Application of hydrophobic extractant in aqueous two-phase systems for selective extraction of cobalt, nickel and cadmium

Abstract: This work developed a new and efficient method of extracting and separating Co(II), Ni(II) and Cd(II) in aqueous two-phase systems (ATPS) composed of triblock copolymer (L64)+Na2C4H4O6 +water and L64+Li2SO4 +water using the hydrophobic extractant 1-nitroso-2-naphtol, which complexes the metal ions and partitions in the triblock copolymer micelles in the ATPS top phase. Metal extraction from the salt-rich phase to the copolymer – rich phase is strongly affected by the fine-tuning of the following parameters: amount of added extractant, type of electrolyte, pH, and tie-line length. Excellent separation factors (S i,j) between the metals were obtained at pH = 3.00 (S Co,Cd = 1550 and S Ni,Cd = 16,700) and pH = 1.00 (S Co,Ni = 826). In the interference study, Co(II) was selectivity extracted in the top phase in the presence of Ni(II) and Cd(II) in a concentration of up to 20 times the cobalt level in the system. [Copyright &y& Elsevier]