Separation of Nickel and Cobalt by Electrodialysis Using Ion-Exchange Membranes in the Presence of EDTA

Abstract

Electrodialytic separation of Ni²⁺ and Co²⁺ cations has been realized by using ion-exchange membranes in the presence of EDTA by preferentially complexing Ni²⁺(Ni²⁺ concentration = EDTA concentration). The degree of complexation is calculated as a function of the pH and of the concentration by using data taken from the literature. Due to a systematic study of the influence of the different separation parameters (nature of the membranes, flow rate, electric current intensity, pH), the conditions_of_separation have been optimized on a computer, and then pure solutions of nickel and cobalt ions have been obtained experimentally. The decomplexation of Ni²⁺ is accomplished in acidic medium by cooling.