Optimization of binary acids pretreatment of corncob biomass for enhanced recovery of cellulose to produce bioethanol

Lignocellulosic agricultural wastes are the most widely utilized resource for bioethanol production due to several advantages. Removal of hemicellulose and lignin is a prerequired step during bioethanol production from lignocellulosic biomass to upgrade cellulose recovery and the substrate porosity for saccharification. Chemical pretreatment of corncob was performed in the current research applying binary acids (H₂SO₄ + CH₃COOH) in different ratios. The attained maximum removal of lignin and hemicellulose were 81.41 ± 2.3% and 85.6 ± 1.8%, respectively, with enhanced cellulose recovery of 93.5 ± 1.3% at the optimum conditions of binary acids concentration (3%, v/v), biomass loading ratio (0.1 g/mL), pretreatment temperature (120 °C) and time (60 min). The SEM, FTIR and XRD results revealed the removal of hemicelluloses and lignin from the corncob biomass by binary acids pretreatment and confirmed a change in the crystallinity index of corncob biomass. Ethanol fermentation was accomplished at 30 °C at 200 rpm for 4 days with the hydrolysates using Saccharomyces cerevisiae and obtained a maximum bioethanol concentration of 24.6 mg/mL. This study demonstrates that binary acids pretreatment is an alternative approach for the pretreatment of lignocellulosic biomass. The optimized process conditions could also increase cellulose recovery and bioethanol yield.