Effect of copper atoms on the adsorption of ethyl xanthate on a sphalerite surface

Ab initio cluster model calculations were performed to study the interaction of hydroxyl ion (OH−) and ethyl xanthate (CH3CH2OCS2-) with a copper doped and pure sphalerite (1 1 1) surface. Calculations showed that both adsorbates interact strongly. The interaction energy of ethyl xanthate depends more on the position of copper and zinc sites of the Cu-doped ZnS structure than the number of copper atoms. The coordination mode of ethyl xanthate is bridge-like. The hydroxyl ion interacts more strongly on the zinc sites of the surface. The replacement of hydroxyl ion by ethyl xanthate is more favourable when hydroxyl ion is on the copper site of the surface and the second layer zinc atom has been replaced with copper. The copper atoms in the sphalerite crystal structure enhance the electron acceptor ability of sphalerite.