Investigation Of Amphiphilic Polymer Blended PVDF Ultrafiltration Membrane And Its Protein Antifouling

Ultrafiltration (UF) technology has been widely used in the separation and purificationof proteins, however membrane fouling becomes a bottleneck which has restricted itsapplication. PEO segment has preferable hydrophilicity and low interface free energywith water, making the non-specific protein adsorption difficult to occur, thus PEO(PEG) polymers have excellent ability to restrain protein adsorption. Aim at reducingUF membrane proteins fouling, the following studies were conducted:1. The amphiphilic copolymer Pluronic F127(F127) was used as additives forPVDF/F127blend UF membrane preparation by immersion precipitation phaseinversion method. The factors which may influence the enrichment of hydrophilic PEOchain on membrane surface were investigated, and the antifouling ability ofPVDF/F127blend membranes to protein was analyzed. The results showed that anappropriate increasement in coagulation bath temperature, enhancing the polarity ofcoagulation bath and shortening the air evaporation time were conducive for theenrichment of hydrophilic PEO chain in F127on PVDF/F127blend membrane surface.PEO surface enrichment ratio of membrane had good correlation with the antifoulingof membrane, the membranes with high surface PEO coverage can effectively inhibitthe adsorption of bovine serum albumin (BSA), and the irreversible fouling index wassmall, membrane cleaning recovery rate increased, which indicated that PEO hadsignificant antifouling to protein.2. With the increase of F127amount, the across-section of PVDF UF blend membraneswas loose, the macroporous structure increased, the hydrophilicity and penetration capacity were improved greatly. The protein adsorption capacity of modified PVDFmembrane decreased. The results of the protein UF experiment showed that F127canthe significantly improve the antifouling performance of PVDF membrane in theprocess of ultrafilterring BSA, the cleaning recovery rate was high and the irreversiblefouling index was low. When the F127content reached25%in PVDF membrane bulk,the washing recovery rate of the PVDF/F127membrane descreased, the irreversiblefouling index increased and the fouling performance declined affected by membranestructure.3. The amphiphilic polymer PVDF-g-PEG was synthesized by ozone induced grafttechniques using PVDF as hydrophobic backbone, PEG as hydrophilic side chain. Andthe PVDF/PVDF-g-PEG blend membranes were prepared by immersion precipitation.Effects of PVDF-g-PEG addition on the structure and properties of the membraneswere investigated, and influence of the density and chain length of PEG on membranesurface on membrane antifouling properties were also studied. The results showed thatthe porosity and the pore size of PVDF/PVDF-g-PEG modified membrane increased,and the hydrophilicity improved when compared with pure PVDF membrane.Modified membrane showed better antifouling properties though the PVDF-g-PEGwas added in the amount of3%. The blend membranes with greater PEG chain densityon its surface showed excellent antifouling performance. Within the range ofexperimental studies, the antifouling performance of membrane improved with PEGchain length increased.