Effect of Microwave Pretreatment on Sugar Recovery from Corn Stover

Abstract Conversion of lignocelluloses is a promising technology for the production of ethanol from corn. Most of the conversion depends on the type of pretreatment method opted. Several pretreatment methods have been studied for efficient conversion of lignocellulosic materials into bioethanol. Pretreatment refers to the disruption of the naturally resistant carbohydrate-lignin shield that limits the accessibility of enzymes to cellulose and hemicellulose. Research was carried out to study the effectiveness of microwave pretreatment and subsequent enzymatic hydrolysis of corn stover. The objective of this study was to investigate the effect of microwave power level (0, 20, 60, and 100%), processing time (0, 5, 10, 15, and 20 min) with various alkali concentrations (0.05, 0.1, 0.2, 0.9% w/w), and acid concentrations (0.1, 0.4, 0.7 % w/w) on the yield of glucose and xylose from corn stover. Corn stover samples were microwave pretreated, followed by enzymatic hydrolysis using NREL procedure and sugars were quantified by HPLC. The alkali and the acid concentrations had a considerable effect on the pretreatment, when the alkali were increased from 0.05 to 0.9% the glucose yield increased with a rise of 19.2% and xylose had an increase of 2.08% . Acid concentrations (0.1 to 0.7%) also showed an increase in the glucose content of 10.28% and 0.5% of xylose. Experimental results proved that increasing the microwave processing time from 0 to 5 min, resulted in a marked increase in glucose and xylose yields by 58.7 and 149.6%, respectively at a constant power level of 20%.