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978-3-8439-1611-0, Reihe Technische Chemie
On Hydrodynamics in Centrifugal Partition Chromatography
225 Seiten, Dissertation Technische Universität Dortmund (2013), Softcover, A5
In centrifugal partition chromatography (CPC) the different solubility of solutes in two immiscible liquid phases is used for the separation process. One phase is kept stationary by applying a centrifugal force field and flowed through by the other, mobile phase. For setting up a CPC separation first a solvent system with suitable partition coefficients and solubility for the sample compounds has to be found. Afterwards operating parameters (mobile phase flow rate, rotational speed and mode of operation) for optimized hydrodynamics for good mass transfer between the phases have to be selected. Most of the existing publications on CPC focused primarily on solvent system selection. Nevertheless, the relationship between physical properties of the solvent system, operating parameters and the resulting hydrodynamics and separation efficiency is still unclear.
In order to simplify the selection of operating parameters and to enhance the understanding of hydrodynamics in a CPC chamber an optical measurement system was set up in the beginning of this thesis. It allowed detailed flow visualization and investigation of mobile phase dispersion and stationary phase retention as function of physical properties and operating parameters. The visualization was coupled with measurements of separation efficiency making the correlation of optimized operating parameters for a given solvent system possible. Performed separation experiments with a commercial rotor confirmed the dependency of separation efficiency on hydrodynamics. Beside the experimental work a CFD model was developed and validated. The model was used for a priori calculations of flow patterns in different chamber geometries.
The results indicate that more symmetrical chambers with bigger rotor radii enhance the separation quality of CPC because the circulation of stationary phase, initiated by the Coriolis force, is reduced. In most separations the less viscous phase should be chosen as mobile phase because of enhanced retention, better dispersion, higher throughput and lower pressure drop resulting in more economic operation of CPC.