Hydrothermal pretreatment of corn residues for second generation ethanol production

Abstract

This work evaluated the potential of second generation ethanol production from husk and corn cob. Corn residues were submitted to hydrothermal pretreatment, enzymatic hydrolysis, and fermentation. The hydrothermal pretreatment was carried out in a stainless steel reactor under two operational conditions: 170°C/15 min and 195°C/10 min. Cellulose, hemicellulose, lignin, ash, protein, and extractives were the quantified components. After hydrothermal pretreatment, husk presented hemicellulose removal of 70.7% (170°C/15 min) and 89.7% (195°C/10 min). The cellulose lost was lower at 170°C. Hemicellulose removal in the corn assay was 58.7 % (170°C/15 min) and 67.8% (195°C/10 min). The cellulose lost was lower at 195°C. Enzymatic hydrolysis and fermentation experiments were conducted after pretreatment step. It was reached 87.5% of fermentative efficiency for the pretreated husk and 86.9% for the pretreated cob. The results suggest that corn residues are promising for second generation ethanol production since almost 2.500.000 ethanol liters can be obtained from processing husk and corn cob at midwest, south and southeast regions in Brazil, without increasing the harvest areas.