The silver content of environmental samples is increased with the increasing use of silver compounds and silver-containing preparations in industry and in medicine [1]. Silver can enter the environment via industrial water because it is often as an impurity in cupper, zinc, arsenic and antimony ores [2]. The liquid membrane technique has been emerging as an alternative technique for the separation and preconcentration of several chemical species [3]. In this study, the transport experiments employed standardized “concentric cells” in which the aqueous source and receiving phases were separated by an organic phase such as: chloroform (CHCl3), 1,2-dichloroethane (1,2-DCE), dichloromethane (DCM), nitrobenzene (NB) and chloroform-nitrobenzene binary mixed solvents. The aqueous source phase consisted of a buffer solution (CH3COOH/CH3COONa) at pH=4.9 and containing an equimolar mixture of Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Ag+ and Pb2+ metal cations. The organic phase contained the macrocyclic ligand, dibenzopyridinio-18-crown-6 (DBPY18C6) as an ionophore and the aqueous receiving phase consisted of a buffer solution (HCOOH/HCOONa) at pH=3. The obtained results show that dibenzopyridinio-18-crown-6 is a highly selective ionophore for silver ion and under the employed experimental conditions; it transports only this metal cation among the seven studied metal cations. The influence of the stearic acid, palmetic acid and oleic acid in the membrane phase on the silver ion transport was also investigated. The results show that the transport efficiency of the Ag+ ion increases in the presence of stearic and palmetic acids. The sequence of transport efficiency for Ag+ ion in organic solvents is: NB>DCM>1,2-DCE>CHCl3.The non-linear behaviour which was observed for variations of the transport rate of silver ion was also investigated.

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