Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Phys Chem Chem Phys. 2012 Feb 7;14(5):1668-76. doi: 10.1039/c1cp22217a. Epub 2011 Oct 12.
Sulfate is one of the most important aerosols in the atmosphere. A new sulfate formation pathway via synergistic reactions between SO(2) and NO(2) on mineral oxides was proposed. The heterogeneous reactions of SO(2) and NO(2) on CaO, α-Fe(2)O(3), ZnO, MgO, α-Al(2)O(3), TiO(2), and SiO(2) were investigated by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (in situ DRIFTS) at ambient temperature. Formation of sulfate from adsorbed SO(2) was promoted by the coexisting NO(2), while surface N(2)O(4) was observed as the crucial oxidant for the oxidation of surface sulfite. This process was significantly promoted by the presence of O(2). The synergistic effect between SO(2) and NO(2) was not observed on other mineral particles (such as CaCO(3) and CaSO(4)) probably due to the lack of the surface reactive oxygen sites. The synergistic reaction between SO(2) and NO(2) on mineral oxides resulted in the formation of internal mixtures of sulfate, nitrate, and mineral oxides. The change of mixture state will affect the physicochemical properties of atmospheric particles and therefore further influence their environmental and climate effects.
硫酸盐是大气中最重要的气溶胶之一。本文提出了一种新的硫酸盐形成途径，即 SO(2)和 NO(2)在矿物氧化物上通过协同反应形成硫酸盐。采用原位漫反射红外傅里叶变换光谱（in situ DRIFTS）技术，在常温条件下研究了 SO(2)和 NO(2)在 CaO、α-Fe(2)O(3)、ZnO、MgO、α-Al(2)O(3)、TiO(2)和 SiO(2)上的多相反应。共存的 NO(2)促进了吸附态 SO(2)形成硫酸盐，而表面 N(2)O(4)则被认为是表面亚硫酸盐氧化的关键氧化剂。该过程在 O(2)存在下显著增强。SO(2)和 NO(2)之间的协同效应在其他矿物颗粒（如 CaCO(3)和 CaSO(4))上可能由于缺乏表面反应性氧位而没有观察到。矿物氧化物上 SO(2)和 NO(2)之间的协同反应导致硫酸盐、硝酸盐和矿物氧化物的内混形成。混合物状态的变化将影响大气颗粒物的物理化学性质，从而进一步影响它们的环境和气候效应。
