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Long Y, Huang J, Xu W, Zhu Y, Ou J, Wang H, Cai Y, Lv Y, Yang M. Mechanistic and kinetic insights into the thermal degradation of decabromodiphenyl ethane. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 359:124539. [PMID: 39019309 DOI: 10.1016/j.envpol.2024.124539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Revised: 06/23/2024] [Accepted: 07/11/2024] [Indexed: 07/19/2024]
Abstract
Decabromodiphenyl ethane (DBDPE), as one of the important new brominated flame retardants, is widely utilized in a variety of plastic products. However, the pyrolysis mechanism of DBDPE remains uncertain. In this article, the evolution behavior of the main products during the thermal decomposition of DBDPE is investigated using density functional theory at the theoretical level of M06-2X/6-311++G(2df,p)//M06-2X/6-311+G(d). The results show that the initial reaction starts with the cleavage of the ethane bridge bond, with an absorbed heat value of 298 kJ/mol, and the cleavage of the Caromatic-Br bond generates bromine radical, which is the main competitive reaction, with a heat absorption of 317 kJ/mol. The initial degradation of DBDPE generates a large number of pentabromobenzyl radicals and bromine radicals, which facilitate the secondary pyrolysis of DBDPE to a certain extent, resulting in the formation of possible products such as pentabromobenzyl bromide, pentabromobenzene, pentabromotoluene, hexabromobenzene, pentabromostyrene, and hydrogen bromide. In the pyrolysis system of DBDPE with hydrogen radicals, the reactions are classified into two types: extraction reaction and addition reaction. It can be known that the addition reaction plays a dominant role in the degradation process, with a branching ratio of 89.8% at 1600 K. The degradation of DBDPE with hydrogen radicals is mainly characterized by debromination, and the main products are hydrogen bromide, low-brominated diphenyl ethanes, brominated phenanthrenes, and brominated monoaromatic compounds. In addition, the lowest reaction energy barrier (18 kJ/mol) is required for the addition of hydrogen radical to the ipso-C site of DBDPE. DBDPE is dangerous for the environment and humans since its fate includes bioaccumulation, biomagnification, and toxicity via hormones and endocrine disruptors.
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Affiliation(s)
- Yang Long
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Jinbao Huang
- Engineering Training Center, Guizhou Minzu University, Guiyang, 550025, China.
| | - Weifeng Xu
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Yan Zhu
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Jiankai Ou
- Engineering Training Center, Guizhou Minzu University, Guiyang, 550025, China
| | - Hong Wang
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Yaqing Cai
- Engineering Training Center, Guizhou Minzu University, Guiyang, 550025, China
| | - Yu Lv
- Engineering Training Center, Guizhou Minzu University, Guiyang, 550025, China
| | - Min Yang
- Engineering Training Center, Guizhou Minzu University, Guiyang, 550025, China
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Wang Y, Huang J, Li S, Xu W, Wang H, Xu W, Li X. A mechanistic and kinetic investigation on the oxidative thermal decomposition of decabromodiphenyl ether. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 333:121991. [PMID: 37328125 DOI: 10.1016/j.envpol.2023.121991] [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: 03/01/2023] [Revised: 05/30/2023] [Accepted: 06/07/2023] [Indexed: 06/18/2023]
Abstract
The thermal processes of materials containing decabromodiphenyl ether (BDE-209) normally result in the exposure of BDE-209 to high-temperature environments, generating a series of hazardous compounds. However, the evolution mechanisms of BDE-209 during oxidative thermal processes remain unclear. Thus, this paper presents a detailed investigation on the oxidative thermal decomposition mechanism of BDE-209 by utilizing density functional theory methods at the M06/cc-pVDZ theoretical level. The results show that the barrierless fission of the ether linkage dominates the initial degradation of BDE-209 at all temperatures, with branching ratio over 80%. The decomposition of BDE-209 in oxidative thermal processes is mainly along BDE-209 → pentabromophenyl and pentabromophenoxy radicals → pentabromocyclopentadienyl radicals → brominated aliphatic products. Additionally, the study results on the formation mechanisms of several hazardous pollutants indicate that the ortho-phenyl-type radicals created by ortho-C-Br bond fission (branching ratio reached 15.1% at 1600 K) can easily be converted into octabrominated dibenzo-p-dioxin and furan, which require overcoming the energy barriers of 99.0 and 48.2 kJ/mol, respectively. The O/ortho-C coupling of two pentabromophenoxy radicals also acts as a non-negligible pathway for the formation of octabrominated dibenzo-p-dioxin. The synthesis of octabromonaphthalene involves the self-condensation of pentabromocyclopentadienyl radicals, followed by an intricately intramolecular evolution. Results presented in this study can enhance our understanding of the transformation mechanism of BDE-209 in thermal processes, and offer an insight into controlling the emissions of hazardous pollutants.
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Affiliation(s)
- Yao Wang
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Jinbao Huang
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China.
| | - Sijia Li
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Weifeng Xu
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Hong Wang
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Weiwei Xu
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Xinsheng Li
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China
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3
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Wang Y, Huang J, Wang H, Lan L, Mu X, Xu W, Lv S, Li X. Theoretical study on pyrolysis mechanism of decabromodiphenyl ether (BDE-209) using DFT method. CHEMOSPHERE 2023; 310:136904. [PMID: 36265714 DOI: 10.1016/j.chemosphere.2022.136904] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 06/16/2023]
Abstract
Decabromodiphenyl ether (BDE-209), as a brominated flame retardant (BFR), is widely applied to various consumer products due to its superior performance and affordable pricing to improve the flame resistance of materials. To better comprehend the pyrolysis behavior of BDE-209 and the evolution process of main pyrolysis products, the thermal degradation mechanism of BDE-209 was studied using density functional theory (DFT) method at the theoretical level of M06/cc-pVDZ, and thermodynamic parameters were calculated in this paper. Unimolecular degradation was dominated by cleavage of the ether linkage, which results in a high yield of hexabromobenzene, and fission of the ortho-position C-Br bond is the main competitive reaction channel. In the system of BDE-209 + H, the pyrolysis reaction is majorly characterized by debromination, leading to the formation of considerable HBr and low-brominated diphenyl ethers. Additionally, the hydrogen-derived splitting of the ether bond acts as a mainly competitive channel, which is the source of polybromophenols and polybromobenzenes. The formation of polybrominated dibenzofuran (PBDF) derives from the cyclization reaction of ortho-phenyl-type radicals, which are readily generated through the ortho-position Br atom abstraction by H radical. The formation of polybrominated dibenzo-p-dioxin (PBDD) involves the ortho-C-O coupling reaction of polybromophenoxy radicals, debromination reaction, and cyclization reaction. And the total yield of PBDD/Fs was significantly increased when H was involved. Results presented in this work will provide the helpful information for the treatment and reuse of BDE-209-containing waste plastics through using pyrolysis technology.
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Affiliation(s)
- Yao Wang
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Jinbao Huang
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China.
| | - Hong Wang
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Lin Lan
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Xin Mu
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Weiwei Xu
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Shanjin Lv
- School of Mechatronics Engineering, Guizhou Minzu University, Guiyang, 550025, China
| | - Xinsheng Li
- School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China.
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Li Y, Jiang L, Wang R, Wu P, Liu J, Yang S, Liang J, Lu G, Zhu N. Kinetics and mechanisms of phenolic compounds by Ferrate(VI) assisted with density functional theory. JOURNAL OF HAZARDOUS MATERIALS 2021; 415:125563. [PMID: 33721780 DOI: 10.1016/j.jhazmat.2021.125563] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 06/12/2023]
Abstract
In this paper, Phenol, 4-Chlorophenol (4-CP), 2,4-Dichlorophenol (2,4-DCP) and 2,4,6-Trichlorophenol (2,4,6-TCP) were selected as model pollutants to explore the oxidant mechanism by ferrate (Fe(VI)). The reactions between ferrate (1000 μM) and four phenolic compounds (100 μM) were conformed to the second-order reaction kinetics at pH 9.2, and the order of kobs followed as: k4-CP (129 M-1 s-1) > k2,4-DCP (96 M-1 s-1) > k2,4,6-TCP (44 M-1 s-1) > kPhenol (12 M-1 s-1). Meanwhile, the degradation rates of all four compounds by Fe(VI) increased with increased pH (3.1-9.2). A total of 14 degradation products were identified by Liquid chromatography-Time-of-Flight-Mass Spectrometry (LC-TOF-MS), and two pathways including hydroxylation of benzene ring and substitution of chlorine atom were proposed. Hydroxyl radicals, played a vital role during the degradation of phenolic compounds. Moreover, density functional theory calculations were used to explore the degradation mechanisms. The results showed that the hydroxyl radical was more favorable to substitute chlorine atom than hydrogen atom, and the substitution on ortho-position was more favorable than para-position for all four compounds. The findings of this study could greatly improve our understanding on the degradation mechanism of chlorophenol-like compounds by Fe(VI) for environmental remediation.
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Affiliation(s)
- Yihao Li
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China
| | - Lu Jiang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China
| | - Rui Wang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; South China Institute of Environmental Sciences, Ministry of Environmental Protection (MEP), Guangzhou 510655, China
| | - Pingxiao Wu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, PR China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, Guangzhou 510006, PR China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, Guangzhou 510006, PR China; Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, Guangzhou 510006, PR China.
| | - Juan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China
| | - Shanshan Yang
- School of Earth and Space Sciences, Peking University, Beijing 100871, PR China
| | - Jiahao Liang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China
| | - Guining Lu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China
| | - Nengwu Zhu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, PR China
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Yang J, Yang Y, Xie Z, Yu H, Huang Q, Xu Y, He J, Wen T, Liu Q. Ca 2+ mediated mechanism of octa-brominated dioxin/furan formation via BDE-209 thermolysis: Introducing the Mayer bond order difference. JOURNAL OF HAZARDOUS MATERIALS 2020; 400:123229. [PMID: 32585521 DOI: 10.1016/j.jhazmat.2020.123229] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 05/29/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
Polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) that form during industrial thermal processes, such as the cement kiln co-processing of BDE-209, are highly toxic contaminants. Nevertheless, the formation mechanisms of octa-brominated dioxins/furans (OBDD/Fs), most PBDD/F congeners, and one precursor of the more toxic lower PBDD/Fs from BDE-209 have received little attention. In cement kiln co-processes, the Ca2+-mediated regulation of OBDD/F formation is still debated. In this study, simulation experiments revealed that the average brominating degree of PBDD/Fs was 7.8, indicating that OBDD/Fs are dominant congeners (93.6 % median). Density functional theory (DFT) calculations found a new transition state (TS1) with a lower energy barrier than that found in a previous study. Three major OBDD/F formation reactions suggested that the presence of Ca2+ was thermodynamically beneficial to the formation of OBDD/Fs. This promotion effect can be attributed to the transfer of electron density leading to a change in the Mayer bond order (MBO) among elements when Ca2+ was bound. Intriguingly, in the transition state structures of the Ca2+-bound and Ca2+-free systems, the MBO difference among the old and new bonds can reveal the difficulty of Ca2+-mediated OBDD/F formation reactions from BDE-209.
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Affiliation(s)
- Jinzhong Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China; College of Water Sciences, Beijing Normal University, Beijing 100875, PR China.
| | - Yufei Yang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Zhen Xie
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Haibin Yu
- China National Environmental Monitoring Centre, Beijing 100012, PR China.
| | - Qifei Huang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Ya Xu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Jie He
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
| | - Tao Wen
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, PR China.
| | - Qingqing Liu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
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6
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Zheng Z, Lu G, Wang R, Huang K, Tao X, Yang Y, Zou M, Xie Y, Yin H, Shi Z, Dang Z. Effects of surfactant on the degradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by nanoscale Ag/Fe particles: Kinetics, mechanisms and intermediates. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 245:780-788. [PMID: 30504035 DOI: 10.1016/j.envpol.2018.11.064] [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: 06/01/2018] [Revised: 11/12/2018] [Accepted: 11/21/2018] [Indexed: 06/09/2023]
Abstract
Surfactants are known to enhance the degradation of halogenated organics by nanoscale zerovalent iron (n-ZVI) or n-ZVI-based bimetallic particles, but the mechanism of the promotion is not well understood. In this study, we used nanoscale Ag/Fe particles (n-Ag/Fe) to degrade 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in different surfactant solutions. The results show that the nonionic surfactant TX-100 had the best promoting effect, which might be attributed to the decrease in particle agglomeration and improvement of mass transfer efficiency after the adsorption of TX-100 on n-Ag/Fe. The distribution analysis of BDE-47 in solid and liquid phases indicates that when the concentration of TX-100 in aqueous solution was above critical micelle concentration, BDE-47 started to dissolve in the liquid phase. Thus, TX-100 micelles can enhance the mass transfer efficiency of BDE-47. However, a too high concentration of TX-100 (above 1.0 mM) would influence the promotion effect of BDE-47 degration, which might be attributed to the excessive and thicker micelles of TX-100 hindering the contact between BDE-47 and n-Ag/Fe. We also studied the degradation pathway of BDE-47 and its products, and found that surfactants did not change the degradation pathway of BDE-47.
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Affiliation(s)
- Zhiqiang Zheng
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
| | - Guining Lu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China; Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, Guangzhou, 510006, China.
| | - Rui Wang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
| | - Kaibo Huang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China
| | - Xueqin Tao
- College of Environmental Science and Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yulu Yang
- College of Environmental Science and Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Mengyao Zou
- College of Environmental Science and Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Yingying Xie
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; School of Chemistry and Environmental Engineering, Hanshan Normal University, Chaozhou, 521041, China
| | - Hua Yin
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Zhenqing Shi
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
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Wang R, Tang T, Feng S, Chen X, Dang D, Huang K, Tao X, Yin H, Dang Z, Lu G. Experimental and theoretical investigations on debromination pathways of polybrominated biphenyls (PBBs) under ultraviolet light. CHEMOSPHERE 2018; 212:1-7. [PMID: 30130655 DOI: 10.1016/j.chemosphere.2018.08.063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2018] [Revised: 07/29/2018] [Accepted: 08/13/2018] [Indexed: 06/08/2023]
Abstract
Polybrominated biphenyls (PBBs) are brominated flame retardants that are widely used in textiles and electronic products. Recently, many researches have been devoted to determining their concentrations in food and in the environment. Yet, their degradation behavior has been less investigated and is not well understood. Here, we have investigated the debromination pathways of PBBs by (UV) light in the case of 2,4,5-tribrominated biphenyl (PBB-29). Our investigation indicates that para-bromine substituent on PBB-29 was preferentially removed. By means of density functional theory (DFT), we found that the energies of the debromination products, the CBr bond length in the excited state (S1), the Mulliken charge of bromine in S1, and the lowest unoccupied molecular orbital (LUMO) in S1 correlated well with the debromination pathways of PBBs. Further, LUMO-based prediction of PBB debromination pathways in S1 suggests that the bromine substituent on all brominated positions (i.e. ortho-, meta- and para-) can be preferentially removed, as the debromination sequence is not based on the brominated position but on the specific brominated arrangement pattern. In addition, reductive debromination preferentially occurs on the benzene ring that has the highest number of bromine substituents. This study provided useful descriptors to predict the debromination pathways of PBBs, and the theoretical result greatly improve our understanding of photolytic debromination of PBBs.
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Affiliation(s)
- Rui Wang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Ting Tang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Siyuan Feng
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xingwei Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
| | - Dai Dang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, China
| | - Kaibo Huang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xueqin Tao
- College of Environmental Science and Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
| | - Hua Yin
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China
| | - Guining Lu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, China.
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Yan Y, Li Y, Ma M, Ma W, Cheng X, Xu K. Effects of coexisting BDE-47 on the migration and biodegradation of BDE-99 in river-based aquifer media recharged with reclaimed water. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:5140-5153. [PMID: 28512710 DOI: 10.1007/s11356-017-9143-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 04/27/2017] [Indexed: 06/07/2023]
Abstract
Two prominent polybrominated diphenyl ether (PBDE) congeners have been included in the persistent organic pollutant list, 2,2',4,4',5-tetrabromodiphenyl ether (BDE-99) and 2,2,4,4'-tetrabromodiphenyl ether (BDE-47), which have been detected in treated municipal wastewater, river water, and sediments in China. A lab-scale column experiment was established to investigate the effects of the competitive sorption of BDE-47 on BDE-99 biodegradation and migration in two types of river-based aquifer soils during groundwater recharge with reclaimed water. Two types of recharge columns were used, filled with either silty clay (SC) or black carbon-amended silty clay (BCA). The decay rate constants of BDE-99 in the BCA and SC systems were 0.186 and 0.13 m-1 in the single-solute system and 0.128 and 0.071 m-1 in the binary-solute system, respectively, showing that the decay of BDE-99 was inhibited by the coexistence of BDE-47. This was particularly evident in the SC system because the higher hydrophobicity of BDE-99 determined the higher affinity and competition for sorption sites onto black carbon. The biodegradation of BDE-99 was suppressed by the coexistence of BDE-47, especially in the SC system. Lesser-brominated congeners (BDE-47 and BDE-28) and higher-brominated congeners (BDE-100, BDE-153, BDE-154, and BDE-183) were generated in the four recharge systems, albeit at different ratios. Bacterial biodiversity was influenced by the presence of BDE-47 in the SC system, while it had no significant effect on the BCA system, because the high sorption capacity of black carbon on the hydrophobic PBDEs effectively reduced their toxicity. The ranking order of the most abundant classes changed markedly due to the coexistence of BDE-47 in both the SC and BCA systems. The ranking order of the most abundant genera changed from Azospira, Methylotenera, Desulfovibrio, Methylibium, and Bradyrhizobium to Halomonas, Hyphomicrobium, Pseudomonas, Methylophaga, and Shewanella, which could be involved in PBDE degradation.
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Affiliation(s)
- Y Yan
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Y Li
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - M Ma
- Graduate School of International Relationship, International University of Japan, Minami Uonuma, 9497248, Japan
| | - W Ma
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China.
| | - X Cheng
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - K Xu
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
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9
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Wang R, Lu G, Lin H, Huang K, Tang T, Xue X, Yang X, Yin H, Dang Z. Relative roles of H-atom transfer and electron transfer in the debromination of polybrominated diphenyl ethers by palladized nanoscale zerovalent iron. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 222:331-337. [PMID: 28034557 DOI: 10.1016/j.envpol.2016.12.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 12/05/2016] [Accepted: 12/07/2016] [Indexed: 06/06/2023]
Abstract
The relative significance of H-atom transfer versus electron transfer in the dehalogenation of halogenated organic compounds (HOCs) in bimetallic systems has long been debated. In this study, we have investigated this question through the case study of the debromination of 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47). The debromination rates of isomer products of BDE-47 by palladized nano zero-valent iron (n-ZVI/Pd) in the same reactor were compared. The results confirmed a shift in the debromination pathway of BDE-47 when treated with unpalladized nano zero-valent iron (n-ZVI) vs. treatment with n-ZVI/Pd. Study showed that BDEs could be rapidly debrominated in a palladium-H2 system, and the debromination pathway in this system is the same as that in the n-ZVI/Pd system. These results suggest that the H-atom species adsorbed on the surface of palladium are responsible for the enhanced reaction rates and the shift of the debromination pathway in the n-ZVI/Pd system. The Mulliken charges, calculated with density functional theory, on bromine atoms of PBDEs were directly correlated with the susceptibility to the e-transfer pathway in the n-ZVI system and inversely correlated with the susceptibility to the H-transfer pathway in n-ZVI/Pd system. These experimentally verified correlations in BDE-47 permit the prediction of the dominant debromination pathway in other BDEs.
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Affiliation(s)
- Rui Wang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Guining Lu
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China; Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, Guangzhou 510006, China.
| | - Haozhong Lin
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Kaibo Huang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Ting Tang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Xiuling Xue
- School of Chemical Engineering, Huaqiao University, Xiamen 361021, China
| | - Xingjian Yang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
| | - Hua Yin
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006, China; Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, Guangzhou 510006, China.
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10
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Yu Q, Xie HB, Li T, Ma F, Fu Z, Wang Z, Li C, Fu Z, Xia D, Chen J. Atmospheric chemical reaction mechanism and kinetics of 1,2-bis(2,4,6-tribromophenoxy)ethane initiated by OH radical: a computational study. RSC Adv 2017. [DOI: 10.1039/c6ra26700a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The mechanism and kinetics of OH-initiated oxidation of BTBPE, an alternative of PBDEs, were investigated.
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11
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Yu Q, Xie HB, Chen J. Atmospheric chemical reactions of alternatives of polybrominated diphenyl ethers initiated by OH: A case study on triphenyl phosphate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 571:1105-1114. [PMID: 27457671 DOI: 10.1016/j.scitotenv.2016.07.105] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 07/13/2016] [Accepted: 07/15/2016] [Indexed: 06/06/2023]
Abstract
Many studies have been performed to evaluate the environmental risk caused by alternative flame retardants (AFRs) of polybrominated diphenyl ethers due to their ubiquitous occurrence in the environment. However, as an indispensable component of the environmental risk assessment, the information on atmospheric fate of AFRs is limited although some AFRs have been frequently and highly detected in the atmosphere. Here, a combined quantum chemical method and kinetics modeling were used to investigate atmospheric transformation mechanism and kinetics of AFRs initiated by OH in the presence of O2, taking triphenyl phosphate (TPhP) as a case. Results show that the pathway involving initial OH addition to phenyl of TPhP to form TPhP-OH adduct, and subsequent reaction of the TPhP-OH adduct with O2 to finally form phenol phosphate, is the most favorable for the titled reaction. The calculated overall reaction rate constant is 1.6×10(-12)cm(3) molecule(-1)s(-1), translating 7.6days atmospheric lifetime of TPhP. This clarifies that gaseous TPhP has atmospheric persistence. In addition, it was found that ice surface, as a case of ubiquitous water in the atmosphere, has little effect on the kinetics of the rate-determining step in the OH-initiated TPhP reaction.
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Affiliation(s)
- Qi Yu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, 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.
| | - Jingwen Chen
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
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