So2 Adsorption and Conversion on Pristine and Defected Calcite {104} Surface : A Density Functional Theory Study

The role of mineral dust on atmospheric pollutions formation is one of the significant challenges in environmental and atmospheric science. The conversion of atmospheric pollutions on mineral dust depends largely on its surface physiochemical properties. However, the adsorption and conversion of polluting gases on typical mineral dust surface in China are still poorly understood. In this study, the impact of calcite surface defects, oxidizers and adsorbed H2O on the adsorption and oxidation process of SO2 on calcite {104} surface is systematically studied by density functional theory (DFT) method. The results indicate that the surface defects enhance the adsorption of SO2 on calcite {104} surface. Compared with O2, O3 is more beneficial for the oxidation conversion of SO2 on various calcite {104} surfaces. For pristine calcite {104} and Mn-doped calcite {104}, SO2 can be converted to adsorbed SO3 by O3, while adsorbed H2O inhibits this process. For CO32- vacancy defected calcite {104} surface, with the aid of dissociated H2O, SO2 can be easily converted to sulfate instead of adsorbed gaseous SO3. Thus, the evolution of the adsorbed SO2 on calcite {104} can be regulated by the surficial physiochemical properties and the adsorbed H2O