title: Buoyancy-induced mixing during wash and elution steps in expanded bed adsorption.
abstract: Buoyancy-induced mixing occurs during expanded bed adsorption processes when the feed stream entering the bottom of the system has a lower density than that of the fluid above it. In the absence of a headspace, mixing in the expanded bed can be modeled as a single, well-mixed vessel, with first-order dynamics. In the presence of a headspace, the system exhibits second-order dynamics for the densities typically encountered in protein chromatography, and can be modeled as two well-mixed vessels (the expanded bed and the headspace) arranged in series. In this paper, the mixing dynamics of the expanded bed are described and a mathematical model of the system is presented. Experimental measurements of density changes during the dilution of sucrose and salt solutions in a STREAMLINE 25 column are presented. These show excellent agreement with predictions using the model. A number of strategies for wash and elution in expanded mode, both in the presence and absence of headspace, are discussed.
authors.affiliation: Department of Materials and Process Engineering, University of Waikato, Hamilton, New Zealand. c.fee@waikato.ac.nz
authors.forename: C J
authors.initials: CJ
authors.lastname: Fee
authors.forename: A D
authors.initials: AD
authors.lastname: Liten
mesh_terms: D000327:Adsorption; D013395:Sucrose
chemical_list: D013395:Sucrose