Importance of Al/Fe oxyhydroxide coating and ionic strength in perfluorooctanoic acid (PFOA) transport in saturated porous media

Lyu, Xueyan; Liu, Xing; Wu, Xiaoqiang; Sun, Yuanyuan; Gao, Bin; Wu, Jichun

doi:10.1016/j.watres.2020.115685

Cited by 41 publications

(20 citation statements)

References 39 publications

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“…The zeta potentials of different sand at pH from 4.5 to 9.7 followed the order of Al-3 (− 19.9 ~ 42. 2), consistent with previous findings (Lyu et al, 2020;Wang et al, 2012). This is likely due to the great disparity in pH PZC (point of zero charge), which followed the order of Al oxyhydroxide (9.9; Figure S3) > Fe oxyhydroxide (7.2; Figure S3) > quartz sand (2-3) (Fisher-Power & Cheng, 2018).…”

Section: Characteristics Of Psnp Suspension and Sandsupporting

confidence: 90%

“…The sand was cleaned using a procedure described previously (Tian et al, 2010). A fraction of cleaned sand (referred to uncoated sand, Un) was coated with different concentrations of Fe/Al oxyhydroxide following methods reported in previous studies (detailed in S1) (Kuan et al, 1998;Lyu et al, 2020;Stahl & James, 1991;Wang et al, 2013). The sand coated with three concentration gradients (low, medium, high) of Fe/Al oxyhydroxide is designated as Fe-1 and Al-1 (low), Fe-2 and Al-2 (medium), and Fe-3 and Al-3 (high), respectively.…”

Section: Porous Mediamentioning

confidence: 99%

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Combined Effects of Fe/Al Oxyhydroxide Coating and pH on Polystyrene Nanoplastic Transport in Saturated Sand Media

Lyu

Gao

et al. 2021

Water Air Soil Pollut

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Fe/Al oxyhydroxide coating dramatically enhanced the retention of negatively charged PSNPs, attributing to the less negatively charged surface and thus reduced electrostatic repulsion. In contrast, for pH values (Fe: 9.7, Al: 11.0) higher than Fe/Al oxyhydroxide pH PZC , Fe/Al oxyhydroxide coating had negligible influence on PSNP retention, because the electrostatic repulsion dominated the transport process. These results clearly demonstrate that pH strongly mediates the transport of PSNPs in Fe/Al oxyhydroxide-coated sand, and emphasize the dominant role of electrostatic interaction in PSNP transport. Findings of this study provide new insight into understanding and predicting the fate and transport of NPs in natural medias with complex physicochemical properties.

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Section: Characteristics Of Psnp Suspension and Sandsupporting

confidence: 90%

Section: Porous Mediamentioning

confidence: 99%

Combined Effects of Fe/Al Oxyhydroxide Coating and pH on Polystyrene Nanoplastic Transport in Saturated Sand Media

Lyu

Gao

et al. 2021

Water Air Soil Pollut

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“…As summarized in recent critical reviews, , retardation of nonpolymeric PFAS within vadose zone soils is a complex combination of multiple retention mechanisms and processes. Specific to the anionic perfluoroalkyl acids (PFAAs) of primary regulatory interest relevant to legacy AFFF formulations, these include hydrophobic interactions with the organic carbon (OC) fraction in soil, electrostatic interactions with the surfaces of variable-charged clay minerals including iron (Fe) and aluminum (Al) oxides and hydroxides to include potential irreversible chemisorption, and fluid–fluid (e.g., air–water) interfacial accumulation resulting in retardation from a “surface excess”. − Laboratory experiments further suggest that PFAA transport in soil is complicated by rate-limiting kinetics attributable to diffusive fluxes into and out of the OC matrix and associated hydrophobic solid-phase interactions, nonlinear (i.e., concentration-dependent) sorption to both solids and air–water interfaces, , and significant desorption hysteresis − resulting at least in part from biphasic porosity domains (highlighting the importance of diffusive fluxes) within natural soils. , In general, PFAS transport through unsaturated soil is “nonideal” even at environmentally relevant concentrations, and studies have suggested that kinetic models with these multiprocess retention mechanisms may be prerequisites for simulating transport under field conditions. , The various soil retention processes and their kinetics, interactions thereof, and potential confounding effects from the accumulation of PFAAs in soil as a result of polyfluorinated precursor transformation are the subject of much ongoing research …”

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confidence: 99%

The Case for Direct Measures of Soil-to-Groundwater Contaminant Mass Discharge at AFFF-Impacted Sites

Anderson

2021

Environ. Sci. Technol.

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Many entities around the world are initiating massive field campaigns to characterize the environmental distribution of per- and polyfluoroalkyl substances (PFAS), particularly at aqueous film-forming foam (AFFF) impacted sites where historic point-source discharges occurred at the ground surface. Concurrently, many regulatory agencies are publishing criteria used in practice to define the “nature and extent” of PFAS-impacted environmental media. Specific to the soil-to-groundwater transport pathway protective of the groundwater ingestion end point, these soil criteria (or screening values) are to date exclusively based on the traditional approach used for hydrophobic organics with a number of simplifying assumptions. Research has clearly contradicted these assumptions, yet alternative methodologies have yet to emerge from the literature. This Perspective provides a rationale for why alternative approaches are critically necessary and proposes the application of lysimetry as a practical solution to accurately assess PFAS transport within unsaturated vadose zone soils. Ultimately, there is an urgent need to justify soil remediation on the basis of groundwater protection and to prioritize remedial efforts in order to optimize limited fiscal resources.

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“…Li et al, 2019;Sima & Jaffé, 2021;Wei et al, 2017). However, it has been demonstrated that other soil constituents such as metal oxides and clay minerals can also contribute to PFAS sorption, particularly for shorter-chain PFAS and soils with lower SOM contents (Higgins & Luthy, 2006;Lyu et al, 2020;Pereira et al, 2018;Wang et al, 2021). PFAS sorption has in some cases been observed to be a function of pH, ionic strength, and the degree of ionization of the PFAS.…”

Section: Soil Retentionmentioning

confidence: 99%

PFAS Experts Symposium 2: Key advances in poly‐ and perfluoroalkyl characterization, fate, and transport

Bryant¹,

Anderson

Bolyard

et al. 2022

Remediation Journal

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The PFAS Experts Symposium 2, held virtually from June 29 to July 1, 2021, brought together experts from a wide range of disciplines to discuss recent advances and current thinking regarding per-and polyfluoroalkyl substances (PFAS) in the environment. Within the general areas of characterization and fate and transport, three topics were identified that are of relevance for site assessment and remediation, and for which our understanding has greatly expanded or evolved since the first PFAS Experts Symposium in 2019: the significance of background PFAS sources to the environment, the relevance and use of nonselective analytes in site characterization, and PFAS retention in soil and the vadose zone. PFAS have been identified in shallow soil nearly worldwide, including far from known or suspected PFAS sources, and PFAS detected in soil and groundwater at sites under environmental investigation may not reflect on-site sources. New advances in nonselective preparation and analytical methods offer promise for more rapid site screening and for assessing the presence and relative concentration of nontargeted PFAS. We also now recognize that a wide range of soil characteristics and processes may affect PFAS sorption and desorption from soil, and ultimately influence PFAS mobility and concentration in groundwater and surface water. 1 | INTRODUCTION This paper was developed as an outcome from presentations by the Characterization, Fate, and Transport group given as part of the PFAS Experts Symposium 2 (Symposium), a virtual, invitation-only conference held from June 29 to July 1, 2021. The Symposium was a follow-up to a previous PFAS Experts Symposium held in May 2019 (Simon et al., 2019). The primary objective of the Symposium was to share current and emerging information and thinking regarding per-and polyfluoroalkyl substances (PFAS) among experts representing a wide range of different scientific and technical fields, and to serve as an update to ideas and concepts first developed in the 2019 Symposium. Each of the listed authors participated in the Symposium and contributed to the discussions and presentations.

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Importance of Al/Fe oxyhydroxide coating and ionic strength in perfluorooctanoic acid (PFOA) transport in saturated porous media

Cited by 41 publications

References 39 publications

Combined Effects of Fe/Al Oxyhydroxide Coating and pH on Polystyrene Nanoplastic Transport in Saturated Sand Media

Combined Effects of Fe/Al Oxyhydroxide Coating and pH on Polystyrene Nanoplastic Transport in Saturated Sand Media

The Case for Direct Measures of Soil-to-Groundwater Contaminant Mass Discharge at AFFF-Impacted Sites

PFAS Experts Symposium 2: Key advances in poly‐ and perfluoroalkyl characterization, fate, and transport

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