Checking of applicability of conditions for reaching the limiting-current mode to flow-by porous electrodes

Abstract

For the flow-by porous electrodes, which differ in thickness, specific surface area, solution flow rate, and a ratio between the phase conductivities, the conditions providing the limiting-current mode over the entire electrode surface at nearly 100% current efficiency are determined using the method of successive refinement of total current and profile of its distribution along the solution flow. The used values of electrode thickness L are compared with available estimates for the limiting thickness of porous electrode L_lim derived for the ideal limiting-current mode and calculated using real values of the width of the limiting-current plateau of overall polarization curve, solution conductivity, and the diffusion limiting current in the zone of solution input into the electrode. It is found that these values are close to each other in all cases. The largest error of estimation of L_lim does not exceed 10% indicating that it can be used for preliminary estimation of the conditions for reaching the limiting-current mode for the flow porous electrodes of this type.