title: OH radical-initiated oxidation degradation and atmospheric lifetime of N-ethylperfluorobutyramide in the presence of O₂/NOx.
abstract: The OH radical-initiated oxidation degradation of N-ethylperfluorobutyramide (EtFBA) in the presence of O2/NOx was investigated theoretically by using density functional theory (DFT). All possible pathways involved in the oxidation process were presented and discussed. The study shows that the H abstraction from the C(2)H(2) group in EtFBA is the most energetically favorable because of the lowest barrier and highest exothermicity. Canonical variational transition-state (CVT) theory with small curvature tunneling (SCT) contribution was used to predict the rate constants over the temperature range of 180-370 K. At 296 K, the calculated overall rate constant of EtFBA with OH radicals is 2.50 × 10(-12)cm(3)molecule(-1)s(-1). The atmospheric lifetime of EtFBA determined by OH radicals is short, about 4.6 days at 296K. However, the atmospheric lifetimes of its primary oxidation products, C3F7C(O)N(H)C(O)CH3, C3F7C(O)N(H)CH2CHO and C3F7C(O)NH2, are much longer, about 30-50 days. It demonstrates the possibility that the atmospheric oxidation degradation of polyfluorinated amides (PFAMs) contributes to the burden of observed perfluorinated pollutants in the Arctic region. This study reveals for the first time that the water molecule plays an important catalytic effect on several key elementary steps and promotes the degradation potential of EtFBA.
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: D000577:Amides / Q000378:metabolism*; D001272:Atmosphere; D007700:Kinetics; D010084:Oxidation-Reduction; D014867:Water
chemical_list: D000577:Amides; D014867:Water
keywords: Atmospheric lifetime; Kinetic parameters; N-ethylperfluorobutyramide; OH radicals; Oxidation degradation