Hydrogen Peroxide Enhances the Oxidation of Oxygenated Volatile Organic Compounds on Mineral Dust Particles: A Case Study of Methacrolein
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- 作者：Yue Zhao ; Dao Huang ; Liubin Huang ; Zhongming Chen
- 刊名：Environmental Science & Technology
- 出版年：2014
- 出版时间：September 16, 2014
- 年：2014
- 卷：48
- 期：18
- 页码：10614-10623
- 全文大小：510K
- ISSN：1520-5851
文摘
Heterogeneous oxidation of oxygenated volatile organic compounds (OVOCs) serves as an important sink of OVOCs as well as a source of secondary organic material. However, the roles of gas phase oxidants in these reactions are poorly understood. In this work, we present the first laboratory study of the heterogeneous reactions of methacrolein (MACR) on various mineral dust particles in the presence of gaseous H<sub>2sub>O<sub>2sub>. It is found that the presence of gaseous H<sub>2sub>O<sub>2sub> significantly promotes both the uptake and oxidation of MACR on kaolinite, 伪-Al<sub>2sub>O<sub>3sub>, 伪-Fe<sub>2sub>O<sub>3sub>, and TiO<sub>2sub>, but not on CaCO<sub>3sub>. The oxidation of MACR produces organic acids as its major low-molecular-weight product, whose yields are enhanced by a factor of 2鈥? in the presence of H<sub>2sub>O<sub>2sub>. In addition, organic peroxides such as methyl hydroperoxide, peroxyformic acid, and peroxyacetic acid are only formed in the presence of H<sub>2sub>O<sub>2sub>, and the formation of methyl hydroperoxide indicates that MACR oxidation on the surface involves reaction with OH radicals. A probe reaction using salicylic acid verifies the production of OH radicals from H<sub>2sub>O<sub>2sub> decomposition on kaolinite, 伪-Al<sub>2sub>O<sub>3sub>, 伪-Fe<sub>2sub>O<sub>3sub>, and TiO<sub>2sub>, which rationalizes the enhanced MACR oxidation observed on these particles. The uptake coefficients of MACR on kaolinite, 伪-Fe<sub>2sub>O<sub>3sub>, and TiO<sub>2sub> in the presence of H<sub>2sub>O<sub>2sub> are on the order of 10<sup>鈥?sup>鈥?0<sup>鈥?sup>. Our results provide new insights into the formation and chemical evolution of organic species in the atmosphere.