Structure-activity of chelating collectors for flotation: A DFT study

Abstract Based on density functional theory calculations, the molecular frontier orbital of six types of chelating collector were studied, including S-S, S-N, N-N, S-O, N-O and O-O types, and mercaptobenzothiazole, ethyl xanthate, diethyldithiophosphate, and diethyldithiocarbamate, dithizone (keto form and enol form), dimethylglyoxime, thiocarboxylic acid, 8-hydroxyquinoline, salicylaldoxime, salicylhydroxamic acid, oleic acid, and cupferron were selected as representatives. The calculation results of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and the orbital coefficients show that the chelating atoms of the collectors have great activity and large coefficient. For S-S type of collectors, the interactions of Cu, Fe Pb and Zn metal ions with double bond S, single-coordinated S and two-coordinated S are different. Moreover, mercaptobenzothiazole is more likely to chelate metal ions by means of S-N but not S-S. In S-N type, the interactions of Cu, Fe Pb and Zn metal ions with N atom are weaker than with S atom. For dimethylglyoxime (N-N type), the interactions of metal with the two N atom are nearly the same. For N-O type, the activity of N atom in a benzene ring is weaker than in a strain chain. The metal-O interactions are also different in S-O, N-O and O-O types of chelating collectors. Calculated results suggest that the electronic structure and spatial structure of an atom are very important to its interaction with metals and minerals.