Internally consistent representation of binary ion exchange equilibria

Citation
S. Ioannidis et al., Internally consistent representation of binary ion exchange equilibria, CHEM ENG SC, 55(14), 2000, pp. 2687-2698
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemical Engineering
Journal title
CHEMICAL ENGINEERING SCIENCE
ISSN journal
0009-2509 → ACNP
Volume
55
Issue
14
Year of publication
2000
Pages
2687 - 2698
Database
ISI
SICI code
0009-2509(200007)55:14<2687:ICROBI>2.0.ZU;2-W
Abstract
A model has been developed to obtain the thermodynamic parameters, i.e., th e equilibrium constant and solid-phase activity coefficients, that describe binary ion exchange reactions. The model is based on the thermodynamic fra mework for adsorption exchange reactions developed by Gaines and Thomas (19 53. Journal of Chemical Physics, 21, 714-718). The Wilson activity coeffici ent model is used for the adsorbed phase and the stoichiometry of the excha nge reaction is taken into account. The solid solution model parameters are regressed with a new data reduction technique, based on the use of the Van selow selectivity coefficient calculated at various points on the isotherm equilibrium surface. Additionally, a consistency test is developed for anal yzing the selectivity coefficient plots. For the estimation of the selectiv ity coefficient, the Bromley-Zemaitis model is used for calculating the act ivity coefficients in the aqueous phase. Also, the speciation of the aqueou s systems is taken into account. The equilibrium constants are calculated u sing their relationship with the selectivity coefficients and the activity coefficients in the solid phase. In addition to accurate representation of experimental data, the data reduction of binary pairs from three ternary sy stems has been shown to satisfy the triangular rule consistency test. Uptak e graphs of the investigated systems have been accurately predicted. (C) 20 00 Published by Elsevier Science Ltd. All rights reserved.