Pretreatment by microwave/alkali of corn cobs for butanol production

Abstract

Biobutanol can be produced by Acetone-Butanol-Ethanol (ABE) fermentation of lignocellulosic biomass which can be converted into fermentable sugar such as glucose and xylose. The complex structure of lignocellulosic biomass minimizes the enzymatic hydrolysis accessibility. Therefore, a pretreatment step is necessary to enhance enzymatic accessibility by removing lignin and/or hemicellulose, increasing the biomass porosity or reducing the cellulose crystallinity.The purpose of this work is to optimize the conditions of a combined pretreatment of corn cobs using microwave and sodium hydroxide (0.75 % to 3 % (w /v )) in the temperature range of 60 to 120.c. The pretreated corn cob s w ere then subjected to enzymatic hydrolysis at 50 c for 48 hours to produce the reducing sugar prior to ABE fermentation. The highest reducing sugar concentration of 45.6 g/L was obtained from the pretreated com cobs with 2 % of sodium hydroxide at 100 .c for 30 minutes. The results indicate that microwave-assisted alkali treatment was an efficient way to improve the enzymatic hydrolysis accessibility of corn cobs.