BACKGROUNDThe hydrometallurgical separation of Co(II) from Mn(II) poses a difficult problem because of their similar chemical and physical properties. A membrane separation method for Co(II) in the presence of Mn(II) has been developed which overcomes the potential technological, environmental and health issues associated with solvent extraction. This paper reports on the development of a polymer inclusion membrane (PIM) capable of efficiently separating these two metal ions. RESULTSThe PIM developed in this study contains 40 wt% N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl] glycine (D2EHAG) as the carrier, 30 wt% cellulose triacetate (CTA) as the base polymer and 30 wt% dioctylphthalate as a plasticizer. The potential of this membrane for Co(II) separation and preconcentration has been demonstrated by the complete transfer of Co(II) from a feed solution containing a similar concentration of Mn(II) into a sulfuric acid receiving solution with less than 5% Mn(II) being transported during the same period. CONCLUSIONSThe PIM developed as part of this study showed potential for the separation and preconcentration of Co(II) from its mildly acidic aqueous solutions in the presence of Mn(II) in applications such as hydrometallurgical processes or recovery of Co(II) from lithium ion batteries. (c) 2015 Society of Chemical Industry