Preparation And Characterization Of Near-critical Water Bagasse Microcrystalline Cellulose

Sugarcane bagasse, an abundant source of agricultural residues, is a fibrous residue of cane stalks left over after the crushing and extraction of the juice from sugar cane. Guangxi has been the biggest sugarcane growing region in our country, having plenty of sugarcane bagasses. However bagasse is a rich natural cellulose resource, when the bagasse cellulose was extracted, it was used to produce high value-added microcrystalline cellulose products, using of the high value of bagasse will be realized. At present,microcrystalline cellulose was prepared mainly with dilute acid, but this approach had brought about equipment corrosion and environmental pollution. In recent years, water had been widely studied in chemical reaction as solvent. Near-critical water is a recently developed high-technology, near critical water itself has the acid catalytic functions, so it can realize some chemical reactions in near critical water, and won't cause to the environment pollution. So preparation of sugarcane bagasse microcrystalline cellulose was researched in near critical water.Effect factors of bagasse cellulose degradation were explored in the experiment.These factors contain the liquid-solid ratio,the reaction time,reaction temperature and reaction origin pressure. On the basis of single factor, the orthogonal experiment were carried out,combined with the yields of sugarcane bagasse microcrystalline cellulose, a better technological conditions were determined on the preparation of bagasse microcrystalline cellulose, that is:the liquid-solid ratio was 40:1; the reaction temperature was 230℃;origin pressure was 2MPa; reaction time was 50min. In these conditions, A optimum bleaching experimental conditions wasExplored, the concentration of H₂O₂ was 5%, bleaching temperature was 40℃,bleaching time was 80min. In this condition, whiteness of the SBMCC was 82.4%.the polymerization degree bagasse microcrystalline cellulose was 215, and yield of sugarcane bagasse microcrystalline cellulose was76%. FT-IR spectra showed that sugarcane microcrystalline cellulose molecular structure still has not be changed when sugarcane microcrystalline cellulose was prepared in near critical water,XRD research showed that sugarcane bagasse microcrystalline cellulose still is celluloseⅠand crystallinity were 73.82%.Properties of bagasse microcrystalline cellulose were studied by using some research methods,compared for Viapure 101 and SBMCC using HCl treating.some results were obtained. Bulking density and tapping density of sugarcane bagasse microcrystalline cellulose were 0.32 g/cm³ and 0.46 g/cm³,SBMCC of using NCW and HCl preparing were no obvios diffence.but Viapure101 was smaller in density. Compared between the SBMCC in NCW and Viapure 101 , whiteness of the SBMCC which prepared NCW was smaller, no difference from the SBMCC prepared in HCl; SEM photos analysis show that SBMCC prepared in the NCW was clavate shape, and in morphology it doesn't make muchdifference from SBMCC prepared in HCl and the commercial MCC(Viapure 101), But microcrystalline cellulose even particle was slightly less,Particle size and size distribution analysis shows that the SBMCC particle size distributionwas no normal distribution prepared in NCW, wherea HCl MCC and Viapure 101 distribution wer better;Thermogravimetric analysis shows that the sugarcane bagasse microcrystalline cellulose begined decomposition at 317℃,maximum thermo-weightlossness temperature reaches 351℃, when temperature reached 364℃, sugarcane bagasse microcrystalline cellulose was decomposed completely. and finally ash was formed when temperature was 480℃. Through the comparing the data of thermalgravimetric analysis they make no difference.between the SBMCC in using NCWand HCl preparing. While the beginning decomposition temperatures, maximum weightlessness temperature and complete decomposition temperature of Viapure 101 were slightly higher than SBMCC.But eventually form of microcrystalline cellulose ash temperature was no more than 480℃. It shows that sugarcane bagasse microcrystalline cellulose which was prepared in the near critical water has excellent thermal stability.