Extraction of metal ions by emulsion liquid membrane using bi-functional surfactant: Equilibrium and kinetic studies

Abstract

Emulsion Liquid Membrane (ELM) is a separation technique, which requires organic solvent, extractant and surfactant for its formulation. All the components play important roles. Surfactant adds stability to the emulsion but at higher concentration lowers extraction rate. Some surfactants, known as bi-functional surfactants, have dual properties of an extractant and an emulsifier. Use of such surfactant may eliminate the addition of an extractant to ELM system. In this study, polyethylene glycol was used as bi-functional surfactant in an ELM process for the extraction of metal ions from a ternary (copper, nickel and cobalt) aqueous solution. Dichloroethane, ammonium thiocyanate and potassium hydroxide were used as solvent, ligand and stripping agent, respectively. The paper presents the results on the characterization of the reactions (stoichiometry and reaction order) obtained through equilibrium and kinetic studies along with some batch emulsion extraction results. (C) 2000 Elsevier Science B.V. All rights reserved.