Combined acid and enzymatic pretreatment of corn cobs

Abstract

Biofuels produced from lignocellulosic materials, so called second generation biofuel, showed energetic economic and environmental advantages in comparison to biofuels produced from starch or sugar. There are mainly two processes involved in the conversion routes: hydrolysis of cellulose to produce reducing sugar and fermentation of sugars to biofuels. Therefore, pretreatment of lignocellulosic materials to remove hemicellulose and lignin can significantly enhance the hydrolysis of cellulose. The main goal of research is to increase the enzyme accessibility by improving digestibility of cellulose. Accordingly, dilute sulfuric acid was used to pretreat corn cobs prior to enzymatic hydrolysis. After pretreatment of corn cobs by dilute acid under the optimal condition (120°C, 5 min), the highest yield of total sugars of 24.73 g/l was obtained. After enzymatic hydrolysis, the highest yield of total sugars of 22.37 g/l was obtained and the final total sugar yield reached 47.11 g/l. It can be concluded that dilute sulfuric acid pretreatment can be successfully applied for corn cobs to achieve high yields of monomeric glucose and xylose