MODELING OF TRANSPORT AND REACTION PROCESSES IN A POROUS-MEDIUM IN ANELECTRICAL-FIELD

A numerical model has been developed to describe the transport and rea ction processes in a porous medium in an electrical field. The model d iscretizes the one-dimensional porous medium by a number of compartmen ts. The governing equations are formulated by material balance over ea ch compartment. The model describes transport processes of advection, dispersion, ionic migration and electroosmosis. Various reactions such as aqueous complexation, precipitation/dissolution, and electrochemic al reactions are treated by kinetic approaches. For fast fluid-phase r eactions such as complexation, local equilibrium assumption may be app lied in the model, which reduces the number of primary components and hence the number of governing equations. The sorption processes occurr ing at the surfaces of the porous medium are at the moment treated onl y by a single-component linear isotherm. Numerical solution to the mod el gives concentration and electrical potential distributions in the p orous medium at different times and gives as well the electrical curre nt history. Modelling results for three sample cases are reported to d emonstrate the application of the model. In the first sample case, the removal of copper from sand by an electrical field is simulated. The second case concerns an electrokinetic soil remediation process with c athode rinsing. The third case models the selective filtering function of the ion exchange membranes. Copyright (C) 1996 Elsevier Science Lt d