Enhancing the Thermal Mineralization of Perfluorooctanesulfonate on Granular Activated Carbon Using Alkali and Alkaline-Earth Metal Additives DOI
Charbel Abou Khalil, L. V. Chernysheva, Anthony Miller

et al.

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(25), P. 11162 - 11174

Published: June 10, 2024

Thermal treatment has emerged as a promising approach for either the end-of-life or regeneration of granular activated carbon (GAC) contaminated with per- and polyfluoroalkyl substances (PFAS). However, its effectiveness been limited by requirement high temperatures, generation products incomplete destruction, necessity to scrub HF in flue gas. This study investigates use common alkali alkaline-earth metal additives enhance mineralization perfluorooctanesulfonate (PFOS) adsorbed onto GAC. When treated at 800 °C without an additive, only 49% PFOS was mineralized HF. All tested demonstrated improved mineralization, Ca(OH)2 had best performance, achieving efficiency 98% air N2. Its ability increase reaction rate shift byproduct selectivity suggests that role may be catalytic. Moreover, reduced gas instead reacting additive form inorganic fluorine (e.g., CaF2) starting waste material. A hypothesized mechanism is proposed involves electron transfer from O2– defect sites CaO intermediates formed during thermal decomposition PFOS. These findings advocate GAC disposal reuse, potential reduce operating costs mitigate environmental impact associated incinerating PFAS-laden wastes.

Language: Английский

Thermal Decomposition of Anionic, Zwitterionic, and Cationic Polyfluoroalkyl Substances in Aqueous Film-Forming Foams DOI
Feng Xiao, Pavankumar Challa Sasi,

Ali Alinezhad

et al.

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(14), P. 9885 - 9894

Published: July 8, 2021

In this study, we investigated thermal decomposition mechanisms of cationic, zwitterionic, and anionic polyfluoroalkyl substances, including those present in aqueous film-forming foam (AFFF) samples. We novel evidence that substances gave quantitative yields perfluoroalkyl different chain lengths during treatment. The results support a radical-mediated transformation mechanism involving random-chain scission end-chain scission, leading to the formation carboxylic acids such as perfluorooctanoic acid (PFOA) from certain amides sulfonamides. Our also direct (chain stripping) on nonfluorinated moiety sulfonamides, resulting perfluorooctanesulfonic (PFOS) other structurally related compounds. Thermal 8:2 fluorotelomer sulfonate occurred through recombination reactions, successively yielding PFOS. All studied began degrade at 200-300 °C, exhibiting near-complete ≥400 °C. Using high-resolution parent ion search method, demonstrated for first time low-temperature treatments AFFF samples led generation fluoroalkyl perfluoroheptanesulfonamide, sulfonic acid, N-methyl perfluorooctane sulfonamide, previously unreported compound N-2-propenyl-perfluorohexylsulfonamide. This study provides key insights into fate processes.

Language: Английский

Citations

62
Application of Hydrothermal Alkaline Treatment for Destruction of Per- and Polyfluoroalkyl Substances in Contaminated Groundwater and Soil DOI
Shilai Hao, Youn Jeong Choi, Rula A. Deeb

et al.

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(10), P. 6647 - 6657

Published: May 6, 2022

Hydrothermal alkaline treatment (HALT) can effectively degrade per- and polyfluoroalkyl substances (PFASs) present in aqueous film-forming foam (AFFF). However, information is lacking regarding the of PFASs actual groundwater soil from AFFF-impacted sites, especially for complex matrices. Given lack studies on direct PFAS destruction, we herein applied HALT to two samples three sites characterized destruction using high-resolution mass spectrometry. Results showed that 148 identified all collected field samples, including 10 cationic, 98 anionic, 40 zwitterionic PFASs, were mostly degraded nondetectable levels within 90 min when treated with 5 M NaOH at 350 °C. The near-complete defluorination, as evidenced by fluoride release measurements, confirmed complete PFASs. While many structures, perfluoroalkyl carboxylic acids polyfluorinated substances, readily degraded, sulfonates (PFSAs, CnF2n+1–SO3–), most notably short chain lengths (n = 3–5), more recalcitrant. Rates PFSA similar those measured laboratory water solutions, but reactions slow, presumably due base-neutralizing properties soil. Further, degradation groundwaters soils was found be a function reaction temperature, concentration, time. These findings have important implications remediation sites.

Language: Английский

Citations

52
Photodegradation of per- and polyfluoroalkyl substances in water: A review of fundamentals and applications DOI
Fuqiang Liu, Xiaohong Guan, Feng Xiao

et al.

Journal of Hazardous Materials, Journal Year: 2022, Volume and Issue: 439, P. 129580 - 129580

Published: July 16, 2022

Language: Английский

Citations

48
Review: Hydrothermal treatment of per- and polyfluoroalkyl substances (PFAS) DOI
Jianna Li, Brian R. Pinkard, Shuzhong Wang

et al.

Chemosphere, Journal Year: 2022, Volume and Issue: 307, P. 135888 - 135888

Published: Aug. 2, 2022

Language: Английский

Citations

47
PFOS destruction in a continuous supercritical water oxidation reactor DOI Creative Commons
Jianna Li, Conrad Austin, Stuart Moore

et al.

Chemical Engineering Journal, Journal Year: 2022, Volume and Issue: 451, P. 139063 - 139063

Published: Sept. 7, 2022

Language: Английский

Citations

42
The first quantitative investigation of compounds generated from PFAS, PFAS-containing aqueous film-forming foams and commercial fluorosurfactants in pyrolytic processes DOI Creative Commons

Bin Yao,

Runze Sun,

Ali Alinezhad

et al.

Journal of Hazardous Materials, Journal Year: 2022, Volume and Issue: 436, P. 129313 - 129313

Published: June 7, 2022

Language: Английский

Citations

39
Mechanistic Investigations of Thermal Decomposition of Perfluoroalkyl Ether Carboxylic Acids and Short-Chain Perfluoroalkyl Carboxylic Acids DOI Creative Commons

Ali Alinezhad,

Heng Shao,

Kateřina Litvanová

et al.

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(23), P. 8796 - 8807

Published: May 17, 2023

In this study, we investigated the thermal decomposition mechanisms of perfluoroalkyl ether carboxylic acids (PFECAs) and short-chain (PFCAs) that have been manufactured as replacements for phased-out per- polyfluoroalkyl substances (PFAS). C-C, C-F, C-O, O-H, C═C bond dissociation energies were calculated at M06-2X/Def2-TZVP level theory. The α-C carboxyl-C energy PFECAs declines with increasing chain length attachment an electron-withdrawing trifluoromethyl (-CF

Language: Английский

Citations

37
Role of Mineral–Organic Interactions in PFAS Retention by AFFF-Impacted Soil DOI
Thomas Wanzek, John Stults,

Mark G. Johnson

et al.

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(13), P. 5231 - 5242

Published: March 22, 2023

A comprehensive, generalized approach to predict the retention of per- and polyfluoroalkyl substances (PFAS) from aqueous film-forming foam (AFFF) by a soil matrix as function PFAS molecular physiochemical properties was developed. An AFFF with 34 major (12 anions 22 zwitterions) added uncontaminated in one-dimensional saturated column experiments mass retained measured. described using an exhaustive statistical generate poly-parameter quantitative structure–property relationship (ppQSPR). The relevant predictive were molar mass, fluorine, number nitrogens molecule, poorly crystalline Fe oxides, organic carbon, specific (BET-N2) surface area. anionic nearly independent largely hydrophobicity, size fluorinated side chain main predictor. Retention nitrogen-containing zwitterionic related metal oxides carbon content. Knowledge extent which suite may respond variations properties, developed here, paves way for development reactive transport algorithms ability capture dynamics source zones over extended time frames.

Language: Английский

Citations

29
Experimental investigations of Per- and Poly-fluoroalkyl substances (PFAS) degradation by non-thermal plasma in aqueous solutions DOI Creative Commons
David Alam, Samiuela Lee, Jungmi Hong

et al.

Journal of environmental chemical engineering, Journal Year: 2023, Volume and Issue: 11(6), P. 111588 - 111588

Published: Nov. 29, 2023

The treatability of perfluorocarboxylic acids (PFCA) (perfluorobutanoic acid (PFBA), perfluorohexanoic (PFHxA), perfluorooctanoic (PFOA) and perfluorodecanoic (PFDA)) perfluorosulfonic (PFSA) (PFBS, Perfluorooctanesulfonic PFHxS (PFOS)) via a bubble column with non-thermal plasma discharges in the argon headspace were investigated individual solutions from surface water sourced contaminated site. High degradation (>90%) could be achieved for PFOA, PFOS within 40 min treating water. Overall, correlated length perfluorinated carbon chain, decrease associated reduction backbone. Experiments prepared PFAS at initial concentrations 10, 25 50 μg/L found higher PFCA PFSA faster rates suggesting treatment efficiency was limited by mass transfer PFAS. Negligible breakdown observed PFBA any trialled, indicating limitations when more hydrophilic PFAS, which may require combining this approach polishing step, such as nanofiltration.

Language: Английский

Citations

27
Application of Hydrothermal Alkaline Treatment to Spent Granular Activated Carbon: Destruction of Adsorbed PFASs and Adsorbent Regeneration DOI
Ori Soker, Shilai Hao, Brian G. Trewyn

et al.

Environmental Science & Technology Letters, Journal Year: 2023, Volume and Issue: 10(5), P. 425 - 430

Published: April 10, 2023

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

Language: Английский

Citations

26