Frontal analysis of protein adsorption on a membrane adsorber

The adsorption behaviour of two kinds of proteins, myoglobin and ovalbumin, with a membrane adsorber, DEAE MemSep 1000 (Millipore), was studied in comparison with a bead-based packed-bed adsorber, DEAE Sephacel (Pharmacia-LKB), by means of frontal analysis. Adsorption isotherms were obtained by integrating the breakthrough curves for various feed concentrations. Adsorption isotherms were expressed by the Langmuir equation and the adsorption capacity for the membrane adsorber was smaller than that for the packed-bed adsorber. The breakthrough curves of myoglobin for the membrane adsorber were independent of the flow-rate, but those of ovalbumin were affected by the flow-rate. Abnormal behaviour was observed for the adsorption of ovalbumin on a membrane adsorber. With the packed-bed adsorber, the breakthrough curves for both proteins were significantly affected by the flow-rate. A mathematical model for the membrane adsorber involving axial dispersion and adsorption kinetics was derived. The model simulated the breakthrough curves for myoglobin well. Axial dispersion was dominant for the membrane adsorber whereas intraparticle diffusion was dominant for the packed-bed adsorber.