DONNAN DIALYSIS CONCENTRATION USING CATION-EXCHANGE MEMBRANE PREPARED BY PASTE METHOD

Donnan dialysis concentration of cupric ions was examined experimentally, using four commercial membranes and synthetic membranes prepared by the past method. The enrichment rate and its ratio in Donnan dialysis were affected by membrane properties. From experimental results using commercial membranes, a large value of (ion-exchange capacity)(self-diffusion coefficient of cupric ion)/(membrane thickness) was found to be a criterion of high ionic flux through a membrane. Diffusion coefficient, ion-exchange capacity and water content of a synthetic membrane were affected mainly by the degree of crosslinking of the membrane. A synthetic membrane with a degree of crosslinking of 0.02 and reinforced by polyvinyl chloride cloth showed higher ionic flux and lower flux of osmotic water, and gave a higher enrichment ration than those of the commercial membranes used in this work.