Alkali and Intensified Heat Treatment of Corn Stalk for Bioethanol Production

Abstract

This study investigated combined alkali and heat pretreatment of lignocellulosic biomass for fermentative bioethanol production. Prior to fermentation, alkali pretreatment of corn stalk (CS) was carried out in NaOH solution under varying concentration which was followed by incubation at 100 °C for 1 h. The slurry of alkali-pretreated CS was supplemented with media and incubated at 30 °C, 96 h and pH 5. The 2.0% alkali pretreatment was most effective. Further optimization studies with filtrate and 5% inoculum size produced 43.8 g/L bioethanol. Chemical analysis of CS shows 61.75 and 71.49% degradation of hemicellulose and lignin, respectively, under optimal conditions. Structural changes of CS biomass monitored via scanning electron microscope showed that pretreatment with NaOH induced porosity and surface area disruption when compared to the untreated samples. Pretreated CS showed higher crystallinity index as revealed by X-ray diffraction analysis. The results showed that alkali-pretreated CS can serve as a potential feed stock for bioethanol production to reduce dependency on fossil fuel.