Selectivity of 2-mercaptobenzimidazole derivatives on metal ions studied by UV–vis spectromentry and DFT calculations

Abstract

UV–vis absorption spectrometry and DFT calculations were used to study the selective binding of 2-mercaptobenzimidazole derivatives (MBI, EMBI, PMBI and BMBI) as chelating collectors with metal ions, including Fe3+, Cu2+, Pb2+, Zn2+ and Ag+. The results showed superior selectivity of these collectors towards Ag+ as compared with the other metal ions. The binding stoichiometry of MBI derivatives with Ag+ was found by Job-plot method to be 1:1. The binding constant determined using Benesi–Hildebrand (B-H) method showed the following order of BMBI-Ag > PMBI-Ag > EMBI-Ag > MBI-Ag. The binding energies of MBI derivatives with Ag+ calculated by DFT method followed the same order as the binding constant calculated by B-H method. All the calculation results were in good agreement with the results of UV–vis experiments which showed the highest selectivity and binding energies of BMBI towards Ag+. This study clearly shows that the BMBI is a good sensor for Ag+ ion. Therefore, the BMBI could be a highly selective and efficient collector to enhance the recovery of silver from silver-rich lead–zinc sulfide minerals.