Study On The Pretreatment Of Rice Straw Cellulose For Preparing Ethanol By Ionic Liquids

Fossil resource with insufficient reserve has caused the global environmental pollution intensively, making people get concerned about the development and utilization of clean energy coming from renewable biological raw materials. Rice straw cellulose is hugely reserved and widely distributed on earth, using it to prepare relatively clean, easily stored and transported fuel ethanol as alternative energy is considered as one of the most valuable research directions.Hydrogen bonds formed by hydroxyl groups within and between the molecules make the rice straw cellulose form dense crystal structure. The complex entangled structures between cellulose, semi-cellulose and lignin restrain the development and application of rice straw cellulose. Therefore rice straw needs to be pretreated to improve the utilization of cellulose. Ionic liquid is a kind of non-oxidizing, non-volatile green solvent with high solvation ability and high stability. Using ionic liquid with strong solvation ability to pretreat rice straw can improves the utilization of cellulose effectively. Using the immobilized fermentation technology to ferment can not only avoids the loss of free yeast’s metabolic capacity during fermentation, but also has the advantages of efficient, reusable and convenient features. In addition, they can be channelized, continuous and automatic controlled in the reaction process. All these outstanding features contribute the ethanol yield of fermentation broth effectively.In this paper, ionic liquid1-allyl-3-methylimidazolium chloride ([AMIM]Cl) was synthesized. The influences of synthesis process and condition on the ionic liquid’s purity and property were studied to decide the best synthesis process and condition. Using different pretreatment method to treat rice straw cellulose to decide the best pretreatment method of improving the sugar-producing capacity of cellulose. Using the immobilized cell technology to prepare the immobilized yeast, the immobilization process condition and the immobilized yeast’s repeated using capacity for fermentation were discussed. The ethanol product was obtained by fermenting the enzymatic liquid. The ethanol yield was measured to decide the best pretreatment method of improving the ethanol yield.The best synthesis process and condition of ionic liquid [AMIM]Cl’s was decided the best when allyl was added first at the temperature of80℃, the product was transparent yellow with high viscosity, the purity was99.1%; When the concentration of the embedding medium sodium alginate was0.15mol/L and that of the fixating medium CaCl2’s was2.0mol/L, the immobilized yeast appeared the best fermentation capacity; The immobilized yeast could be reused for fermentation four times, the ethanol yield of the fermentation broth maintained at a high level. The intermittent microwave heating of [AMIM]Cl solvent pretreatment was the best method to improve the cellulose’s sugar-producing ability and the ethanol yield. When the microwave power was118W, treating5min each time, after5times pretreatment, the cellulose conversion ratio of the regenerated rice straw cellulose was96.94%, the glucose conversion ratio of the target product was85.38%...