Comparison between Maxwell-Stefan and Nernst-Planck Equations to Describe Ion Exchange in Microporous Materials
Two models comprising external and intraparticle mass transfer resistances developed to describe ion exchange in microporous materials are compared. Maxwell-Stefan and Nernst-Planck equations account for both concentration and electric potential gradients. However, under certain conditions, Maxwell-Stefan approach can be more advantageous particularly due to taking into account ion-ion and ion-solid interactions separately. The models were tested and compared with data available in the literature, namely batch experiments on cadmium (II) removal from aqueous solution using ETS-4 microporous titanosilicate. Calculated results reveal both models provide good and similar representations as well as fine predictive capability. Therefore, under the conditions investigated, both models can be successfully applied to describe intraparticle ionic transport.
Andreas Öchsner and Graeme E. Murch
P. F. Lito and C. M. Silva, "Comparison between Maxwell-Stefan and Nernst-Planck Equations to Describe Ion Exchange in Microporous Materials", Defect and Diffusion Forum, Vols. 273-276, pp. 776-781, 2008