Experimental and computational study of the differential sulfidization mechanism of smithsonite and calcite

Abstract

The crystal structures of smithsonite and calcite are very similar. However, their sulfidization performances have a huge difference. Herein, DFT computations, XPS, and ICP experiments were innovatively used to research the differential sulfidization mechanism of smithsonite and calcite. The computation results showed that the HS interaction with hydrated smithsonite surface was far more energy supported than that with hydrated calcite surface, and the interaction ability of H2O and HS on smithsonite and calcite surfaces was just the opposite. The interaction of smithsonite surface with HS was stronger than that of H2O, and the pre-adsorbed H2O on smithsonite surface can be desorbed by HS. However, the interaction of calcite surface with HS was weaker than that of H2O, and the HS adsorption was blocked by the pre-adsorbed H2O on calcite surface. It was clarified from the atomic level that smithsonite was sulfidized but calcite was not. Besides, after sulfidization treatment, XPS test showed that a new peak of S appeared on smithsonite surface while not appeared on calcite surface. ICP test showed that the adsorbed amount of S species on smithsonite surface was far larger than that on calcite surface. These further provided experimental support for the computation results.