Interactions between Per- and Polyfluoroalkyl Substances (PFAS) at the Water–Air Interface

Environmental Science & Technology, Год журнала: 2025, Номер unknown

Опубликована: Янв. 21, 2025

Per- and polyfluoroalkyl substances (PFAS)─so-called "forever chemicals"─contaminate the drinking water of about 100 million people in U.S. alone are inefficiently removed by standard treatment techniques. A key property these compounds that underlies their fate transport efficacy several promising remediation approaches is they accumulate at water–air interface. This phenomenon remains incompletely understood, particularly under conditions relevant to natural systems where interfaces often carry significant loads other organic contaminants or matter. To understand impact loading on PFAS adsorption, we carried out molecular dynamics simulations varying interfacial densities. We find adsorbed form strong mutual interactions (attraction between perfluoroalkyl chains electrostatic among charged head groups) give rise ordered coatings. These involve near-cancellation hydrophobic attraction Coulomb repulsion. Our findings explain an apparent paradox whereby adsorption isotherms suggest minimal while simultaneously displaying a high sensitivity composition density Consideration present with interface has potential allow for more accurate predictions design efficient approaches.

Язык: Английский

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Evaluation of Per- and Polyfluoroalkyl Substances Leaching from Biosolids and Mitigation Potential of Biochar through Undisturbed Soil Columns

ACS ES&T Water, Год журнала: 2024, Номер 4(2), С. 413 - 426

Опубликована: Янв. 25, 2024

Land application of biosolids recycles nutrients and reduces the need for commercial fertilizers. However, per- polyfluoroalkyl substances (PFAS) may leach from biosolids, resulting in groundwater contamination. We measured PFAS leaching land-applied through undisturbed soil column trials evaluated treatment potential amending with biochar. Synthetic rainfall was applied weekly to columns four regions Wisconsin, including two fields a history biosolid application, simulating annual precipitation. The treatments consisted control (soil only), amended receiving mixture Concentrations total leachate were significantly affected by location site One-time result contamination, as concentrations exceeded local standard (a combined perfluorooctanoic acid perfluorooctanesulfonic concentration 20 ng L–1) at three locations. Legacy pose risk human health years after an intensive standards. Incorporation biochar during mitigated (specifically soils elevated potential) significant reductions C7–C10 perfluoroalkyl carboxylic acids C4 C6–C8 perfluorosulfonic (40% 64% reduction Σ28 PFAS). Biochar facilitate sustainable use mitigation long-chain leaching, pending long-term field evaluation.

Язык: Английский

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In Situ Insight into the Availability and Desorption Kinetics of Per- and Polyfluoroalkyl Substances in Soils with Diffusive Gradients in Thin Films

Environmental Science & Technology, Год журнала: 2023, Номер 57(20), С. 7809 - 7817

Опубликована: Май 8, 2023

The physicochemical exchange dynamics between the solid and solution phases of per- polyfluoroalkyl substances (PFAS) in soils needs to be better understood. This study employed an situ tool, diffusive gradients thin films (DGT), understand distribution kinetics five typical PFAS four soils. Results show a nonlinear relationship masses DGT time, implying that were partially supplied by phase all A dynamic model DGT-induced fluxes soils/sediments (DIFS) was used interpret results derive coefficients for labile fraction (Kdl), response time (tc), adsorption/desorption rates (k1 k–1). larger pool size (indicated Kdl) longer chain implies their higher potential availability. shorter tend have tc relatively smaller k–1, release these might kinetically limited but not more hydrophobic compounds, such as perfluorooctanesulfonic acid (PFOS), although soil properties play important role. Kdl ultimately controls availability soils, while from constrained (which may also hold biota uptake), particularly hydrophilic PFAS.

Язык: Английский

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Treatment of per- and polyfluoroalkyl substances (PFAS): A review of transformation technologies and mechanisms

Journal of environmental chemical engineering, Год журнала: 2023, Номер 12(1), С. 111833 - 111833

Опубликована: Дек. 28, 2023

Язык: Английский

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Repeated Aqueous Film-Forming Foams Applications: Impacts on Polyfluoroalkyl Substances Retention in Saturated Soil

Environmental Science & Technology, Год журнала: 2024, Номер 58(3), С. 1659 - 1668

Опубликована: Янв. 10, 2024

Historical practices at firefighter-training areas involved repeated aqueous film-forming foams (AFFFs) applications, resulting in source zones characterized by high concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFAS). Repeated applications AFFF composed 14 anionic 23 zwitterionic (PFAS) were conducted on a single one-dimensional saturated soil column to quantify PFAS retention. An electrofluorination-based (3M) Milspec AFFF, which was above the mixture's critical micelle concentration (CMC), application strength (3%, v/v). Retention retardation mass increased with each successive addition, although profiles for subsequent differed from initial. Greater degree retention correlated longer carbon–fluorine chain length charged-headgroup type as function number. Anionic increasingly retained application, while exhibited an alternating pattern sorption desorption. Surfactant–surfactant adsorption competition during repeat that are CMC resulted adsorbed first changing nature surface preferential release due competitive elution. Applying polyparameter quantitative structure–property relationship developed describe AFFF-derived uncontaminated, attempted our experimental conditions. The model had been derived data where is below apparent conditions included presence mixed micelles (aggregates consisting different kinds surfactants exhibit characteristics properties surfactant) overall average 27.3% ± 2.7% (standard error) predicted values. correlation significantly improved adding "micelle parameter" account cases applied CMC. Our results highlight importance interactions between components can only be investigated employing complex mixtures present actual strength, their In (AFFF zones), desorption may result downgradient when desorbed become resorbed uncontaminated soil.

Язык: Английский

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Air-water interfacial collapse and rate-limited solid desorption control Perfluoroalkyl acid leaching from the vadose zone

Journal of Contaminant Hydrology, Год журнала: 2024, Номер 265, С. 104382 - 104382

Опубликована: Июнь 5, 2024

Язык: Английский

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Influence of Tension-Driven Flow on the Transport of AFFF in Unsaturated Media

ACS ES&T Water, Год журнала: 2024, Номер 4(2), С. 564 - 574

Опубликована: Янв. 17, 2024

Per- and polyfluoroalkyl substances, other chemicals in aqueous fire-fighting foam (AFFF), accumulate at air–water interfaces the vadose zone, reducing interfacial tension potentially causing tension-driven flow (TDF). This study investigates importance of TDF on AFFF lateral spreading zone using bench-scale column experiments numerical modeling. Understanding beyond an original spill footprint would enhance site conceptual models, wherein understanding contaminant source is critical. Our demonstrate that exhibits noteworthy TDF, characterized by substantial water spreading, variations moisture content, which alters capillary pressure hydraulic conductivity. The modified HYDRUS model accurately simulated was then used to simulate site-scale dynamics. investigation demonstrated could lead a significant increase surface where wetter conditions yield 6-fold compared initial spill, while drier soils exhibit 4-fold expansion. expansion occurs over decades, highly relevant for our both historic relatively new spills. highlights due important transport mechanism controls zone.

Язык: Английский

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Intense Turbulent Bursts Promote the Release of Perfluoroalkyl Acids from Sediments at High Flow Velocity

Environmental Science & Technology, Год журнала: 2024, Номер 58(26), С. 11737 - 11747

Опубликована: Июнь 18, 2024

Despite frequent detection of high levels perfluoroalkyl acids (PFAAs) in sediments, research on the environmental fate PFAAs particularly under hydrodynamic conditions, is rather limited, challenging effective management PFAA loadings. Therefore, this study investigated release and transport 15 sediments environmentally relevant flow velocities using recirculating flumes revealed underlying mechanisms by identifying related momentum transfer. An increased velocity enhanced magnitude total a factor 3.09. The capacity short-chain was notably higher than that long-chain PFAAs, pattern further amplified velocity. Pore-water drainage major pathway for release, with amount predominantly determined velocity-induced intensity depth, as well affected perfluorocarbon chain length sediment size. weak anion exchanger-diffusion gradients thin-film technique confirmed depth Quadrant analysis rise frequency turbulent bursts driven sweeps ejections at cause PFAAs.

Язык: Английский

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Effect of chain length, electrolyte composition and aerosolization on the removal of per- and polyfluoroalkyl substances during electrochemical oxidation

Environmental Science Water Research & Technology, Год журнала: 2024, Номер 10(6), С. 1377 - 1388

Опубликована: Янв. 1, 2024

We utilized a BDD anode in two-electrode system to investigate the degradation of suite PFASs aqueous matrices.

Язык: Английский

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“Forever chemicals”: a sticky environmental problem

Frontiers of Environmental Science & Engineering, Год журнала: 2024, Номер 18(10)

Опубликована: Июль 18, 2024

Язык: Английский

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