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Feijoo S, Baluchová S, Kamali M, Buijnsters JG, Dewil R. Single-crystal vs polycrystalline boron-doped diamond anodes: Comparing degradation efficiencies of carbamazepine in electrochemical water treatment. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 347:123705. [PMID: 38442825 DOI: 10.1016/j.envpol.2024.123705] [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: 11/16/2023] [Revised: 02/21/2024] [Accepted: 03/02/2024] [Indexed: 03/07/2024]
Abstract
The ongoing challenge of water pollution by contaminants of emerging concern calls for more effective wastewater treatment to prevent harmful side effects to the environment and human health. To this end, this study explored for the first time the implementation of single-crystal boron-doped diamond (BDD) anodes in electrochemical wastewater treatment, which stand out from the conventional polycrystalline BDD morphologies widely reported in the literature. The single-crystal BDD presented a pure diamond (sp3) content, whereas the three other investigated polycrystalline BDD electrodes displayed various properties in terms of boron doping, sp3/sp2 content, microstructure, and roughness. The effects of other process conditions, such as applied current density and anolyte concentration, were simultaneously investigated using carbamazepine (CBZ) as a representative target pollutant. The Taguchi method was applied to elucidate the optimal operating conditions that maximised either (i) the CBZ degradation rate constant (enhanced through hydroxyl radicals (•OH)) or (ii) the proportion of sulfate radicals (SO4•-) with respect to •OH. The results showed that the single-crystal BDD significantly promoted •OH formation but also that the interactions between boron doping, current density and anolyte concentration determined the underlying degradation mechanisms. Therefore, this study demonstrated that characterising the BDD material and understanding its interactions with other process operating conditions prior to degradation experiments is a crucial step to attain the optimisation of any wastewater treatment application.
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Affiliation(s)
- Sara Feijoo
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter de Nayerlaan 5, 2860, Sint-Katelijne-Waver, Belgium
| | - Simona Baluchová
- Delft University of Technology, Department of Precision and Microsystems Engineering, Mekelweg 2, 2628 CD, Delft, the Netherlands; Charles University, Faculty of Science, Department of Analytical Chemistry, Albertov 6, 128 00, Prague, Czech Republic
| | - Mohammadreza Kamali
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter de Nayerlaan 5, 2860, Sint-Katelijne-Waver, Belgium
| | - Josephus G Buijnsters
- Delft University of Technology, Department of Precision and Microsystems Engineering, Mekelweg 2, 2628 CD, Delft, the Netherlands.
| | - Raf Dewil
- KU Leuven, Department of Chemical Engineering, Process and Environmental Technology Lab, Jan Pieter de Nayerlaan 5, 2860, Sint-Katelijne-Waver, Belgium; University of Oxford, Department of Engineering Science, Parks Road, Oxford, OX1 3PJ, United Kingdom
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2
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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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Kim J, Kim T, Park H, Kim MK, Eom S, Choe Y, Choe JK, Zoh KD. Kinetics and proposed mechanisms of hexafluoropropylene oxide dimer acid (GenX) degradation via vacuum-UV (VUV) photolysis and VUV/sulfite processes. JOURNAL OF HAZARDOUS MATERIALS 2024; 463:132864. [PMID: 37907009 DOI: 10.1016/j.jhazmat.2023.132864] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/04/2023] [Accepted: 10/24/2023] [Indexed: 11/02/2023]
Abstract
We investigated the degradation of hexafluoropropylene oxide dimer acid (GenX) in water via VUV photolysis and VUV/sulfite reactions under nitrogen-saturated conditions. Approximately 35% and 90% of GenX were degraded in 3 h in the VUV photolysis and VUV/sulfite reaction. While GenX removal rate was highest at pH 6 in VUV photolysis, it increased under alkaline pHs, especially at pH 10, in VUV/sulfite reaction. Radical scavenging experiments showed that, while both eaq- and •H contributed to VUV photolysis, eaq- played a significant role and •OH had a negative effect during VUV/sulfite reaction. Two transformation products (TPs) (TFA and PFPrA) were identified in VUV photolysis, whereas five TPs (TFA, PFPrA, TP182, TP348, and TP366) were identified in VUV/sulfite reaction by LCMS/MS and LCQTOF/MS. Defluorination of GenX was observed with the defluorination efficiency after 6 h reaching 17% and 67% in the VUV photolysis and VUV/sulfite reactions, respectively. Degradation mechanism for GenX based on the identified TPs and the theoretical calculation confirmed the susceptibility of GenX to nucleophilic attack. The initial reactions for GenX decomposition were C-C and C-O bond cleavage in both reactions, whereas sulfonation followed by decarboxylation was observed only in the VUV/sulfite reaction. ECOSAR ecotoxicity simulation showed that the toxicities of the TPs were not as harmful as those of GenX.
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Affiliation(s)
- Jaehee Kim
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, Seoul, South Korea
| | - Taeyeon Kim
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, Seoul, South Korea
| | - Heungjoo Park
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, Seoul, South Korea
| | - Moon-Kyung Kim
- Institute of Health and Environment, Seoul National University, Seoul, South Korea
| | - Soyeon Eom
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, Seoul, South Korea
| | - Yerin Choe
- Department of Civil and Environmental Engineering, Seoul National University, Seoul, South Korea
| | - Jong Kwon Choe
- Department of Civil and Environmental Engineering, Seoul National University, Seoul, South Korea
| | - Kyung-Duk Zoh
- Department of Environmental Health Sciences, School of Public Health, Seoul National University, Seoul, South Korea.
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4
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Hughes K, Pineda M, Omanovic S, Yargeau V. Study on the importance of the reductive degradation of GenX in its overall electrochemical degradation process on different cathode materials. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168415. [PMID: 37944604 DOI: 10.1016/j.scitotenv.2023.168415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/12/2023]
Abstract
Per- and polyfluoro alkylated substances (PFAS) are well known for their recalcitrant nature caused by the abundance of CF bonds. It has been proven that electrochemical degradation is a potentially suitable technique for treating PFAS; however, most studies solely focus on electrochemical oxidation, with limited attention given to electrochemical reduction, and the relative contribution of the two towards the total PFAS degradation has not yet been elucidated. This manuscript reports an investigation on the contribution of electroreduction to the overall electrodegradation of a target PFAS, HFPO-DA (i.e. GenX), using a boron doped diamond (BDD) anode and different cathode materials (Cu, Ti, Au). The oxidation and reduction reactions were successfully decoupled from each other and studied simultaneously using an electrochemical H-cell with an agar membrane. It was determined that reduction plays a significant role in the overall degradation of GenX for each of the cathodes studied, with its contribution ranging from 52 % for the Ti cathode, to 66 % for Cu, and to 92 % for Au.
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Affiliation(s)
- Kara Hughes
- Department of Chemical Engineering, McGill University Montreal, Quebec, Canada.
| | - Marco Pineda
- Department of Chemical Engineering, McGill University Montreal, Quebec, Canada
| | - Sasha Omanovic
- Department of Chemical Engineering, McGill University Montreal, Quebec, Canada
| | - Viviane Yargeau
- Department of Chemical Engineering, McGill University Montreal, Quebec, Canada
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Farissi S, Abubakar GA, Akhilghosh KA, Muthukumar A, Muthuchamy M. Sustainable application of electrocatalytic and photo-electrocatalytic oxidation systems for water and wastewater treatment: a review. ENVIRONMENTAL MONITORING AND ASSESSMENT 2023; 195:1447. [PMID: 37945768 DOI: 10.1007/s10661-023-12083-y] [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: 06/06/2023] [Accepted: 10/31/2023] [Indexed: 11/12/2023]
Abstract
Wastewater treatment and reuse have risen as a solution to the water crisis plaguing the world. Global warming-induced climate change, population explosion and fast depletion of groundwater resources are going to exacerbate the present global water problems for the forthcoming future. In this scenario, advanced electrochemical oxidation process (EAOP) utilising electrocatalytic (EC) and photoelectrocatalytic (PEC) technologies have caught hold of the interest of the scientific community. The interest stems from the global water management plans to scale down centralised water and wastewater treatment systems to decentralised and semicentralised treatment systems for better usage efficiency and less resource wastage. In an age of rising water pollution caused by contaminants of emerging concern (CECs), EC and PEC systems were found to be capable of optimal mineralisation of these pollutants rendering them environmentally benign. The present review treads into the conventional electrochemical treatment systems to identify their drawbacks and analyses the scope of the EC and PEC to mitigate them. Probable electrode materials, potential catalysts and optimal operational conditions for such applications were also examined. The review also discusses the possible retrospective application of EC and PEC as point-of-use and point-of-entry treatment systems during the transition from conventional centralised systems to decentralised and semi-centralised water and wastewater treatment systems.
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Affiliation(s)
- Salman Farissi
- Department of Environmental Science, Central University of Kerala, Thejaswini Hills, Periye, Kasaragod-671320, Kerala, India
| | - Gado Abubakar Abubakar
- Department of Physics, Kebbi State University of Science and Technology, Aleiro, Kebbi State, Nigeria
| | | | - Anbazhagi Muthukumar
- Department of Environmental Science, Central University of Kerala, Thejaswini Hills, Periye, Kasaragod-671320, Kerala, India
| | - Muthukumar Muthuchamy
- Department of Environmental Science, Central University of Kerala, Thejaswini Hills, Periye, Kasaragod-671320, Kerala, India.
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Zhang C, Xu Y, Liu W, Zhou H, Zhang N, Fang Z, Gao J, Sun X, Feng D, Sun X. New insights into the degradation mechanism and risk assessment of HFPO-DA by advanced oxidation processes based on activated persulfate in aqueous solutions. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 263:115298. [PMID: 37499385 DOI: 10.1016/j.ecoenv.2023.115298] [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: 05/07/2023] [Revised: 07/09/2023] [Accepted: 07/21/2023] [Indexed: 07/29/2023]
Abstract
Hexafluoropropylene oxide dimer acid (HFPO-DA) is widely used as a substitute for perfluorooctanoic acid (PFOA). HFPO-DA exhibits high water solubility and low adsorption potential, conferring significant fluidity in aquatic environments. Given that the toxicity of HFPO-DA is similar to PFOA, it is necessary to control its content in aquatic environments. Electrochemical and thermally-activated persulfates have been successfully used to degrade HFPO-DA, but UV-activated persulfates cannot degrade the compound. Given that research on degradation mechanisms is still incomplete and lacks kinetic research, the mechanism and kinetic calculations of oxidative degradation were studied in detail using DFT calculations. And the toxicity of HFPO-DA degradation intermediates and products was evaluated to reveal the feasibility of using advanced oxidation process (AOP) technology based on persulfate to degrade HFPO-DA in wastewater. The results showed that the committed step of HFPO-DA degradation was initiated by the electron transfer reaction of SO4•- radicals. This reaction is not spontaneous at room temperature and requires sufficient electrical or thermal energy to be absorbed from the external environment. The perfluoroalcohol produced during this reaction can subsequently undergo four possible reactions: H atom abstraction from alcohol groups by an OH radical; H atom abstraction by SO4•-; direct HF removal; and HF removal with water as the catalyst. The final degradation products of HFPO-DA mainly include CO2, CF3CF2COOH, CF3COOH, FCOOH and HF, which has been identified through previous experimental analysis. Ecotoxicity assessment indicates that degradation does not produce highly toxic intermediates, and that the final products are non-toxic, supporting the feasibility of persulfate-based AOP technologies.
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Affiliation(s)
- Chenxi Zhang
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China; Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Youxin Xu
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China; Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Wenyan Liu
- School of agriculture, Ludong University, Yantai 264025, China
| | - Huaiyu Zhou
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China
| | - Ningning Zhang
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China
| | - Zhihao Fang
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China
| | - Junping Gao
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China
| | - Xiaoan Sun
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China
| | - Di Feng
- Shandong Facility Horticulture Bioengineering Research Center, Weifang University of Science and Technology, Weifang 262700, China.
| | - Xiaomin Sun
- Environment Research Institute, Shandong University, Qingdao 266237, China.
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7
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Yang Z, Zhuo Q, Wang W, Guo S, Chen J, Li Y, Lv S, Yu G, Qiu Y. Fabrication and characterizations of Zn-doped SnO 2-Ti 4O 7 anode for electrochemical degradation of hexafluoropropylene oxide dimer acid and its homologues. JOURNAL OF HAZARDOUS MATERIALS 2023; 455:131605. [PMID: 37196440 DOI: 10.1016/j.jhazmat.2023.131605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/01/2023] [Accepted: 05/08/2023] [Indexed: 05/19/2023]
Abstract
Hexafluoropropylene oxide dimer acid (HFPO-DA) and its homologues, as perfluorinated ether alkyl substances with strong antioxidant properties, have rarely been reported by electrooxidation processes to achieve good results. Herein, we report the use of an oxygen defect stacking strategy to construct Zn-doped SnO2-Ti4O7 for the first time and enhance the electrochemical activity of Ti4O7. Compared with the original Ti4O7, the Zn-doped SnO2-Ti4O7 showed a 64.4% reduction in interfacial charge transfer resistance, a 17.5% increase in the cumulative rate of •OH generation, and an enhanced oxygen vacancy concentration. The Zn-doped SnO2-Ti4O7 anode exhibited high catalytic efficiency of 96.4% for HFPO-DA within 3.5 h at 40 mA/cm2. Hexafluoropropylene oxide trimer and tetramer acid exhibit more difficult degradation due to the protective effect of the -CF3 branched chain and the addition of the ether oxygen atom leading to a significant increase in the C-F bond dissociation energy. The degradation rates of 10 cyclic degradation experiments and the leaching concentrations of Zn and Sn after 22 electrolysis experiments demonstrated the good stability of the electrodes. In addition, the aqueous toxicity of HFPO-DA and its degradation products was evaluated. This study analyzed the electrooxidation process of HFPO-DA and its homologues for the first time, and provided some new insights.
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Affiliation(s)
- Zehong Yang
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
| | - Qiongfang Zhuo
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510275, China; Dongguan Key Laboratory of Emerging Contaminants, Dongguan 523808, Guangdong, China.
| | - Wenlong Wang
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
| | - Shuting Guo
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
| | - Jianfeng Chen
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
| | - Yanliang Li
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
| | - Sihao Lv
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
| | - Gang Yu
- Advanced Interdisciplinary Institute of Environment and Ecology, Beijing Normal University, Zhuhai 519000, Guangdong, China
| | - Yongfu Qiu
- School of Environment and Civil Engineering, Dongguan University of Technology, Dongguan 523808, Guangdong, China
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8
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Zhao L, Teng M, Zhao X, Li Y, Sun J, Zhao W, Ruan Y, Leung KMY, Wu F. Insight into the binding model of per- and polyfluoroalkyl substances to proteins and membranes. ENVIRONMENT INTERNATIONAL 2023; 175:107951. [PMID: 37126916 DOI: 10.1016/j.envint.2023.107951] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/18/2023] [Accepted: 04/24/2023] [Indexed: 05/03/2023]
Abstract
Legacy per- and polyfluoroalkyl substances (PFASs) have elicited much concern because of their ubiquitous distribution in the environment and the potential hazards they pose to wildlife and human health. Although an increasing number of effective PFAS alternatives are available in the market, these alternatives bring new challenges. This paper comprehensively reviews how PFASs bind to transport proteins (e.g., serum albumin, liver fatty acid transport proteins and organic acid transporters), nuclear receptors (e.g., peroxisome proliferator activated receptors, thyroid hormone receptors and reproductive hormone receptors) and membranes (e.g., cell membrane and mitochondrial membrane). Briefly, the hydrophobic fluorinated carbon chains of PFASs occupy the binding cavities of the target proteins, and the acid groups of PFASs form hydrogen bonds with amino acid residues. Various structural features of PFAS alternatives such as chlorine atom substitution, oxygen atom insertion and a branched structure, introduce variations in their chain length and hydrophobicity, which potentially change the affinity of PFAS alternatives for endogenous proteins. The toxic effects and mechanisms of action of legacy PFASs can be demonstrated and compared with their alternatives using binding models. In future studies, in vitro experiments and in silico quantitative structure-activity relationship modeling should be better integrated to allow more reliable toxicity predictions for both legacy and alternative PFASs.
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Affiliation(s)
- Lihui Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
| | - Miaomiao Teng
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China.
| | - Xiaoli Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China
| | - Yunxia Li
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
| | - Jiaqi Sun
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, China
| | - Wentian Zhao
- Innovation Center of Pesticide Research, Department of Applied Chemistry, College of Science, China Agricultural University, Beijing, China
| | - Yuefei Ruan
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, 999077, Hong Kong Special Administrative Region
| | - Kenneth M Y Leung
- State Key Laboratory of Marine Pollution and Department of Chemistry, City University of Hong Kong, 999077, Hong Kong Special Administrative Region
| | - Fengchang Wu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, China.
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9
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Fang Y, Meng P, Schaefer C, Knappe DRU. Removal and destruction of perfluoroalkyl ether carboxylic acids (PFECAs) in an anion exchange resin and electrochemical oxidation treatment train. WATER RESEARCH 2023; 230:119522. [PMID: 36577256 DOI: 10.1016/j.watres.2022.119522] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 11/18/2022] [Accepted: 12/18/2022] [Indexed: 06/17/2023]
Abstract
Perfluoroalkyl ether carboxylic acids (PFECAs) are a group of emerging recalcitrant contaminants that are being developed to replace legacy per- and polyfluoroalkyl substances (PFAS) in industrial applications and that are generated as by-products in fluoropolymer manufacturing. Here, we report on the removal and destruction of four structurally different PFECAs using an integrated anion exchange resin (AER) and electrochemical oxidation (ECO) treatment train. Results from this work illustrated that (1) flow-through columns packed with PFAS-selective AERs are highly effective for the removal of PFECAs and (2) PFECA affinity is strongly correlated with their hydrophobic features. Regeneration of the spent resin columns revealed that high percentage (e.g., 80%) of organic cosolvent is necessary for achieving 60-100% PFECA release, and regeneration efficiency was higher for a macroporous resin than a gel-type resin. Treatment of spent regenerants showed (1) >99.99% methanol removal was achieved by distillation, (2) >99.999% conversion of the four studied PFECAs was achieved during the ECO treatment of the still bottoms after 24 hours with an energy per order of magnitude of PFECA removal (EE/O) <1.03 kWh/m3 of total groundwater treated, and (3) >85% of the organic fluorine was recovered as inorganic fluoride. Trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), and perfluoro-2-methoxyacetic acid (PFMOAA) were confirmed via high-resolution mass spectrometry as transformation products (TPs) in the treated still bottoms, and two distinctive degradation schemes and four reaction pathways are proposed for the four PFECAs. Lastly, dissolved organic matter (DOM) inhibited uptake, regeneration, and oxidation of PFECAs throughout the treatment train, suggesting pretreatment steps targeting DOM removal can enhance the system's treatment efficiency. Results from this work provide guidelines for developing effective separation-concentration-destruction treatment trains and meaningful insights for achieving PFECA destruction in impacted aquatic systems.
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Affiliation(s)
- Yida Fang
- CDM Smith, 14432 SE Eastgate Way, #100, Bellevue, Washington 98007, United States.
| | - Pingping Meng
- North Carolina State University, 915 Partners Way, Raleigh, North Carolina 27695, United States
| | - Charles Schaefer
- CDM Smith, 110 Fieldcrest Avenue, #8, Edison, New Jersey 08837, United States
| | - Detlef R U Knappe
- North Carolina State University, 915 Partners Way, Raleigh, North Carolina 27695, United States
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10
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Li Z, Luo ZM, Huang Y, Wang JW, Ouyang G. Recent trends in degradation strategies of PFOA/PFOS substitutes. CHEMOSPHERE 2023; 315:137653. [PMID: 36581124 DOI: 10.1016/j.chemosphere.2022.137653] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 06/17/2023]
Abstract
The global elimination and restriction of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), respectively, have urged manufacturers to shift production to their substitutes which still pose threat to the environment with their bioaccumulation, toxicity and migration issues. In this context, efficient technologies and systematic mechanistic studies on the degradation of PFOA/PFOS substitutes are highly desirable. In this review, we summarize the progress in degrading PFOA/PFOS substitutes, including four kinds of mainstream methods. The pros and cons of the present technologies are analyzed, which renders the discussion of future prospects on rational optimizations. Additional discussion is made on the differences in the degradation of various kinds of substitutes, which is compared to the PFOA/PFOS and derives designing principles for more degradable F-containing compounds.
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Affiliation(s)
- Zizi Li
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Zhi-Mei Luo
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Yanjun Huang
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China
| | - Jia-Wei Wang
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
| | - Gangfeng Ouyang
- KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275, China.
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