MECHANISMS FOR BSA FOULING DURING MICROFILTRATION

Although protein fouling is one of the critical factors governing the effectiveness of many microfiltration processes, the underlying chemical and physical mechanisms that influence the initiation and growth of the fouling layer have not yet been clearly established. We have obtained data for the flux decline during the stirred cell microfiltration of bovine serum albumin (BSA) preparations with different physical and/or chemical characteristics through isotropic polyvinylidene fluoride microfiltration membranes. The initial fouling in this system was caused by the convective deposition of protein aggregates onto the membrane surface. Native (non-aggregated) BSA only fouled the membrane by chemical attachment to an existing protein deposit via the formation of intermolecular disulfide linkages. A mathematical model was developed to describe this dual-mode fouling process, with the model calculations being in very good agreement with the experimental data. These results provide important new insights into the physical and chemical interactions governing protein fouling during microfiltration.