title: Equilibrium theory analysis of liquid chromatography with non-constant velocity.
abstract: In liquid chromatography, adsorption and desorption lead to velocity variations within the column if the adsorbing compounds make up a high volumetric ratio of the mobile phase and if there is a substantial difference in the adsorption capacities. An equilibrium theory model for binary systems accounting for these velocity changes is derived and solved analytically for competitive Langmuir isotherms. Characteristic properties of concentration and velocity profiles predicted by the derived model are illustrated by two exemplary systems. Applicability of the model equations for the estimation of isotherm parameters from experimental data is investigated, and accurate results are obtained for systems with one adsorbing and one inert compound, as well as for systems with two adsorbing compounds.
authors.affiliation: ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 Zurich, Switzerland.
authors.forename: Franziska
authors.initials: F
authors.lastname: Ortner
authors.affiliation: ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 Zurich, Switzerland.
authors.forename: Lisa
authors.initials: L
authors.lastname: Joss
authors.affiliation: ETH Zurich, Institute of Process Engineering, Sonneggstrasse 3, CH-8092 Zurich, Switzerland. Electronic address: marco.mazzotti@ipe.mavt.ethz.ch.
authors.forename: Marco
authors.initials: M
authors.lastname: Mazzotti
mesh_terms: D000327:Adsorption; D002853:Chromatography, Liquid / Q000379:methods*; D013816:Thermodynamics
keywords: Equilibrium theory; Liquid chromatography; Mathematical modeling; Velocity variations