Nonstationary processes in an ion-exchange membranes-diaphragm-ion-exchange resin system. 1. Concentration polarization

Abstract

Potential drop distribution in a system comprising ion exchange membranes, a diaphragm, and an ion exchange resin layer has been experimentally studied and theoretically analyzed. It has been estab lished that the potential drop is redistributed in the system due to not only different electrical resistances of its elements, but also their concentration polarization, which depends on both the voltage applied to elec trodes and relative positions of the system elements.

Nonstationary processes in an ion-exchange membranes-diaphragm-ion-exchange resin system. 2. Electroosmosis

“…At the same time, due to the polar ization of the cation exchange membranes, the elec trolyte concentration decreases at the cathode facing membrane surface and increases at the anode facing surface (see Fig. 2 in [1]). Thus, when cation exchange particles are located in sections I and II, the region of an increased electro lyte concentration at the membrane surface and the region of a decreased electrolyte concentration at the surface of cation exchange resin are overlapped in the region of the membrane-cation exchange resin con tact.…”

“…OF ELECTROOSMOSIS VELOCITY The scheme of the experimental setup and the vari ants of the relative positions of the diaphragm and cat ion exchange particles have been presented in [1]. To make comparison more convenient, the data on the electroosmosis velocity are presented in this work in the same order as the experimental data on the poten tial distribution are given in [1].…”

“…To make comparison more convenient, the data on the electroosmosis velocity are presented in this work in the same order as the experimental data on the poten tial distribution are given in [1].…”

“…Electroosmosis through a system having a constant cross sectional area, pore radius, porosity, and electrokinetic poten tial of material may be described based on the Smolu chowski formula for linear electroosmosis [2] using correction coefficient for the effective porosity of an examined material as w e : (1) and (2) for the linear velocity and volume velocity, respec tively. Here ε is the dielectric permittivity of a solution; η is its dynamic viscosity; ζ is the electrokinetic poten tial of a disperse material; Е is electric field strength; and…”

“…The study of potential distribution along a cell con taining ion exchange membranes, a diaphragm, and/or a layer of cation exchange particles [1] has demonstvelocityd its strong dependence on the con figuration of the studied system and the duration of an experiment. It is natural that polarization processes developing with time and the relevant nonuniformity and nonstationarity of the potential drops across the sections of the cell make the local field strength and, hence, the velocity of electroosmosis to essentially depend on time.…”