The Mathematical Modelling of the Electrodialysis Process of Ammonium Sulfate Solutions

摘要

The experimental study was carried out on a laboratory-scale electrodialysis (ED) unit model TS2-5 (Eurodia-Tokuyama) equipped with five cell pairs.The membranes used were AMX type anion-exchange membranes,and CMS type cation-exchange membranes,each of 0.02 m~2 surface area.The feed was an ammonium sulfate aqueous solution with 88-92 mol/m~3.The evolution with time of the solution concentration in dilute and in concentrate compartments has been determined for two flow rates and four voltages,at 300 K.A phenomenological mathematical model was derived to describe the concentration evolution time.The integrated model contains two semi-empirical constants which have been identified by confronting the experimental data with the computed ones.The relative errors of the model including the average values of the constants have been estimated.The validated model was finally used to extrapolate the ED process in order to determine the necessary time for an almost complete (over 98%,or less then 1.5 mol/m~3 residual salt in the final dilute) removal of ammonium sulfate.