Abstract
(1) From the membrane potential measurement of ion exchange membranes immersed in aqueous sodium chloride, concentration changes at diffusion layer and thickness of the diffusion layer were estimated. It was recognized that concentration polarization showed a trend to occur more easily at cation exchange membranes than at anion exchange membranes.(2) In the dialysis of aqueous sodium chloride or sea water, the limiting current density for concentration polarization and for dissociation of water was measured from current density-voltage curve and current density-solution pH curve. It was observed that with anion exchange membranes, both limiting current densities coincided with each other for the most part, but that with cation exchange membranes, the limiting current density for the dissociation of water was larger than that for the concentration polarization.(3) The influence of the concentration and velocity of the solution in a desalting cell upon the limiting current density was measured.(4) The limiting current density formula for the concentration polarization, which is applicable in the dialysis of multiple component ionic solutions, was led, and the limiting current density in the dialysis of sea water was estimated by using this formula.
