Optimization of pretreatment conditions for corn cob with alkali liquor

Alkali liquor pretreatment conditions for lignocellulosic corn cob were optimized to remove lignin and improve the enzymatic hydrolysis yield of hemicellulose and cellulose. By multilevel of single-factor test and orthogonal test methods, the results for the optimal pretreatment conditions were as follows : reaction time 12 h, temperature 70℃, liquid to solid ratio 23:1, aqueous ammonia concentration 2.5%(W/V), hydrogen peroxide 0.6%, sodium silicate 5%, magnesium sulfate 0.05% in reaction mixture. Under this optimal condition, the residue yield of corn cob was 59.74%, the remaining rates of hemicellulose, cellulose, and lignin were 56.60%, 86.20%, 11.83%, respectively, in corn cob. The enzymatic hydrolysis yield of hemicellulose, cellulose, total of corn cob residue was 41.36%, 88.09%, 69.21%, respectively, by two steps hydrolysis (xylanase and cellulose). Compared with the untreated straw, the enzymatic hydrolysis yield increased 39.18%, 40.89%, 44.88%, respectively. The enzymatic digestibility is related with the removal of lignin and hemicelluloses.