Chronopotentiometric Characterization of Electrodialysis Module

Classical and chronopotentiometric characterization of the electrodialysis module at the same concentrations of diluate and concentrate was performed. Limiting current was determined from the Cowan-Brown plot, the current efficiency and the mean transport number of counterions – from the concentration changes on the exit of the ED module. The electric resistance was determined from the chronopotentiometric curve. For electric currents higher than the limiting one, the transition time (inflection point) was observed. Thus, having such curves for different values of electric current, the limiting current can be roughly estimated. To estimate a mean counterion transport number from the transition time, an equation, analogous to the Sand equation, should be developed which include both types of membrane.