KINETIC-ANALYSIS OF A BIMETALLIC ION-EXCHANGE SYSTEM BY MICROSCOPIC MEASUREMENT OF THE MOVING BOUNDARIES

Two different colored layers surrounding the central core have been observed during the simultaneous uptake of copper and cobalt onto an iminodiacetic-type ion exchange resin that was initially in the sodium form. By measuring their width it is possible to calculate metal load on the basis of the local equilibrium assumption by using an equilibrium model for multimetallic systems. A kinetic pseudohomogeneous model has been developed which considers two successive mechanisms: first, diffusion of metal ions through the reacted layer, and second, metal-metal displacement from the solid phase. (C) 1994 Academic Press, Inc.