Studies On The Pretreatment And Isolation,Modification Of The Wood Cellulose

The development and utilization of renewable resources has attracted more and more attention in recent years, specially in producing new materials and chemical raw materials from agriculture and forestry biomass. Therefore, it has the important theoretical and practical significance for study. Wood is mainly composed of cellulose, hemicellulose and lignin, the cellulose is one of the most abundant natural polymer on earth, it has many advantageous properties, such as sustain able, renewable and biodegradable. In addition to the macromolecular material, wood also contains a small amount of low molecular substances, the presence of these small molecules, can affect the chemical and physical properties of wood, and finally limit the application of the wood.For the purpose of effectively utilizing resource of wood, Eucalyptus and Pine was studied. In this study, the composition of wood was analyzed first, and then the pretreatment of wood was investigated. Moreover, the preparation of wood fibers was discussed in ionic liquid without removal of hemicelluloses and lignin. The primary results are described as follows:(1)The main components of the wood Eucalyptus and Pine were determined respectively. As the results shows, that the content of cellulose of Eucalyptus is41.72%, hemicellulose is13.21%, lignin is23.99%, its more than Pine, the three contents of Pine are39.94%.12.89%、22.97%.(2)The pretreatment of wood was optimized by orthogonal test, and the result was analyzed by enzymatic hydrolysis of cellulose and electron-microscopic scanning, the optimization of process is conclusion below: a mixed solution of ethanol and benzene with the volume ratio of1:2are used as the solvents for Eucalyptus, extracting time is4h, the temperature is66℃, solid-liquid ratio is1:15. Ethanol are used as the solvents for Pine, extracting time is4h, the temperature is78℃, and solid-liquid ratio is1:15. Through the orthogonal experiment, the influence of the size of the order is obtained: extraction temperature> extraction time> solid-liquid ratio, temperature as the main impact factors, its influence is significantly. Finally, the pretreatment of wood can improved its chemical and physical properties, even chemical components, such as structure, pore size, and accessible surface:the ash content is below0.1%, the surface of the wood turned from initially smooth into rough and the cross-sections turned from compact into porous.(3)A new method to prepare biomass fibers directly from wood, without the removal of hemicelluloses and lignin was presented using ionic liquid as a solvent. At assist of microwave the wood could be completely dissolved in ionic liquid within50s. The results of FT-IR indicated that [Bmim]Cl was a direct solvent for wood. After dissolution of the wood, cellulose can be obtained by adding the solution of water/acetone, and lignin was regeneration after evaporate the acetone. The dissolution of the experimental results shows that, the yield of cellulose and lignin was33.29%and12.23%.Homogeneous acetylation of wood cellulose was successfully synthesized in ionic liquid, the structure and DS of the cellulose derivatives were investigated by FT-IR. The results indicated that the highest DS of cellulose acetate,0.46was obtained at100℃for60min.