Competitive Bulk Liquid Membrane Transport of Transition and Post Transition Metal Cations Using (2,3-Diphenylquinoxaline)- 4',4"-dithiotriethylene glycol

Abstract

A series of competitive metal ion transport experiments have been performed, each involved transport from an aqueous source phase across an organic membrane phase into an aqueous receiving phase. The source phase contained equimolar concentrations of cobalt(II), nickel(II), copper(II), zinc(II), silver(I) and lead(II) metal cations and the source and receiving phases being buffered at pH = 4.9 and 3.0, respectively. The membrane phase incorporated a new synthesized ionophore, (2,3- diphenylquinoxaline)-4',4"-dithio triethylene glycol. The membrane solvents include: dichloromethane, chloroform, 1,2-dichloroethane and chloroform-1,2-dichloroethane binary solvents. The obtained results show that the selectivity and the efficiency of transport for these heavy metal cations change with the nature of the organic solvents which were used as liquid membranes in these experiments. A good transport efficiency and selectivity of silver ion transport from aqueous solutions were observed in this investigation. The transport rate of the silver ion in chloroform-1,2-dichloroethane binary solvents is sensitive to the solvent composition. The transport processes were studied in absence and presence of the stearic acid and the results show that the transport rates change in the presence of the stearic acid.