Properties of microfiltration membranes: flux loss during constant pressure permeation of bovine serum albumin.

An experimental study of permeation of dilute BSA solutions (filtration) at microfiltration membranes has been carried out. Most measurements were made with capillary pore aluminum oxide membranes, with some comparative measurements with tortuous and capillary pore polymeric membranes. In all cases, a continuous and substantial decrease in the rate of permeation with time was observed. This decrease in permeation with time was observed. This decrease in permeation rate was due neither to concentration polarization nor to protein adsorption alone. However, it could be quantified using the standard blocking filtration law, which describes a decrease in pore volume due to deposition of protein on the walls of the pore. The maximum calculated thickness of the deposited layers was 55 nm on the walls of 200-nm diameter pores. This phenomenon is quite different to adsorption of protein at such surfaces, this latter giving only sub-monolayer or monolayer protein coverage under the conditions studied.