Remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS) is particularly challenging due to the resistance of the molecule to oxidation because of the strength of the carbon-fluorine bond and the need to achieve low nanogram per liter drinking water targets. Previous studies have shown that activated carbon is an effective sorbent for removal of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in conventional water treatment systems. The objective of this study was to evaluate the in situ delivery and sorptive capacity of an aqueous suspension containing powdered activated carbon (PAC) stabilized with polydiallyldimethylammonium chloride (polyDADMAC). Batch reactor studies demonstrated substantial adsorption of PFOA and PFOS by polyDADMAC-stabilized PAC, which yielded Freundlich adsorption coefficients of 156 and 629 L/g-n, respectively. In columns packed with 40-50 mesh Ottawa sand, injection of a PAC (1000 mg/L) + polyDADMAC (5000 mg/L) suspension created a sorptive region that increased subsequent PFOA and PFOS retention by 3 orders of magnitude relative to untreated control columns, consistent with the mass of retained PAC. Experiments conducted in a heterogeneous aquifer cell further demonstrated the potential for stabilized-PAC to be an effective in situ treatment option for PFAS-impacted groundwater.
Bibliographical noteFunding Information:
The authors thank Dr. Jennifer Guelfo (Texas Tech University), Dr. Bonnie Marion (Air Liquide/Balazs) and Dr. Jed Costanza (U.S. EPA) for their assistance with the LC–MS/MS analysis. The Strategic Environmental Research and Development Program (SERDP) provided funding for this research under Contract W912HQ-14-C-0042 “Development of a Novel Approach for in situ Remediation of PFC Contaminated Groundwater (ER-2425)” and contract W912HQ-18-C0002 “Development of Coupled Physiochemical and Biological Systems for In-Situ Remediation of Mixed Perfluorinated Chemical and Chlorinated Solvent Groundwater Plumes (ER-2714)”. The contents of this manuscript have not been subject to agency review and do not necessarily represent the views of the sponsoring agency. A provisional application for a patent has been filed (US 2017-625555885) for the S-PAC process. The authors declare no other competing interest.
© 2020 American Chemical Society.
PubMed: MeSH publication types
- Journal Article
- Research Support, Non-U.S. Gov't