Uncovering the oxidation mechanism of sphalerite (ZnS) in the absence and presence of water: A first-principles investigation
Yuanjia Luo, Wei Sun, Haisheng Han, Jian Peng, Feng Jiang
Abstract
Herein, a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H 2 O. The findings showed that single O 2 was preferred to be dissociated adsorption on sphalerite surface by generating S O and Zn O bonds, and the S atom on the surface was the most energy-supported site for O 2 adsorption, on which a Zn O S O Zn structure will be formed. However, dissociated adsorption of single H 2 O will not happen. It was preferred to be adsorbed on the top Zn atom on sphalerite surface in molecular form through Zn O bond. Besides, sphalerite oxidation can occur as if O 2 was present regardless of the presence of H 2 O, and when H 2 O and O 2 coexisted, the formation of sulfur oxide (SO 2 ) needed a lower energy barrier and it was easier to form on sphalerite surface than that only O 2 existed. In the absence of H 2 O, when SO 2 was generated, further oxidation of which would form neutral zinc sulfate. In the presence of H 2 O, the formation of SO 2 on sphalerite surface was easier and the rate of further oxidation to form sulfate was also greater. Consequently, the occurrence of sphalerite oxidation was accelerated.