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), cupper (II), zinc (II), silver (I) and lead(II) metal cations and the source and receiving phases being buffered at pH=4.9 and pH=3, respectively. The membrane phase incorporated a new synthesized ionophore, (2,3-Diphenylquinoxaline)-4,4 -dithiotriethylene glycol. The membrane solvents include:dichloromethane (DCM), chloroform (CHCl3), 1,2dichloroethane (1,2- DCE) 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. The order of the transport ability of the ligand for this metal cation in different membrane systems was found to be:dichloromethane > chloroform > 1,2- dichloroethane. 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 (CHCl3)-1,2-dichloroethane (1,2- DCE) binary solvents is sensitive to the solvent composition. The transport processes were studied in absence an dpresence of the stearic acid and the results show that the transport rates change in the presence of the stearic acid.

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