Speaker
Mr
Bradley Nemutudi
(UL)
Description
The atmospheric oxidation of minerals either by weathering or aging involves physical and chemical adsorption of oxygen on the surfaces and this forms various peroxides and hydroxides. In this study ab-initio computational method was employed to investigate the interaction of oxygen and water molecules at different adsorption sites on the most stable surfaces of NiS2 and NiAs2. Their calculated surface energies showed that the NiS2 (100) and NiAs2 (111) surfaces are more stable. We predicted the order of surface stability as: (100) > (111) > (210) > (110) for NiS2 and (111) > (110) > (100) > (210) for NiAs2. The adsorption of O2 was found to dissociate on mineral surfaces and different bonding mechanisms of the oxygen atoms were depicted. The O2 adsorption on both NiS2 (100) and NiAs2 (111) surfaces was exothermic with adsorption energies of -3.19 eV and -4.83 eV, respectively. The H2O adsorption on both NiS2 (100) and NiAs2 (111) mineral surfaces were found to relax deep into the surface. The H2O adsorption on Ni-top site was more exothermic, suggesting preferential adsorption on Ni atoms than on S and As atoms on both NiS2 and NiAs2. These investigations suggests that the oxidation of NiS2 and NiAs2 prefer adsorbing on S and As atoms than on Ni, while the hydration of NiS2 and NiAs2 prefer adsorbing on Ni atoms than S and As atoms. These investigations provide information on the bonding mechanism and chemistry of oxygen and water molecules onto NiS2 (100) and NiAs2 (111) surfaces that may be applicable to the atmospheric oxidation and during flotation process or mineral extraction.
Supervisor details<br><b>If not a student, type N/A.</b><br>Student abstract submision<br>requires supervisor permission:<br>please give their name,<br> institution and email address.
Prof P E Ngoepe
University of Limpopo
phuti.ngoepe@ul.ac.za
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Primary author
Mr
Bradley Nemutudi
(UL)
Co-authors
Mr
Godfrey Masilu Mulaudzi
(UL)
Dr
Peace Prince Mkhonto
(UL)
Prof.
Phuti Ngoepe
(UL)
Dr
Thabo Ezekiel Letsoalo
(UL)
