A MODEL FOR SALT AND WATER TRANSPORT IN POLYELECTROLYTE SOLUTIONS

As a model for salt and water movement in polyelectrolyte solutions, we present theoretical calculations of small-ion and water transport through regular arrays of parallel, charged circular cylinders. We formulate the problem for steady fluxes of water and univalent co- and counterions in response to gradients of salt concentration, pressure, and electric potential. The fluxes are related to these gradients by effective transport coefficients, such as the flow resistance and the effective ionic diffusion coefficients. These coefficients, and the equilibrium ionic partition coefficients, are calculated numerically in two approximations. First a linear approximation is used, appropriate when the cylinders are weakly charged, and second a nonlinear calculation is performed, in which the geometry is simplified using a cylindrical-cell model. The physical significance of these numerical results is discussed.