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Jiang Z, Denisov S, Adjei D, Mostafavi M, Ma J. Overlooked Activation Role of Sulfite in Accelerating Hydrated Electron Treatment of Perfluorosulfonates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:9427-9435. [PMID: 38747404 DOI: 10.1021/acs.est.4c01444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Photoexcitation of sulfite (SO32-) is often used to generate hydrated electrons (eaq-) in processes to degrade perfluoroalkyl and polyfluoroalkyl substances (PFASs). Conventional consensus discourages the utilization of SO32- concentrations exceeding 10 mM for effective defluorination. This has hindered our understanding of SO32- chemistry beyond its electron photogeneration properties. In contrast, the radiation-chemical study presented here, directly producing eaq- through water radiolysis, suggests that SO32- plays a previously overlooked activation role in the defluorination. Quantitative 60Co gamma irradiation experiments indicate that the increased SO32- concentration from 0.1 to 1 M enhances the defluorination rate by a remarkable 15-fold, especially for short-chain perfluoroalkyl sulfonate (PFSA). Furthermore, during the treatment of long-chain PFSA (C8F17-SO3-) with a higher concentration of SO32-, the intermediates of C8H17-SO3- and C3F7-COO- were observed, which are absent without SO32-. These observations highlight that a higher concentration of SO32- facilitates both reaction pathways: chain shortening and H/F exchange. Pulse radiolysis measurements show that elevated SO32- concentrations accelerate the bimolecular reaction between eaq- and PFSA by 2 orders of magnitude. 19F NMR measurements and theoretical simulations reveal the noncovalent interactions between SO32- and F atoms, which exceptionally reduce the C-F bond dissociation energy by nearly 40%. As a result, our study offers a more effective strategy for degrading highly persistent PFSA contaminants.
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Affiliation(s)
- Zhiwen Jiang
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
- Institute de Chimie Physique, UMR8000 CNRS/Université Paris-Saclay, Orsay 91405, France
| | - Sergey Denisov
- Institute de Chimie Physique, UMR8000 CNRS/Université Paris-Saclay, Orsay 91405, France
| | - Daniel Adjei
- Institute de Chimie Physique, UMR8000 CNRS/Université Paris-Saclay, Orsay 91405, France
| | - Mehran Mostafavi
- Institute de Chimie Physique, UMR8000 CNRS/Université Paris-Saclay, Orsay 91405, France
| | - Jun Ma
- School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China
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Liu Z, Jin B, Rao D, Bentel MJ, Liu T, Gao J, Men Y, Liu J. Oxidative Transformation of Nafion-Related Fluorinated Ether Sulfonates: Comparison with Legacy PFAS Structures and Opportunities of Acidic Persulfate Digestion for PFAS Precursor Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6415-6424. [PMID: 38528735 PMCID: PMC11008247 DOI: 10.1021/acs.est.3c06289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 03/09/2024] [Accepted: 03/11/2024] [Indexed: 03/27/2024]
Abstract
The total oxidizable precursor (TOP) assay has been extensively used for detecting PFAS pollutants that do not have analytical standards. It uses hydroxyl radicals (HO•) from the heat activation of persulfate under alkaline pH to convert H-containing precursors to perfluoroalkyl carboxylates (PFCAs) for target analysis. However, the current TOP assay oxidation method does not apply to emerging PFAS because (i) many structures do not contain C-H bonds for HO• attack and (ii) the transformation products are not necessarily PFCAs. In this study, we explored the use of classic acidic persulfate digestion, which generates sulfate radicals (SO4-•), to extend the capability of the TOP assay. We examined the oxidation of Nafion-related ether sulfonates that contain C-H or -COO-, characterized the oxidation products, and quantified the F atom balance. The SO4-• oxidation greatly expanded the scope of oxidizable precursors. The transformation was initiated by decarboxylation, followed by various spontaneous steps, such as HF elimination and ester hydrolysis. We further compared the oxidation of legacy fluorotelomers using SO4-• versus HO•. The results suggest novel product distribution patterns, depending on the functional group and oxidant dose. The general trends and strategies were also validated by analyzing a mixture of 100000- or 10000-fold diluted aqueous film-forming foam (containing various fluorotelomer surfactants and organics) and a spiked Nafion precursor. Therefore, (1) the combined use of SO4-• and HO• oxidation, (2) the expanded list of standard chemicals, and (3) further elucidation of SO4-• oxidation mechanisms will provide more critical information to probe emerging PFAS pollutants.
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Affiliation(s)
- Zekun Liu
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
- Claros
Technologies Inc., Minneapolis, Minnesota 55413, United States
| | - Bosen Jin
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Dandan Rao
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Michael J. Bentel
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Tianchi Liu
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Jinyu Gao
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yujie Men
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Jinyong Liu
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
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3
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Jin B, Zhu Y, Zhao W, Liu Z, Che S, Chen K, Lin YH, Liu J, Men Y. Aerobic Biotransformation and Defluorination of Fluoroalkylether Substances (ether PFAS): Substrate Specificity, Pathways, and Applications. ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS 2023; 10:755-761. [PMID: 37719205 PMCID: PMC10501197 DOI: 10.1021/acs.estlett.3c00411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 09/19/2023]
Abstract
Fluoroalkylether substances (ether PFAS) constitute a large group of emerging PFAS with uncertain environmental fate. Among them, GenX is the well-known alternative to perfluorooctanoic acid and one of the six proposed PFAS to be regulated by the U.S. Environmental Protection Agency. This study investigated the structure-biodegradability relationship for 12 different ether PFAS with a carboxylic acid headgroup in activated sludge communities. Only polyfluorinated ethers with at least one -CH2- moiety adjacent to or a C=C bond in the proximity of the ether bond underwent active biotransformation via oxidative and hydrolytic O-dealkylation. The bioreactions at ether bonds led to the formation of unstable fluoroalcohol intermediates subject to spontaneous defluorination. We further demonstrated that this aerobic biotransformation/defluorination could complement the advanced reduction process in a treatment train system to achieve more cost-effective treatment for GenX and other recalcitrant perfluorinated ether PFAS. These findings provide essential insights into the environmental fate of ether PFAS, the design of biodegradable alternative PFAS, and the development of cost-effective ether PFAS treatment strategies.
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Affiliation(s)
- Bosen Jin
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yiwen Zhu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Weiyang Zhao
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Zekun Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Shun Che
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Kunpeng Chen
- Department
of Environmental Sciences, University of
California, Riverside, California 92521, United States
| | - Ying-Hsuan Lin
- Department
of Environmental Sciences, University of
California, Riverside, California 92521, United States
| | - Jinyong Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yujie Men
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
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Tenorio R, Maizel AC, Schaefer CE, Higgins CP, Strathmann TJ. Application of High-Resolution Mass Spectrometry to Evaluate UV-Sulfite-Induced Transformations of Per- and Polyfluoroalkyl Substances (PFASs) in Aqueous Film-Forming Foam (AFFF). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:14774-14787. [PMID: 36162863 DOI: 10.1021/acs.est.2c03228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
UV-sulfite has been shown to effectively degrade per- and polyfluoroalkyl substances (PFASs) in single-solute experiments. We recently reported treatment of 15 PFASs, including perfluoroalkyl sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), and fluorotelomer sulfonic acids (FTSs), detected in aqueous film-forming foam (AFFF) using high-resolution liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) targeted analysis. Here, we extend the analysis within those original reaction solutions to include the wider set of PFASs in AFFF for which reactivity is largely unknown by applying recently established LC-QTOF-MS suspect screening and semiquantitative analysis protocols. Sixty-eight additional PFASs were detected (15 targeted + 68 suspect screening = 83 PFASs) with semiquantitative analysis, and their behavior was binned on the basis of (1) detection in untreated AFFF, (2) PFAS photogeneration, and (3) reactivity. These 68 structures account for an additional 20% of the total fluorine content in the AFFF (targeted + suspect screening = 57% of total fluorine content). Structure-reactivity trends were also revealed. During treatment, transformations of highly reactive structures containing sulfonamide (-SO2N-) and reduced sulfur groups (e.g., -S- and -SO-) adjacent to the perfluoroalkyl [F(CF2)n-] or fluorotelomer [F(CF2)n(CH2)2-] chain are likely sources of PFCA, PFSA, and FTS generation previously reported during the early stages of reactions. The results also show the character of headgroup moieties adjacent to the F(CF2)n-/F(CF2)n(CH2)2- chain (e.g., sulfur oxidation state, sulfonamide type, and carboxylic acids) and substitution along the F(CF2)n- chain (e.g., H-, ketone, and ether) together may determine chain length-dependent reactivity trends. The results highlight the importance of monitoring PFASs outside conventional targeted analytical methodologies.
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Affiliation(s)
- Raul Tenorio
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Avenue, Urbana, Illinois 61801, United States
- Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Andrew C Maizel
- Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
- Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, D.C. 20057, United States
| | - Charles E Schaefer
- CDM Smith, 110 Fieldcrest Avenue, Edison, New Jersey 08837, United States
| | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, United States
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Fennell BD, Odorisio A, McKay G. Quantifying Hydrated Electron Transformation Kinetics in UV-Advanced Reduction Processes Using the Re-,UV Method. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:10329-10338. [PMID: 35791772 DOI: 10.1021/acs.est.2c02003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ultraviolet advanced reduction processes (UV-ARP) have garnered significant attention recently for the degradation of several hard to treat contaminants, including recalcitrant per- and polyfluoroalkyl substances (PFAS). The rate of contaminant degradation in UV-ARP is directly related to the available hydrated electron concentration ([eaq-]). However, reports of [eaq-] and other parameters typically used to characterize photochemical systems are not widely reported in the UV-ARP literature. Deploying monochloroacetate as a probe compound, we developed a method (Re-,UV) to quantify the time-based hydrated electron concentration ([eaq]t) available for contaminant degradation relative to inputted UV fluence. Measured [eaq]t was then used to understand the impact of eaq- rate of formation and scavenging capacity on the degradation of two contaminants─nitrate and perfluorooctane sulfonate (PFOS)─in four source waters with varying background water quality. The results show that the long-term treatability of PFOS by UV-ARP is not significantly impacted by the initial eaq- scavenging conditions but rather is influenced by the presence of eaq- scavengers like dissolved organic carbon and bicarbonate. Lastly, using [eaq]t, degradation of nitrate and PFOS was modeled in the source waters. We demonstrate that the Re-,UV method provides an effective tool to assess UV-ARP treatment performance in a variety of source waters.
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Affiliation(s)
- Benjamin D Fennell
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
| | - Adam Odorisio
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
| | - Garrett McKay
- Zachry Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77845, United States
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Wen Y, Rentería-Gómez Á, Day GS, Smith MF, Yan TH, Ozdemir ROK, Gutierrez O, Sharma VK, Ma X, Zhou HC. Integrated Photocatalytic Reduction and Oxidation of Perfluorooctanoic Acid by Metal-Organic Frameworks: Key Insights into the Degradation Mechanisms. J Am Chem Soc 2022; 144:11840-11850. [PMID: 35732040 DOI: 10.1021/jacs.2c04341] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The high porosity and tunability of metal-organic frameworks (MOFs) have made them an appealing group of materials for environmental applications. However, their potential in the photocatalytic degradation of per- and polyfluoroalkyl substances (PFAS) has been rarely investigated. Hereby, we demonstrate that over 98.9% of perfluorooctanoic acid (PFOA) was degraded by MIL-125-NH2, a titanium-based MOF, in 24 h under Hg-lamp irradiation. The MOF maintained its structural integrity and porosity after three cycles, as indicated by its crystal structure, surface area, and pore size distribution. Based on the experimental results and density functional theory (DFT) calculations, a detailed reaction mechanism of the chain-shortening and H/F exchange pathways in hydrated electron (eaq-)-induced PFOA degradation were revealed. Significantly, we proposed that the coordinated contribution of eaq- and hydroxyl radical (•OH) is vital for chain-shortening, highlighting the importance of an integrated system capable of both reduction and oxidation for efficient PFAS degradation in water. Our results shed light on the development of effective and sustainable technologies for PFAS breakdown in the environment.
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Affiliation(s)
- Yinghao Wen
- Department of Civil and Environmental Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Ángel Rentería-Gómez
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Gregory S Day
- Framergy Inc., 800 Raymond Stotzer Pkwy, College Station, Texas 77945, United States
| | - Mallory F Smith
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Tian-Hao Yan
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Ray Osman K Ozdemir
- Framergy Inc., 800 Raymond Stotzer Pkwy, College Station, Texas 77945, United States
| | - Osvaldo Gutierrez
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Virender K Sharma
- Program for the Environment and Sustainability, Department of Environmental and Occupational Health, Texas A&M University, College Station, Texas 77843, United States
| | - Xingmao Ma
- Department of Civil and Environmental Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Hong-Cai Zhou
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.,Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States
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7
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Liu Z, Chen Z, Gao J, Yu Y, Men Y, Gu C, Liu J. Accelerated Degradation of Perfluorosulfonates and Perfluorocarboxylates by UV/Sulfite + Iodide: Reaction Mechanisms and System Efficiencies. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:3699-3709. [PMID: 35226468 PMCID: PMC9481055 DOI: 10.1021/acs.est.1c07608] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The addition of iodide (I-) in the UV/sulfite system (UV/S) significantly accelerated the reductive degradation of perfluorosulfonates (PFSAs, CnF2n+1SO3-) and perfluorocarboxylates (PFCAs, CnF2n+1COO-). Using the highly recalcitrant perfluorobutane sulfonate (C4F9SO3-) as a probe, we optimized the UV/sulfite + iodide system (UV/S + I) to degrade n = 1-7 PFCAs and n = 4, 6, 8 PFSAs. In general, the kinetics of per- and polyfluoroalkyl substance (PFAS) decay, defluorination, and transformation product formations in UV/S + I were up to three times faster than those in UV/S. Both systems achieve a similar maximum defluorination. The enhanced reaction rates and optimized photoreactor settings lowered the EE/O for PFCA degradation below 1.5 kW h m-3. The relatively high quantum yield of eaq- from I- made the availability of hydrated electrons (eaq-) in UV/S + I and UV/I two times greater than that in UV/S. Meanwhile, the rapid scavenging of reactive iodine species by SO32- made the lifetime of eaq- in UV/S + I eight times longer than that in UV/I. The addition of I- also substantially enhanced SO32- utilization in treating concentrated PFAS. The optimized UV/S + I system achieved >99.7% removal of most PFSAs and PFCAs and >90% overall defluorination in a synthetic solution of concentrated PFAS mixtures and NaCl. We extended the discussion over molecular transformation mechanisms, development of PFAS degradation technologies, and the fate of iodine species.
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Affiliation(s)
- Zekun Liu
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Zhanghao Chen
- State
Key Laboratory of Pollution Control and Resource Reuse, School of
the Environment, Nanjing University, Nanjing 210023, Jiangsu, China
| | - Jinyu Gao
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yaochun Yu
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
- Department
of Civil & Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yujie Men
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
- Department
of Civil & Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Cheng Gu
- State
Key Laboratory of Pollution Control and Resource Reuse, School of
the Environment, Nanjing University, Nanjing 210023, Jiangsu, China
| | - Jinyong Liu
- Department
of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
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