Solution-membrane equilibrium at metal-deposited cation-exchange membranes: Chronopotentiometric characterization of metal-modified membranes

Copper- and lead-deposited interpolymer cationic membranes have been prepared by electroless plating by an ion-exchange method and characterized by chronopotentiometry and cyclic voltammetry, The parameters such as transition time (tau), I tau(1/2), the potential drop (E-0) across these membranes immediately after the application of constant current (I), and the height of the potential jump (Delta E) across the membrane at tau have been measured by chronopotentiometry and compared with those of plain membranes. The approximate percentage of metal coverage and the number of ionic sites masked by the deposited metal in terms of NaCl concentration have been estimated from the differences in I tau(1/2) values of plain and metal-deposited membranes, The quantity of metal deposited in a unit area of the membrane surface was measured by differential pulse polarography. The oxidation and reduction peak potentials corresponding to Cu(0)/Cu(II) and Pb(0)/Pb(II) couples were identified by cyclic voltammetry at pH 2.8 and 4.5 of 0.2 M CH3COONa-H2SO4. (C) 1999 Academic Press.