Dissertation
Increasing the scale of electrophoretic true moving bed enantiomer separations using voltage gradients and filtration enhancement
Washington State University
Doctor of Philosophy (PhD), Washington State University
12/2006
DOI:
https://doi.org/10.7273/000005662
Abstract
Over the past decade the moving bed process has become a common tool for the continuous separation of chiral compounds, and its recent adaptation to electrophoretic separations has provided a model system for determining the effects of gradients in electric field or velocity on the process. Several approaches were used to explore the addition of gradients to True Moving Bed (TMB) electrophoresis. A linear mathematical model of the TMB process was developed that allowed the dynamics of the technique to be studied in great detail, and this provided the foundation for experimental work using stepped electric field gradients and counterflow velocity gradients using filtration. The modeling work showed that the addition of a stepped electric field gradient allowed a 7.66 fold increase in the maximum homatropine throughput when compared to the nongradient case. Continuous electric field gradients were also explored, resulting in a maximum throughput of 7 fold over the non-gradient case. Continuous gradients resulted in a significant decrease in product concentrations within the unit, lowering the chance of precipitation and reducing the time required to reach steady state. Experimental work using stepped field gradients in a three electrode Vortex Stabilized Electrophoresis Apparatus encountered problems with both dialysis and anion exchange membranes at the middle electrode during homatropine separations. Due to this, the electric field gradient process was tested using bovine serum albumin and hemoglobin. The results showed that a 63% increase in throughput was attainable using an electric field step gradient, and while this is nowhere near the 7.66 fold increase predicted by the homatropine model, it is still a significant enhancement. The model was then adapted for use with velocity gradients created by the addition of a filtration unit. An increase in throughput of 3.14 fold was predicted due to a reversal of the unfavorable step in counterflow velocity in between sections II and III. Experimental results showed a 3 fold benefit in section II, but the tailing in section III was increased due to dispersion caused by flow oscillations stemming from the pump used in the membrane system preventing useful results to be obtained in that region.
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Details
- Title
- Increasing the scale of electrophoretic true moving bed enantiomer separations using voltage gradients and filtration enhancement
- Creators
- Brian Matthew Thome
- Contributors
- Cornelius F. Ivory (Chair)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Chemical Engineering and Bioengineering
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 148
- Identifiers
- 99901054532001842
- Language
- English
- Resource Type
- Dissertation