Current density distribution, limiting current density and saturation current density in an ion-exchange membrane electrodialyzer

The current density distribution in a seawater electrodialyzer is approximated by a quadratic equation. The equation is solved using a three-dimensional simultaneous equation, and the current density distribution and the coefficients expressing the current density distribution are calculated. The method for estimating the limiting current density and the saturation current density of an electrodialyzer is established using the current density distribution coefficients. Electrodialytic conditions (current density, solution velocity and electrolyte concentration in desalting cells, the thickness and flow-pass length of a desalting cell, the standard deviation of the solution velocity ratio in desalting cells and the overall osmotic coefficient of a membrane pair) versus the current density distribution coefficients, limiting current density and saturation current density are obtained. Electrodialytic conditions at which current density reaches the limiting current density or saturation current density are determined.