Synergistic extraction of cadmium and nickel by solvent extraction

Cadmium and its compounds have found wide range of applications in a number of industrial and technological fields. However, one of the main drawbacks that these compounds have is the separation of cadmium from nickel. These two elements are usually found together, and they have very similar physical and chemical properties, making them very hard to be purified. Moreover, The supply-demand gap for nickel and other valuable ores have been increasing with limited supply and increasing demand. With this in mind, one of the practical solutions to the problem would be recycling of solid and liquid waste containing trace amounts of precious metals, which lately has drawn very much attention. Furthermore, the separation of nickel and cadmium from aqueous solutions by solvent extraction, a method that depends on the selective dissolving of metal ions in aqueous solution, has been overstudied, and found many applications in various industries.In this study, we investigated the selective cadmium extraction from aqueous acidic solutions by solvent extraction. Triisooctylamine (TIOA) and tributylphosphate (TBP) were used as synergistic extractants. After several trials, the optimum extraction conditions (the solvent type, the concentration of the extractant, acid and potasium iodine, the stirring speed, the rate of the reactants (V0/Va), and the extraction time) were found. Under the optimum conditions, the cadmium extraction from the Cd/Co/Ni solutions in various concentrations was performed. The extracted cadmium was transferred back to the aqueous phase by washing with natrium hydroxide solution.