title: Quantum chemical investigation on the mechanism and kinetics of OH radical-initiated atmospheric oxidation of PCB-47.
abstract: The OH radical-initiated atmospheric oxidation degradation of 2,2',4,4'-tetrachlorobiphenyl (PCB-47) was investigated by using quantum chemical calculations. All possible pathways involved in the oxidation process were discussed. Potential barriers and reaction heats have been obtained to assess the energetically favorable reaction pathways and the relatively stable products. The study shows that the OH radicals are more likely to attack the C3 and C5 atom of the aromatic ring in the PCB-47 molecule to form PCB-OH adducts. Subsequent reactions are the addition of O2 or NO2 molecule to the PCB-OH adducts at the ortho position of the OH group. Water molecule plays an important role during the whole degradation process. The individual and overall rate constants were calculated by using the Rice-Ramsperger-Kassel-Marcus (RRKM) theory over the temperature range of 180-370K. At 298K, the atmospheric lifetime of PCB-47 determined by OH radicals is about 9.1d. The computational results are crucial to risk assessment and pollution prevention of PCBs.
authors.affiliation: Environment Research Institute, Shandong University, Jinan 250100, PR China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Environment Research Institute, Shandong University, Jinan 250100, PR China. Electronic address: zqz@sdu.edu.cn.
authors.forename: Qingzhu
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: School of Environment, Tsinghua University, Beijing 100084, PR China. Electronic address: wanghui@tsinghua.edu.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Environment Research Institute, Shandong University, Jinan 250100, PR China.
authors.forename: Wenxing
authors.initials: W
authors.lastname: Wang
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D001272:Atmosphere / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D010084:Oxidation-Reduction; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D011789:Quantum Theory; D014867:Water / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D014867:Water; D017665:Hydroxyl Radical; C035976:2,4,2',4'-tetrachlorobiphenyl; D011078:Polychlorinated Biphenyls
keywords: Kinetic parameters; OH radicals; PCB-47; Reaction mechanism