Protein Transport in Open Ultrafiltration

Summary

Ultrafiltration (UF) is a mild separation technology commonly used to retain macromolecules by the membrane. UF, with moderate rejection to protein, can be utilized to fractionate protein mixtures to obtain more valuable individual proteins. The separation of solutes can be improved by controlling the pH and ionic strength of the system. However, the fractionation of proteins in such systems (UF with permeating macromolecules and electrostatic interactions) has not been extensively studied. This thesis provides guidelines to describe the solute rejection in open UF systems and rigorously examines the influence of electrostatic interaction on protein rejection for a single protein with semi-mechanistic equations with varying complexities. For protein mixtures, protein−protein electrostatic interaction also plays an important role in the separation of the proteins. The knowledge gained in this thesis is useful for fractionation of protein mixtures.