Ion and water transport through permselective membranes

Electroosmotic transport of water accompanying ion transport across an anion-selective membrane has been measured at 25°C using 0.01 N NaC1 solution. Also electrical conductance, self-diffusion coefficient of counterion, and hydrodynamic permeability of the membrane have been measured. These data and others, such as water content and exchange capacity, have been used in the relations derived by Scattergood and Lightfoot employing the generalized Stefan-Maxwell equations to obtain values for the diffusivity coefficients D _1*1, D ₁₃, D ₁₄, and D_34. The isotope interaction term D _1*1 was the lowest.

Assuming the applicability of the Nernst-Einstein relation to the membrane system, the number of moles of water transported by electroconvection has been evaluated. The difference between the moles of total water transport and the moles of water moved electro-convectively has been assigned as the moles of water firmly associated with a mole of the moving ion. This way a value of 0.58 mole has been derived for the hydration of the Cl^? ion.