Effect of Mg2+ binding on transmission of bovine serum albumin (BSA) through ultrafiltration membranes

Protein fractionation by membrane technology has many advantages for separations, in comparison with conventional methods. In this paper, the influence of different type and concentration of two electrolytes: NaCl and MgCl2 on buffer capacity and hydrodynamic radius of bovine plasma proteins were analyzed as a way to improve protein separation by cross-flow ultrafiltration. A tubular ceramic membrane with 0.2 μm pore size was used. The evolution of permeate flux and BSA transmission was determined at 25 °C and transmembrane pressure range of 0.2-1.4 bar. The membrane fouling was evaluated through the resistance model application, identifying the operational conditions of the highest BSA transmission through the membrane. In this regard, it was demonstrated that the effective radius of the protein and its buffering capacity were affected by the use of MgCl2 at 0.006 (w/v), which caused conformation changes in the protein structure resulting in a less resistance to transport.