Magnetic ion-exchange (MIEX) resin for perfluorinated alkylsubstance (PFAS) removal in groundwater: Roles of atomic charges for adsorption

Park, Minkyu; Daniels, Kevin D.; Wu, Shimin; Ziska, Austin D.; Snyder, Shane A.

doi:10.1016/j.watres.2020.115897

Cited by 85 publications

(53 citation statements)

References 44 publications

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“…These results indicate that most adsorbents showed higher adsorption percentage for PFSAs (10–90%) after 1 day compared to that for PFCAs (5–65%), but equilibrium for both classes of PFAAs is generally reached within 5 days. Such results agree with the equilibration time observed by other resin/PFAS studies. , However, because the residual PFAS aqueous concentrations can continue to drop for a longer period of time even when >95% adsorption has occurred, a 10 day equilibration time was used for subsequent experiments to ensure PFAS equilibrium with the resins. Furthermore, initial concentrations remained unchanged in resin-free control reactors, consistent with the reported recalcitrance of PFAAs to degradation. − A full analysis and fitting of the kinetics data are provided in Section SI-4.…”

Section: Resultssupporting

confidence: 87%

“…Through density-functional theory (DFT) calculations, Park et al discovered that sulfonic PFASs can induce greater negative atomic charges per unit of oxygen than carboxylic PFASs due to resonance stabilization. This increased negative atomic charge per oxygen and the additional oxygen atom in the sulfonate head group significantly increases the total negative charge of the head group interacting with the cationic amine surface functional groups on the resin . Within each PFAA class, the K ex values also increase with increasing perfluoroalkyl acid chain length (Figure ).…”

Section: Resultsmentioning

confidence: 97%

“…This increased negative atomic charge per oxygen and the additional oxygen atom in the sulfonate head group significantly increases the total negative charge of the head group interacting with the cationic amine surface functional groups on the resin. 44 Within each PFAA class, the K ex values also increase with increasing perfluoroalkyl acid chain length (Figure 3). The average log K ex change per CF 2 group is found to range between 0.14 and 0.65 for the studied AERs (Table S6).…”

Section: F-nmr (Data Not Yet Published)mentioning

confidence: 98%

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Removal of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foam (AFFF) Using Ion-Exchange and Nonionic Resins

Fang

Ellis

Choi

et al. 2021

Environ. Sci. Technol.

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Despite benefits to the firefighting industry, the release of per-and polyfluoroalkyl substances (PFASs) from aqueous film-forming foam (AFFF) into aquatic systems poses significant risks to human health and other organisms. While anion-exchange technologies have proven to be effective for removing perfluoroalkyl acids (PFAAs) from water, their effectiveness for removing the diverse PFAS structures discovered in AFFF remains unknown. Here, we report on the adsorption of 75 PFASs, including 63 polyfluorinated substances, in a diluted AFFF mixture using 14 commercially available ion-exchange (IX)/nonionic resins and granular activated carbon (GAC). Results showed that anion-exchange resins (AERs) exhibited significant adsorption of PFASs compared to cation-exchange resins (CERs), nonionic resins (NIRs), and GAC regardless of the PFAS's predicted charge. Isotherm data showed that macroporous AERs have a higher PFAS adsorption capacity compared to gel-type AERs. Cross-correlation comparison of PFAS/Cl − selectivity coefficients (K ex ) for each PFAS−AER combination showed that the hydrophobicity of the AER functional group, and polymer matrix played a dominant role in determining resin affinity for PFASs. PFAS structural characteristics also significantly affected adsorption, with increasing chain length and a net negative charge increasing the extent of adsorption. Results from this study provide guidelines for the selection of resins to adsorb a wider range of PFASs and meaningful insights for the development of quantitative models for IX treatment of AFFF-impacted water.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 97%

Section: F-nmr (Data Not Yet Published)mentioning

confidence: 98%

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Removal of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foam (AFFF) Using Ion-Exchange and Nonionic Resins

Fang

Ellis

Choi

et al. 2021

Environ. Sci. Technol.

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“…Density functional theory (DFT) calculations support the stronger electrostatic interactions between the sulfonate group of PFSAs and quaternary ammonium functional group of resin than between the carboxylate group of PFCAs and functional group of resin (Park et al, 2020). Interestingly, DFT calculations suggested that increasing length of perfluoroalkyl tail resulted in greater net negative charge on PFAAs resulting in stronger electrostatic interactions with resin and did not use van der Waals interactions to explain the results (Park et al, 2020).…”

Section: Aer Polymer Compositionmentioning

confidence: 99%

“…Various head groups are attached to the C F chain with perfluoroalkyl acids (PFAAs) characterized by the acidic head group. The two most widely studied and detected subgroups of PFAAs are the perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs), with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) being the most prevalent species (Pontius, 2019).…”

Section: Introductionmentioning

confidence: 99%

Regeneration efficiency of strong‐base anion exchange resin for perfluoroalkyl and polyfluoroalkyl substances

2021

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The objectives of this research were to evaluate the regeneration efficiency of strong-base anion exchange resin (AER) considering (i) total perfluoroalkyl and polyfluoroalkyl substances (PFAS) concentration, (ii) AER polymer composition, and (iii) regeneration solution composition. Laboratory column experiments were conducted over multiple treatment and regeneration cycles using groundwater spiked with six perfluoroalkyl acids (PFAAs): perfluorobutanoic acid, perfluorohexanoic acid perfluorooctanoic acid, perfluorobutane sulfonic acid, perfluorohexane sulfonic acid, and perfluorooctane sulfonic acid. Regeneration efficiency was calculated as the mass of PFAAs desorbed from the resin during regeneration divided by the mass of PFAAs adsorbed to the resin during treatment. Higher PFAS concentration in the influent resulted in higher PFAS loading on the resin and higher regeneration efficiency. This was especially true for polystyrene AER, which exhibited greater removals of perfluoroalkyl sulfonic acids than perfluoroalkyl carboxylic acids, and greater removal of long-chain PFAAs than short-chain analogs. The most important result was the higher regeneration efficiency for solution composed of salt + organic cosolvent than the aqueous-only solution.

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Various Remediation Measures for Groundwater Contamination

Kaur

Dawar

Singh

2021

Groundwater Geochemistry

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Magnetic ion-exchange (MIEX) resin for perfluorinated alkylsubstance (PFAS) removal in groundwater: Roles of atomic charges for adsorption

Cited by 85 publications

References 44 publications

Removal of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foam (AFFF) Using Ion-Exchange and Nonionic Resins

Removal of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foam (AFFF) Using Ion-Exchange and Nonionic Resins

Regeneration efficiency of strong‐base anion exchange resin for perfluoroalkyl and polyfluoroalkyl substances

Various Remediation Measures for Groundwater Contamination

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