Intensification of bioethanol production by using Tween 80 to enhance dilute acid pretreatment and enzymatic saccharification of corncob

Abstract

In second-generation bioethanol production, pretreatment and saccharification have been considered one of the most expensive steps. Thus, we present an approach to improve bioethanol yield by using surfactant concomitantly with corncob pretreatment and saccharification. A response surface methodology (RSM) evaluated the Tween 80 (0%, 5.0%, and 10.0% w/w), in both corncob pretreatment and saccharification, and the enzyme dosage (CellicCTec2: 5.0, 17.5, and 30.0 FPU/gdry matter) on enzymatic digestibility of the acid pretreated biomass. According to the results, higher glucose yields (∼80-85%) could be obtained by reducing the highest enzyme dosage to 41.67% concomitantly by reducing the Tween 80 to 34.2% or 63% by adding it (10% w/w) into only the pretreatment or saccharification, respectively. The RSM suggested applying enzyme dosage between 17.5 and 25.5 FPU/gdry matter associated with the highest Tween 80 amount to improve glucose yield. For statistical validation model, the maximum glucose (80.54%) and xylose (70.66%) yields were obtained for 10.0% of surfactant in both pretreatment and saccharification (25.50 FPU/gdry matter). The hydrolysate was supplemented and fermented by Scheffersomyces stipitis CBS 6054. This yeast fermented the sugars glucose (98.95%), xylose (64.90%), and cellobiose (60.12%) efficiently into ethanol with high yield (0.37 g/g) and volumetric productivity (1.02 gethanol/L.h).