The Purification Process Of Corn Straw Cellulose And The Research Of Reducing Sugar By Enzymatic Hydrolisis

In the present study, corn straw as experimental object, was pretreated by HNO3.Through the single factor experiment, and according to the results design orthogonaltest, the optimum values of the four factors were obtained which were: reaction timeof110min, liquid-solid ratio of8, temperature of95℃and HNO3mass fraction of4.5%. In this condition, the content of each component of corn straw is: cellulose of63.03%, hemicellulose of5.91%and lignin of13.67%. Through scanning electronmicroscope, compared with corn straw treated by HNO3and untreated, the resultsshowed that the fiber bundle structure isn’t complete, and presents more ravines andmassive debris on surface, and fine fibrosis is clear.Pretreated corn straw which was treated by HNO3by NaOH, through the singlefactor experiment, and according to the results design orthogonal test, the optimumvalues of the four factors were obtained which were: reaction time of90min,liquid-solid ratio of9, temperature of90℃and NaOH mass fraction of3.5%. In thiscondition, the content of each component of corn straw is: cellulose of89.37%,hemicellulose of3.61%and lignin of2.67%. Infrared spectrum analysis of thecharacteristic peak of compositions in corn straw which treated by differentconditions, the results found that the characteristic peak of hemicellulose and ligninchanged obviously, and cellulose characteristic peak just slightly changes；Scanningelectron microscope pictures found that, after alkali optimization, the surface of strawfiber bundle become more porous, and it’s hardly to see the original bundle structure；X-ray diffraction analysis results showed that, the crystallinity of crushed strawmaterial was28.14%, and increased by124.13%after alkali optimization, andbecome to63.07%；Straw composition analysis results showed that cellulose contentincreased by128.28%, hemicellulose decreased by87.81%, the content of lignin fellby68.36%compare to corn straw which wasn’t purified by acid and alkali.Corn straw cellulose purified by acid and alkali processing to enzyme producereducing sugar experiments, on the basis of single factor experiment, design multi-factor experiment of according to Central Composite Design and use the Design-Expert software to analyze the experimental results, reducing sugar yield as responsevalue, establish the regression model to optimize enzymatic conditions, and theoptimum values of the five factors were obtained which were: reaction time of44.0h,liquid-solid ratio of22, enzyme concentration of54.5U/g, pH of4.5and temperatureof47℃. In this condition, the reducing sugar yield of85.95%. The scanning electronmicroscope picture of enzymolysis corn straw under optimized conditions showedthat cellulose was almost digested by cellulase.