Abstract The importance of the oxidizing capacity of reactive chlorine species, and the heterogeneous reactions of atmospheric pollution gases on the surface of particles has been well established in field observation, modeling simulation and laboratory exploration. However, less is known about the reactions of reactive chlorine on mineral particles. We studied the effect of Cl2 on the heterogeneous reaction of NO2 with γ-Al2O3 by using ion chromatography and positron annihilation lifetime spectroscopy. The presence of Cl2 can promote the uptake of NO2 on γ-Al2O3 at humid conditions. The probable explanations are that Cl2 rapidly reacts with NO2 on the γ-Al2O3 surface in the presence of adsorbed water, and nitrites, as the intermediate products during the heterogeneous reaction of NO2 on mineral dust, are immediately oxidized by adsorbed Cl2. In the positron annihilation lifetime spectroscopy experiment, a porous γ-Al2O3 was demonstrated by the relatively high fourth lifetime intensity. The increase in the number of anions (onto γ-Al2O3) when the reaction time was prolonged was a direct consequence of the decrease in the o-Ps intensity and the o-Ps lifetime, which illustrated that the heterogeneous reactions might occur on the porous surface of γ-Al2O3. Our results suggest that the oxidative effect of Cl2 on the heterogeneous conversion of NO2 to nitrogen-containing particles might have a significant contribution to the fine particle growth and to the unknown sources of nitrate observed in secondary inorganic aerosols.

中文翻译：

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Cl 2 和NO 2 在γ-Al 2 O 3 上的非均相反应：二次气溶胶的潜在形成途径

摘要 活性氯物质的氧化能力以及大气污染气体在颗粒表面的非均相反应的重要性已在现场观察、建模模拟和实验室探索中得到充分证实。然而，人们对活性氯在矿物颗粒上的反应知之甚少。我们通过离子色谱和正电子湮没寿命光谱研究了 Cl2 对 NO2 与 γ-Al2O3 非均相反应的影响。Cl2 的存在可以促进 γ-Al2O3 在潮湿条件下对 NO2 的吸收。可能的解释是，Cl2 在吸附水的存在下与 γ-Al2O3 表面上的 NO2 迅速反应，而亚硝酸盐作为 NO2 在矿物粉尘上的非均相反应过程中的中间产物，立即被吸附的 Cl2 氧化。在正电子湮没寿命光谱实验中，相对较高的第四寿命强度证明了多孔γ-Al2O3。当反应时间延长时，阴离子数量增加（在 γ-Al2O3 上）是 o-Ps 强度和 o-Ps 寿命降低的直接结果，这说明多孔材料上可能发生非均相反应。 γ-Al2O3 表面。我们的结果表明，Cl2 对 NO2 向含氮颗粒的非均相转化的氧化作用可能对细颗粒生长和二次无机气溶胶中观察到的未知硝酸盐来源有重要贡献。当反应时间延长时，阴离子数量增加（在 γ-Al2O3 上）是 o-Ps 强度和 o-Ps 寿命降低的直接结果，这说明多孔材料上可能发生非均相反应。 γ-Al2O3 表面。我们的结果表明，Cl2 对 NO2 向含氮颗粒的非均相转化的氧化作用可能对细颗粒生长和二次无机气溶胶中观察到的未知硝酸盐来源有重要贡献。当反应时间延长时，阴离子数量增加（在 γ-Al2O3 上）是 o-Ps 强度和 o-Ps 寿命降低的直接结果，这说明多孔材料上可能发生非均相反应。 γ-Al2O3 表面。我们的结果表明，Cl2 对 NO2 向含氮颗粒的非均相转化的氧化作用可能对细颗粒生长和二次无机气溶胶中观察到的未知硝酸盐来源有重要贡献。