Study On The Bacterial Cellulose Composites And Properties

In this paper, bacterial cellulose (BC) was cultivated by the static culture method, and BC was respectively treated as suspension by cell pulverizer. Adding tetraethoxysilane as silicon source and polymerizing external BC, bacterial cellulose/silica (BC/SiO2) composite was prepared by means of in-situ composite in room temperature. The influences of catalysts (HCl, CH3COOH, H3PO4, HNO3 and Na2HPO4), catalytic environment, and reaction time on reaction process were researched by virtue of Visible Spectrophotometer, Scanning Electron Microscopy (SEM), Thermal Weightlessness (TGA) and Infrared Absorption Spectrum analysis, ect. At the same time, the morphology characteristics and the component of composites were analysed.The results showed that the catalytic effect was the best with HCl. In this case, the structure of the composite was clear, and SiO2 was equally distributed. When the catalysts were H3PO4 and HNO3, the reaction rates of composites were increased, the fiber structures in the composites were unconspicuous, and the granules of SiO2 were bigger. When CH3COOH as the catalyst, the reaction rate of composite was the lowest, the fiber structure in the composite was obvious, and the granules of SiO2 were smaller and uniform distributed.The influence of environmental catalysis on BC/SiO2 composites was also tremendous. The experiment showed that the reaction rate of composites was the largest in alkaline environment when H3PO4 and HNO3 were catalysts. Alkaline environment was conducive to the reaction when HNO3 as the catalyst. But it was against Na2HPO4, that the structure of the composite was unconspicuous. Instead, the fiber structures in the composites were obvious and the reaction was complete when HCl and CH3COOH played catalysts. In acidic environment, the reaction rates of H3PO4 and Na2HPO4 were the fastest, and the lowest with CH3COOH. The acidic environment was harmful to the catalyst of HNO3, that the rate of the reaction was greatly reduced. The structures of the composites catalyzed by Na2HPO4 and HNO3 were improved in some extend.In conclusion, the catalytic environment of reaction was insignificance to H3PO4. The catalyst of Na2HPO4 was adequate for acidic environment. And alkaline environment was in favor of HNO3.Adding BC into the PVDF, PVDF/BC composite membrane was prepared by means of wet phase separation method. The influences of BC content on structures and properties of composites were evaluated. By the addition of hydrophilic BC, the water flux increased as well as the retention rate decreased. When the content of BC was 0.4%, the integrated performance of the PVDF/BC composite membrane was excellent.PVDF/BC/SiO2 composite membranes were prepared by the same method with the addition of BC/SiO2 composites mentioned above. The research showed that SiO2 was imported into BC successfully, and had some impact on composite membranes. By the addition of BC/SiO2 composites, the water flux decreased. The retention rate reached the maximum, when BC/SiO2 composite catalyzed by HCl.