A DFT prediction on the chemical reactivity of novel azolethione derivatives as chelating agents: Implications for copper minerals flotation and copper corrosion inhibition

Abstract

Abstract Azolethione derivatives have attracted much attention in coordination chemistry, but their engineering applications as metal corrosion inhibitors or flotation collectors remain underexplored. In this work, the chemical reactivity of azolethione surfactants was investigated using density functional theory (DFT) method. The results indicate that the S and N atoms in the conjugated azolethione group of 5-heptyl-1,3,4-oxadiazole-2-thione (HpOT), 5-heptyl-1,3,4-thiadiazole-2-thione (HpST), 5-heptyl-1,2,4-triazole-3-thione (HpNT), 4-amino-5-heptyl-1,2,4-triazole-3-thione (HpATT) and 6-heptyl-1,2,4,5-tetrazine-3-thione (HpNNT) are the chemical reaction center. Based on the electron-donating ability, the reactivity of azolethione derivatives is forecasted to be HpNNT > HpNT > HpATT > HpST > HpOT. The computed binding energies of heptyl-substituted azolethione ions with Cu2+ and Cu+ are less than −150 kJ/mol, implying the potential chemisorption of azolethione compounds on the surfaces of copper minerals/metal/alloys. The micro-flotation results indicate that the heptyl azolethione surfactants are excellent collectors for the flotation of chalcopyrite and malachite. The collecting ability to malachite is in the sequence of HpOT > HpNT > HpATT > HpST > HpNNT, matching precisely with the results of contact angle measurements. This study provides an atomic scale understanding of the structure-property relationship of azolethione derivatives as chelating agents for copper minerals flotation and copper corrosion inhibition.