| Poly (vinylidene fluoride) (PVDF) is extensively used in preparing separation membranes with regard to its excellent thermal stability, chemical resistance and mechanical properties. Nevertheless, the intrinsic hydrophobic property of PVDF often causes severe membrane fouling and decline of permeability, which is a major challenge for the widespread application in water and wastewater treatments. Graphene oxide (GO) has gained increasing appeal due to its salient features such as abundant oxygenous functional groups and extremely high specific surface area, which offers innovative alternatives for the development of PVDF membrane modification. However, GO, has pinpointed an inherent dilemma as encountered in blending modification method:large amounts of nanoparticles are embedded within the polymer matrix during the blending process, which limits the amount of nanoparticles on the membrane surface and cuts down the modification efficiency. Therefore, it is a prevailing challenge to enrich nanoparticles anchoring on the membrane surface and thus engineer a robust antifouling membrane surface, which can truly exploite the modification efficiency rather than embedding nanoparticles within the polymer matrix. Hence, in this study, a novel PVDF hybrid ultrafiltration membrane with enhanced hydrophilicity and antifouling performance was developed by manipulating phase separation and magnetic field induced casting through incorporating magnetic GO/Fe3O4 nanoparticles. For this purpose, magnetic GO/ Fe3O4 nanocomposites were firstly synthesized via a facile one-step chemical co-precipitation method, in hopes of endowing GO with magnetism and thereby migrating and enriching the resultant magnetic GO particles on membrane and pore surfaces with the aid of magnetic field during the membrane preparation process. The main contents of this study include two aspects:(1) Magnetic GO/Fe3O4 nanocomposites were firstly synthesized via a facile one-step chemical co-precipitation method. The results of TEM and XRD of GO/ Fe3O4 nanocomposites indicated a high crystalline nature of the magnetite. The results of FTIR and XPS of GO/Fe3O4 nanocomposites illustrated some interaction between the carbonyl and hydroxyl groups of GO and Fe on the surface of the magnetic particles, showing the bonding of the iron oxide nanoparticles to GO. The results of TGA and VSM of GO/Fe3O4 nanocomposites indicated a good thermal stability and magnetism of the nanocomposites. All the characterization results illustrated the successful synthesis of GO/Fe3O4 nanocomposites, which would be important for the preparation of GO/Fe3O4-PVDF hybrid ultrafiltration membranes via magnetic field induced casting and phase inversion method.(2) The novel GO/Fe3O44-PVDF hybrid ultrafiltration membranes were developed from the GO/Fe3O4/PVDF blends via magnetic field induced casting and phase inversion method. The morphology of membranes demonstrated that the hybrid membranes have bigger pore size and porosity, which undoubtedly played a positive role in permeation flux. The results of EDS. XPS and EA showed that the oxygen element on the surface of the hybrid membrane were higher than that of the substrate, implying the migration and enrichment of the resultant magnetic GO particles on membrane surface with the aid of magnetic field during the phase inversion process. Compared with the pristine PVDF (74.5°), the hydrophilicity of the hybrid membrane showed a marked improvement (55°) in contact angle. The pure water flux of the hybrid membrane was 595.4 L m-2 h-1, being enhanced by 206% compared with that of pristine PVDF membranes(194.6 L m-2 h-1). yet attaining a high bovine serum albumin (BSA) rejection of 92%. Additionally, an atomic force microscope (AFM) analysis with a BSA-immobilized tip indicated low adhesion force with the hybrid membrane, consistent with the fouling properties of membranes. The pure water flux recovery of the hybrid membrane achieved 86.4%. demonstrating an impressive prospect for the anti-irreversible fouling performance in dead-end filtration experiments.Therefore, this research presents an effective method to tailor membrane performance via manipulating magnetic field induced casting and phase separation through incorporating magnetic GO/Fe3O4 nanocomposites, thus highlighting new avenues to the development of hybrid membranes with effective reinforced permeation and antifouling performance.
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