Updated review on emerging technologies for PFAS contaminated water treatment

Kazwini, Tayma; Yadav, Sudesh; Ibrar, Ibrar; Al-Juboori, Raed A.; Singh, Lovdeep; Ganbat, Namuun; Karbassiyazdi, Elika; Samal, Akshaya K.; Subbiah, Senthilmurugan; Altaee, Ali

doi:10.1016/j.cherd.2022.04.009

Cited by 83 publications

(42 citation statements)

References 252 publications

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“…Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants that have been dispersed through multiple water sites around the globe. − These surfactant-like species contain a highly stable C–F bond that makes them resistant to degradation and can lead to bioaccumulation. Despite multiple efforts to reduce PFAS emissions, their concentration in water is still significant, especially of legacy long-chain PFAS such as perfluorooctanoic acid (PFOA). − Hence, considerable attention has been devoted to developing separation methods to remove PFOA and other PFAS from water. − Conventional methods for treatment include reverse osmosis, filtration, ion-exchange, among other adsorption and membrane processes. ,, For adsorption, the predominant materials for PFAS adsorption are carbon-based, , due to their low cost. However, carbon-derived sorbents can incur downstream environmental impacts as they often rely on incineration, while state-of-the-art reusable adsorbents require harsh chemicals for regeneration. ,, At the same time, electrosorption has emerged as a promising approach for PFAS remediation due to its modularity and regeneration solely by electrochemical control. , Electrosorbents mitigate the need for chemicals, solvents, or pH inputs for desorption due to the electrochemical control of binding and release and thus can minimize secondary pollution.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Electrochemically Driven Capture and Release of Long-Chain PFAS by Redox Metallopolymer Sorbents

Medina

Contreras

Hartmann

et al. 2023

ACS Appl. Mater. Interfaces

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The remediation of perfluoroalkyl substances (PFAS) is an urgent challenge due to their prevalence and persistence in the environment. Electrosorption is a promising approach for wastewater treatment and water purification, especially through the use of redox polymers to control the binding and release of target contaminants without additional external chemical inputs. However, the design of efficient redox electrosorbents for PFAS faces the significant challenge of balancing a high adsorption capacity while maintaining significant electrochemical regeneration. To overcome this challenge, we investigate redox-active metallopolymers as a versatile synthetic platform to enhance both electrochemical reversibility and electrosorption uptake capacity for PFAS removal. We selected and synthesized a series of metallopolymers bearing ferrocene and cobaltocenium units spanning a range of redox potentials to evaluate their performance for the capture and release of perfluorooctanoic acid (PFOA). Our results demonstrate that PFOA uptake and regeneration efficiency increased with more negative formal potential of the redox polymers, indicating possible structural correlations with the electron density of the metallocenes. Poly(2-(methacryloyloxy)ethyl cobaltoceniumcarboxylate hexafluorophosphate) (PMAECoPF 6 ) showed the highest affinity toward PFOA, with an uptake capacity of more than 90 mg PFOA/g adsorbent at 0.0 V vs Ag/AgCl and a regeneration efficiency of more than 85% at −0.4 V vs Ag/AgCl. Kinetics of PFOA release showed that electrochemical bias greatly enhanced the regeneration efficiency when compared to open-circuit desorption. In addition, electrosorption of PFAS from different wastewater matrices and a range of salt concentrations demonstrated the capability of PFAS remediation in complex water sources, even at ppb levels of contaminants. Our work showcases the synthetic tunability of redox metallopolymers for enhanced electrosorption capacity and regeneration of PFAS.

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Section: Introductionmentioning

confidence: 99%

Investigating the Electrochemically Driven Capture and Release of Long-Chain PFAS by Redox Metallopolymer Sorbents

Medina

Contreras

Hartmann

et al. 2023

ACS Appl. Mater. Interfaces

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“…Water treatment at the community level will provide a more equitable strategy at a lower cost than home-based treatment in certain circumstances. Although reverse osmosis is a proven technology for PFAS removal, most commonly activated carbon or specialized resins are used to remove them . These options are currently used in communities with severe PFAS contamination.…”

Section: Cost For Treatmentmentioning

confidence: 99%

“…Although reverse osmosis is a proven technology for PFAS removal, most commonly activated carbon or specialized resins are used to remove them. 22 These options are currently used in communities with severe PFAS contamination. In the coming years, we will need to determine where and to what extent we can generalize this approach to many more communities with lower PFAS concentrations.…”

Section: ■ Cost For Treatmentmentioning

confidence: 99%

How Should We Interpret the New Water Quality Regulations for Per- and Polyfluoroalkyl Substances?

Sauvé,

Barbeau,

Bouchard

et al. 2023

ACS EST Water

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Water quality regulations for per-and polyfluoroalkyl substances (PFAS) are currently in turmoil given the toxicological evidence of human health effects at background levels of exposure. Many countries are currently considering regulating the usage of PFAS as a group while also lowering the water quality standards for drinking water. It is somewhat disconcerting that different countries have different approaches to regulate PFAS in drinking water, focusing either on specific PFAS targets (such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS)) or on larger groups of PFAS ranging from 12 to roughly 30 target PFAS compounds. Considering that there are between 5000 and over 10 000 estimated potential PFAS compounds and that they may transform into one another in the environment, this poses significant regulatory challenges and may cause incoherent regulations across various jurisdictions. Regulatory policies for drinking water have evolved much more rapidly than other pathways of exposure, i.e., food, soil, dust, and atmospheric exposure. We must ensure that proposed regulations are coherent to minimize exposure and risks and that remediation approaches are balanced to reduce overall exposure across the various sources of exposure.

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“…Currently, granular activated carbon (GAC) adsorption, which transfers dissolved compounds to a solid phase, is the most widely used technology for treatment of PFASs. − This process results from hydrophobic interactions between PFASs and GAC that enable transport through GAC mesopores. , However, GAC materials have a limited capacity for PFAS uptake, and PFAS breakthrough occurs after a certain volume of water is treated. ,,, Once breakthrough occurs, the GAC must be safely discarded or regenerated. , Regeneration and PFAS destruction are typically accomplished by off-site thermal treatment and reactivation at temperatures of >700 °C, a costly and energy-intensive process requiring the evaporation of all residual water absorbed by the spent GAC. − In terms of GAC reusability, thermal regeneration decreases the material’s specific surface area, potentially leading to poorer performance over repeated regeneration cycles. , Given the frequent exchanging of GAC, it would be ideal to perform regeneration on site …”

Section: Introductionmentioning

confidence: 99%

Application of Hydrothermal Alkaline Treatment to Spent Granular Activated Carbon: Destruction of Adsorbed PFASs and Adsorbent Regeneration

Soker

Hao

Trewyn

et al. 2023

Environ. Sci. Technol. Lett.

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Granular activated carbon (GAC) adsorption is the most common technology applied to treat water contaminated with per- and polyfluoroalkyl substances (PFASs), but rapid exhaustion of the media necessitates frequent replacement and costly off-site thermal regeneration. Here, we extend the application of hydrothermal alkaline treatment (HALT), which uses strong alkali and near-critical temperatures and pressures (e.g., 350 °C, 16.5 MPa, and 1 M NaOH) to degrade and mineralize PFASs, to the regeneration of spent GAC. Mass balance experiments wherein a known mass of perfluorooctanesulfonate (PFOS) was adsorbed onto GAC prior to treatment showed that HALT achieved >99% destruction of PFOS and 96 ± 4% defluorination with no observed fluoro-organic intermediates [167 g L–1 GAC, 350 °C, 1 M NaOH, t rxn = 400 min, and 10–15 mg of PFOS (g of GAC)−1]. Treatment of GAC collected from a field pilot study also showed effective destruction of the range of adsorbed PFASs. Moreover, repeated HALT cycles did not significantly affect the GAC specific surface area, and similar adsorption isotherms for perfluoropentanoic acid and PFOS were recorded for virgin and HALT-treated GAC. These findings suggest a promising strategy for on-site regeneration of PFAS-contaminated GAC and other adsorbent media that may be an alternative to off-site thermal regeneration practices.

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Updated review on emerging technologies for PFAS contaminated water treatment

Cited by 83 publications

References 252 publications

Investigating the Electrochemically Driven Capture and Release of Long-Chain PFAS by Redox Metallopolymer Sorbents

Investigating the Electrochemically Driven Capture and Release of Long-Chain PFAS by Redox Metallopolymer Sorbents

How Should We Interpret the New Water Quality Regulations for Per- and Polyfluoroalkyl Substances?

Application of Hydrothermal Alkaline Treatment to Spent Granular Activated Carbon: Destruction of Adsorbed PFASs and Adsorbent Regeneration

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