标题：Atmospheric degradation of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins in the presence of NO3 at night
作者：Yuyang Zhao;Xiaomin Sun;Jing Bai
作者机构：[Zhao, Y] Environment Research Institute, Shandong University, Jinan 250100, China;[ Sun, X] Environment Research Institute, Shandong University, Jina 更多
通讯作者地址：[Sun, XM]Shandong Univ, Environm Res Inst, Jinan 250100, Peoples R China.
来源：Canadian Journal of Chemistry
关键词：2;3;7;8-TeCDD;≥NO3 radical;atmospheric reaction mechanism;rate constant.
摘要：The density functional theory (DFT) has been applied to studies on the homogeneous gas-phase degradation of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins (2,3,7,8-TeCDD) initiated by the NO3 radical, which is an important atmospheric species at night. The geometrical parameters and vibrational frequencies of all the stationary points were calculated at the MPWB1K/6-31+G (d,p) level. Potential energies were calculated at the MPWB1K/6-311+G (3df,2p) level. Three sites on 2,3,7,8-TeCDD react with the NO3 radical with different barriers and reaction heats. The addition of NO3 to the carbon atom on the central C-O ring is the most appropriate pathway and with the lower barriers, and the central ring of polychlorinated dibenzo-p-dioxin is opened in the subsequent reactions. Some other pathways are stressed for the dechlorination mechanism. Canonical variational transition-state theory with small curvature tunneling contribution was used to calculate the rate constants of each elementary reaction over the temperature range of 200-400 K. The Arrhenius equations were fitted to show the relationship between rate constants and temperature.