Effect of kinds of membrane materials on membrane fouling with BSA

Three kinds of membranes were prepared via non-solvent-induced phase separation using poly(ethylene-co-vinyl alcohol) (EVOH), polyether sulfone (PES) and poly(vinylidene fluoride) (PVDF), which are used widely membrane materials. The resulting membranes had structures with skin layers and macrovoids, and their molecular weight cut-offs (MWCOs) and pure water permeabilities were 45-130 kDa and 70-100L/(m(2) bar h), respectively. In BSA filtration experiments, the EVOH membrane showed high relative permeability after 60 min of filtration, while the PVDF membrane showed severe permeability decline. The results of filtrations for BSA solution by three membranes could not be explained by the difference of pure water permeabilities and initial MWCOs. The adsorption behaviors of BSA on the polymers were examined using a quartz crystal microbalance with the dissipation monitoring (QCM-D) method. The order of BSA adsorption amounts on polymers measured by QCM-D was in agreement with the order of BSA rejection during filtration. PVDF showed the highest adsorption amount and the most rigid adsorption layer, while EVOH showed the lowest adsorption amount and the softest adsorption layer. Adhesion force measurements of PVDF-BSA and BSA-BSA were also conducted using atomic force microscopy. The PVDF-BSA interaction was much stronger than the BSA-BSA interaction, indicating that membrane fouling resulted from the physicochemical interactions between polymers and BSA rather than that between BSA and BSA on the membrane surface. (C) 2011 Elsevier B.V. All rights reserved.