Examining the robustness and concentration dependency of PFAS air-water and NAPL-water interfacial adsorption coefficients

WATER RESEARCH

卷:190

Article

Brusseau, Mark L.^1,2 

[1] Univ Arizona, Dept Environm Sci, Tucson, AZ 85721 USA

[2] Univ Arizona, Hydrol & Atmospher Sci Dept, Tucson, AZ 85721 USA

关键词: PFOS;    PFOA;    Perfluoroalkyl substances;    Transport;    Leaching;    Retention;   

DOI  :  10.1016/j.watres.2020.116778

来源: Elsevier

【 摘 要 】

Determining robust values for the air-water or NAPL-water interfacial adsorption coefficient, K-IA, is key to characterizing and modeling PFAS transport and fate in several environmental systems. Direct, high-resolution measurements of surfactant adsorption at the fluid-fluid interface were aggregated from the literature. This data set was used to examine the accuracy and applicability of Gamma and K-IA measurements determined for three PFAS from transport experiments and surface-tension data. The transport-measured Gamma and K-IA data were observed to be fully consistent with the directly-measured data. Specifically, Gamma values for the two methods were entirely coincident in the region of overlapping concentrations, which spanned similar to 4 orders-of-magnitude. Furthermore, the two data sets adhered to an identical Gamma-C profile. These results conclusively demonstrate the accuracy of the transport-measured values. Gamma and K-IA values determined from the application of the Gibbs adsorption equation to measured surface-tension data were fully consistent with the directly-measured and transport-measured data sets, demonstrating their applicability for representing PFAS transport in environmental systems. The directly-measured data were used to examine the concentration dependency of K-IA values, absent the potential confounding effects associated with the use of surface-tension or transport-measured data. The directly-measured data clearly demonstrate that K-IA attains a constant, maximum limit at lower concentrations. Two separate analyses of the transport-measured data both produced observations of constant K-IA values at lower concentrations, consistent with the directly-measured data. These outcomes are discussed in terms of surface activities, relative surface coverages, and critical concentrations. (c) 2020 Elsevier Ltd. All rights reserved.

【 授权许可】

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