Chromatography of Latex Particles in Packed Columns (Hydrodynamic, Dispersion)
Francis, Debra Carol
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https://hdl.handle.net/2142/69759
Description
Title
Chromatography of Latex Particles in Packed Columns (Hydrodynamic, Dispersion)
Author(s)
Francis, Debra Carol
Issue Date
1985
Department of Study
Chemical Engineering
Discipline
Chemical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Chemical
Abstract
A recent major development in the characterization of colloidal particles has been the adaptation of liquid chromatography techniques to the determination of particle size distributions of polymer latexes. In this work, techniques that involve packed columns with either nonporous packing material (termed hydrodynamic chromatography) or porous packing material (termed porous hydrodynamic chromatography or size exclusion chromatography) were studied.
A formalism for the chromatography of suspended particles in packed columns was developed based on established theories for the chromatography of dissolved species. This formalism was used to examine the role of phase partitioning in the mean residence time behavior in porous packing systems. Modeling calculations for an entirely partitioning process and for a combination of partitioning and hydrodynamic processes are presented which show that calculated values of the separation factor from the combination description agree very well with experimental values (both literature and this work).
Since resolution depends on dispersion behavior as well as mean residence time behavior a fundamental understanding of dispersion processes would be useful for optimizing a chromatography system. Modeling calculations of the peak spread for both nonporous and porous packing systems are presented which show agreement with the observed increase in peak spread with increasing ionic strength (this work) but not with the observed decrease in peak spread with increasing particle size (literature data and this work). This latter observation is shown to be accounted for by an empirical modification of the expression for the standard deviation in a phase partitioning (porous packing) system. The theoretical basis for the resulting expression is not at present understood. Comparison with the random walk theory indicates that the additional factor is due to eddy dispersion and thus a means of accounting for this phenomenon is needed.
To quantify the mechanism of incomplete particle recovery, the rate of deposition of suspended particles on collector spheres due to hydrodynamic and electrostatic forces was calculated. These calculations show no significant deposition due to cross streamline motion by hydrodynamic forces.
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