Interaction of salicylhydroxamic acid with the surface of MgTi2O5: a study combined DFT and experiment

Salicylhydroxamic acid (SHA) is a typical chelate collector. This study elucidated the effect of steric hindrance on SHA adsorption on the MgTi2O5 surface using density functional theory. The geometry optimisation and electronic structures of SHA ion and the MgTi2O5 (110) surface were calculated. Subsequently, six adsorption configurations of SHA ion on the MgTi2O5 (110) surface were calculated and compared by analysing geometric configuration, bond length, adsorption energy, density of states (DOS), and Mulliken population. The results show that both the oxygen molecules of C╱╲=O and N╱╲O− in SHA ion can coordinate to the metal ion. Steric hindrance affects the formation of a five-membered ring structure. The four adsorption configurations of the newly established structure can effectively avoid steric hindrance, and stable chelate rings are formed. The adsorption energies of the four new configurations range from −300 kJ/mol to −400 kJ/mol, and the bond lengths are about 2 Å. DOS and Mulliken population results indicate that O atoms bond to Ti and Mg atoms. Traditional chelate collector adsorption theory ignores the presence of steric hindrance. At the same time, the species distribution of SHA solution, zeta potential and flotation have also been studied in this paper, and there is a consistency between the calculation and experiment results. This study provides insights into the adsorption mechanism of a chelate collector on a mineral surface.