Frontal analysis method to determine competitive adsorption isotherms

In order to design and to optimise preparative separations, the knowledge o f the underlying thermodynamic functions, i.e., the adsorption isotherms, i s the most essential information. Usually these functions cannot be predict ed and various methods have been suggested to determine them experimentally . In particular, dynamic methods are attractive regarding time requirements and reliability. Frontal analysis (FA) is frequently applied to measure si ngle solute isotherms. The theoretical background of this method is offered by the classical equilibrium theory of adsorption. Although this theory al so explains the shape of multicomponent breakthrough curves, FA is only sel dom applied to determine competitive isotherms. In this work FA was used to measure adsorption isotherms of three components as single solutes and in binary and ternary mixtures in a reversed-phase system. The obtained equili brium data were correlated using the competitive Langmuir isotherm, equatio n, a bi-langmuir model, the ideal adsorbed solution theory and the real ads orbed solution theory. No substantial improvement of the predictions was ac hieved using the more complex models instead of the most simple Langmuir mo del. (C) 2001 Elsevier Science B.V. All rights reserved.