Column versus batch methods for measuring PFOS and PFOA sorption to geomedia

Glubt, Sarah Van; Brusseau, Mark L.; Yan, Ni; Huang, Dandan; Khan, Naima; Carroll, Kenneth C.

doi:10.1016/j.envpol.2020.115917

Cited by 45 publications

(44 citation statements)

References 48 publications

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“…Notably, the K d value for PFOA sorption by the sand with no SDS present is consistent with our prior measurements from batch and column isotherm experiments. 29 In addition, the results are consistent with those reported by other investigators who have conducted PFOA transport experiments with PFOA and the same sand, as discussed in Wang et al 31 The K d value for PFOA sorption by the sand with SDS = 1 μg/L is the same as that with no SDS present. This indicates that the presence of very low levels of SDS has no impact on PFOA sorption.…”

Section: ■ Results and Discussionsupporting

confidence: 90%

“…Prior field sampling and mathematical modeling have demonstrated that soil and the vadose zone at many sites are primary reservoirs of PFAS that can serve as long-term sources to groundwater. ,,,− The migration of PFAS in the soil profile and vadose zone can be influenced by multiple retention processes . The influence of sorption by soil on PFAS transport has been investigated in a number of studies. − In addition, laboratory and modeling studies have illustrated that retention and transport of PFAS in unsaturated porous media can be significantly affected by adsorption at air–water interfaces. ,,,,− Furthermore, it has long been established that the transport of hydrocarbon surfactants in unsaturated porous media is influenced by both solid-phase sorption and air–water interfacial adsorption. − Therefore, the co-existence of hydrocarbon surfactants may have the potential to influence the retention and transport behavior of PFAS in the subsurface.…”

Section: Introductionmentioning

confidence: 99%

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Impact of a Hydrocarbon Surfactant on the Retention and Transport of Perfluorooctanoic Acid in Saturated and Unsaturated Porous Media

Yan

Brusseau

et al. 2021

Environ. Sci. Technol.

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The transport and retention behavior of perfluorooctanoic acid (PFOA) in the presence of a hydrocarbon surfactant under saturated and unsaturated conditions was investigated. Miscible-displacement transport experiments were conducted at different PFOA and sodium dodecyl sulfate (SDS) input ratios to determine the impact of SDS on PFOA adsorption at solid–water and air–water interfaces. A numerical flow and transport model was employed to simulate the experiments. The PFOA breakthrough curves for unsaturated conditions exhibited greater retardation compared to those for saturated conditions in all cases, owing to air–water interfacial adsorption. The retardation factor for PFOA with a low concentration of SDS (PFOA–SDS ratio of 10:1) was similar to that for PFOA without SDS under unsaturated conditions. Conversely, retardation was greater in the presence of higher levels of SDS (1:1 and 1:10) with retardation factors increasing from 2.4 to 2.9 and 3.6 under unsaturated conditions due to enhanced adsorption at the solid–water and air–water interfaces. The low concentration of SDS had no measurable impact on PFOA air–water interfacial adsorption coefficients (K ia) determined from the transport experiments. The presence of SDS at the higher PFOA–SDS concentration ratios increased the surface activity of PFOA, with transport-determined K ia values increased by 27 and 139%, respectively. The model provided very good independently predicted simulations of the measured breakthrough curves and showed that PFOA and SDS experienced various degrees of differential transport during the experiments. These results have implications for the characterization and modeling of poly-fluoroalkyl substances (PFAS) migration potential at sites wherein PFAS and hydrocarbon surfactants co-occur.

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Section: ■ Results and Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Impact of a Hydrocarbon Surfactant on the Retention and Transport of Perfluorooctanoic Acid in Saturated and Unsaturated Porous Media

Yan

Brusseau

et al. 2021

Environ. Sci. Technol.

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“…The R value measured for PFOS transport in the fully water-saturated system (no NAPL present) is 1.3 ( K d = 0.064 cm 3 /g). This K d value is consistent with that measured by batch and column isotherm experiments . An R of 1.3 was also measured for the PFOS column experiment conducted with TCE dissolved in solution but not present as residual NAPL.…”

Section: Resultssupporting

confidence: 88%

“…The smaller R measured for the higher input concentration results from two factors. First, the sorption of PFOS by the sand is nonlinear, as demonstrated by prior batch and column isotherm measurements . Second, NAPL–water interfacial adsorption is nonlinear in this concentration range (see respective K i values in Table ).…”

Section: Resultsmentioning

confidence: 82%

“…Predicted R values were determined using eq 8 in the SI and column-independent data. K d values for the specific input concentrations used in the transport experiments were determined from measured Freundlich parameters reported in a recent study investigating PFOS and PFOA sorption by the sand . The K n values are those measured herein with the batch NAPL-partitioning experiments, and the K i values are from the interfacial-tension measurements.…”

Section: Resultsmentioning

confidence: 99%

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Contribution of Nonaqueous-Phase Liquids to the Retention and Transport of Per and Polyfluoroalkyl Substances (PFAS) in Porous Media

Glubt

Brusseau

2021

Environ. Sci. Technol.

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Per and polyfluoroalkyl substances (PFAS) cocontamination with nonaqueous-phase organic liquids (NAPLs) has been observed or suspected at various sites, particularly at fire-training areas at which aqueous film-forming foams (AFFFs) were applied. The objectives of this study are to (1) delineate the relative significance of specific PFAS-NAPL processes on PFAS retention, including partitioning into the bulk NAPL phase and adsorption to the NAPL–water interface; (2) investigate the influence of NAPL properties, saturation, and mass-transfer constraints on PFAS retention; and (3) determine whether PFAS may impact NAPL distribution through mobilization or dissolution. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are used as representative PFAS, and trichloroethene (TCE) and decane are used as representative NAPLs. NAPL–water interfacial adsorption was quantified with NAPL–water interfacial-tension measurements; partitioning into NAPL was quantified with batch experiments, and retardation factors (R) in the absence and presence of residual NAPL were determined with miscible-displacement transport experiments. R values increased in the presence of residual NAPL, with adsorption to the NAPL–water interface accounting for as much as ∼77% of retention and solid-phase adsorption also significantly contributing to retention. Additionally, this study provides the first QSPR analysis focused on NAPL–water interfacial adsorption coefficients, with results consistent with those from previous air–water studies. Lastly, this initial investigation into PFAS impacts on NAPL behavior determined that PFOS/PFOA are unlikely to enhance solubilization or mobilization of NAPL under the conditions present at many AFFF legacy sites.

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Leaching and Transformation of Perfluoroalkyl Acids and Polyfluoroalkyl Phosphate Diesters in Unsaturated Soil Column Studies

Weidemann

Lämmer

Stahl

et al. 2022

Enviro Toxic and Chemistry

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Per-and polyfluoroalkyl substances (PFAS) are environmentally ubiquitous, anthropogenic substances with adverse effects on organisms, which shows the need to study their environmental fate and leaching behavior. In the present soil columns study, the leaching behavior and fate of nontransformable and transformable (precursors) were investigated. Ten nontransformable PFAS in two different soils, two precursors and two field soils, which were already contaminated with a mixture of PFAS, and two uncontaminated controls, were set up for a time span of 2 years. At the end of the study, the molecular balance could not be closed for nontransformable PFAS. This effect was positively correlated to the fluorinated carbon chain length. The precursors, which were both polyfluoroalkyl phosphate diesters (diPAP), had different transformation products and transformation rates, with a higher rate for 6:2 diPAP than 8:2 diPAP. After 2 years, amounts of diPAP were still found in the soil with no significant vertical movement, showing high adsorption to soils. Transformation products were estimated to be simultaneously formed. They were predominantly found in the percolation water; the amounts left in soil were negligible. Up to half of the initial precursor amounts could not be balanced and were considered missing amounts. The results of contaminated field soil experiments showed the challenge to estimate PFAS leaching without knowing all occurring precursors and complex transformation dynamics. For this purpose, it was shown that a broad examination of contaminated soil with different analytical methods can help with qualitative estimations of leaching risks. For a better quantitative estimation, analytical determination of more PFAS and a quantification of the missing amounts are needed.

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Column versus batch methods for measuring PFOS and PFOA sorption to geomedia

Cited by 45 publications

References 48 publications

Impact of a Hydrocarbon Surfactant on the Retention and Transport of Perfluorooctanoic Acid in Saturated and Unsaturated Porous Media

Impact of a Hydrocarbon Surfactant on the Retention and Transport of Perfluorooctanoic Acid in Saturated and Unsaturated Porous Media

Contribution of Nonaqueous-Phase Liquids to the Retention and Transport of Per and Polyfluoroalkyl Substances (PFAS) in Porous Media

Leaching and Transformation of Perfluoroalkyl Acids and Polyfluoroalkyl Phosphate Diesters in Unsaturated Soil Column Studies

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