Effect of microwave pretreatment on component fractionation and saccharification of corn stalk

In order to realize component fractionation in corn stalk, a two-stage microwave pretreatment method，which includes microwave-alkali pretreatment for hemicelluloses extraction and microwave-glycerine pretreatment for lignin extraction，was studied in a special microwave reactor. The effects of particle size, liquid-to-solid ratio, alkali and glycerine consumption, processing time and microwave power on extraction were investigated respectively. The performance of enzymatic hydrolysis saccharification of microwave pretreated corn stalk was studied also. The results showed that the liquid-to-solid ratio 20 mL/g, alkali consumption 150%wt, treatment time 10 min, microwave power 116.7 w/g and the particle size 40-80 mesh were appropriate parameters for hemicelluloses extraction with microwave-alkali pretreatment; while the liquid-to-solid ratio 20 mL/g, pure glycerine as solvent, treatment time 30 min, and microwave power 66.7 w/g were found to be optimal for lignin extraction with microwave-glycerine pretreatment. Consequently the extraction products of 2.48 g hemicelluloses, 0.95 g lignin and 3.55 g reducing sugars were obtained from every 10 g corn stalk in terms of the two optimal conditions. This indicates that the component fractionation of corn stalk can be accomplished and enzymatic hydrolysis saccharification can be enhanced by two-stage microwave pretreatment method.