Abstract
Permeability coefficients of KCl, K2SO4, K2HPO4, MgCl2, CaCl2 and MgSO4 were measured as a function of concentration of external solution in the system of silk fibroin membrane-electrolyte aqueous solution. Cation and anion mobilities (ω+, ω-) were obtained from the electrolyte permeability coefficient excluding the effects of the fixed charge groups in the membrane. Ion mobilities for KCl, CaCl2 and MgCl2 in the membrane were 1/100 of that in the water, and for K2SO4, K2HPO4 and MgSO4 1/1000. Anion mobilities were nearly constant irrespective of coupled counter ions. On the other hand, cation mobilities were much more affected by the coupled counter ions. Two-valent anions were much affected by the obstruction of polymer chains.
