Changes of the Structures and Properties of Corn Stover during Acid Sulfite Pretreatment for Improved Enzymatic Hydrolysis

Acid sulfite pretreatment has been shown to be an effective and practical method for improving the enzymatic hydrolysis of corn stover (CS) for bioethanol production. In the present study, the changes in the structures and properties of CS during the acid sulfite pretreatment process were investigated. The results showed that the crystallinity of cellulose in CS was increased by the pretreatment. The recalcitrant structure of untreated CS was destroyed by the acid sulfite pretreatment, which led to an increase in surface area being exposed. Thermogravimetric analysis indicated that the temperature for the maximum mass loss rate of the acid sulfite-pretreated CS shifted by 40 °C compared to that of the untreated CS. Large amounts of gas species, such as CO2, CO, CH4, and H2O, were released during the pyrolysis process. This work provides a theoretical reference to the determination of the optimal pretreatment parameters for the conversion of CS into bioethanol.