Preparation and chronopotentiometric characterization of platinum deposited anionic membranes

Platinum metal has been deposited on an anion exchange membrane by electrol ess plating. In this method, a solution of 2 mM platinic chloride placed on one side of the membrane which was mounted horizontally in a vertical cell has been allowed to react with 1% hydrazine hydrate from the other side fo r 30, 60 and 90 min to have different metallated membranes. The quantity of the deposited platinum has been estimated by differential pulse polarograp hy. Electrical properties of these metallated membranes have been examined by chronopotentiometry in dilute sodium chloride solutions. The parameters such as transition time (tau), the potential drop (E-0) across the membrane instantly after the application of a constant current (I), the equilibrium potential (E-a1) and I tau(1/2) have been measured and compared with those of undeposited membrane. The results reveal that the deposited metal layer is porous by nature and it has deposited firmly on the membrane. Consequen tly, the ion exchange property of the membrane has been found to be reduced gradually with the increase in deposited metal thickness. The approximate percentage of metal coverage and the number of ionic sites masked by the de posited metal in terms of molar concentration have also been estimated for a given NaCl concentration.