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Research article - Peer-reviewed, 2022

Per- and polyfluoroalkyl substance (PFAS) retention by colloidal activated carbon (CAC) using dynamic column experiments

Niarchos, Georgios; Ahrens, Lutz; Kleja, Dan Berggren; Fagerlund, Fritjof

Abstract

Developing effective remediation methods for per- and polyfluoroalkyl substance (PFAS)-contaminated soils is a substantial step towards counteracting their widespread occurrence and protecting our ecosystems and drinking water sources. Stabilisation of PFAS in the subsurface using colloidal activated carbon (CAC) is an innovative, yet promising technique, requiring better understanding. In this study, dynamic soil column tests were used to assess the retardation of 10 classical perfluoroalkyl acids (PFAAs) (C-5-C-11 perfluoroalkyl carboxylic acids (PFCAs) and C-4, C-6, C-8 perfluoroalkane sulfonates (PFSAs)) as well as two alternative PFAS (6:2 and 8:2 fluorotelomer sulfonates) using CAC at 0.03% w/w, to investigate the fate and transport of PFAS under CAC treatment applications. Results showed high retardation rates for long-chain PFAS and eight times higher retardation for the CAC-treated soil compared to the non-treated reference soil for the Sigma PFAS. Replacement of shorter chain perfluorocarboxylic acids (PFCAs), such as perfluoropentanoic acid (PFPeA), by longer chained PFAS was observed, indicating competition effects. Partitioning coefficients (K-d values) were calculated for the CAC fraction at similar to 10(3)-10(5) L kg(-1) for individual PFAS, while there was a significant positive correlation (p < 0.05) between perfluorocarbon chain length and K-d. Mass balance calculations showed 37% retention of Sigma PFAS in treated soil columns after completion of the experiments and 99.7% higher retention rates than the reference soil. Redistribution and elution of CAC were noticed and quantified through organic carbon analysis, which showed a 23% loss of carbon during the experiments. These findings are a step towards better understanding the extent of CAC's potential for remediation of PFAS-contaminated soil and groundwater and the limitations of its applications.

Keywords

PFAS; Fluorotelomer sulfonates (FTSAs); Perfluoroalkyl acids (PFAAs); Adsorption; Transport; Colloidal activated carbon

Published in

Environmental Pollution
2022, volume: 308, article number: 119667
Publisher: ELSEVIER SCI LTD

Authors' information

Niarchos, Georgios
Uppsala University
Swedish University of Agricultural Sciences, Department of Aquatic Sciences and Assessment
Swedish University of Agricultural Sciences, Department of Soil and Environment
Fagerlund, Fritjof
Uppsala University

Sustainable Development Goals

SDG6 Clean water

UKÄ Subject classification

Environmental Sciences

Publication Identifiers

DOI: https://doi.org/10.1016/j.envpol.2022.119667

URI (permanent link to this page)

https://res.slu.se/id/publ/118688