Ma Qingxin, Liu Yongchun, He Hong
Research Center for Eco-Environmental Science, Chinese Academy of Sciences, Haidian District, Beijing, China.
J Phys Chem A. 2008 Jul 24;112(29):6630-5. doi: 10.1021/jp802025z. Epub 2008 Jun 26.
Field measurements showed that there exists a correlation between nitrate and sulfate on mineral dust. In this work, the synergistic mechanism of adsorption and reaction between SO2 and NO2 on gamma-alumina was studied using in situ diffusion reflectance infrared Fourier spectroscopy (in situ DRIFTS) and temperature programmed desorption (TPD). The results revealed that the reaction pathway of NO2 adsorbed on alumina was altered in the presence of SO2. In the absence of SO2, nitrite was found to be an intermediate in the oxidation of NO2 to surface nitrate species. However, in the presence of SO2, the formation of nitrite was inhibited and a new intermediate, dinitrogen tetraoxide (N2O4), was observed. On the other hand, surface tetravalent sulfur species S(IV), including bisulfite and sulfite, were oxidized to sulfate in air condition when NO2 was present. The atmospheric implication of this synergistic effect was also discussed.
现场测量表明，矿物尘埃中的硝酸盐和硫酸盐之间存在相关性。在这项工作中，利用原位漫反射红外傅里叶光谱（原位漫反射红外光谱法）和程序升温脱附（TPD）研究了SO₂和NO₂在γ-氧化铝上的吸附和反应协同机制。结果表明，在SO₂存在的情况下，吸附在氧化铝上的NO₂的反应途径发生了改变。在没有SO₂的情况下，发现亚硝酸盐是NO₂氧化为表面硝酸盐物种的中间体。然而，在SO₂存在的情况下，亚硝酸盐的形成受到抑制，并观察到一种新的中间体四氧化二氮（N₂O₄）。另一方面，当存在NO₂时，包括亚硫酸氢盐和亚硫酸盐在内的表面四价硫物种S(IV)在空气条件下被氧化为硫酸盐。还讨论了这种协同效应的大气意义。
