow GAC or IX adsorption systems using real drinking water sources. In this study, rapid small‐scale column tests (RSSCTs) were used to investigate the effects of PFAS type and chain length on adsorption by GAC and IX resin for six groundwaters used as drinking water supplies. Seven PFAS substances with chain lengths of C4–C9 were detected in the groundwaters with the sum of their concentrations (ΣPFAS) ranging from 156 to 7,044 ng/L. Adsorption capacities (qΣPFAS) were calculated to compare the removal capacity among different sorbents and qΣPFAS values ranged from 10.3 to 228 ng PFAS/mg sorbent after about 100,000 bed volumes treated. Coal‐based GACs had higher adsorption capacity compared with coconutshell‐based GAC, which was likely due to higher mesopore and macropore volumes. IX resins performed better than GAC in removing PFAS, but they were not effective in treating short‐chain perfluorocarboxylic acids (PFCAs). Perfluorosulfonic acids (PFSAs) broke through later than PFCAs with the same chain length. Within PFSA or PFCA classes, shorter‐chain PFAS species always broke through before longer‐chain PFAS. Statistical analysis demonstrated that PFAS with higher hydrophobicity and molecular weight are more amenable to GAC adsorption. Empirical models were developed and predicted PFAS breakthrough. By quantifying PFAS selectivity and removal efficiency, this work provides benchmark data for commercially available treatment technologies and guidance toward specific PFAS classes for which new treatment technologies may be most beneficial.

Foam fractionation removal of multiple per‐ and polyfluoroalkyl substances from landfill leachate

“…Proven methods for PFAS removal include adsorption via granular active carbon (GAC), powdered activated carbon (PAC), and anion exchange (AIX) or via size exclusion using reverse osmosis (RO) or nanofiltration (NF) (Appleman et al, 2013; Appleman et al, 2014; Belkouteb et al, 2020; Crone et al, 2019; Du et al, 2014; Franke et al, 2019; Franke et al, 2021; Kucharzyk et al, 2017; McNamara et al, 2018; Ochoa‐Herrera & Sierra‐Alvarez, 2008; Rahman et al, 2014; Senevirathna et al, 2010; Woodard et al, 2017; Zaggia et al, 2016; Zeng et al, 2020) and have been utilized in full‐scale predominantly for drinking water and groundwater treatment. For GAC and AIX adsorption processes, PFAS removal efficiency has been shown to be dependent on the PFAS chain length, functional group, pH, and is typically negatively affected by the presence of dissolved organic matter (DOC) (Dixit et al, 2019; Gagliano et al, 2020; Kothawala et al, 2017; McCleaf et al, 2017; Schuricht et al, 2017; Siriwardena et al, 2019) and other negatively charged ions.…”

Reversible adsorption and desorption of PFAS on inexpensive graphite adsorbents via alternating electric field

“…6 Sorption is perhaps the most promising technology to remove PFAS from water. Various adsorbents including metalorganic frameworks (MOF), 35,36 zeolites, 37,38 activated carbons, 39,40 and anion exchange resins [41][42][43] have been utilized.…”

“…Carbonaceous adsorbents 39,40,[44][45][46] (e.g., activated carbon, graphene, carbon nanotubes) are attractive due to their chemical durability and thermal stability, 47 and a large specic surface area that can accelerate the adsorption kinetics. 48 However, most carbonaceous adsorbents exhibit a relatively low adsorption capacity (i.e., the amount of contaminant taken up by the unit mass of adsorbent) 49 for PFAS with a short uoroalkyl chain length.…”

Per‐ and polyfluoroalkyl substances removal with granular activated carbon and a specialty adsorbent: A case study

“…While RSSCTs require the use of scale‐up factors that make exact reflection of full‐scale breakthrough times difficult to predict, particularly in the presence of natural organic matter, the tests are valuable in determining relative performance of media (Corwin & Summers, 2010). RSSCTs for IX have only recently begun to be used (Schaefer et al, 2020; Zeng et al, 2020).…”