Potential of Corn Cob Sustainable Valorization to Fuel-Grade Bioethanol: A Simulation Study Using Superpro Designer®

Abstract

The massive dependence on fossil fuels to produce ethanol has damaged the environment. This compels the quest for other alternatives using lignocellulosic materials (2nd generation bioethanol) so as not to compete and disturb food security purposes. The promising biomass to be valorized is corn cob because of its high productivity and short harvest period. Coupled with the fact that simulation studies of its fermentation with Zymomonas mobilis to produce bioethanol are still lacking, a corn cob sustainable valorization to fuel-grade bioethanol is hence disclosed. Superpro Designer 8.5® was employed for simulation. Corn cob undergoes pretreatment, 2-h hydrolysis of cellulose and hemicellulose, delignification, 48-h glucose and xylose anaerobic fermentation, cells removal, vaporation, and distillation. Bioethanol is produced at 10.85%-wt from direct fermentation. Subsequently, the 1st distillation (13 actual stages number) upgrades its concentration to 92.34%-wt. The second one (23 actual stages number) rectifies up to 99.96% and the product finally meets the criteria of fuel grade. Afterward, the calculated yield is 0.35 g/g corn cob or 44.30% based on glucose and xylose. Several by-products are also produced and to comply with the concept of sustainability, water is returned to the river, lignin and extractives are utilized for phenolic producers, wet CO2 gas is proposed for microalgae inorganic carbon sources, and stillage is returned to nature as liquid fertilizer.