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Title: Investigations into electrostatic interactions during ultrafiltration of (bio) colloids
Author: Jain, M.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1999
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The influence of physiochemical conditions on the fouling and fractionation of charged solutes, particularly proteins, during ultrafiltration has been investigated in this study. There exists great scope for improvement of ultrafiltration selectivity and efficiency through manipulation of pH, ionic strength and pressure. With a knowledge of the inherent physiochemical properties of the (bio)colloids and membranes one can apply colloid science insights to model interactions taking place a the membrane surface. Charged solutes are driven towards the membrane pores by hydrodynamic forces. As they approach the pore entrance they usually experience repulsive electrostatic forces. An important concept to be discussed is that of the 'critical pressure', the applied pressure at which the hydrodynamic forces and repulsive electrostatic forces are exactly balanced. This is calculated using finite element techniques. If pressures below the critical pressure are applied the solute will not come into intimate contact with the membrane. Solutes will be retained by the membrane at pressures below the critical pressure, and at pressures above the critical pressure they may be transmitted through the membrane. Experiments with dead-end ultrafiltration of colloidal silica through fully retentive membranes have tested the model and allowed study of electrostatic effects in ultrafiltration in detail. Filtration and fractionation experiments have also been conducted with the proteins bovine serum albumin (BSA), hemoglobin and lactoferrin using polycarbonate ultrafiltration membranes. These proteins have a similar size but different physiochemical properties, which were measured experimentally. Results for single protein transmission and mixed protein fractionation show good agreement with the model predictions. The work has tested an ab inititio based model to predict the rejection and non-fouling conditions in which to run a membrane separation. It has highlighted the additional important effects of protein-protein interactions in the concentration polarisation layer, with which the model's predictive capabilities could be furthered.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available