Abstract
The ion -exchange equilibrium and transport rate of yttrium and lanthanum were examined for a cation -exchange membrane, SELEMION CMV. Yttrium and lanthanum were selectively sorbed by the membrane in a low -concentration region. Their selectivity coefficients were higher than those of divalent ions, depending on the degree of solution concentration. Experimental results were successfully correlated with separate experimental equations for Y -H and La -H systems over a wide range of solution concentration. In Donnan dialysis experiments with YCl3-HCl and LaCl3-HCl systems under the conditions of membrane diffusion control, the apparent diffusivities of yttrium and lanthanum were considerably affected by solution con-centration. Self -diffusivities of ions in the membrane were estimated from a part of the experimental results with a model using the Nernst -Planck equation by means of the Marquardt optimizing method. Those of H+, Y3+, and La3+ were 1.1×10-10, 1.1×10-12, and 4.4×10-13m2/s respectively. The model with the self-diffusivities explainedthe experimental results well.
