Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere
Carbazole is one of the typical heterocyclic aromatic compounds (NSO-HETs) observed in polluted urban atmosphere, which has become a serious environmental concern. The most important atmospheric loss process of carbazole is the reaction with OH radical. The present work investigated the mechanism of...
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MDPI AG
2022-07-01
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| author | Zhuochao Teng Xiaotong Wang Mohammad Hassan Hadizadeh Yanan Han Xianwei Zhao Qi Zhang Hetong Wang Ying Li Fei Xu Yanhui Sun |
| author_facet | Zhuochao Teng Xiaotong Wang Mohammad Hassan Hadizadeh Yanan Han Xianwei Zhao Qi Zhang Hetong Wang Ying Li Fei Xu Yanhui Sun |
| author_sort | Zhuochao Teng |
| collection | DOAJ |
| description | Carbazole is one of the typical heterocyclic aromatic compounds (NSO-HETs) observed in polluted urban atmosphere, which has become a serious environmental concern. The most important atmospheric loss process of carbazole is the reaction with OH radical. The present work investigated the mechanism of OH-initiated atmospheric oxidation degradation of carbazole by using density functional theory (DFT) calculations at the M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. The rate constants were determined by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The lifetime of carbazole determined by OH was compared with other typical NSO-HETs. The theoretical results show that the degradation of carbazole initiated by OH radical includes four types of reactions: OH additions to “bend” C atoms, OH additions to “benzene ring” C atoms, H abstractions from C-H bonds and the H abstraction from N-H bond. The OH addition to C1 atom and the H abstraction from N-H bond are energetically favorable. The main oxidation products are hydroxycarbazole, dialdehyde, carbazolequinone, carbazole-ol, hydroxy-carbazole-one and hydroperoxyl-carbazole-one. The calculated overall rate constant of carbazole oxidation by OH radical is 6.52 × 10<sup>−12</sup> cm<sup>3</sup> molecule<sup>−1</sup> s<sup>−1</sup> and the atmospheric lifetime is 37.70 h under the condition of 298 K and 1 atm. The rate constant of carbazole determined by OH radical is similar with that of dibenzothiophene oxidation but lower than those of pyrrole, indole, dibenzofuran and fluorene. This work provides a theoretical investigation of the oxygenated mechanism of NSO-HETs in the atmosphere and should help to clarify their potential health risk for determining the reaction pathways and environmental influence of carbazole. |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-09T12:14:33Z |
| publishDate | 2022-07-01 |
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| series | Atmosphere |
| spelling | doaj.art-1f12ba938b9a45378734c53ff1c791b32023-11-30T22:47:21ZengMDPI AGAtmosphere2073-44332022-07-01137112910.3390/atmos13071129Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the AtmosphereZhuochao Teng0Xiaotong Wang1Mohammad Hassan Hadizadeh2Yanan Han3Xianwei Zhao4Qi Zhang5Hetong Wang6Ying Li7Fei Xu8Yanhui Sun9Environment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Qingdao 266237, ChinaCollege of Environment and Safety Engineering, Qingdao University of Science & Technology, Qingdao 266042, ChinaCarbazole is one of the typical heterocyclic aromatic compounds (NSO-HETs) observed in polluted urban atmosphere, which has become a serious environmental concern. The most important atmospheric loss process of carbazole is the reaction with OH radical. The present work investigated the mechanism of OH-initiated atmospheric oxidation degradation of carbazole by using density functional theory (DFT) calculations at the M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. The rate constants were determined by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The lifetime of carbazole determined by OH was compared with other typical NSO-HETs. The theoretical results show that the degradation of carbazole initiated by OH radical includes four types of reactions: OH additions to “bend” C atoms, OH additions to “benzene ring” C atoms, H abstractions from C-H bonds and the H abstraction from N-H bond. The OH addition to C1 atom and the H abstraction from N-H bond are energetically favorable. The main oxidation products are hydroxycarbazole, dialdehyde, carbazolequinone, carbazole-ol, hydroxy-carbazole-one and hydroperoxyl-carbazole-one. The calculated overall rate constant of carbazole oxidation by OH radical is 6.52 × 10<sup>−12</sup> cm<sup>3</sup> molecule<sup>−1</sup> s<sup>−1</sup> and the atmospheric lifetime is 37.70 h under the condition of 298 K and 1 atm. The rate constant of carbazole determined by OH radical is similar with that of dibenzothiophene oxidation but lower than those of pyrrole, indole, dibenzofuran and fluorene. This work provides a theoretical investigation of the oxygenated mechanism of NSO-HETs in the atmosphere and should help to clarify their potential health risk for determining the reaction pathways and environmental influence of carbazole.https://www.mdpi.com/2073-4433/13/7/1129carbazoleOH radicalrate constantsoxidation mechanismdensity functional theory (DFT) |
| spellingShingle | Zhuochao Teng Xiaotong Wang Mohammad Hassan Hadizadeh Yanan Han Xianwei Zhao Qi Zhang Hetong Wang Ying Li Fei Xu Yanhui Sun Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere Atmosphere carbazole OH radical rate constants oxidation mechanism density functional theory (DFT) |
| title | Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere |
| title_full | Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere |
| title_fullStr | Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere |
| title_full_unstemmed | Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere |
| title_short | Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere |
| title_sort | theoretical perspectives on the gas phase oxidation mechanism and kinetics of carbazole initiated by oh radical in the atmosphere |
| topic | carbazole OH radical rate constants oxidation mechanism density functional theory (DFT) |
| url | https://www.mdpi.com/2073-4433/13/7/1129 |
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