1
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Rasmusson K, Fagerlund F. Per- and polyfluoroalkyl substances (PFAS) as contaminants in groundwater resources - A comprehensive review of subsurface transport processes. CHEMOSPHERE 2024; 362:142663. [PMID: 38908440 DOI: 10.1016/j.chemosphere.2024.142663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 06/24/2024]
Abstract
Per- and polyfluorinated alkyl substances (PFAS) are persistent contaminants in the environment. An increased awareness of adverse health effects related to PFAS has further led to stricter regulations for several of these substances in e.g. drinking water in many countries. Groundwater constitutes an important source of raw water for drinking water production. A thorough understanding of PFAS subsurface fate and transport mechanisms leading to contamination of groundwater resources is therefore essential for management of raw water resources. A review of scientific literature on the subject of processes affecting subsurface PFAS fate and transport was carried out. This article compiles the current knowledge of such processes, mainly focusing on perfluoroalkyl acids (PFAA), in soil- and groundwater systems. Further, a compilation of data on transport parameters such as solubility and distribution coefficients, as well as, insight gained and conclusions drawn from the reviewed material are presented. As the use of certain fire-fighting foams has been identified as the major source of groundwater contamination in many countries, research related to this type of pollution source has been given extra focus. Uptake of PFAS in biota is outside the scope of this review. The review showed a large spread in the magnitude of distribution coefficients and solubility for individual PFAS. Also, it is clear that the influence of multiple factors makes site-specific evaluation of distribution coefficients valuable. This article aims at giving the reader a comprehensive overview of the subject, and providing a base for further work.
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Affiliation(s)
- Kristina Rasmusson
- Uppsala Water and Waste AB, Virdings allé 32B, SE-75450, Uppsala, Sweden.
| | - Fritjof Fagerlund
- Uppsala University, Department of Earth Sciences, Villavägen 16, 75236, Uppsala, Sweden
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2
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Brahana P, Patel R, Bharti B. Surface Science View of Perfluoroalkyl Acids (PFAAs) in the Environment. ACS ENVIRONMENTAL AU 2024; 4:173-185. [PMID: 39035868 PMCID: PMC11258754 DOI: 10.1021/acsenvironau.3c00079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/19/2024] [Accepted: 04/19/2024] [Indexed: 07/23/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) constitute a notorious category of anthropogenic contaminants, detected across various environmental domains. Among these PFAS, perfluoroalkyl acids (PFAAs) stand out as a focal point in discussions due to their historical industrial utilization and environmental prominence. Their extensive industrial adoption is a direct consequence of their remarkable stability and outstanding amphiphilic properties. However, these very traits that have made PFAAs industrially desirable also render them environmentally catastrophic, leading to adverse consequences for ecosystems. The amphiphilic nature of PFAAs has made them highly unique in the landscape of anthropogenic contaminants and, thereby, difficult to study. We believe that well-established principles from surface science can connect the amphiphilic nature of PFAAs to their accumulation and transport in the environment. Specifically, we discuss the role of interfacial science in describing the stability, interfacial uptake (air-liquid and solid-liquid), and wetting capability of PFAAs. Surface science principles can provide new insights into the environmental fate of PFAAs, as well as provide context on their deleterious effects on both the environment and human health.
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Affiliation(s)
- Philip
J. Brahana
- Cain Department of Chemical
Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Ruchi Patel
- Cain Department of Chemical
Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Bhuvnesh Bharti
- Cain Department of Chemical
Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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3
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Zhai Z, Zhang C, Chu L, Zhao Y, Zhou X, Zhang Y. Effective defluorination of novel hexafluoropropylene oxide oligomer acids under mild conditions by UV/sulfite/iodide: mechanisms and ecotoxicity. WATER RESEARCH 2024; 258:121804. [PMID: 38781621 DOI: 10.1016/j.watres.2024.121804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/08/2024] [Accepted: 05/18/2024] [Indexed: 05/25/2024]
Abstract
It has recently been discovered that HFPO-TA (a processing aid in the production of fluoropolymers) has high levels of bioaccumulation and biotoxicity. Hydrated electrons (eaq-) have been proposed to be potent nucleophiles that may decompose PFAS. Unlike previous studies in which the generation of eaq- was often restricted to anaerobic or highly alkaline environments, in this study, we applied the UV/SO32-/I- process under mild conditions of neutrality, low source chemical demand, and open-air, which achieved effective degradation (81.92 %, 0.834 h-1) and defluorination (48.99 %, 0.312 h-1) of HFPO-TA. With I- as the primary source of eaq-, SO32- acting as an I- regenerator and oxidizing substances scavenger, UV/SO32-/I- outperformed others under mild circumstances. The eaq- were identified as the main active species by quenching experiments and electron paramagnetic resonance (EPR). During degradation, the first site attacked by eaq- was the ether bond (C6-O7), followed by the generation of HFPO-DA, TFA, acetic and formic acid. Degradation studies of other HFPOs have shown that the defluorination of HFPOs was accompanied by a clear chain-length correlation. At last, toxicological experiments confirmed the safety of the process. This study updated our understanding of the degradation of newly PFASs and the application of eaq- mediated photoreductive approaches under mild conditions.
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Affiliation(s)
- Zhenyu Zhai
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Chaojie Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
| | - Liquan Chu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Yunmeng Zhao
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Xuefei Zhou
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Yalei Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
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4
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Liu S, Chen G, Shi Q, Gan J, Jin B, Men Y, Liu H. Promotive Effects of Chloride and Sulfate on the Near-Complete Destruction of Perfluorocarboxylates (PFCAs) in Brine via Hydrogen-tuned 185-nm UV Photolysis: Mechanisms and Kinetics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:10347-10356. [PMID: 38808621 PMCID: PMC11171456 DOI: 10.1021/acs.est.3c10552] [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: 12/14/2023] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/30/2024]
Abstract
Hydrogen-tuned 185 nm vacuum ultraviolet (VUV/H2) photolysis is an emerging technology to destroy per- and polyfluoroalkyl substance (PFAS) in brine. This study discovered the promotive effects of two major brine anions, i.e., chloride and sulfate in VUV/H2 photolysis on the hydrated electron (eaq-) generation and perfluorocarboxylates (PFCAs) destruction and established a kinetics model to elucidate the promotive effects on the steady-state concentration of eaq- ([eaq-]ss). Results showed that VUV/H2 achieved near-complete defluorination of perfluorooctanoic acid (PFOA) in the presence of up to 1000 mM chloride or sulfate at pH 12. The defluorination rate constant (kdeF) of PFOA peaked with a chloride concentration at 100 mM and with a sulfate concentration at 500 mM. The promotive effects of chloride and sulfate were attributed to an enhanced generation of eaq- via their direct VUV photolysis and conversion of additionally generated hydroxyl radical to eaq- by H2, which was supported by a linear correlation between the predicted [eaq-]ss and experimentally observed kdeF. The kdeF value increased from pH 9 to 12, which was attributed to the speciation of the H·/eaq- pair. Furthermore, the VUV system achieved >95% defluorination and ≥99% parent compound degradation of a concentrated PFCAs mixture in a synthetic brine, without generating any toxic perchlorate or chlorate.
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Affiliation(s)
- Sitao Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Gongde Chen
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Qingyang Shi
- Department
of Environmental Sciences, University of
California, Riverside, California 92521, United States
| | - Jay Gan
- Department
of Environmental Sciences, University of
California, Riverside, California 92521, United States
| | - Bosen Jin
- 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
| | - Haizhou Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
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5
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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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Chen B, Xu J, Zhu L. Controllable chemical redox reactions to couple microbial degradation for organic contaminated sites remediation: A review. J Environ Sci (China) 2024; 139:428-445. [PMID: 38105066 DOI: 10.1016/j.jes.2023.06.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/09/2023] [Accepted: 06/10/2023] [Indexed: 12/19/2023]
Abstract
Global environmental concern over organic contaminated sites has been progressively conspicuous during the process of urbanization and industrial restructuring. While traditional physical or chemical remediation technologies may significantly destroy the soil structure and function, coupling moderate chemical degradation with microbial remediation becomes a potential way for the green, economic, and efficient remediation of contaminated sites. Hence, this work systematically elucidates why and how to couple chemical technology with microbial remediation, mainly focused on the controllable redox reactions of organic contaminants. The rational design of materials structure, selective generation of reactive oxygen species, and estimation of degradation pathway are described for chemical oxidation. Meanwhile, current progress on efficient and selective reductions of organic contaminants (i.e., dechlorination, defluorination, -NO2 reduction) is introduced. Combined with the microbial remediation of contaminated sites, several consideration factors of how to couple chemical and microbial remediation are proposed based on both fundamental and practical points of view. This review will advance the understanding and development of chemical-microbial coupled remediation for organic contaminated sites.
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Affiliation(s)
- Bin Chen
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Agriculture & Forest University, Lin'an 311300, China
| | - Jiang Xu
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China.
| | - Lizhong Zhu
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University, Hangzhou 310058, China
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7
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Amador CK, Vyas S, Strathmann TJ. Kinetic Model for Predicting Perfluoroalkyl Acid Degradation During UV-Sulfite Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6425-6434. [PMID: 38554136 DOI: 10.1021/acs.est.3c10584] [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: 04/01/2024]
Abstract
Hydrated electron (eaq-) treatment processes show great potential in remediating recalcitrant water contaminants, including perfluoroalkyl and polyfluoroalkyl substances (PFAS). However, treatment efficacy depends upon many factors relating to source water composition, UV light source characteristics, and contaminant reactivity. Here, we provide critical insights into the complex roles of solution parameters on contaminant abatement through application of a UV-sulfite kinetic model that incorporates first-principles information on eaq- photogeneration and reactivity. The model accurately predicts decay profiles of short-chain perfluoroalkyl acids (PFAAs) during UV-sulfite treatment and facilitates quantitative interpretation of the effects of changing solution composition on PFAS degradation rates. Model results also confirm that the enhanced degradation of PFAAs observed under highly alkaline pH conditions results from changes in speciation of nontarget eaq- scavengers. Reverse application of the model to UV-sulfite data collected for longer chain PFAAs enabled estimation of bimolecular rate constants (k2, M-1 s-1), providing an alternative to laser flash photolysis (LFP) measurements that are not feasible due to the water solubility limitations of these compounds. The proposed model links the disparate means of investigating eaq- processes, namely, UV photolysis and LFP, and provides a framework to estimate UV-sulfite treatment efficacy of PFAS in diverse water sources.
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Affiliation(s)
- Camille K Amador
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Shubham Vyas
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
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8
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Qi Y, Yang Y, Cui S, Tang X, Zhang P, Wang C, Liang Y, Sun H, Ma C, Xing B. Novel Defluorination Pathways of Perfluoroether Compounds (GenX): α-Fe 2O 3 Nanoparticle Layer Retains Higher Concentrations of Effective Hydrated Electrons. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:5567-5577. [PMID: 38488517 DOI: 10.1021/acs.est.3c09879] [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: 03/27/2024]
Abstract
The development of efficient defluorination technology is an important issue because the kind of emerging pollutant of hexafluoropropylene oxide dimer acid (GenX) as an alternative to perfluorooctanoic acid (PFOA) has the higher environmental risks. In the UV/bisulfite system, we first developed a hydrophobic confined α-Fe2O3 nanoparticle layer rich in oxygen vacancies, which accelerated the enrichment of HSO3- and GenX on the surface and pores through electrostatic attraction and hydrophobic interaction, retaining more hydrated electrons (eaq-) and rapidly destroying GenX under UV excitation. Especially, under anaerobic and aerobic conditions, the degradation percentage of GenX obtain nearly 100%, defluorination of GenX to 88 and 57% respectively. It was amazed to find that the three parallel H/F exchange pathways triggered by the rapid reactions of eaq- and GenX, which were unique to anaerobic conditions, improved the efficiency of fluoride removal and weaken the interference of dissolved oxygen and H+. Therefore, this study provided an available material and mechanism for sustainable fluoride removal from wastewater in aerobic and anaerobic conditions.
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Affiliation(s)
- Yuwen Qi
- Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
| | - Yinbo Yang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300354, PR China
| | - Shengyan Cui
- Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
| | - Xuejiao Tang
- Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
| | - Peng Zhang
- Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
| | - Cuiping Wang
- Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
| | - Yanna Liang
- Department of Environmental and Sustainable Engineering, University at Albany, SUNY, Albany, New York 12222, United States
| | - Hongwen Sun
- Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, PR China
| | - Chuanxin Ma
- Key Laboratory for City Cluster Environmental Safety and Green Development of the Ministry of Education, School of Ecology, Environment and Resources, Guangdong University of Technology, Guangzhou 510006, PR China
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Tang Z, Vogel TM, Wang Q, Wei C, Ali M, Song X. Microbial defluorination of TFA, PFOA, and HFPO-DA by a native microbial consortium under anoxic conditions. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133217. [PMID: 38101019 DOI: 10.1016/j.jhazmat.2023.133217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 11/30/2023] [Accepted: 12/08/2023] [Indexed: 12/17/2023]
Abstract
In this study, the biodegradability of trifluoroacetate (TFA), perfluorooctanoic acid (PFOA), and perfluoro-2-methyl-3-oxahexanoic acid (HFPO-DA) by a native microbial community was evaluated over a 10-month incubation period. The observed microbial defluorination ratios and removal efficiency were 3.46 ( ± 2.73) % and 8.03 ( ± 3.03) %, 8.44 ( ± 1.88) % and 13.52 ( ± 4.96) %, 3.02 ( ± 0.62) % and 5.45 ( ± 2.99) % for TFA, PFOA and HFPO-DA, respectively. The biodegradation intermediate products, TFA and pentafluoropropionic acid (PFA), of PFOA and HFPO-DA were detected in their biodegradation treatment groups. Furthermore, the concentrations of the PFOA metabolites, perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA), in the aqueous solutions after incubation were quantified to be 0.21 and 4.14 µg/L. TFA, PFOA and HFPO-DA significantly reduced the microbial diversity and changed the structure of the community. The co-occurrence network analysis showed that low abundance species, such as Flexilinea flocculi, Bacteriovorax stolpii, and g_Sphingomonas, are positively correlated with the generation of fluoride ion, implying their potential collaborative functions contributing to the observed biodefluorination. The findings in this study can provide insights for the biodegradation of perfluoroalkyl carboxylic acids and their emerging alternatives by indigenous microorganisms in the environment.
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Affiliation(s)
- Zhiwen Tang
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Timothy M Vogel
- Ecologie Microbienne, Université Claude Bernard Lyon 1, Villeurbanne F-69622, France
| | - Qing Wang
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Changlong Wei
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Mukhtiar Ali
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Song
- Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Antonopoulou M, Spyrou A, Tzamaria A, Efthimiou I, Triantafyllidis V. Current state of knowledge of environmental occurrence, toxic effects, and advanced treatment of PFOS and PFOA. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 913:169332. [PMID: 38123090 DOI: 10.1016/j.scitotenv.2023.169332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 12/11/2023] [Accepted: 12/11/2023] [Indexed: 12/23/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are anthropogenic synthetic compounds, with high chemical and thermal stability and a persistent, stable and bioaccumulative nature that renders them a potential hazard for the environment, its organisms, and humans alike. Perfluorooctane sulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the most well-known substances of this category and even though they are phased out from production they are still highly detectable in several environmental matrices. As a result, they have been spread globally in water sources, soil and biota exerting toxic and detrimental effects. Therefore, up and coming technologies, namely advanced oxidation processes (AOPs) and advanced reduction processes (ARPs) are being tested for their implementation in the degradation of these pollutants. Thus, the present review compiles the current knowledge on the occurrence of PFOS and PFOA in the environment, the various toxic effects they have induced in different organisms as well as the ability of AOPs and ARPs to diminish and/or eliminate them from the environment.
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Affiliation(s)
- Maria Antonopoulou
- Department of Sustainable Agriculture, University of Patras, 30131 Agrinio, Greece.
| | - Alexandra Spyrou
- Department of Sustainable Agriculture, University of Patras, 30131 Agrinio, Greece
| | - Anna Tzamaria
- Department of Sustainable Agriculture, University of Patras, 30131 Agrinio, Greece
| | - Ioanna Efthimiou
- Department of Biology, Section of Genetics Cell Biology and Development, University of Patras, 26500 Patras, Greece
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11
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Chen Z, Dong R, Wang X, Huang L, Qiu L, Zhang M, Mi N, Xu M, He H, Gu C. Efficient Decomposition of Perfluoroalkyl Substances by Low Concentration Indole: New Insights into the Molecular Mechanisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 38329941 DOI: 10.1021/acs.est.3c08453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2024]
Abstract
Perfluoroalkyl substances (PFAS) are a class of persistent organic pollutants known as "forever chemicals". Currently, the hydrated electron-based advanced reduction process (ARP) holds promise for the elimination of PFAS. However, the efficiency of ARP is often challenged by an oxygen-rich environment, resulting in the consumption of hydrated electron source materials in exchange for the high PFAS decomposition efficiency. Herein, we developed a ternary system constructed by indole and isopropyl alcohol (IPA), and the addition of IPA significantly enhanced the PFOA degradation and defluorination efficiency in the presence of low-concentration indole (<0.4 mM). Meanwhile, opposite results were obtained with a higher amount of indole (>0.4 mM). Further exploring the molecular mechanism of the reaction system, the addition of IPA played two roles. On one hand, IPA built an anaerobic reaction atmosphere and improved the yield and utilization efficiency of hydrated electrons with a low concentration of indole. On the other hand, IPA suppressed the attraction between indole and PFOA, thus reducing the hydrated electron transfer efficiency, especially with more indole. In general, the indole/PFAS/IPA system significantly improved the PFAS destruction efficiency with a small amount of hydrated electron donors, which provided new insights for development of simple and efficient techniques for the treatment of PFAS-contaminated wastewater.
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Affiliation(s)
- Zhanghao Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Ruochen Dong
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Xinhao Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Liuqing Huang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Longlong Qiu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Ming Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
- Department of Environmental Engineering, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, P. R. China
| | - Na Mi
- Ministry of Ecology and Environment, Nanjing Institute of Environmental Science, Nanjing 210042, P. R. China
| | - Min Xu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Huan He
- School of Environment, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Cheng Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
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12
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Verma S, Mezgebe B, Hejase CA, Sahle-Demessie E, Nadagouda MN. Photodegradation and photocatalysis of per- and polyfluoroalkyl substances (PFAS): A review of recent progress. NEXT MATERIALS 2024; 2:1-12. [PMID: 38840836 PMCID: PMC11151751 DOI: 10.1016/j.nxmate.2023.100077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are oxidatively recalcitrant organic synthetic compounds. PFAS are an exceptional group of chemicals that have significant physical characteristics due to the presence of the most electronegative element (i.e., fluorine). PFAS persist in the environment, bioaccumulate, and have been linked to toxicological impacts. Epidemiological and toxicity studies have shown that PFAS pose environmental and health risks, requiring their complete elimination from the environment. Various separation technologies, including adsorption with activated carbon or ion exchange resin; nanofiltration; reverse osmosis; and destruction methods (e.g., sonolysis, thermally induced reduction, and photocatalytic dissociation) have been evaluated to remove PFAS from drinking water supplies. In this review, we will comprehensively summarize previous reports on the photodegradation of PFAS with a special focus on photocatalysis. Additionally, challenges associated with these approaches along with perspectives on the state-of-the-art approaches will be discussed. Finally, the photocatalytic defluorination mechanism of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) following complete mineralization will also be examined in detail.
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Affiliation(s)
- Sanny Verma
- Pegasus Technical Services INC., Cincinnati, OH 45219, USA
| | - Bineyam Mezgebe
- Groundwater Characterization and Remediation Division, Center for Environmental Solutions and Emergency Response, US EPA, Ada, OK 74820, USA
| | - Charifa A. Hejase
- Pegasus Technical Services INC., Cincinnati, OH 45219, USA
- Department of Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Endalkachew Sahle-Demessie
- Land Remediation and Technology Division, Center for Environmental Solutions and Emergency Response, US EPA, Cincinnati, OH 45268, USA
| | - Mallikarjuna N. Nadagouda
- Water Infrastructure Division, Center for Environmental Solutions and Emergency Response, US EPA, Cincinnati, OH 45268, USA
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13
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Wang Z, Jin X, Hong R, Wang X, Chen Z, Gao G, He H, Liu J, Gu C. New Indole Derivative Heterogeneous System for the Synergistic Reduction and Oxidation of Various Per-/Polyfluoroalkyl Substances: Insights into the Degradation/Defluorination Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:21459-21469. [PMID: 38056012 DOI: 10.1021/acs.est.3c05940] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
The hydrated electron (eaq-) system is typically suitable for degrading perfluoroalkyl substances (PFASs). To enhance eaq- utilization, we synthesized a new indole compound (DIHA) that forms stable nanospheres (100-200 nm) in water via a supramolecular assembly. Herein, the DIHA nanoemulsion system exhibits high degradation efficiencies toward a broad category of PFASs, regardless of the headgroup, chain length, and branching structure, under UV (254 nm) irradiation. The strong adsorption of PFAS on the DIHA surface ensures its effective degradation/defluorination. Quenching experiments further demonstrated that the reaction took place on the surface of DIHA nanospheres. This specific heterogeneous surface reaction unveiled novel PFAS degradation and defluorination mechanisms that differ from previously reported eaq- systems. First, the photogenerated surface electrons nonselectively attacked multiple C-F bonds of the -CF2- chain. This plays a dominant degrading/defluorinating role in the DIHA system. Second, abundant hydroxyl radicals (•OH) were also produced, leading to synergistic reduction (by surface electron) and oxidation (by surface •OH) in a single system. This facilitates faster and deeper defluorination of different structured PFASs through multiple pathways. The new mechanism inspires the design of innovative organo-heterogeneous eaq- systems possessing synergistic reduction and oxidation functions, thereby making them potentially effective for treating PFAS-contaminated water.
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Affiliation(s)
- Zhe Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Xin Jin
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
- School of Environment, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Ran Hong
- School of Chemical and Environmental Engineering, Anhui Polytechnic University, Wuhu 241000, P. R. China
| | - Xinhao Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Zhanghao Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Guandao Gao
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
| | - Huan He
- School of Environment, Nanjing Normal University, Nanjing 210023, P. R. China
| | - Jinyong Liu
- Department of Chemical & Environmental Engineering and Materials Science & Engineering Program, University of California, Riverside, California 92521, United States
| | - Cheng Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 210023, P. R. China
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14
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Vatankhah H, Anderson RH, Ghosh R, Willey J, Leeson A. A review of innovative approaches for onsite management of PFAS-impacted investigation derived waste. WATER RESEARCH 2023; 247:120769. [PMID: 37931356 DOI: 10.1016/j.watres.2023.120769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 10/19/2023] [Accepted: 10/20/2023] [Indexed: 11/08/2023]
Abstract
The historic use of aqueous film-forming foam (AFFF) has led to widespread detection of per- and polyfluoroalkyl substance (PFAS) in groundwater, soils, sediments, drinking water, wastewater, and receiving aquatic systems throughout the United States (U.S.). Prior to any remediation activities, in order to identify the PFAS-impacted source zones and select the optimum management approach, extensive site investigations need to be conducted. These site investigations have resulted in the generation of considerable amount of investigation-derived waste (IDW) which predominantly consists of well purging water and drill fluid, equipment washing residue, soil, drill cuttings, and residues from the destruction of asphalt and concrete surfaces. IDW is often impacted by varying levels of PFAS which poses a substantial challenge concerning disposal to prevent potential mobilization of PFAS, logistical complexities, and increasing requirement for storage as a result of accumulation of the associated wastes. The distinct features of IDW involve the intermittent generation of waste, substantial volume of waste produced, and the critical demand for onsite management. This article critically focuses on innovative technologies and approaches employed for onsite treatment and management of PFAS-impacted IDW. The overall objective of this study centers on developing and deploying end-of-life treatment technology systems capable of facilitating unrestricted disposal, discharge, and/or IDW reuse on-site, thereby reducing spatial footprints and mobilization time.
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Affiliation(s)
- Hooman Vatankhah
- Strategic Environmental Research and Development Program and the Environmental Security Technology Certification Program, Arlington, VA, USA; Oak Ridge Institute for Science and Education, Oak Ridge, TN, USA; Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.
| | | | | | | | - Andrea Leeson
- Strategic Environmental Research and Development Program and the Environmental Security Technology Certification Program, Arlington, VA, USA
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15
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Tomei G, Saleem M, Ceriani E, Pinton A, Marotta E, Paradisi C. Cold Plasma for Green Advanced Reduction/Oxidation Processes (AROPs) of Organic Pollutants in Water. Chemistry 2023; 29:e202302090. [PMID: 37621157 DOI: 10.1002/chem.202302090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/21/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
Cold plasma is gaining increasing attention as a novel tool to activate energy demanding chemical processes, including advanced reduction/oxidation processes (AROPs) of organic pollutants in water. The very complex milieu generated by discharges at the water/plasma interface comprises photons, strong oxidants and strong reductants which can be exploited for achieving the degradation of most any kind of pollutants. Despite the complexity of these systems, the powerful arsenal of mechanistic tools and chemical probes of physical organic chemists can be usefully applied to understand and develop plasma chemistry. Specifically, the added value of air plasma generated by in situ discharge with respect to ozonation (ex situ discharge) is demonstrated using phenol and various phenol derivatives and mechanistic evidence for the prevailing role of hydroxyl radicals in the initial attack is presented. On the reduction front, the impressive performance of cold plasma in inducing the degradation of recalcitrant perfluoroalkyl substances, which do not react with OH radicals but are attacked by electrons, is reported and discussed. The widely different reactivities of perfluorooctanoic acid (PFOA) and of perfluorobutanoic acid (PFBA) underline the crucial role played in these processes by the interface between plasma and solution and the surfactant properties of the treated pollutants.
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Affiliation(s)
- Giulia Tomei
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Mubbshir Saleem
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Elisa Ceriani
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Anna Pinton
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Ester Marotta
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Cristina Paradisi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
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16
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Biondo O, Tomei G, Saleem M, Sretenović GB, Magarotto M, Marotta E, Paradisi C. Products, reactive species and mechanisms of PFOA degradation in a self-pulsing discharge (SPD) plasma reactor. CHEMOSPHERE 2023; 341:139972. [PMID: 37640214 DOI: 10.1016/j.chemosphere.2023.139972] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/31/2023] [Accepted: 08/25/2023] [Indexed: 08/31/2023]
Abstract
Non-thermal plasma is a promising tool for novel technologies to treat water contaminated by recalcitrant pollutants. We report here on products, reactive species and mechanisms of the efficient degradation of perfluorooctanoic acid (PFOA) achieved with a self-pulsing discharge developed previously in our lab. Air or argon were used as plasma feed gas, ultrapure or tap water as aqueous medium. Identified organic intermediate products arise from chain-shortening and defluorination reactions, the latter achieving not only C-F to C-H exchange (hydro-de-fluorination), as reported in the literature, but also C-F to C-OH exchange (hydroxy-de-fluorination). In contrast with chain-shortening, yielding lower homologues of PFOA via selective cleavage of the C-C bond at the carboxylate group, defluorination occurs at various sites of the alkyl chain giving mixtures of different isomeric products. Plasma generated reactive species were investigated under all experimental conditions tested, using specific chemical probes and optical emission spectroscopy. Cross-analysis of the results revealed a striking direct correlation of energy efficiency for PFOA degradation and for production of plasma electrons. In contrast, no correlation was observed for emission bands of either Ar+ or OH radical. These results indicate a prevalent role of plasma electrons in initiating PFOA degradation using self-pulsing discharge plasma above the liquid.
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Affiliation(s)
- Omar Biondo
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Giulia Tomei
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Mubbshir Saleem
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
| | - Goran B Sretenović
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy; University of Belgrade, Faculty of Physics, PO Box 44, 11001, Belgrade, Serbia
| | - Mirko Magarotto
- Department of Industrial Engineering, University of Padova, Via Venezia 1, 35131, Padova, Italy; Department of Information Engineering, University of Padova, via Gradenigo 6/b, 35135, Padova, Italy
| | - Ester Marotta
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy.
| | - Cristina Paradisi
- Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131, Padova, Italy
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17
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Tsuda N, Honda Y, Schaefer E, Lian P, Muneer A, Blake TJ, Hammad LA. The environmental degradability of DEMNUM, a typical PFPE polymer. CHEMOSPHERE 2023:139331. [PMID: 37379990 DOI: 10.1016/j.chemosphere.2023.139331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 06/30/2023]
Abstract
The three environmental degradation tests of hydrolysis, indirect photolysis and Zahn-Wellens microbial degradation were conducted according to the OECD and the US EPA guidelines on DEMNUM, a typical linear perfluoropolyether polymer. Low mass degradation products that formed in each test were structurally characterized and indirectly quantified by liquid chromatography mass spectrometry (LC/MS) using a reference compound and an internal standard of similar structure. The degradation of the polymer was assumed to directly correlate with the appearance of lower mass species. The hydrolysis experiment at 50 °C showed the appearance of less than a dozen low mass species with increasing pH but at the negligible total estimated amount of ∼2 ppm relative to polymer. A dozen low mass perfluoro acid entities also appeared following the indirect photolysis experiment in synthetic humic water. Their maximum total amount was at ∼150 ppm relative to polymer. The largest amount of low mass species formed during the Zahn-Wellens biodegradation test amounted to only ∼80 ppm relative to polymer. The Zahn-Wellens conditions tended to produce larger low mass molecules than the ones formed under photolysis. The results from all three tests indicate that the polymer is stable and non-degradable in the environment.
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Affiliation(s)
- Nobuhiko Tsuda
- Daikin Industries, Ltd., 1-1 Nishi-Hitotsuya, Settsu-shi, Osaka, 566-8585, Japan.
| | - Yoshitaka Honda
- Daikin Industries, Ltd., 1-1 Nishi-Hitotsuya, Settsu-shi, Osaka, 566-8585, Japan
| | - Edward Schaefer
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Peizhi Lian
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Asmaa Muneer
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Timothy J Blake
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Loubna A Hammad
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
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18
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Isowamwen O, Li R, Holsen T, Thagard SM. Plasma-assisted degradation of a short-chain perfluoroalkyl substance (PFAS): Perfluorobutane sulfonate (PFBS). JOURNAL OF HAZARDOUS MATERIALS 2023; 456:131691. [PMID: 37236102 DOI: 10.1016/j.jhazmat.2023.131691] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/20/2023] [Accepted: 05/22/2023] [Indexed: 05/28/2023]
Abstract
This study investigates the degradation of perfluorobutane sulfonate (PFBS), a chemical compound belonging to a group of per- and polyfluoroalkyl substances (PFAS), by gas-phase electrical discharge plasma. Plasma alone was ineffective in degrading PFBS due to its poor hydrophobicity, which inhibited the compound from accumulating at the plasma-liquid interface, the region of chemical reactivity. To overcome bulk liquid mass transport limitations, a surfactant, hexadecyltrimethylammonium bromide (CTAB), was introduced to interact with and transport PFBS to the plasma-liquid interface. In the presence of CTAB, ∼99% of PFBS was removed from the bulk liquid and concentrated at the interface, where 67% of the concentrate was degraded and 43% of that amount was defluorinated within one hour. PFBS degradation was further improved by optimizing the surfactant concentration and dosage. Experiments with a range of cationic, non-ionic, and anionic surfactants revealed that the PFAS-CTAB binding mechanism is predominantly electrostatic. A mechanistic understanding of the PFAS-CTAB complex formation, its transport to and destruction at the interface is proposed, alongside the chemical degradation scheme, which includes the identified degradation byproducts. This study shows that surfactant-assisted plasma treatment is one of the most promising techniques for destroying short-chain PFAS in contaminated water.
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Affiliation(s)
- Osakpolo Isowamwen
- Department of Chemical and Biomolecular Engineering, Plasma Research Laboratory, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA
| | - Rui Li
- Department of Chemical and Biomolecular Engineering, Plasma Research Laboratory, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA
| | - Thomas Holsen
- Department of Civil and Environmental Engineering, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA
| | - Selma Mededovic Thagard
- Department of Chemical and Biomolecular Engineering, Plasma Research Laboratory, Clarkson University, 8 Clarkson Avenue, Potsdam, NY 13699, USA.
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19
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Hu Y, Zhan Y, Wei C, Chen F, Cheng J, Shen Y, Zhou Z, Wang L, Liang Y. Hydrochar coupled with iodide for efficient photodegradation of perfluorooctanoic acid and perfluorooctane sulfonic acid under ultraviolet light. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 868:161621. [PMID: 36649771 DOI: 10.1016/j.scitotenv.2023.161621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 06/17/2023]
Abstract
Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are typical emerging persistent organic pollutants that are raising concerns regarding their environmental persistence. The photodegradation of these chemicals in water can be promoted by generating hydrated electrons (eaq-). The present work demonstrates a highly efficient process combining ultraviolet (UV) radiation, hydrochar (H-BC) and KI that is capable of decomposing PFOA and PFOS. After 60 min of photolysis using this technique, 99.5 % and 94.1 % of the initial amounts of PFOA and PFOS in aqueous solution were degraded, respectively, with corresponding defluorination percentages of 87.8 % and 71.7 %, respectively. These degradation values were higher than the sum of those obtained using UV radiation with only H-BC or KI, implying a synergistic effect from the combination of H-BC and KI. This effect can be attributed to the unique structure and numerous oxygen-containing functional groups of the H-BC. This material was able to absorb PFOA and PFOS, reduce iodide oxidation products back to I-, act as an electron shuttle and shorten the diffusion distance to the target substrate. These factors all increased the probability of reactions between the contaminants and eaq-. Analyses by liquid chromatography/electrospray ionization/tandem mass spectrometry showed that short-chain perfluoroalkyl carboxylic acids with less than seven carbons were the primary degradation intermediates, suggesting that the photodegradation proceeded stepwise. These results confirmed the cooperative effect of the H-BC and iodide, leading to effective eaq- generation. This work is expected to facilitate the development of new strategies for the treatment of water systems contaminated with PFOA and PFOS.
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Affiliation(s)
- Yuning Hu
- Department of Chemistry, Wuhan University, Wuhan, PR China
| | - Yuhang Zhan
- Wuhan City College, Wuhan, PR China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
| | - Cuiyun Wei
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
| | - Fengjie Chen
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
| | - Jing Cheng
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
| | - Yunxiang Shen
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
| | - Zhen Zhou
- Department of Chemistry, Wuhan University, Wuhan, PR China; Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China.
| | - Ling Wang
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
| | - Yong Liang
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan, PR China
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20
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Bowers BB, Lou Z, Xu J, De Silva AO, Xu X, Lowry GV, Sullivan RC. Nontarget analysis and fluorine atom balances of transformation products from UV/sulfite degradation of perfluoroalkyl contaminants. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:472-483. [PMID: 36722905 DOI: 10.1039/d2em00425a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of highly fluorinated, anthropogenic compounds that are used in a wide variety of consumer applications. Due to their widespread use and high persistence, PFAS are ubiquitous in drinking water, which is of concern due to the threats these compounds pose to human health. Reduction via the hydrated electron is a promising technology for PFAS remediation and has been well-studied. However, since previous work rarely reports fluorine atom balances and often relies on suspect screening, some transformation products are likely unaccounted for. Therefore, we performed non-target analysis using high-resolution mass spectrometry on solutions of perfluorooctanesulfonate (PFOS), perfluorobutanesulfonate (PFBS), perfluorooctanoate (PFOA), and 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate (GenX) that had been treated with UV/sulfite to produce hydrated electrons. We determined fluorine atom balances for all compounds studied, finding high fluorine atom balances for PFOS and PFBS. PFOA and GenX had lower overall fluorine atom balances, likely due to the production of volatile or very polar transformation products that were not measured by our methods. Transformation products identified by our analysis were consistent with literature, with a few exceptions. Namely, shorter-chain perfluorosulfonates (PFSA) and their H/F substituted counterparts were also detected from PFOS. This is an unexpected result based on literature, as no documented pathway exists for the formation of shorter-chain PFSA during UV/sulfite treatment. Furthermore, the nontarget approach we employed allowed for identification of novel, unsaturated products from the hydrated electron treatment of perfluorooctanesulfonate (PFOS) that warrant further investigation.
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Affiliation(s)
- Bailey B Bowers
- Institute for Green Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Zimo Lou
- Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, Zhejiang University of Technology, Hangzhou, Zhejiang, China
| | - Jiang Xu
- College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China
| | - Amila O De Silva
- Environment and Climate Change Canada, Burlington, Ontario, L7S 1A1, Canada
| | - Xinhua Xu
- Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Gregory V Lowry
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Ryan C Sullivan
- Institute for Green Science, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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21
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Al Amin M, Luo Y, Nolan A, Mallavarapu M, Naidu R, Fang C. Thermal kinetics of PFAS and precursors in soil: Experiment and surface simulation in temperature-time plane. CHEMOSPHERE 2023; 318:138012. [PMID: 36720409 DOI: 10.1016/j.chemosphere.2023.138012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 01/16/2023] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are chemically and thermally stable due to the presence of carbon-fluorine (C-F) bond in their molecular structures, hence have been previously formulated as firefighting ingredients. During the firefighting process, however, owing to the high temperature, PFAS can be potentially degraded, particularly for PFAS precursors that contain non-C-F bonds, which is studied herein by exposing PFAS-contaminated soil in a muffle furnace oven. Different temperatures and time intervals are applied to the real soil sample to mimic the firing process and to evaluate the degradation and conversion of PFAS. This thermal treatment can not only degrade precursors (e.g. 6:2 fluorotelomer sulphonate), but also degrade perfluoroalkyl carboxylates (PFCA, e.g. perfluorooctanoic acid PFOA) and perfluoroalkyl sulfonates (PFSA, e.g. perfluorooctane sulfonate PFOS). The concentration dependence of the PFAS on temperature and time is fitted using a 2D Gaussian surface to simulate the complex thermal kinetic, and to compare with the traditional approach such as thermogravimetric analysis (TGA) (1D dependence on temperature only). The 2D simulation can directly visualise the thermal kinetic of individual or sum PFAS in the complex temperature-time plane, which depends on the sample background and particularly on the coexist PFAS precursors. Overall, this study provides a simple approach to monitor and optimise the thermal treatment of the PFAS-contaminated soil.
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Affiliation(s)
- Md Al Amin
- Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan NSW, 2308, Australia
| | - Yunlong Luo
- Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of Newcastle, Callaghan NSW, 2308, Australia
| | - Annette Nolan
- Ramboll Australia, The Junction, NSW, 2291, Australia
| | - Megharaj Mallavarapu
- Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of Newcastle, Callaghan NSW, 2308, Australia
| | - Ravi Naidu
- Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of Newcastle, Callaghan NSW, 2308, Australia
| | - Cheng Fang
- Global Centre for Environmental Remediation (GCER), University of Newcastle, Callaghan NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), University of Newcastle, Callaghan NSW, 2308, Australia.
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22
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Li Y, Lv L, Yang L, He L, Chen Y, Wu L, Zhang Z. Boosting degradation and defluorination efficiencies of PFBS in a vacuum-ultraviolet/S(Ⅳ) process with iodide involvement. CHEMOSPHERE 2023; 313:137531. [PMID: 36509188 DOI: 10.1016/j.chemosphere.2022.137531] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Perfluorobutane sulfonate (PFBS) is considered to be a promising alternative of perfluorooctane sulfonates (PFOS), while it is also hazardous. The UV/S (Ⅳ) system has been confirmed to be effective for PFOS removal from water, while it is inefficient for PFBS decomposition. A hybrid vacuum-ultraviolet (VUV)/S (Ⅳ)/KI process was investigated for the degradation of PFBS in aqueous solution. With KI involvement, the degradation rate of PFBS was boosted from 1.8802 μg h-1 up to 3.5818 μg h-1 in the VUV/S (Ⅳ) process. Alkaline conditions significantly increased the degradation efficiency of PFBS, which can be explained that S (Ⅳ) was dominated by SO32- rather than HSO3- and H2SO3 in alkaline conditions. Cl-, HCO3-, NO3-, NO2-, and HA would inhibit the performance of the VUV/S (Ⅳ)/KI process via various reactions. In addition, the toxicity of PFBS was significantly reduced by the VUV/S (Ⅳ)/KI process. Even in actual waters, the VUV/S (Ⅳ)/KI process also presented a satisfying performance in the degradation of PFBS.
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Affiliation(s)
- Yulong Li
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Lixin Lv
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Lie Yang
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China.
| | - Liuyang He
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Yulin Chen
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Li Wu
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China
| | - Zulin Zhang
- Hubei Key Laboratory of Mineral Resources Processing and Environment, School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, PR China; The James Hutton Institute, Craigiebuckler, Aberdeen, ABI5 8QH, UK
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23
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Saawarn B, Mahanty B, Hait S, Hussain S. Sources, occurrence, and treatment techniques of per- and polyfluoroalkyl substances in aqueous matrices: A comprehensive review. ENVIRONMENTAL RESEARCH 2022; 214:114004. [PMID: 35970375 DOI: 10.1016/j.envres.2022.114004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 07/04/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS), a class of synthetic organic pollutants, have prompted concerns about their global prevalence and possible health effects. This review consolidates the most recent data on different aspects of PFAS, such as their occurrence, and prominent sources. The current literature analysis of PFAS occurrence suggests significant variation in their concentration ranging from 0.025 to 1.2 × 108 ng/L in wastewater, 0.01 to 8.9 × 105 ng/L in surface water, and <0.01 to 1.3 × 104 ng/L in groundwater globally. Since conventional treatment techniques are inadequate in remediating PFAS, innovative treatment approaches based on their removal or mineralization mechanism have been comprehensively reviewed. Advanced treatment technologies have shown degradation or removal of PFAS to be around 6 and > 99.9% in different aqueous matrices. However, due to significant drawbacks in their applicability in wastewater treatment plants (WWTPs), a novel treatment train approach has emerged as an effective alternative. This approach synergistically integrates multiple remediation techniques while addressing the impediments of individual treatments. Furthermore, nanofiltration (NF270) combined with electrochemical degradation has been demonstrated to be the most efficient (>98%) treatment train approach in PFAS remediation. If implemented in WWTPs, nanofiltration followed by adsorption using activated carbon is also a viable method for PFAS removal.
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Affiliation(s)
- Bhavini Saawarn
- Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Bihar, 801 106, India
| | - Byomkesh Mahanty
- Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Bihar, 801 106, India
| | - Subrata Hait
- Department of Civil and Environmental Engineering, Indian Institute of Technology Patna, Bihar, 801 106, India.
| | - Sahid Hussain
- Department of Chemistry, Indian Institute of Technology Patna, Bihar, 801 106, India
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24
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Zhou Y, Lv H, Lin J, Lv T, Wang N, Tang H, Zhu L. Complete mechanochemical defluorination of perfluorooctanoic acid using Al 2O 3 and Al powders through matching electron-mediated reduction with decarboxylation. CHEMOSPHERE 2022; 307:135872. [PMID: 35934094 DOI: 10.1016/j.chemosphere.2022.135872] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
This work reports a mechanochemical (MC) method for complete defluorination of perfluorooctanoic acid (PFOA) by using Al and Al2O3 as milling agents. Both the Al/Al2O3 molar ratio ( [Formula: see text] ) and the pre-thermal treatment of Al2O3 strongly influenced the defluorination of PFOA. When commercial γ-Al2O3 was pre-treated at 1200 °C, the use of Al and heat-treated γ-Al2O3 with [Formula: see text] of 1: 1 led to PFOA defluorination of 100% after ball milling for 26 min at 350 rpm, being much higher than those (8.3%-58.1%) for using singlet milling agents or binary milling agents containing γ-Al2O3 pre-heated at temperatures lower than 700 °C. It was clarified that the carboxylate-mediated adsorption of PFOA on Al2O3 was essential for the MC decarboxylation as a degradation initiation step, and the in-situ generated electron on milled Al consequently caused the reductive dissociation of C-F bonds in the decarboxylation intermediate. A larger [Formula: see text] increased the in-situ electron generation rate (re), and a higher heat-treatment temperature decreased OH-/H2O adsorbed on Al2O3 to low the PFOA decarboxylation rate (rdec). The re/rdec ratio determined defluorination pathways, and the percentage of the defluorination of PFOA in its total degradation including the generation of any degradation intermediates increased linearly with increasing re/rdec.
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Affiliation(s)
- Yuqi Zhou
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan, 430074, PR China; Hubei Key Laboratory of Resources and Ecological Environment Geology, Hubei Geological Bureau, Wuhan, 430022, PR China
| | - Hanqing Lv
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan, 430074, PR China; School of Life Science, Jiaying University, Meizhou, 514015, PR China
| | - Jin Lin
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan, 430074, PR China
| | - Tianyu Lv
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan, 430074, PR China
| | - Nan Wang
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan, 430074, PR China.
| | - Heqing Tang
- College of Resources and Environmental, South-Central Minzu University, Wuhan, 430074, PR China
| | - Lihua Zhu
- Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan, 430074, PR China.
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25
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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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26
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Zhao Y, Zhang C, Chu L, Zhou Q, Huang B, Ji R, Zhou X, Zhang Y. Hydrated electron based photochemical processes for water treatment. WATER RESEARCH 2022; 225:119212. [PMID: 36223677 DOI: 10.1016/j.watres.2022.119212] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/03/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Hydrated electron (eaq-) based photochemical processes have emerged as a promising technology for contaminant removal in water due to the mild operating conditions. This review aims to provide a comprehensive and up-to-date summary on eaq- based photochemical processes for the decomposition of various oxidative contaminants. Specifically, the characteristics of different photo-reductive systems are first elaborated, including the environment required to generate sufficient eaq-, the advantages and disadvantages of each system, and the comparison of the degradation efficiency of contaminants induced by eaq-. In addition, the identification methods of eaq- (e.g., laser flash photolysis, scavenging studies, chemical probes and electron spin resonance techniques) are summarized, and the influences of operating conditions (e.g., solution pH, dissolved oxygen, source chemical concentration and UV type) on the performance of contaminants are also discussed. Considering the complexity of contaminated water, particular attention is paid to the influence of water matrix (e.g., coexisting anions, alkalinity and humic acid). Moreover, the degradation regularities of various contaminants (e.g., perfluorinated compounds, disinfection by-products and nitrate) by eaq- are summarized. We finally put forward several research prospects for the decomposition of contaminants by eaq- based photochemical processes to promote their practical application in water treatment.
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Affiliation(s)
- Yunmeng Zhao
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Chaojie Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
| | - Liquan Chu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Qi Zhou
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Baorong Huang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Ruixin Ji
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Xuefei Zhou
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China
| | - Yalei Zhang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
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27
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Jin X, Wang Z, Hong R, Chen Z, Wu B, Ding S, Zhu W, Lin Y, Gu C. Supramolecular assemblies of a newly developed indole derivative for selective adsorption and photo-destruction of perfluoroalkyl substances. WATER RESEARCH 2022; 225:119147. [PMID: 36206684 DOI: 10.1016/j.watres.2022.119147] [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] [Received: 06/15/2022] [Revised: 08/31/2022] [Accepted: 09/16/2022] [Indexed: 06/16/2023]
Abstract
Per-/polyfluoroalkyl substances (PFASs) contamination has caused worldwide health concerns, and increased demand for effective elimination strategies. Herein, we developed a new indole derivative decorated with a hexadecane chain and a tertiary amine center (named di-indole hexadecyl ammonium, DIHA), which can form stable nanospheres (100-200 nm) in water via supramolecular assembly. As the DIHA nanospheres can induce electrostatic, hydrophobic and van der Waals interactions (all are long-ranged) that operative cooperatively, in addition to the nano-sized particles with large surface area, the DIHA nanocomposite exhibited extremely fast adsorption rates (in seconds), high adsorption capacities (0.764-0.857 g g-1) and selective adsorption for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), outperformed the previous reported high-end PFASs adsorbents. Simultaneously, the DIHA nanospheres can produce hydrated electron (eaq-) when subjected to UV irradiation, with the virtue of constraining the photo-generated eaq- and the adsorbed PFOA/PFOS molecules entirely inside the nanocomposite. As such, the UV/DIHA system exhibits extremely high degradation/defluorination efficiency for PFOA/PFOS, even under ambient conditions, especially with the advantages of low chemical dosage requirement (μM level) and robust performance against environmental variables. Therefore, it is a new attempt of using supramolecular approach to construct an indole-based nanocomposite, which can elegantly combine adsorption and degradation functions. The novel DIHA nanoemulsion system would shed light on the treatment of PFAS-contaminated wastewater.
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Affiliation(s)
- Xin Jin
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 201123, China
| | - Zhe Wang
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 201123, China
| | - Ran Hong
- School of Chemical and Environmental Engineering, Anhui Polytechnic University, Wuhu 241000, China
| | - Zhanghao Chen
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 201123, China
| | - Bing Wu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 201123, China
| | - Shichao Ding
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA
| | - Wenlei Zhu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 201123, China.
| | - Yuehe Lin
- School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, USA
| | - Cheng Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of Environment, Nanjing University, Nanjing 201123, China.
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28
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Liu F, Guan X, Xiao F. Photodegradation of per- and polyfluoroalkyl substances in water: A review of fundamentals and applications. JOURNAL OF HAZARDOUS MATERIALS 2022; 439:129580. [PMID: 35905606 DOI: 10.1016/j.jhazmat.2022.129580] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/05/2022] [Accepted: 07/09/2022] [Indexed: 06/15/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent, mobile, and toxic chemicals that are hazardous to human health and the environment. Several countries, including the United States, plan to set an enforceable maximum contamination level for certain PFAS compounds in drinking water sources. Among the available treatment options, photocatalytic treatment is promising for PFAS degradation and mineralization in the aqueous solution. In this review, recent advances in the abatement of PFAS from water using photo-oxidation and photo-reduction are systematically reviewed. Degradation mechanisms of PFAS by photo-oxidation involving the holes (hvb+) and oxidative radicals and photo-reduction using the electrons (ecb-) and hydrated electrons (eaq-) are integrated. The recent development of innovative heterogeneous photocatalysts and photolysis systems for enhanced degradation of PFAS is highlighted. Photodegradation mechanisms of alternative compounds, such as hexafluoropropylene oxide dimer acid (GenX) and chlorinated polyfluorinated ether sulfonate (F-53B), are also critically evaluated. This paper concludes by identifying major knowledge gaps and some of the challenges that lie ahead in the scalability and adaptability issues of photocatalysis for natural water treatment. Development made in photocatalysts design and system optimization forges a path toward sustainable treatment of PFAS-contaminated water through photodegradation technologies.
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Affiliation(s)
- Fuqiang Liu
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China
| | - Xiaohong Guan
- School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China.
| | - Feng Xiao
- Department of Civil Engineering, University of North Dakota, 243 Centennial Drive Stop 8115, Grand Forks, ND 58202, United States.
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29
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DiMento BP, Tusei CL, Aeppli C. Photochemical degradation of short-chain chlorinated paraffins in aqueous solution by hydrated electrons and hydroxyl radicals. CHEMOSPHERE 2022; 303:134732. [PMID: 35525447 DOI: 10.1016/j.chemosphere.2022.134732] [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] [Received: 01/10/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
Short-chain chlorinated paraffins (SCCPs) are a complex mixture of polychlorinated alkanes (C10-C13, chlorine content 40-70%), and have been categorized as persistent organic pollutants. However, there are knowledge gaps about their environmental degradation, particularly the effectiveness and mechanism of photochemical degradation in surface waters. Photochemically-produced hydrated electrons (e-(aq)) have been shown to degrade highly chlorinated compounds in environmentally-relevant conditions more effectively than hydroxyl radicals (·OH), which can degrade a wide range of organic pollutants. This study aimed to evaluate the potential for e-(aq) and ·OH to degrade SCCPs. To this end, the degradation of SCCP model compounds was investigated under laboratory conditions that photochemically produced e-(aq) or ·OH. Resulting SCCP degradation rate constants for e-(aq) were on the same order of magnitude as well-known chlorinated pesticides. Experiments in the presence of ·OH yielded similar or higher second-order rate constants. Trends in e-(aq) and ·OH degradation rate constants of the investigated SCCPs were consistent with those of other chlorinated compounds, with higher chlorine content producing in higher rate constants for e-(aq) and lower for ·OH. Above a chlorine:carbon ratio of approximately 0.6, the e-(aq) second-order rate constants were higher than rate constants for ·OH reactions. Results of this study furthermore suggest that SCCPs are likely susceptible to degradation in sunlit surface waters, facilitated by dissolved organic matter as a source of photochemically produced e-(aq) and ·OH.
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Affiliation(s)
- Brian P DiMento
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr, East Boothbay, ME, USA; Colby College, 5750 Mayflower Hill Drive, Waterville, ME, 04901, USA.
| | - Cristina L Tusei
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr, East Boothbay, ME, USA; Humboldt State University, 1 Harpst St, Arcata, CA, USA
| | - Christoph Aeppli
- Bigelow Laboratory for Ocean Sciences, 60 Bigelow Dr, East Boothbay, ME, USA; Colby College, 5750 Mayflower Hill Drive, Waterville, ME, 04901, USA
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30
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Wang M, Cai Y, Zhou B, Yuan R, Chen Z, Chen H. Removal of PFASs from water by carbon-based composite photocatalysis with adsorption and catalytic properties: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 836:155652. [PMID: 35508243 DOI: 10.1016/j.scitotenv.2022.155652] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/24/2022] [Accepted: 04/28/2022] [Indexed: 05/27/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) are a class of persistent organic pollutants widely distributed in aquatic environments. The adsorption and photocatalytic methods have been widely used to remove PFASs in water because of their respective advantages. Still, they have apparent defects when used alone. Therefore, the adsorption and photocatalytic technologies are combined through suitable preparation methods, and the excellent properties of the two are used to synergize the treatment of organic pollutants. This strategy of "concentrating" pollutants and then degrading them in a centralized manner plays an essential role in removing trace PFASs. Nevertheless, a review focusing on this kind of adsorption photocatalyst system is lacking. This review will fill this gap and provide a reference for developing a carbon-based composite photocatalyst. Firstly, different carbon-based composite photocatalysts are reviewed in detail, focusing on the differences in various composite materials' excellent adsorption and catalytic properties. Secondly, the factors influencing the removal effect of carbon-based composite photocatalysts are discussed. Thirdly, the removal mechanism of carbon-based composite photocatalysts is summarized in detail. The removal process involves two steps: adsorption and photodegradation. The adsorption process involves multiple cooperative adsorption mechanisms, and photocatalytic degradation includes oxidative and reductive degradation. Fourthly, the comparison of adsorption-photocatalysis with common treatment techniques (including removal rate, range of adaptation, cost, and the possibility of expanding application) is summarized. Finally, the prospects of carbon-based composite photocatalysts for repairing PFASs are given by evaluating the performance of different composites.
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Affiliation(s)
- Mingran Wang
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Yanping Cai
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Beihai Zhou
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Rongfang Yuan
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zhongbing Chen
- Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16500 Prague, Czech Republic
| | - Huilun Chen
- Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China.
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31
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Cong Y, Shen L, Wang B, Cao J, Pan Z, Wang Z, Wang K, Li Q, Li X. Efficient removal of Cr(VI) at alkaline pHs by sulfite/iodide/UV: Mechanism and modeling. WATER RESEARCH 2022; 222:118919. [PMID: 35933816 DOI: 10.1016/j.watres.2022.118919] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/16/2022] [Accepted: 07/27/2022] [Indexed: 06/15/2023]
Abstract
Efficient removal of toxic hexavalent chromium (Cr(VI)) under alkaline conditions is still a challenge due to the relatively low reactivity of CrO42-. This study proposed a new sulfite/iodide/UV process to remove Cr(VI). The removal of Cr(VI) followed pseudo-zero-order kinetics at alkaline pHs, and was enhanced by sulfite and iodide with synergy. Compared with sulfite/UV, iodide in sulfite/iodide/UV showed about 40 times higher concentration-normalized enhancement for Cr(VI) removal, and reduced the requirement of sulfite ([S(IV)]0/[Cr(VI)]0 of about 2.1:1) by more than 90%. The Cr(VI) removal was accelerated by decreasing pH and by increasing temperature, and was slightly influenced by dissolved oxygen, carbonate, and humic acid. The process was still effective in real surface water and industrial wastewater. Mechanism and pathways of Cr(VI) removal were revealed by quenching experiments, competition kinetic analysis, product identification and quantification, and mass and electron balance. Both eaq- and SO3•- were responsible for Cr(VI) removal, making contributions of about 75% and 25%, respectively. When eaq- mainly reacted with Cr(VI), SO3•- participated in reduction of Cr(V) and Cr(IV) intermediates, with Cr(III), S2O62-, and SO42- as the final products. A model was developed to predict removal kinetics of Cr(VI), and well interpreted the roles of S(IV) and iodide in the process. This study sheds light on mechanism of Cr(VI) removal at alkaline pHs by kinetic modeling, and thus advances the applicability of this promising process for water decontamination.
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Affiliation(s)
- Yanqing Cong
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Lidong Shen
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Baimei Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Jianlai Cao
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Zixuan Pan
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Ziyu Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Kai Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Qiangbiao Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China
| | - Xuchun Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou 310018, China.
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32
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Üner NB, Baldaguez Medina P, Dinari JL, Su X, Sankaran RM. Rate, Efficiency, and Mechanisms of Electrochemical Perfluorooctanoic Acid Degradation with Boron-Doped Diamond and Plasma Electrodes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:8975-8986. [PMID: 35838411 DOI: 10.1021/acs.langmuir.2c01227] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The removal of per- or polyfluorinated alkyl substances (PFAS) has received increasing attention because of their extreme stability, our increasing awareness of their toxicity at even low levels, and scientific challenges for traditional treatment methods such as separation by activated carbon or destruction by advanced oxidation processes. Here, we performed a direct and systematic comparison of two electrified approaches that have recently shown promise for effective degradation of PFAS: plasma and conventional electrochemical degradation. We tailored a reactor configuration where one of the electrodes could be a plasma or a boron-doped diamond (BDD) electrode and operated both electrodes galvanostatically by continuous direct current. We show that while both methods achieved near-complete degradation of PFAS, the plasma was only effective as the cathode, whereas the BDD was only effective as the anode. Compared to the BDD, plasma required more than an order of magnitude higher voltage but lower current to achieve similar degradation efficiency with more rapid degradation kinetics. All these factors considered, it was noted that plasma or BDD degradation resulted in similar energy efficiencies. The BDD electrode exhibited zero-order kinetics, and thus, PFAS degradation using the conventional electrochemical method was kinetically controlled. On the contrary, analysis using a film model indicated that the plasma degradation kinetics of PFAS using plasma were mass-transfer-controlled because of the fast reaction kinetics. With the help of a simple quantitative model that incorporates mass transport, interfacial reaction, and surface accumulation, we propose that the degradation reaction kinetically follows an Eley-Rideal-type mechanism for the plasma electrode, and an intrinsic rate constant of 2.89 × 108 m4 mol-1 s-1 was obtained accordingly. The investigation shows that to realize the true kinetic potential of plasma degradation for water treatment, mass transfer to the interface must be enhanced.
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Affiliation(s)
- Necip B Üner
- Department of Nuclear, Plasma and Radiological Engineering, University Illinois at Urbana-Champaign, Urbana 61801, Illinois, United States
- Chemical Engineering Department, Middle East Technical University, Ankara 06800, Turkey
| | - Paola Baldaguez Medina
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana 61801, Illinois, United States
| | - Jasmine L Dinari
- Department of Nuclear, Plasma and Radiological Engineering, University Illinois at Urbana-Champaign, Urbana 61801, Illinois, United States
| | - Xiao Su
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana 61801, Illinois, United States
| | - R Mohan Sankaran
- Department of Nuclear, Plasma and Radiological Engineering, University Illinois at Urbana-Champaign, Urbana 61801, Illinois, United States
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33
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Zhu Y, Ji H, He K, Blaney L, Xu T, Zhao D. Photocatalytic degradation of GenX in water using a new adsorptive photocatalyst. WATER RESEARCH 2022; 220:118650. [PMID: 35640506 DOI: 10.1016/j.watres.2022.118650] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 05/19/2022] [Accepted: 05/21/2022] [Indexed: 06/15/2023]
Abstract
GenX, the ammonium salt of hexafluoropropylene oxide dimer acid, has been used as a replacement for perfluorooctanoic acid. Due to its widespread uses, GenX has been detected in waters around the world amid growing concerns about its persistence and adverse health effects. As relevant regulations are rapidly evolving, new technologies are needed to cost-effectively remove and degrade GenX. In this study, we developed an adsorptive photocatalyst by depositing a small amount (3 wt.%) of bismuth (Bi) onto activated-carbon supported titanate nanotubes, Bi/TNTs@AC, and tested the material for adsorption and subsequent solid-phase photodegradation of GenX. Bi/TNTs@AC at 1 g/L was able to adsorb GenX (100 µg/L, pH 7.0) within 1 h, and then degrade 70.0% and mineralize 42.7% of pre-sorbed GenX under UV (254 nm) in 4 h. The efficient degradation also regenerated the material, allowing for repeated uses without chemical regeneration. Material characterizations revealed that the active components of Bi/TNTs@AC included activated carbon, anatase, and Bi nanoparticles with a metallic Bi core and an amorphous Bi2O3 shell. Electron paramagnetic resonance spin-trapping, UV-vis diffuse reflectance spectrometry, and photoluminescence analyses indicated the superior photoactivity of Bi/TNTs@AC was attributed to enhanced light harvesting and generation of charge carriers due to the UV-induced surface plasmon resonance effect, which was enabled by the metallic Bi nanoparticles. •OH radicals and photogenerated holes (h+) were responsible for degradation of GenX. Based on the analysis of degradation byproducts and density functional theory calculations, photocatalytic degradation of GenX started with cleavage of the carboxyl group and/or ether group by •OH, h+, and/or eaq-, and the resulting intermediates were transformed into shorter-chain fluorochemicals following the stepwise defluorination mechanism. Bi/TNTs@AC holds the potential for more cost-effective degradation of GenX and other per- and polyfluorinated alkyl substances.
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Affiliation(s)
- Yangmo Zhu
- Department of Civil & Environmental Engineering, Auburn University, Auburn, AL 36849, USA
| | - Haodong Ji
- School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Ke He
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, MD 21250, USA
| | - Lee Blaney
- Department of Chemical, Biochemical, and Environmental Engineering, University of Maryland Baltimore County, MD 21250, USA
| | - Tianyuan Xu
- School of Resource and Geosciences, China University of Mining and Technology, Xuzhou, Jiangsu 221116, China.
| | - Dongye Zhao
- Department of Civil & Environmental Engineering, Auburn University, Auburn, AL 36849, USA.
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34
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Chen Y, Ma H, Zhu J, Gu Y, Liu T. New insights into ferric iron-facilitated UV 254 photolytic defluorination of perfluorooctanoic acid (PFOA): Combined experimental and theoretical study. JOURNAL OF HAZARDOUS MATERIALS 2022; 434:128865. [PMID: 35405606 DOI: 10.1016/j.jhazmat.2022.128865] [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] [Received: 01/17/2022] [Revised: 03/14/2022] [Accepted: 04/02/2022] [Indexed: 06/14/2023]
Abstract
UV/Fe3+-facilitated PFOA defluorination was often reported and recognized to proceed through a "ligand-to-metal charge transfer (LMCT)" mechanism in the literatures. Sufficient Fe3+ supply is important for sustaining the LMCT reaction pathway. In this study, an interesting "excessive defluorination" was observed, even the continuous Fe3+ supply was cut off, implying a parallel mechanism strengthening PFOA defluorination. Based the results of intermediate products detection, 19F NMR analysis, and exploration of electron density alternation, transition energy evolution, and bonds characteristics, remarkable electron density perturbation in [PFOA-Fe]2+ was revealed. This effect was triggered by the complexation between PFOA anion and Fe3+, diminishing electron shielding on the perfluorinated carbon chain. Hence, the dissociation energy of C-C bonds was reduced by maximally 53% (C4-C5). Once attacked by high-flux UV254 photons, the perfluorinated carbon chain underwent scission, and subsequent defluorination was achieved via hydrolysis reactions. This parallel mechanism cooperated with the LMCT mechanism, leading to the observed "excessive defluorination." The degree of UV/Fe3+-synergized PFOA defluorination depended on UV254 photon flux and Fe3+ dosage. High UV254 intensity guaranteed fast defluorination kinetics. A [Fe3+]/[PFOA] molar ratio near 1 showed the best UV/Fe3+ synergic effect on PFOA defluorination.
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Affiliation(s)
- Yihua Chen
- Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China
| | - Hang Ma
- Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China
| | - Jiaxin Zhu
- Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China
| | - Yurong Gu
- Shenzhen Polytechnic, Shenzhen 518055, PR China
| | - Tongzhou Liu
- Harbin Institute of Technology (Shenzhen), Shenzhen 518055, PR China.
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35
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Fennell B, Mezyk SP, McKay G. Critical Review of UV-Advanced Reduction Processes for the Treatment of Chemical Contaminants in Water. ACS ENVIRONMENTAL AU 2022; 2:178-205. [PMID: 37102145 PMCID: PMC10114900 DOI: 10.1021/acsenvironau.1c00042] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
UV-advanced reduction processes (UV-ARP) are an advanced water treatment technology characterized by the reductive transformation of chemical contaminants. Contaminant abatement in UV-ARP is most often accomplished through reaction with hydrated electrons (eaq -) produced from UV photolysis of chemical sensitizers (e.g., sulfite). In this Review, we evaluate the photochemical kinetics, substrate scope, and optimization of UV-ARP. We find that quantities typically reported in photochemical studies of natural and engineered systems are under-reported in the UV-ARP literature, especially the formation rates, scavenging capacities, and concentrations of key reactive species like eaq -. The absence of these quantities has made it difficult to fully evaluate the impact of operating conditions and the role of water matrix components on the efficiencies of UV-ARP. The UV-ARP substrate scope is weighted heavily toward contaminant classes that are resistant to degradation by advanced oxidation processes, like oxyanions and per- and polyfluoroalkyl substances. Some studies have sought to optimize the UV-ARP treatment of these contaminants; however, a thorough evaluation of the impact of water matrix components like dissolved organic matter on these optimization strategies is needed. Overall, the data compilation, analysis, and research recommendations provided in this Review will assist the UV-ARP research community in future efforts toward optimizing UV-ARP systems, modeling the eaq --based chemical transformation kinetics, and developing new UV-ARP systems.
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Affiliation(s)
- Benjamin
D. Fennell
- Zachry
Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77843, United States
| | - Stephen P. Mezyk
- Department
of Chemistry and Biochemistry, California
State University, Long Beach, Long Beach, California 90840, United States
| | - Garrett McKay
- Zachry
Department of Civil & Environmental Engineering, Texas A&M University, College Station, Texas 77843, United States
- . Phone: 979-458-6540
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36
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Li J, Li B, Pan H, Wei Y, Yang Y, Xu N, Chen B, Mohseni M, Esfahani EB. Total organic fluorine (TOF) analysis by completely converting TOF into fluoride with vacuum ultraviolet. JOURNAL OF HAZARDOUS MATERIALS 2022; 429:128389. [PMID: 35236042 DOI: 10.1016/j.jhazmat.2022.128389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/17/2022] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Quantifying total organic fluorine (TOF) in water is vital in monitoring the occurrence and persistence of all fluorine-containing organic compounds in the environment, while currently most studies focus on analyzing individual fluorine-containing organic compounds. To fill the technology gap, we herein proposed to convert TOF completely into fluoride with vacuum ultraviolet (VUV) photolysis, followed by analysis of fluoride with ion chromatography. Results showed that the tailored VUV photoreactor achieved satisfying recoveries of fluorine from ten model TOF compounds not only in ultrapure water (83.9 ± 2.0% to 109.4 ± 0.8%) but also in real water samples (92.1 ± 1.0%-106.2 ± 15.7%). Unlike other ultraviolet-based processes that favor alkaline conditions, this VUV process preferred either neutral or acidic conditions to defluorinate selected compounds. While the mechanisms remain to be explored in the future, it has been evidenced that the photo-degradation and photo-defluorination rates of these TOF compounds varied significantly among compounds and operation conditions. The method obtained a method detection limit (MDL) of 0.15 μg-F/L, which is lower than the MDLs of many other TOF analytical methods, along with excellent calibration curves for concentrations ranging from 0.01 to 10.0 mg-F/L. Notably, minimizing fluoride in sample prior to photoconversion was necessary to avoid subtraction-induced errors for TOF measurement, especially when the fluoride/TOF ratio was high. The robust VUV is also green for sample pretreatment due to its unreliance of chemicals or additives.
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Affiliation(s)
- Juan Li
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Shenzhen 518055, China
| | - Boqiang Li
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Shenzhen 518055, China
| | - Huimei Pan
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Shenzhen 518055, China
| | - Yiya Wei
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Shenzhen 518055, China
| | - Yang Yang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Shenzhen 518055, China
| | - Nan Xu
- School of Environment and Energy, Peking University, China
| | - Baiyang Chen
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Shenzhen 518055, China.
| | - Madjid Mohseni
- Department of Chemical & Biological Engineering University of British Columbia Vancouver, BC V6T 1Z3, Canada
| | - Ehsan Banayan Esfahani
- Department of Chemical & Biological Engineering University of British Columbia Vancouver, BC V6T 1Z3, Canada
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37
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Niu Y, Yang Z, Wang J, Zhou Y, Wang H, Wu S, Xu R. Decomposition of perfluorooctanoic acid from wastewater using coating electrode: efficiency, the anode characteristics and degradation mechanism. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120734] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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38
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Cao H, Zhang W, Wang C, Liang Y, Sun H. Photodegradation of F-53B in aqueous solutions through an UV/Iodide system. CHEMOSPHERE 2022; 292:133436. [PMID: 34968513 DOI: 10.1016/j.chemosphere.2021.133436] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 12/20/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
Advanced reduction by strong reducing hydrated electrons is a promising approach to degrade per- and polyfluoroalkyl substances (PFAS). This research aimed to investigate the effectiveness of UV/Iodide system for 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA, F-53B) degradation in aqueous solutions. Results from this work demonstrated that UV irradiation with an addition of 0.3 mM KI resulted in 55.99% degradation of F-53B within 15 min and almost 100% within 2 h. The defluorination efficiency of F-53B in the UV/Iodide system was 2.6 times higher than that in the sole UV system after 2 h of irradiation. The degradation efficiency of F-53B was not significantly affected by air purging. The defluorination efficiency with air bubbling, however, was 14.57% lower than that with nitrogen purging. The photodegradation of F-53B in the UV/Iodide system could be well described by a pseudo-first-order kinetic model. Degradation rate constant of F-53B correlated positively with the initial concentration. At 20 μg/L, the pseudo-first-order rate constant was 5.641 × 10-2 min-1 and the half-life was 12.29 min. Higher initial concentration also required less energy input to achieve the same degradation efficiency. The detection and identification of degradation intermediates implied that destruction of F-53B started from dechlorination and followed by continuously "flaking off" CF2 units.
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Affiliation(s)
- Huimin Cao
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, PR China; Department of Environmental and Sustainable Engineering, University at Albany, SUNY, Albany, NY, 12222, USA
| | - Weilan Zhang
- Department of Environmental and Sustainable Engineering, University at Albany, SUNY, Albany, NY, 12222, USA
| | - Cuiping Wang
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, PR China.
| | - Yanna Liang
- Department of Environmental and Sustainable Engineering, University at Albany, SUNY, Albany, NY, 12222, USA.
| | - Hongwen Sun
- College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, PR China
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39
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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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40
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Wackett LP. Nothing lasts forever: understanding microbial biodegradation of polyfluorinated compounds and perfluorinated alkyl substances. Microb Biotechnol 2022; 15:773-792. [PMID: 34570953 PMCID: PMC8913905 DOI: 10.1111/1751-7915.13928] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/12/2021] [Accepted: 09/13/2021] [Indexed: 12/20/2022] Open
Abstract
Poly- and perfluorinated chemicals, including perfluorinated alkyl substances (PFAS), are pervasive in today's society, with a negative impact on human and ecosystem health continually emerging. These chemicals are now subject to strict government regulations, leading to costly environmental remediation efforts. Commercial polyfluorinated compounds have been called 'forever chemicals' due to their strong resistance to biological and chemical degradation. Environmental cleanup by bioremediation is not considered practical currently. Implementation of bioremediation will require uncovering and understanding the rare microbial successes in degrading these compounds. This review discusses the underlying reasons why microbial degradation of heavily fluorinated compounds is rare. Fluorinated and chlorinated compounds are very different with respect to chemistry and microbial physiology. Moreover, the end product of biodegradation, fluoride, is much more toxic than chloride. It is imperative to understand these limitations, and elucidate physiological mechanisms of defluorination, in order to better discover, study, and engineer bacteria that can efficiently degrade polyfluorinated compounds.
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Affiliation(s)
- Lawrence P. Wackett
- Department of Biochemistry, Molecular Biology and BiophysicsUniversity of MinnesotaSt. PaulMN55108USA
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41
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Fenti A, Jin Y, Rhoades AJH, Dooley GP, Iovino P, Salvestrini S, Musmarra D, Mahendra S, Peaslee GF, Blotevogel J. Performance testing of mesh anodes for in situ electrochemical oxidation of PFAS. CHEMICAL ENGINEERING JOURNAL ADVANCES 2022. [DOI: 10.1016/j.ceja.2021.100205] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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42
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Cao H, Peng J, Zhou Z, Sun Y, Wang Y, Liang Y. Insight into the defluorination ability of per- and polyfluoroalkyl substances based on machine learning and quantum chemical computations. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 807:151018. [PMID: 34662613 DOI: 10.1016/j.scitotenv.2021.151018] [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] [Received: 09/23/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 06/13/2023]
Abstract
UV-generated hydrated electrons play a critical role in the defluorination reaction of poly- and perfluoroalkyl substances (PFAS). However, limited experimental data hinder insight into the effects of the structural characteristics of emerging PFAS on their defluorination abilities. Therefore, in this study, we adopted quantity structure-activity relationship models based on machine learning algorithms to develop the predictive models of the relative defluorination ability of PFAS. Five-fold cross-validations were used to perform the hyperparameter tuning of the models, which suggested that the gradient boosting algorithms with PaDEL descriptors as the best model possessed superior predictive performance (R2test = 0.944 and RMSEtest = 0.114). The importance of the descriptor indicated that the electrostatic properties and topological structure of the compounds significantly affected the defluorination ability of the PFAS. For the emerging PFAS the best model showed that most compounds, such as potential alternatives of perfluorooctane sulfonic acid, were recalcitrant to reductive defluorination, whereas perfluoroalkyl ether carboxylic acids had relatively stronger defluorination abilities than perfluorooctanoic acid. The theoretical calculations implied that additional electrons on PFAS could cause molecular deconstruction, such as changes in the dihedral angle involved in the carbon chain, as well as C-F bond and ether C-O bond cleavages. In general, the current computational models could be useful for screening emerging PFAS to assess their defluorination ability for the molecular design of fluorochemical structures.
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Affiliation(s)
- Huiming Cao
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Jianhua Peng
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Zhen Zhou
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yuzhen Sun
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yawei Wang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yong Liang
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China.
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43
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Bai L, Jiang Y, Xia D, Wei Z, Spinney R, Dionysiou DD, Minakata D, Xiao R, Xie HB, Chai L. Mechanistic Understanding of Superoxide Radical-Mediated Degradation of Perfluorocarboxylic Acids. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:624-633. [PMID: 34919383 DOI: 10.1021/acs.est.1c06356] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Perfluorocarboxylic acids (PFCAs) exhibit strong persistence in sunlit surface waters and in radical-based treatment processes, where superoxide radical (O2•-) is an important and abundant reactive oxygen species. Given that the role of O2•- during the transformation of PFCAs remains largely unknown, we investigated the kinetics and mechanisms of O2•--mediated PFCAs attenuation through complementary experimental and theoretical approaches. The aqueous-phase rate constants between O2•- and C3-C8 PFCAs were measured using a newly designed in situ spectroscopic system. Mechanistically, bimolecular nucleophilic substitution (SN2) is most likely to be thermodynamically feasible, as indicated by density functional theory calculations at the CBS-QB3 level of theory. This pathway was then investigated by ab initio molecular dynamics simulation with free-energy samplings. As O2•- approaches PFCA, the C-F bond at the alpha carbon is spontaneously stretched, leading to the bond cleavage. The solvation mechanism for O2•--mediated PFCA degradation was also elucidated. Our results indicated that although the less polar solvent enhanced the nucleophilicity of O2•-, it also decreased the desolvation process of PFCAs, resulting in reduced kinetics. With these quantitative and mechanistic results, we achieved a defined picture of the O2•--initiated abatement of PFCAs in natural and engineered waters.
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Affiliation(s)
- Lu Bai
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China
- Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Ying Jiang
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China
- Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Deming Xia
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Zongsu Wei
- Centre for Water Technology (WATEC) & Department of Engineering, Aarhus University, Hangøvej 2, Aarhus N DK-8200, Denmark
| | - Richard Spinney
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Dionysios D Dionysiou
- Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Daisuke Minakata
- Department of Civil and Environmental Engineering, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Ruiyang Xiao
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China
- Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Hong-Bin Xie
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Liyuan Chai
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China
- Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
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44
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Gevaerd de Souza N, Parenky AC, Nguyen HH, Jeon J, Choi H. Removal of perfluoroalkyl and polyfluoroalkyl substances in water and water/soil slurry using Fe 0 -modified reactive activated carbon conjugated with persulfate. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2022; 94:e1671. [PMID: 34854167 DOI: 10.1002/wer.1671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 11/18/2021] [Accepted: 11/23/2021] [Indexed: 06/13/2023]
Abstract
Treatment of highly persistent perfluoroalkyl and polyfluoroalkyl substances (PFAS) has been a challenging but significant task. Herein, we propose adsorption-mediated chemical decomposition of PFAS implemented by using granular activated carbon (GAC) impregnated with zerovalent nanoiron (ZVI, Fe0 ), so-called reactive activated carbon (RAC). The effects of reaction temperature, injection of persulfate (PS), and presence of soil on removal of PFAS in water were evaluated. Results showed that RAC conjugated with PS at 60°C exhibited decomposition of PFAS, exclusively all three carboxylic PFAS tested, obviously producing various identifiable short-chain PFAS. Carboxylic PFAS were removed via physical adsorption combined with chemical decomposition while sulfonic PFAS were removed via solely adsorption mechanism. The presence of soil particles did not greatly affect the overall removal of PFAS. Carbon mass balance suggested that chemical oxidation by radical mechanisms mutually influences, in a complex manner, PFAS adsorption to GAC, ZVI and its iron derivatives, and soil particles. Nonetheless, all tested six PFAS were removed significantly. If successfully developed, the adsorption-mediated decomposition strategy may work for treatment of complex media containing PFAS and co-contaminants under different environmental settings. PRACTITIONERS POINTS: Treatment of persistent per- and polyfluoroalkyl substances (PFAS) was addressed. Activated carbon with zerovalent iron was examined in the presence of persulfate. The system significantly removed and decomposed PFAS in water and soil mixture.
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Affiliation(s)
- Naomi Gevaerd de Souza
- Department of Civil Engineering, The University of Texas at Arlington, Arlington, Texas, USA
- Ramboll Americas Engineering, Syracuse, New York, USA
| | - Akshay Chandrashekar Parenky
- Department of Civil Engineering, The University of Texas at Arlington, Arlington, Texas, USA
- Parsons Corporation, Syracuse, New York, USA
| | - Hiep Hoang Nguyen
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA
| | - Junha Jeon
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA
| | - Hyeok Choi
- Department of Civil Engineering, The University of Texas at Arlington, Arlington, Texas, USA
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45
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Chowdhury N, Prabakar S, Choi H. Dependency of the photocatalytic and photochemical decomposition of per- and polyfluoroalkyl substances (PFAS) on their chain lengths, functional groups, and structural properties. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2021; 84:3738-3754. [PMID: 34928840 DOI: 10.2166/wst.2021.458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
This study reports the removal of per- and polyfluoroalkyl substances (PFAS) in water using various photocatalytic and photochemical processes. PFAS were chosen, based on chain lengths, functional groups, and structural properties: four perfluorocarboxylic acids (PFCAs), including perfluorooctanoic acid (PFOA), three perfluorosulfonic acids (PFSAs), including perfluorooctanesulfonic acid (PFOS), hexafluoropropylene oxide dimer (GenX), and 6:2 fluorotelomer sulfonate (6:2 FTS), and dependency of the photocatalytic decomposition of PFAS on their properties was investigated. Oxidants and reductants were introduced to study the photochemical decomposition of PFAS, and reactive species and reaction byproducts were identified to elucidate the decomposition mechanism of PFAS. Some notable findings include: long chain PFCAs (95% in 48 h) and 6:2 FTS (100%) were removed via chemical decomposition in TiO2/UVC while GenX (37%), long chain PFSAs (60%), short chain PFSAs (0-10%) and short chain PFCAs (5-18%) were removed via physical adsorption. Sulfate radicals generated with persulfate (PS) played an important role in decomposing PFCAs (60-90%). Sulfite activated by UVC worked for defluorination of PFOA (75%) and PFOS (80%). PFOA was removed faster by UVC/sulfite > UVC/TiO2/sulfite ≈ UVC/TiO2/PS ≥ UVC/PS > UVC/TiO2 while PFOS was removed faster by UVC/sulfite ≫ UVC/TiO2/sulfite ≈ UVC/TiO2/PS ≈ UVC/TiO2 ≫ UVC/PS. Susceptibility of PFAS to the chemical reactions could be explained by their properties and the reactive species produced in each system.
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Affiliation(s)
- Nusrat Chowdhury
- Department of Civil Engineering, The University of Texas at Arlington, 416 Yates Street, Arlington, Texas 76019-0308, USA E-mail:
| | - Srinivas Prabakar
- Department of Civil Engineering, The University of Texas at Arlington, 416 Yates Street, Arlington, Texas 76019-0308, USA E-mail:
| | - Hyeok Choi
- Department of Civil Engineering, The University of Texas at Arlington, 416 Yates Street, Arlington, Texas 76019-0308, USA E-mail:
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46
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Reductive and Oxidative UV Degradation of PFAS—Status, Needs and Future Perspectives. WATER 2021. [DOI: 10.3390/w13223185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) consist of a group of environmentally persistent, toxic and bio-accumulative organic compounds of industrial origin that are widely present in water and wastewater. Despite restricted use due to current regulations on their use, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) remain the most commonly detected long-chain PFAS. This article reviews UV-based oxidative and reductive studies for the degradation of PFAS. Most of the UV-based processes studied at lab-scale include low pressure mercury lamps (emitting at 254 and 185 nm) with some studies using medium pressure mercury lamps (200–400 nm). A critical evaluation of the findings is made considering the degradation of PFAS, the impact of water quality conditions (pH, background ions, organics), types of oxidizing/reducing species, and source of irradiation with emphasis given to mechanisms of degradation and reaction by-products. Research gaps related to understanding of the factors influencing oxidative and reductive defluorination, impact of co-existing ions from the perspective of complexation with PFAS, and post-treatment toxicity are highlighted. The review also provides an overview of future perspectives regarding the challenges in relation to the current knowledge gaps, and future needs.
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47
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Ye T, Zhang TY, Tian FX, Xu B. The fate and transformation of iodine species in UV irradiation and UV-based advanced oxidation processes. WATER RESEARCH 2021; 206:117755. [PMID: 34695669 DOI: 10.1016/j.watres.2021.117755] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/04/2021] [Accepted: 10/08/2021] [Indexed: 06/13/2023]
Abstract
Iodinated disinfection byproducts (I-DBPs) formed in water treatment are of emerging concern due to their high toxicity and the tase-and-odor problems associated with iodinated trihalomethanes (I-THMs). Iodoacetic acid and dichloroiodomethane are currently regulated in Shenzhen, China and the Ministry of Health of the People's Republic of China has also been considering regulating I-DBPs. Iodide (I-), organoiodine compounds (e.g., iodinated X-ray contrast media [ICM]), and iodate (IO3-) are the three common iodine sources in aquatic environment that lead to I-DBP formation. While UV irradiation effectively inactivate a wide range of microorganisms in water, it induces the transformation of these iodine sources, enabling the formation of I-DBPs. This review focuses on the fate and transformation of these iodine sources in UV-based water treatment (i.e., UV irradiation and UV-based advanced oxidation processes [UV-AOPs]) and the formation of I-DBPs in post-disinfection. I- released in UV-based treatments of ICM and can be oxidized in subsequent disinfection to hypoiodous acid (HOI), which reacts with natural organic matter (NOM) to produce I-DBPs. Both UV and UV-AOPs are not able to fully mineralize ICM and completely oxidize the released I- to (except UV/O3). Results reveal that UV and UV-AOPs are adequate for I-DBP degradation but require high UV doses. While the ideal I-DBP mitigation strategy awaits to be developed, understanding their sources and formation pathways aids in informed selections of water treatment processes, empowers water suppliers to meet drinking water standards, and minimizes consumers' exposure to I-DBPs.
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Affiliation(s)
- Tao Ye
- Department of Civil and Environmental Engineering, South Dakota School of Mines and Technology, Rapid City, SD 57701, USA.
| | - Tian-Yang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Fu-Xiang Tian
- School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418 China
| | - Bin Xu
- State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Yangtze Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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48
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Deng Y, Liang Z, Lu X, Chen D, Li Z, Wang F. The degradation mechanisms of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) by different chemical methods: A critical review. CHEMOSPHERE 2021; 283:131168. [PMID: 34182635 DOI: 10.1016/j.chemosphere.2021.131168] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/04/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) are a class of artificial compounds comprised of a perfluoroalkyl main chain and a terminal functional group. With them being applied in a wide range of applications, PFASs have drawn increasing regulatory attention and research interests on their reductions and treatments due to their harmful effects on environment and human beings. Among numerous studies, chemical treatments (e.g., photochemical, electrochemical, and thermal technologies) have been proved to be important methods to degradation PFASs. However, the pathways and mechanisms for the degradation of PFASs through these chemical methods still have not been well documented. This article therefore provides a comprehensive review on the degradation mechanisms of two important PFASs (perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS)) with photochemical, electrochemical and thermal methods. Different decomposition mechanisms of PFOA and PFOS are reviewed and discussed. Overall, the degradation pathways of PFASs are associated closely with their head groups and chain lengths, and H/F exchange and chain shortening were found to be predominant degradation mechanisms. The clear study on the degradation mechanisms of PFOA and PFOS should be very useful for the complete degradation or mineralization of PFASs in the future.
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Affiliation(s)
- Yun Deng
- School of Environment, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, 510632, China
| | - Zhihong Liang
- The Pearl River Water Resources Research Institute, Guangzhou, Guangdong, 510611, China
| | - Xingwen Lu
- School of Environmental Science and Engineering and Institute of Environmental Health and Pollution Control, Guangdong University of Technology, Guangzhou, 510006, China
| | - Da Chen
- School of Environment, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, 510632, China
| | - Zhe Li
- School of Engineering and Materials Science, Faculty of Science and Engineering, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Fei Wang
- School of Environment, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, 510632, China.
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49
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Gao J, Liu Z, Bentel MJ, Yu Y, Men Y, Liu J. Defluorination of Omega-Hydroperfluorocarboxylates (ω-HPFCAs): Distinct Reactivities from Perfluoro and Fluorotelomeric Carboxylates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:14146-14155. [PMID: 34618445 DOI: 10.1021/acs.est.1c04429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Omega-hydroperfluorocarboxylates (ω-HPFCAs, HCF2-(CF2)n-1-COO-) are commercially available in bulk quantities and have been applied in agrochemicals, fluoropolymer production, and semiconductor coating. In this study, we used kinetic measurements, theoretical calculations, model compound experiments, and transformation product analyses to reveal novel mechanistic insights into the reductive and oxidative transformation of ω-HPFCAs. Like perfluorocarboxylates (PFCAs, CF3-(CF2)n-1-COO-), the direct linkage between HCnF2n- and -COO- enables facile degradation under UV/sulfite treatment. To our surprise, the presence of the H atom on the remote carbon makes ω-HPFCAs more susceptible than PFCAs to decarboxylation (i.e., yielding shorter-chain ω-HPFCAs) and less susceptible to hydrodefluorination (i.e., H/F exchange). Like fluorotelomer carboxylates (FTCAs, CnF2n+1-CH2CH2-COO-), the C-H bond in HCF2-(CF2)n-1-COO- allows hydroxyl radical oxidation and limited defluorination. While FTCAs yielded PFCAs in all chain lengths, ω-HPFCAs only yielded -OOC-(CF2)n-1-COO- (major) and -OOC-(CF2)n-2-COO- (minor) due to the unfavorable β-fragmentation pathway that shortens the fluoroalkyl chain. We also compared two treatment sequences-UV/sulfite followed by heat/persulfate and the reverse-toward complete defluorination of ω-HPFCAs. The findings will benefit the treatment and monitoring of H-containing per- and polyfluoroalkyl substance (PFAS) pollutants as well as the design of future fluorochemicals.
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Affiliation(s)
- Jinyu Gao
- Department of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Zekun Liu
- 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
| | - 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
| | - Jinyong Liu
- Department of Chemical & Environmental Engineering, University of California, Riverside, California 92521, United States
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50
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Liu CJ, McKay G, Jiang D, Tenorio R, Cath JT, Amador C, Murray CC, Brown JB, Wright HB, Schaefer C, Higgins CP, Bellona C, Strathmann TJ. Pilot-scale field demonstration of a hybrid nanofiltration and UV-sulfite treatment train for groundwater contaminated by per- and polyfluoroalkyl substances (PFASs). WATER RESEARCH 2021; 205:117677. [PMID: 34624586 DOI: 10.1016/j.watres.2021.117677] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
Previous laboratory scale studies indicate nanofiltration (NF) and UV-sulfite photochemical treatments as promising technologies for the removal and destruction, respectively, of per- and polyfluoroalkyl substances (PFASs) from contaminated water. This study reports on a field demonstration of a pilot-scale hybrid NF and UV-sulfite treatment train for the remediation of 12 PFASs detected in groundwater impacted by aqueous film-forming foam (AFFF) at a U.S. Department of Defense installation. For most of the detected PFASs, NF rejection was consistently ≥ 95% over a 30-day field trial when operating at 90% total permeate recovery. Rejection of short-chain perfluorosulfonic acids (PFSAs) by NF decreased when recoveries increased from 90 to 97%; tests with a reverse osmosis (RO) membrane showed ≥ 99% rejection of all PFASs regardless of increasing recovery. UV treatment of the NF reject following 90% permeate recovery resulted in variable destruction of individual PFASs, with rates also being dependent on pH and the identity and concentration of UV photosensitizer. Rates of perfluorocarboxylic acid (PFCA) degradation were greater than those measured for PFSAs and perfluoroalkyl acid (PFAA) precursors and were independent of perfluoroalkyl chain length. In contrast, rates of PFSA degradation increased with increasing chain length. Consistent levels of PFAS degradation by UV-sulfite were observed during a 30-day demonstration experiment in NF reject water amended with 10 mM sulfite and adjusted to pH 11.2. Collectively, > 75% of the detected PFAS mass in the NF reject was destroyed after 4 h of UV treatment, increasing to > 90% after 8 h of treatment. An analysis of electrical energy inputs for the hybrid NF/UV-sulfite treatment train showed energy per order magnitude (EE/O) requirements ranging from ≤ 13.1 kWh/m3 for PFCAs and 14.1 kWh/m3 for PFOS to values > 100 kWh/m3 for more recalcitrant short-chain PFSA analogues. The UV reactor and water-cooling system were the major contributors to overall energy requirements and represent the greatest opportunities for improving efficiency of the technology.
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Affiliation(s)
- Charlie J Liu
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA; Kennedy Jenks Consultants, San Francisco, CA 94104, USA
| | - Garrett McKay
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA; Zachry Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Daqian Jiang
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA; Department of Civil, Construction and Environmental Engineering, University of Alabama, Tuscaloosa, AL 35487, USA
| | - Raul Tenorio
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - J Tani Cath
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Camille Amador
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Conner C Murray
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Juliane B Brown
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | | | | | - Christopher P Higgins
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Christopher Bellona
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA
| | - Timothy J Strathmann
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO 80401, USA.
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