Preparation And Characterization Of PVDF/SiO₂ Internal Support Hollow Fiber Hybrid Membrane

This paper mainly explored the Organic–inorganic polyvinylidene fluoride（PVDF）/silica（SiO--₂） internal support hollow fiber hybrid membranes were prepared by the coating and phase separation method, in which the nano-sized SiO--₂ were blended into PVDF casting solution by using PET woven tube for internal support layer. The effect of SiO--₂ content in casting solution on membrane performance were investigated; Using SEM, AFM and XRD to observe the microstructure characterization of hybrid membrane; testing the indices such as pure water flux, rejection rate of BSA and porosity to determine the macro performance of the fiber membrane; analyzing the effects of casting solution with different distribution ratio on high strength hybrid membrane properties and the hybrid membrane pollution resistance were studied.The main conclusions of this study are listed as follows:（1） Using PET fiber woven tube as the support material and using PVDF/PVP/SiO--₂/DMAC as the casting solution, the coating of prepared membrane attached on the external surface of the woven tube and made the tensile strength of the hybrid membrane greater than 50 MPa.（2）The addition of nano SiO--₂ particles in the PVDF/PVP/DMAC casting solution system improved the hydrophilic modification of internal support hollow fiber hybrid membrane. And the results show that: 1) With the addition of nano SiO--₂ in the casting solution, the water flux of membrane, porosity and average pore size are all promoted in a certain degree; 2) As the increase of the concentration of nano SiO--₂ in the casting solution, the casting solution viscosity increased rapidly, the film became thicker, and the membrane surface became dense. And when the nano-SiO--₂ content exceeds 1.5%, the flux of the membrane and porosity started to decrease; 3) The porosity of internal supported hollow fiber hybrid membrane are between 50⁶8%, the rejection rate of BSA is higher than 85%, and the pure water flux could be up to 192.6 L/（m2?h）. When the casting solution of PVDF/PVP/SiO--₂ ratio is 14:6:1.5, the temperature of casting solution is 60℃ and the coagulation bath is pure water under 25℃, the performance of internal supported hollow fiber membrane is the best.（3）As the increase of PVP concentration in casting solution, the water flux and the average pore size of the hybrid membrane increased firstly and then decreased and the porosity increased gradually. When the concentration of PVP was 6%, the pure water flux of the hybrid membrane was 201.6L/（m2?h）. And the content of PVDF also had an influence on the performance of the hybrid membrane. When PVDF content is higher, the phase separation slower and the water flux decreased rapidly due to the rise of casting solution viscosity.（4）The anti-pollution performance of the hybrid membrane is high performance, and flux recovery rate after the BSA solution pollution is 77%. Casting solution add SiO--₂ nanoparticles produce hydration in the surface of the film hole formed after hydration layer, it can effectively prevent the adsorption effect of hydrophobic proteins in the membrane surface.