Formation of sulfur oxide groups by SO and their roles in mercury adsorption on carbon-based materials.

The presence of SO display significant effect on the mercury (Hg) adsorption ability of carbon-based sorbent. Yet the adsorption and oxidation of SO on carbon with oxygen group, as well as the roles of different sulfur oxide groups in Hg adsorption have heretofore been unclear. The formation of sulfur oxide groups by SO and their effects on Hg adsorption on carbon was detailed examined by the density functional theory. The results show that SO can be oxidized into SO by oxygen group on carbon surface. Both C-SO and C-SO can improve Hg adsorption on carbon site, while the promotive effect of C-SO is stronger than C-SO. Electron density difference analyses reveal that sulfur oxide groups enhance the charge transfer ability of surface unsaturated carbon atom, thereby improving Hg adsorption. The experimental results confirm that surface active groups formed by SO adsorption is more active for Hg adsorption than the groups generated by SO.