Influence of temperature and soda concentration in a thermo-mechano-chemical pretreatment for bioethanol production from sweet corn co-products

A continuous process combining an alkaline pretreatment, neutralization and injection of enzymes within a twin screw extruder was previously implemented and demonstrate industrial potential. The present work focuses on the investigation of the effects of alkali and temperature during the alkaline pretreatment of sweet corn co-products (SCC) for the production of fermentable sugars with a lower chemical input. Study of NaOH/SCC and internal temperature was performed in ranges of 4-8% (w/w) and 50-170 degrees C in a laboratory scale twin screw extruder. Analysis of carbohydrates and lignin of the pretreated biomass was performed and the filtration efficiency was also monitored through extrudate dry matter and filtrate mineral matter. The carbohydrate accessibility and process performances were studied by the enzymatic hydrolysis of the extrudate. Increasing temperature reinforces the effects of soda on solubilization of hemicelluloses, thus a hemicelluloses removal reach more than 50%. At optimal conditions, the cellulose-rich substrate after enzymatic hydrolysis achieve a glucose released of 70%, with glucose and xylose yields of 250 g per 1Kg of dry SCC.