| Polyvinylidene fluoride (PVDF) is one of the widely used separation membrane materials, however, the strong hydrophobicity of PVDF leads to the low flux and easy contamination of membrane in the filtration of water medium, thus its application in water treatment is restricted. It is of great importance to increase the hydrophilicity of PVDF.Because organic/inorganic hybrid materials bear both of the excellent properties of organic macro-molecular materials and inorganic materials, the researches on preparation of PVDF/inorganic nano hybrid membrane were paid broad attention to. Researches were carried mainly to illuminate the effects of inorganic nano component on the structure and properties of hybrid membrane, but it was short of theoretical analysis, and nanoparticles were direct dispersed in the membrane materials by most researches. So some phase separation between inorganic and organic materials could be found.In this article, sol-gel technique was applied to prepare PVDF/Al2O3 nano hibrid membrane, nanosized alumina was formed in site by the hydrolysis and condensation polymerization of aluminium isopropoxide (AIP) in PVDF casting solution, and vinyl-trimethoxy-silicane was used as coupling agent to enhance the consistency of organic/inorganic phases, thus the phase separation phenomenon could be avoided effectively. The membrane morphological structure and characteristics were studed, and the membrane formation mechanism of hybrid membrane was preliminary discussed in the view of thermodynamics and kinetics, and the application of membrane bioreactor prepared by hybrid membrane for the treatment of rosin waste water was undertaken. The major experiment methods and results were summarized as follows:1. Preparation and characterization of PVDF/Al2O3 hybrid MembranePVDF/Al2O3 hibrid membrane was prepared using aluminium isopropoxide as inorganic precursors by sol-gel process. The chemical structure, microstructure and properties of the hybrid membrane were studied respectively. The results showed that, the resulting nano particles promoted the formation of micropores on the membrane surface, the porosity of the membrane increased, and the finger-like pore in the membrane developed, but the over-dose of AIP could destroy the structure of membrane and lead to the formation of big cavity. So it could be concluded from the results that suitable addition of AIP would improve the separation properties of membrane, increase both the water flux and retention. In addtion, the formation of nano alumina would result in a toughening effect on the membrane. And the anti-fouling ability of the membrane could be improved because of reduced surface roughness and increased hydrophilicity. However, the effects of hybrization on the thermal stability and melting point of membrane were not obvious.2. Preparation and characterization of modified PVDF/Al2O3 hybrid MembraneThe PVDF/ Al2O3 hybrid membrane linked in chemical bonds was prepared with modified PVDF and using vinyl-trimethoxy-silicane as coupling agent. FT-IR, surface contact angle testing, DSC and AFM were applied to characterize the modified PVDF membrane, and the effects of coupling agent on the structure and properties of the hybrid membrane were explored. Results showed that, C=C double bond, hydroxyl group and carbonyl group were discovered in the modified PVDF, and this laid a foundation for the further modification of PVDF. The presence of active center and coupling agent might enhance the acting force between the two phases of the hybrid membrane, and the formation of nano particles could improve both the strength and toughness of the hybrid membrane.3. Study on the mechanism of PVDF/Al2O3 membrane formationThe effects of AIP on the phase behavior and gelation kinetics of the casting solution were studied to discuss the mechanism of the influence of AIP on hybrid membrane morphological structure and characteristics. Results showed that, the phase equilibrium of casting solution was changed as the concentration of AIP increased, and the system become thermodynamic unstable, thus its contained capacity with nonsolvent was decreased and the gelation rate of casting solution was speedup. Gelation rate was largest in the initial period of membrane formation. Then the increases of gelation rate and phase separation rate of the system were slow with the increasing of AIP concentration, but the gelation rate was decrease when AIP overdosed.4. Application of PVDF/Al2O3 membrane bioreactor in rosin waste water treatmentA submerged membrane bioreactor was constructed with the prepared hybrid membrane for the treatment of rosin waste water. Microscopy was used directly to judge the performance of the membrane bioreactor and the growth of microorganism, sludge property and waste water treatment effect of each period were analysed. Results showed that, in the process of culture and domestication of active sludge, as the formation and growth of zoogloea, the variety of indicated organisms changed thoroughly. The results also showed that HRT, DO value and sludge concentration had great influence on the treatingt effect of membrane bioreactor. When the concentration of sludge was 6000mg/L, DO at 2mg/L and HRT for 8h, the removal rates of COD and BOD were 90% and 88% respetively.
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