Liquid membrane multiple emulsion process of separation of copper(II) from waste waters

A liquid membrane (multiple emulsion, water-in-oil-in-water, WIII/OII/WI) method of separation of copper(II) from simulated waste water has been described. The effect of variation of oil membrane constituents in OII, different concentrations of sulphuric acid as strippant in the internal phase WI, pH and the object ion concentration in the raffinate WIII have been studied in detail with an aim to optimize the process so that the copper(II) content in the waste water be made lower than the toxic limit (1.5 ppm, WHO.) The ion-exchange behaviour of the carriers in the membrane and the coupled counter-transport resembling a ‘Chemical pump’ have been ascertained. Interference, in the process, of some metals (ions) occurring naturally with copper, e.g. Pb(II), Cd(II), Zn(II), Co(II), Ni(II) and Mn(II) through their co-transport have been studied. The relative extents of their accompaniment have been explained from the consideration of the stability of the carrier-metal (ion) complexes and exchange reactions at the interfaces. The application of the reaction site model and involvement of a pseudo first order process have been found to be reasonably justified in the present transport method of separation of copper(II).