The Preparation Of TiO₂ Modified PVDF Ultrafiltration Membrane And Its Characterization Of Anti-fouling Behaviour

In this paper, the inorganic nano TiO₂ and PVDF/PVP/LiCl system were modified by physical blending, and the TiO₂/PVDF modified ultrafiltration membrane and TiO₂/PVDF modified hollow fiber ultrafiltration membranes were prepared by the non-solvent induced phase separation method. The effects of the ratio of TiO₂ and PVDF/PVP/LiCl system on the structure and properties of the flat membrane were discussed. On this basis, to bovine serum albumin（BSA）, humic acid（HA） and sodium alginate（SA） as the representative of the proteins, humus and polysaccharide substance, was made by those of TiO₂ / PVDF modified ultrafiltration flat membrane for BSA, HA and SA, and the secondary effluent from urban macroscopic membrane separation. The optimum obtains optimal performance of modified ultrafiltration flat membrane. Secondly, we investigated the effects of the spinning conditions on TiO₂ and PVDF/PVP/LiCl blend system after hollow fiber ultrafiltration membrane structure and performance of the impact, with an emphasis on the effect of spinning conditions to form a hollow fiber ultrafiltration membrane section internal hole shape. The main conclusions were showed as follows:（1） Through to those of TiO₂ / PVDF modified membrane FT-IR spectroscopy and X-ray diffraction（XRD） analysis shows that addition of TiO₂, part of TiO₂ and PVDF crosslinking, modified membrane surface enrichment of hydrophilic hydroxyl groups; in addition, crystallization of TiO₂ film has certain influence, may strengthen the role of PVDF crystal structure.（2） Through the membrane surface morphology, shape and sectional shape analysis indicate that the modified with addition of TiO₂ using AFM and SEM, change of membrane filtration area increases, increases while surface roughness; cross section of the film to reduce hole shape, the surface of TiO₂ reunion phenomenon.（3） When those of TiO₂ / PVDF instead of flat ultrafiltration membrane in the TiO₂ content is 0.5%, the hydrophilicity contact angle of the membrane is 60.37 degree, porosity of 84.48%, the pure water flux for 679.92 L /m2·H, retention rate is 87.67% in comprehensive performance in the film best.（4） Through the use of three common characteristics of pollutants（BSA, HA and SA） and urban secondary effluent to those of TiO₂/PVDF blend modified membranes were macroscopic membrane pollution filtration test. The results showed that TiO₂ is 0.5% of those of TiO₂/PVDF membrane modification of BSA, SA and urban secondary effluent of anti pollution and anti pollution of the good and all the modified membranes of HA, anti pollution and resistance to less pollution.（5） After the addition of nano TiO₂ and those of TiO₂/PVDF modified hollow fiber membrane water flux and BSA rejection rate is improved to a certain extent, but silk membrane mechanical strength and elongation at break decreased; dry process on the basic performance of hollow fiber ultrafiltration membrane effect is larger, the test in dry process is 15 cm, hollow fiber ultrafiltration membrane filaments had the best overall performance.（6） Spinning conditions（dry process, composition of liquid core, and composition of coagulation bath and drawing speed） of PVDF hollow fiber ultrafiltration membrane cross section shape of the inner bore of the analysis shows that can effectively inhibit membrane irregular section shape formation: increase the spinning process of dry process;（DMAc） solvent liquid core content decreased;（DMAc） solvent bath gel content increased; improve the drawing speed.