Study On The Application Of Imidazolium Ionic Liquid In The Preparation Of Reducing Sugar From Soybean Hulls And Soybean Dregs

Soybean hulls and soybean dregs are the byproducts of soybean proecessing and are rich incellulose and other polysaccharides. Cellulose and other polysaccharides are mainly composed ofglucose through glycosidic bonds to the polymer.Polysaccharides completely hydrolyzed toglucoseand other reducing sugars that may be prepared as bio-ethanol by fermentation, and bio-ethanol isa renewable green organicenergy. However, due to the strong hydrogen bond and the highly cryst-alline, cellulose is difficult to be decomposed. Ionic liquids as “green” organic solvents have gooddissolved and catalytic capabilities.Study on the preparation of reducing sugar from soybean bypro-duct in ionic liquids is crucial for the utilization of soybean byproduct, the appilication of ionicliquids and the preparation of biofules.In this study, soybean hulls and soybean dregs were used as raw material. Functional ionicliquids were employed to prepare reducing sugar from soybean byproduct. A series offunctionalionicliquidsincluding[Amim]Cl,[Bmim]Cl,[SO₃-pmim][HSO₄],[mim]₂C₃[HSO₄]₂,[mim]₂C₄[HSO₄]₂,[mim]₂C₅[HSO₄]₂,[mim]₂C₆[HSO₄]₂,[Hmim]Cl,[Hmim]AC,[Hmim]HSO₄and[Hmim]H₂PO₄，were synthesized,1H-nmr had been used to characterize the structure of the ionic liquids.Subcritical water hydrolyzed soybean hulls to prepare reducing sugar was studied first. Theeffect of reaction temperature, reaction time, liquid-solid ratio and pressure on the yield ofreducing sugar were examined. On the basis of single factor experiments and quadratic regressionorthogonal rotational combination design, the optimal hydrolysis conditions were as follows:hydrolysis temperature was170℃, the hydrolysis time was8.1min, liquid-solid ratio was69.3mL/g, pressure was1mpa, and the yield reducing sugar was up to39.17%.In the study of hydrolysis of soybean hulls catalyzed by ionic liquid in subcritical water toprepare reducing sugar, five kinds of acidic ionic liquids were investigated for their catalyticactivies on the hydrolysis of soybean hulls. Results showed that five kinds of acidic ionic liquidshad good catalytic activities for the hydrolysis of soybean hulls compared with subcritical water without catalyst. The acidic ionic liquid（mim）2C₄（HSO₄）2showed the highest catalytic activity.Therefore we choose （mim）2C₄（HSO₄）2as a catalyst, and reaction temperature, reaction time,liquid-solid ratio and the dosage of the catalyst on the yield of reducing sugar were examined.On the basis of single factor experiment and the combination of response surface design, theoptimum hydrolysis conditions were as follows: temperature was175.4℃, time was5min,liquid-solid ratio was81ml/g, the amount of catalyst was0.11g, and the yield of reducing sugarwas up to50.78%.In the study of ultrasound assisted ionic liquids to prepare reducing sugar from soybeanbyproducts, three kinds of ionic liquids as solvents, five kinds of acidic ionic liquids andconcentrated sulfuric acid as catalysts were investigated for the hydrolysis of soybean hulls andsoybean dregs to prepare reducing sugar. The research results showed that with sulfuric acid as acatalyst, good results were obtained with [Amim] Cl as a reaction solvent. In [Amim] Cl, fivekinds of acidic ionic liquid exhibited excellent catalytic properties. The catalytic activites werehigher than sulfuric acid and the optimal activity was observed using （mim）2c4（HSO₄）2as acatalyst. Then [Amim] Cl was used as solvent with （mim）2c4（HSO₄）2as a catalyst, temperature,time,, the dosage of the catalyst, the amount of water on the influence of the hydrolysis reactionwere investigated. According to single factor experiments and orthogonal experiments, the optimalconditions were as follows: temperature was95℃, the hydrolysis time was65min, theliquid-solid ratio was15ml/g, the quality of the catalyst was1.2g and the reducing sugar yieldwere as high as71.15%. The optimal condition is also suitable for hydrolysis of soybean dregscellulose to prepare reducing sugar.In the research of pretreatment of soybean dregs using ionic liquid and enzymatichydrolysis,six kinds of ionic liquid were investigated for their performance on pretreatment ofsoybean dregs and their influence on cellulase. Good results were obtained in [Hmim] Cl when thetemperature was120℃in oil bath, pretreatment time was30min [Hmim] Cl was then used forpretreatment. Temperature, time, substrate concentration, pH, dosage of enzyme were examined onenzymatic hydrolysis reaction. Results were as follows: the enzyme solution for10h, celluloseenzyme of0.04g, the quality of the substrate concentration of20mg/mL, enzymolysistemperature of50℃, and the yield of reducing sugar was41.13%.