LAUSR

Abstract The objective of this study was to determine the influence of the selective layer properties of ceramic multi-channel microfiltration (MF) membranes on the filtration performance during milk protein fractionation. Membranes with selective layer material of Al2O3, TiO2, or ZrO2 (nominal pore size 0.1 µm) were compared with respect to flux and β–Lactoglobulin (β-Lg) permeation at different transmembrane pressures (ΔpTM) at 10 °C and 55 °C. Differences in the membrane performance could be linked to the specific characteristics of the selective layer material, zeta-potential, pore size distribution as well as the membrane and fouling resistance. Furthermore, it could be shown that the flux decreases for Al2O3 and TiO2 after reaching the limiting flux, when a stepwise increase in ΔpTM was performed. This effect was caused by the over-proportional increase in the fouling resistance due to a pressure-driven increase of the pore fouling. Caustic and acidic conditioning of the membrane were shown to affect flux as well as β-Lg permeation in the dependence of the selective layer material. After an acidic conditioning, the decrease in flux became more pronounced for materials with a wider pore size distribution, whereas the β-Lg permeation was reduced, which could be explained by the related zeta-potentials.