Selectivity of 2-mercaptobenzimidazole derivatives on metal ions studied by UV–vis spectromentry and DFT calculations
2016
Qin, Wei | Wang, Junlian | Xu, Shengming | Xie, Qiang | Xu, Zhenghe
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.
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