Groundwater solutes influence the adsorption of short-chain perfluoroalkyl acids (PFAA) to colloidal activated carbon and impact performance for in situ groundwater remediation

Subsurface injection of colloidal activated carbon (CAC) is an in situ remediation strategy for perfluoroalkyl acids (PFAA), but the influence of groundwater solutes on longevity is uncertain, particularly for short-chain PFAA. We quantify the impact of inorganic anions, dissolved organic matter (DO...

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Published inJournal of hazardous materials Vol. 474; p. 134746
Main Authors Molé, Rachel A., Velosa, Adriana C., Carey, Grant R., Liu, Xitong, Li, Guangbin, Fan, Dimin, Danko, Anthony, Lowry, Gregory V.
Format Journal Article
LanguageEnglish
Published Netherlands Elsevier B.V 05.08.2024
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Summary:Subsurface injection of colloidal activated carbon (CAC) is an in situ remediation strategy for perfluoroalkyl acids (PFAA), but the influence of groundwater solutes on longevity is uncertain, particularly for short-chain PFAA. We quantify the impact of inorganic anions, dissolved organic matter (DOM), and stabilizing polymer on PFAA adsorption to a commercial CAC. Surface characterization supported PFAA chain-length dependent adsorption results and mechanisms are provided. Inorganic anions decreased adsorption for short-chain PFAA (<7 perfluorinated carbons) due to competitive effects, while long-chain PFAA (≥ 7 perfluorinated carbons) were less impacted. DOM decreased adsorption of all PFAA in a chain-length dependent manner. High DOM concentrations (10 mg/L, ∼5 mg OC/L) decreased PFOA adsorption by a factor of 2, PFPeA by one order of magnitude, and completely hindered PFBA adsorption. High MW DOM has less impact on short-chain PFAA than low MW DOM, possibly due to differences in the ability to access CAC micropores. Low DOM concentrations (1 mg/L, ∼0.5 mg OC/L) did not impact adsorption. CMC (90 kDa average MW) had negligible impact on PFAA adsorption likely due to minimal CAC surface coverage. Longevity modeling demonstrated that groundwater solutes limit the capacity for PFAA in a CAC barrier, particularly for short-chain PFAA. [Display omitted] ●Adsorption of PFAA on engineered colloidal activated carbon (CAC) is quantified.●CAC surface chemical properties explain trends in PFAA sorption.●Ionic strength decreases short-chain PFAA adsorption more than long-chain PFAA.●Small molecular weight DOM causes the greatest decrease in PFAA adsorption.●Short-chain PFAA barrier lifetimes are significantly lower than long-chain PFAA.
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ISSN:0304-3894
1873-3336
1873-3336
DOI:10.1016/j.jhazmat.2024.134746