Modeling of the dynamic adsorption of an anionic dye through ion-exchange membrane adsorber

The present study examines the dynamic adsorption through ion-exchange membrane adsorbers. The model used in the study includes convection, axial dispersion with simultaneous adsorption and desorption of the solute in the membrane. Adsorption and desorption processes give the Langmuir isotherm for the equilibrium. The mathematical model makes use of dimensionless parameters in terms of characteristic times for the different mechanisms that take place during the process (convection, dispersion, adsorption and desorption characteristic times). The model has five independent dimensionless parameters. Three of these parameters are related to the equilibrium isotherm and the other two are related to the dynamic process. Equilibrium and dynamic experiments were carried out in order to fit their respective parameters. In order to examine the suitability of the model to describe real processes, the adsorption of an anionic dye (Orange-G) through the ion-exchange membrane adsorber was investigated as a function of dye and KCl concentration, obtaining strong correlation between fitted and experimental breakthrough curves. The results show the relative importance of axial dispersion, adsorption and desorption as a function of operational variables.