Matthias Johannink, Adel Mhamdi, Wolfgang Marquardt:
Towards a rigorous model of electrodialysis processes
In: E.N. Pistikopoulos; M.C. Georgiadis; A.C. Kokossis (Eds.): 21st European Symposium On Computer Aided Process Engineering - ESCAPE 21, 116-120
In electrodialysis (ED), ion exchange membranes are used to separate ions of opposite charges in an electric field. Only few mechanistic models for ED are proposed in literature, which are based on a quasi-stationary one-dimensional formulation. We present a generalization of the frequently used set of equations to the multi-dimensional dynamic case. The resulting set of partial-differential algebraic equations (PDAE) is thoroughly analyzed by means of an extended index analysis. It is shown that the introduction of the electroneutrality condition, which is frequently used in models arising in electrochemistry, leads to a high index in time and spatial coordinates. In this context, a reformulation to an index one PDAE system is proposed and additional “hidden” constraints for a consistent set of initial and boundary conditions are derived.
electromembrane processes, electrodialysis, index analysis, electroneutrality