The determination of dynamic characteristics of ion-exchange columns by the application of one-dimensional mathematical models

Abstract

The one-dimensional mathematical models describing the processes in ion-exchange columns with packed bed and counter-current phase motion are compared. The exchange of Li + with H +, Na + with H + and K + with H + was studied on a sulphonated cation exchanger KU-2 × 8. The parameters of the models were determined by the method of random search from the experimental curves showing the responses to pulse perturbations of the hydrogen-ion concentration. Under the experimental conditions, the diffusion model (ED) and the plug-flow (PF) model are equally adequate. A more complicated model (LD) which takes into account the interphase non-equilibrium and axial dispersion in the liquid phase was also studied. The ranges of parameters for which the LD model reduces to the ED and PF models are established. It is shown that the LD model has no advantages over the ED and PF models, because axial dispersion and interphase non-equilibrium are additive.