A diffusion model of protein and eluant for affinity filtration

A mathematical model taking into account the film and interior diffusions of protein and eluant was developed to describe the whole affinity filtration process, including broth feeding, contaminant washing and elution steps. Affinity filtration experiments were conducted to evaluate the model using bovine serum albumin as a model protein and a highly substituted Blue Sepharose as an affinity adsorbent. The results showed that the model could well predict the performance of the whole affinity filtration using the mass transfer parameters independently determined by batch kinetic experiments. Comparisons with a lumped kinetic model indicated that the diffusion model was more precise and acceptable. Thus the performance of the affinity filtration processing a crude broth containing contaminant proteins was analyzed by computer simulations using the diffusion model. The simulation results showed that at each operating condition there was an optimal protein loading that yielded a maximum recovery yield of the desired protein with a constant purity. Concentrating the crude broth was beneficial to increase the recovery yield of the desired protein.