SO2 adsorption and conversion on pristine and defected calcite {1 0 4} surface: A density functional theory study

Influence of the surficial physiochemical properties on the adsorption and conversion of SO 2 on calcite {1 0 4}. • The adsorption of SO 2 can be enhanced by both the surface defects and the adsorbed H 2 O on the calcite {1 0 4}. • Oxidation of SO 2 with O 3 is proposed to occur by an Eley-Rideal mechanism. • For Mn-doped calcite {1 0 4}, SO 2 can be converted to adsorbed SO 3 by O 3 . The presence of H 2 O is adverse to the conversion of SO 2 . • For CO 3 2– vacancy defected calcite {1 0 4}, with the aid of dissociated H 2 O, SO 2 can be easily converted into sulfate. 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 H 2 O on the adsorption and oxidation process of SO 2 on calcite {1 0 4} surface is systematically studied by density functional theory (DFT) method. The results indicate that the surface defects enhance the adsorption of SO 2 on calcite {1 0 4} surface. Compared with O 2 , O 3 is more beneficial for the oxidation conversion of SO 2 on various calcite {1 0 4} surfaces. For pristine calcite {1 0 4} and Mn-doped calcite {1 0 4}, SO 2 can be converted to adsorbed SO 3 by O 3 , while adsorbed H 2 O inhibits this process. For CO 3 2– vacancy defected calcite {1 0 4} surface, with the aid of dissociated H 2 O, SO 2 can be easily converted to sulfate instead of adsorbed gaseous SO 3 . Thus, the evolution of the adsorbed SO 2 on calcite {1 0 4} can be regulated by the surface physiochemical properties and the adsorbed H 2 O.