Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-43PHOTO ELECTROCHEMISTRY APPLIED IN THE SEPARATIONOF METALLIC IONS BY MEMBRANE PROCESSAmara M.Faculty of chemistry,USTHB University, Algiers,Laboratoire d’Hydrométallurgie et de Chimie Inorganique Moléculaire,Faculté de Chimie USTHB,BP 32,El Alia, Algiers,ALGERIA. 2 Laboratoire de Stockage et de Valorisation des Energies Renouvelables,Faculté de Chimie USTHB,BP 32, El Alia, Algiers,ALGERIAThe transport phenomena through ion exchange membrane may be improved by theapplication of different forces inside or outside the systems. The electrical current, producedby synthetic photo electrode, is applied to enhance the separation of metallic ions. The cationexchange membrane placed between the two compartments permitted the separation andconcentration of the ions M 2+ (= Cu 2+ , Zn 2+ and Ni 2+ ). The movements of M 2+ from theaqueous solution to the membrane and inside the membrane are followed by the fluxdeterminations and the potential measurements. In this study, the three cations are studiedalone or as binary and ternary systems. It was observed that the illuminated CdS electrodeleads to an increasing of the transport flux at least 10 times more than that calculated in theobscurity. Moreover, in all the cases the potential of the first specie electrode M/M 2+ in thefeed compartment increases until a maximal value reached at ~ 100 min. above which itundergoes a diminution. The membrane is more selective to Zn 2+ ; this selectivity decreases inthe binary and ternary systems. On the other hand, the photo electrochemical properties of thehexagonal CdS showed strong light absorption of wave lengths shorter than 520 nm. Theshape of the intensity potential curve under illumination and the negative flat band potential(-1.02 VSCE) provide unambiguous evidence of n-type conductivity. The conduction bandlocated at -1.25 VSCE leads to a thermodynamically M 2+ reduction under visible light andaccentuates the diffusion process.386