Study On Sulfite Pretreatment To Enhance Effect Of Enzymatic Hydrolysis Of Corn Stalk

Lignocellulosic biomass is a renewable, cheap, abundantly available resource, and its bioconversion to fuel ethanol is very meaningful in the sustaining development of our society and economy. But the efficiency of the enzymatic hydrolysis of cellulose is low because of the high crystallinity of cellulose and the package of lignin and hemicellulose which affecting the enzyme-substrate contact and then affecting the efficiency of enzymatic hydrolysis. Therefore the lignocellulosics must be pretreated to destroy the connection of cellulose-lignin-hemicellulose, increase the enzyme substrate availability, and then improve the conversion rate of enzymatic hydrolysis. In this paper, the pretreatment technology and the surfactant assisted enzyme-catalysis technology were studied, moreover, the related influencing factors were discussed.In this paper, corn stalk were pretreated with sodium bisulfite and sulfurous acid, the effects of pretreatment conditions including pretreatment temperature, the dosage of reagents and pH value on the efficiency of enzymatic hydrolysis of corn stalk were studied. The results indicated that the effect of sodium bisulfite pretreatment was better than sulfurous acid pretreatment. The efficiency of enzymatic hydrolysis was increased with the dosage of sodium bisulfite increasing, with7%sodium bisulfite at180℃for30min, the conversion of enzymatic hydrolysis and glucose yield were about69.40%and62.44%respectively. The higher pretreatment temperature was, the better efficiency of enzymatic hydrolysis was. pH value had great effect on the efficiency of enzymatic hydrolysis. When the pH value was in the range of4.2-4.7, the efficiency of enzymatic hydrolysis rose significantly.The dosage of enzyme is a key factor which affecting the cost in the process of enzymatic hydrolysis of cellulose. In this paper, the dosage and the combining form of cellulase, hemicellulase and cellobiase were studied. The results indicated that the efficiency of enzymatic hydrolysis was increasing first then flating as the dosage of cellulase increasing. When the cellobiase dosage was10%(v/v) of the dosage of cellulase, the conversion of enzymatic hydrolysis and glucose yield were about66.10%and61.28%respectively. When the hemicellulase was added the efficiency of enzymatic hydrolysis was lower than the cellobiase was added and the combination of three kinds of enzyme had great efficiency in the enzymatic hydrolysis, however, the change extent is not large compared the effect of the combination of cellulase and cellobiase.Surfactant can increase the hydrolysis rate of enzyme catalysis and decrease the adsorption of enzyme on the lignin surface in this paper, nonionic surfactant-Poly Ethlene Oxide (PEO), polyethylene glycol (PEG), OP/AEO series, polyalcohol(Span and Tween) and anionic surfactant were applied in the process of the enzymatic hydrolysis of the lignocellulosic. The results indicated that nonionic surfactants play an obvious role in the process of enzymatic hyrolysis, in which alkyl phenol polyoxyethylene ether OP-10achieved best promotion, the conversion of enzymatic hydrolysis and glucose yield were about90.06%and73.24%respectively when the dosage of OP-10was1.5%. However, the anionic surfactant can inhibit the enzyme catalyzed hydrolysis.