Evaluation of the Effect of Electroosmosis on the Efficiency of Electrobaromembrane Separation Using Track-Etched Membranes

Abstract

The results of a theoretical analysis of the influence of the electroosmotic flow on the electromigration and convective transport of competing ions separated by the electrobaromembrane method are presented. Separated ions of the same charge sign move in an electric field through the pores of a track-etched membrane to the corresponding electrode, while due to the pressure drop across the membrane, a commensurate counter convective flow is created. A simplified model based on the equation of convective electrodiffusion and Hagen–Poiseuille equation allows the analysis of experimental data applying only the ion effective transport numbers in the membrane pores as fitting parameters. Using a mathematical model described by the system of equations of Nernst–Planck, Navier–Stokes and Poisson, it is shown that the electroosmotic flow can cause the effective transport numbers of competing ions to exceed their values in solution, even if these ions are coions for the membrane.