Evaluation of Cd(II) transport with imidazolium bromides bearing butyl and isobutyl groups as extractants from acidic iodide solutions by liquid-liquid solvent extraction

The aim of the paper is the selective extraction and stripping of Cd(II) from acidic iodide solutions containing Cd(II) and Ni(II) by liquid-liquid solvent extraction technique using synthesized and characterized imidazolium salts as carriers, which are 3-butyl-1-methyl-1H-imidazol-3-ium bromide (IM1), 1,3-dibutyl-1H-midazol-3-ium bromide (IM2), 3-isobutyl-1-methyl-1H-imidazol-3-ium bromide (IM3), 1,3-diisobutyl-1H-midazol-3-ium bromide (IM4), in dichloromethane. The important parameters affecting extraction and stripping behavior of Cd(II) were studied experimentally. Complex formation and its stoichiometric rate between IMs and CdI42− was explained with comparison of ATR-FTIR spectrums of pure and CdI42−(aq) loaded IMs and slope analysis. According to these evaluations, the adduct formation was confirmed as IM2CdI4(org). In the light of obtained results, the symmetric IMs substituting n-butyl group on nitrogen atoms have been determined as the best appropriate IMs to transport of Cd(II). Under optimum conditions, 99.24% of Cd(II) has been extracted from acidic iodide solution containing 500 mg/L of Cd(II) and Ni(II). Ni(II) extraction percentages were observed as negligible throughout experiments. The extraction selectivity of Cd(II) over the other metal ion impurities has been identified in the order βCd/Ni > βCd/Co > βCd/Zn > βCdCu.