Ion exchange membrane adsorption of bovine serum albumin-Impact of operating and buffer conditions on breakthrough curves

The relevant phenomena underlying the adsorption of proteins on ion exchange membranes with grafted polymer layers are not well understood yet. In this work the influence of operating and buffer conditions on the adsorption of bovine serum albumin (BSA) on anion and cation exchange membrane adsorbers is systematically investigated in order to find indications on the relevant mechanisms. The experimental results obtained at different buffer conditions are analyzed using the steric mass action model. Large differences were observed between the adsorption behavior of BSA on anion and cation exchange membranes. On the anion exchange membranes the dynamic binding capacity at 10% breakthrough was independent of the applied flow rate and decreased with increasing salt concentration. This in contrast to the cation exchange membranes, for which the dynamic binding capacity was strongly dependent on the flow rate and for which an optimum in binding capacity was observed at an intermediate salt concentration. Especially, the results obtained on cation exchange suggest a strong role of non-ideal effects such as steric hindrance and electrostatic repulsion in membrane adsorption. An improved understanding of these effects is required for further optimization of membrane adsorber materials. (c) 2012 Elsevier B.V. All rights reserved.