| Ion-exchange is the most commonly used technique for the recovery and separation of proteins on a process scale. As a result, there is an increasing interest in improving the efficiency and productivity of ion-exchange media. A recent advance in this area is the development of polymeric ion-exchange media based on functionalized acrylamido monomers. These materials combine high capacity and rapid mass transfer with mechanical strength and chemical stability. The overall goal of this dissertation is to determine the relationship between the physical and morphological characteristics of these materials and the adsorptive behavior of proteins. Two anion-exchangers, BRX-Q and BRX-QP, and a cation-exchanger, BRX-S are used in this work. The first is comprised of particles with a heterogeneous structure containing a low density phase interspersed through denser polymer aggregates. This material has a very low size exclusion limit for neutral macromolecules. However, it possesses a very high binding capacity for oppositely-charged proteins and rapid mass transfer kinetics. The second material is comprised of particles with large open pores. In this case, while the size-exclusion limit for neutral macromolecules is high, the binding capacity for proteins and the mass transfer rates are low. Finally, the third media appears to be intermediate with particles containing both large and small pores yielding intermediate protein binding capacities and mass transfer rates. Models are developed to describe the kinetics of protein adsorption in these materials. These models provide a valuable tool to determine the dominant mass transfer mechanisms for different conditions and for the design and optimization of chromatographic separations. |
