Application of the two-film theory to the determination of mass transfer coefficients for bovine serum albumin on anion-exchange columns

The paper describes a method of simultaneous determination of the external and the solid-phase mass-transfer coefficients from frontal analysis data. The protein flux to the solid particles is determined from the slope of the breakthrough curve and the mass-transfer coefficients are determined by fitting the two-film model to the experimentally determined flux. The two-film model is compared with two apparent overall driving force models: the apparent overall mobile phase driving force model and the apparent overall solid-phase driving force model. The experiments show that the apparent overall driving force models fail to describe the flux correctly and this is substantiated by the theory. Results obtained with bovine serum albumin on the anion-exchange media Q HyperD, Source, and Poros show that the external film resistance is significant for Reynolds numbers less than one. The experimental Sherwood numbers are lower than expected and their dependence on the Reynolds number are much higher than expected.