مهدی اسرافیلی دیزجی

The acidic dissolution of chalcopyrite in the sulfated medium is dependent on the rate of ferric (F3þ) ionreduction. Due to the formation of elemental sulfur passive layer on the chalcopyrite surface, the ferricion reduction rate decreases at the surface and prevents electron transfer from the surface to ferric ion. Inthis research, the interaction of ferric ion with sulfur passive layer in different modes has been studiedusing studio material software and density functional theory method. The results showed that the sulfurpassive layer is insulated and ferric ion does not react on this surface, but the layer can be activated bychanges in the structure. Defects in the passive layer structure (removal of sulfur atoms) or substitutionof metal ions (iron and copper) cause surface reactivity, which by interaction with ferric ion will result inelectron transfer to 3d orbital of Fe3þion. The overlap of 3p orbital surface sulfur atoms and the 3dorbital ferric ion conduction band provide the conditions for electron transfer. Also, the Fe3þionadsorption energies for different surface states, structure defects; ferrous and cupric ions substitutionwere obtained at244,229 and228 kcal/mol, respectively. In addition, energy change (DE) due to thereduction of Fe3þion for structure defects more than the other two surfaces