Multiphase oxidation of SO 2 by NO 2 on CaCO 3 particles
Multiphase oxidation of SO 2 by NO 2 on CaCO 3 particles
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DOI：
10.5194/acp-18-2481-2018
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发表时间：
2018-02
影响因子：
6.3
通讯作者：
Defeng Zhao;Xiaojuan Song;T. Zhu;Zefeng Zhang;Yingjun Liu;J. Shang
中科院分区：
文献类型：
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作者：
Defeng Zhao;Xiaojuan Song;T. Zhu;Zefeng Zhang;Yingjun Liu;J. Shang
抽象。SO2被NO2在固体或水相颗粒上的非均相/多相氧化被认为是大气中硫酸盐的潜在重要来源，例如，在严重污染事件（霾）期间，但反应机制和速率尚不确定。在这项研究中，为了评估的重要性，SO2的直接氧化NO2，我们研究了SO2与NO2的非均相/多相反应的单个CaCO 3颗粒在氮气中使用显微拉曼光谱。在SO2-scinNO 2-scinH 2 O-scinN 2气体混合物中，CaCO 3固体颗粒首先通过与NO2的反应和Ca（NO3）2的潮解转化为Ca（NO3）2液滴，然后NO2氧化Ca（NO3）2液滴中的SO2形成CaSO 4，其表现为针状晶体。硫酸盐主要是在CaCO 3完全转化为Ca（NO3）2后，即NO2多相氧化SO2过程中形成的。CaSO 4从液滴溶液中沉淀促进硫酸盐形成。SO2形成硫酸盐的反应性吸收系数约为10−8，RH增强了吸收系数。我们估计，与气相中OH对SO2的氧化相比，NO2对SO2的直接多相氧化并不是环境大气中硫酸盐的重要来源，并且不如其他水相途径（例如SO2与H2的反应）重要。O2、O3和O2（有或没有过渡金属）。
Abstract. Heterogeneous/multiphase oxidation of SO2 by NO2 on solid or aqueous particles is thought to be a potentially important source of sulfate in the atmosphere, for example, during heavily polluted episodes (haze), but the reaction mechanism and rate are uncertain. In this study, in order to assess the importance of the direct oxidation of SO2 by NO2 we investigated the heterogeneous/multiphase reaction of SO2 with NO2 on individual CaCO3 particles in N2 using Micro-Raman spectroscopy. In the SO2 ∕ NO2 ∕ H2O ∕ N2 gas mixture, the CaCO3 solid particle was first converted to the Ca(NO3)2 droplet by the reaction with NO2 and the deliquescence of Ca(NO3)2, and then NO2 oxidized SO2 in the Ca(NO3)2 droplet forming CaSO4, which appeared as needle-shaped crystals. Sulfate was mainly formed after the complete conversion of CaCO3 to Ca(NO3)2, that is, during the multiphase oxidation of SO2 by NO2. The precipitation of CaSO4 from the droplet solution promoted sulfate formation. The reactive uptake coefficient of SO2 for sulfate formation is on the order of 10−8, and RH enhanced the uptake coefficient. We estimate that the direct multiphase oxidation of SO2 by NO2 is not an important source of sulfate in the ambient atmosphere compared with the SO2 oxidation by OH in the gas phase and is not as important as other aqueous-phase pathways, such as the reactions of SO2 with H2O2, O3, and O2, with or without transition metals.