Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636643
Title: Protein ultrafiltration : a colloidal interaction approach
Author: Williams, P. M.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1997
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Abstract:
The influence of the physicochemical conditions on the permeation rate in dead-end and cross flow ultrafiltration of protein dispersions is investigated. The rigorous mathematical models developed are based on sophisticated descriptions of the protein-protein interactions within the layer close to the membrane surface which is responsible for controlling the permeation rate. The calculations are expressed in terms of an osmotic pressure which accounts for the multiparticle electrostatic interactions, dispersion forces and configurational entropy. Electrostatic interactions are accounted for by a Wigner-Seitz cell approach including a numerical solution of the non-linear Poisson-Boltzmann equation. London-van der Waals forces are calculated using a computationally efficient means of approximating screened, retarded Lifshitz-Hamaker constants. Configurational entropy effects are calculated using an equation of state giving excellent agreement with molecular dynamic data. Electroviscous effects are also taken into account. These descriptions of colloidal interactions are used to develop a priori models, with no adjustable parameters, that allow quantitative prediction of the osmotic pressure and the rate of filtration of protein dispersions as a function of zeta potential (and hence pH), protein size, ionic strength, protein concentration, applied pressure and membrane resistance. The model shows good agreement with literature experimental data for the osmotic pressure of the protein bovine serum albumin (BSA). A further refinement to the models has been the development of a surface charge regulation model from knowledge of the amino acid groups giving rise to the protein charge. For cross flow ultrafiltration, the osmotic pressure is further used in the calculation of the gradient diffusion coefficient from the generalised Stokes-Einstein equation. The filtration models have been tested by conducting dead-end and cross flow ultrafiltration experiments with protein dispersions of BSA and lactoferrin. Good agreement between theory and experiment has been obtained for the dead-end model, but further work is required for the cross flow filtration model.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.636643  DOI: Not available
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