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Ding Z, Yi Y, Wang W, Zhang Q. Understanding the role of Cl and NO 3 radicals in initiating atmospheric oxidation of fluorene: A mechanistic and kinetic study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 716:136905. [PMID: 32044478 DOI: 10.1016/j.scitotenv.2020.136905] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/21/2020] [Accepted: 01/22/2020] [Indexed: 06/10/2023]
Abstract
The photooxidation of volatile organic compounds (VOCs) initiated by Cl and NO3 radicals has been investigated for decades to assess the atmospheric fates of pollutants. Gas-phase fluorene is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) that can be oxidized by activated radicals. In this study, we used quantum chemical calculation to study the atmospheric degradation of fluorene initiated by Cl and NO3 radicals. The results showed that the Cl radical initiated reaction of fluorene mainly produces 9-fluorene radical that has significant potential to form secondary pollutants with more persistent toxic properties. The NO3 radical initiated reaction of fluorene leads to the formation of oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) including nitrooxyfluorene, nitrooxyfluorenone and 1,4-fluorenequinone. The rate constants and branch ratios of elementary reactions were determined based on Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The atmospheric lifetime of fluorene determined by NO3 radical is deduced to be 1.52 days according to the calculated overall rate constant, 1.52 × 10-14 cm3 molecule-1 s-1. The derivatives produced from the atmospheric degradation of fluorene initiated by Cl and NO3 radicals increase the environmental risks of fluroene. Combined with previous experimental and theoretical findings, this work can help to clarify the atmospheric fate and assess the environmental risks of fluorene.
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Affiliation(s)
- Zhezheng Ding
- Environment Research Institute, Shandong University Qingdao, 266237, PR China
| | - Yayi Yi
- Environment Research Institute, Shandong University Qingdao, 266237, PR China
| | - Wenxing Wang
- Environment Research Institute, Shandong University Qingdao, 266237, PR China
| | - Qingzhu Zhang
- Environment Research Institute, Shandong University Qingdao, 266237, PR China.
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Karimova NV, Chen J, Gord JR, Staudt S, Bertram TH, Nathanson GM, Gerber RB. S N2 Reactions of N 2O 5 with Ions in Water: Microscopic Mechanisms, Intermediates, and Products. J Phys Chem A 2020; 124:711-720. [PMID: 31880456 DOI: 10.1021/acs.jpca.9b09095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Reactions of dinitrogen pentoxide (N2O5) greatly affect the concentrations of NO3, ozone, OH radicals, methane, and more. In this work, we employ ab initio molecular dynamics and other tools of computational chemistry to explore reactions of N2O5 with anions hydrated by 12 water molecules to shed light on this important class of reactions. The ions investigated are Cl-, SO42-, ClO4-, and RCOO- (R = H, CH3, C2H5). The following main results are obtained: (i) all the reactions take place by an SN2-type mechanism, with a transition state that involves a contact ion pair (NO2+NO3-) that interacts strongly with water molecules. (ii) Reactions of a solvent-separated nitronium ion (NO2+) are not observed in any of the cases. (iii) An explanation is provided for the suppression of ClNO2 formation from N2O5 reacting with salty water when sulfate or acetate ions are present, as found in recent experiments. (iv) Formation of novel intermediate species, such as (SO4NO2-) and RCOONO2, in these reactions is predicted. The results suggest atomistic-level mechanisms for the reactions studied and may be useful for the development of improved modeling of reaction kinetics in aerosol particles.
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Affiliation(s)
- Natalia V Karimova
- Department of Chemistry , University of California, Irvine , Irvine 92697 , California , United States
| | - James Chen
- Department of Chemistry , University of California, Irvine , Irvine 92697 , California , United States
| | - Joseph R Gord
- Department of Chemistry , University of Wisconsin-Madison , Madison 53706 , Wisconsin , United States
| | - Sean Staudt
- Department of Chemistry , University of Wisconsin-Madison , Madison 53706 , Wisconsin , United States
| | - Timothy H Bertram
- Department of Chemistry , University of Wisconsin-Madison , Madison 53706 , Wisconsin , United States
| | - Gilbert M Nathanson
- Department of Chemistry , University of Wisconsin-Madison , Madison 53706 , Wisconsin , United States
| | - R Benny Gerber
- Department of Chemistry , University of California, Irvine , Irvine 92697 , California , United States.,Institute of Chemistry and Fritz Haber Research Center , Hebrew University of Jerusalem , Jerusalem 91904 , Israel
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Ma F, Ding Z, Elm J, Xie HB, Yu Q, Liu C, Li C, Fu Z, Zhang L, Chen J. Atmospheric Oxidation of Piperazine Initiated by ·Cl: Unexpected High Nitrosamine Yield. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9801-9809. [PMID: 30063348 DOI: 10.1021/acs.est.8b02510] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Chlorine radicals (·Cl) initiated amine oxidation plays an important role for the formation of carcinogenic nitrosamine in the atmosphere. Piperazine (PZ) is considered as a potential atmospheric pollutant since it is an alternative solvent to monoethanolamine (MEA), a benchmark solvent in a leading CO2 capture technology. Here, we employed quantum chemical methods and kinetics modeling to investigate ·Cl-initiated atmospheric oxidation of PZ, particularly concerning the potential of PZ to form nitrosamine compared to MEA. Results showed that the ·Cl-initiated PZ reaction exclusively leads to N-center radicals (PZ-N) that mainly react with NO to produce nitrosamine in their further reaction with O2/NO. Together with the PZ + ·OH reaction, the PZ-N yield from PZ oxidation is still lower than that of the corresponding MEA reactions. However, the nitrosamine yield of PZ is higher than the reported value for MEA when [NO] is <5 ppb, a concentration commonly encountered in a polluted urban atmosphere. The unexpected high nitrosamine yield from PZ compared to MEA results from a more favorable reaction of N-center radicals with NO compared to O2. These findings show that the yield of N-center radicals cannot directly be used as a metric for the yield of the corresponding carcinogenic nitrosamine.
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Affiliation(s)
- Fangfang Ma
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Zhezheng Ding
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Jonas Elm
- Department of Chemistry and Climate , Aarhus University , Aarhus 8000 , Denmark
| | - 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
| | - 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
| | - Cong Liu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Chao Li
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment , Northeast Normal University , Changchun 130117 , China
| | - Zhiqiang Fu
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology , Dalian University of Technology , Dalian 116024 , China
| | - Lili Zhang
- 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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