Alcohol pretreatment for depolymerization and fractionation of corn stalk

Abstract

The development of an efficient pretreatment technology to depolymerize and fractionate lignocellulose into glucan, xylan, and lignin is crucial for lignocellulose biorefinery. In this study, alcohol pretreatments using methanol and pentanol were developed and compared. Based on the solubility of the two alcohols, the methanol and pentanol pretreatments are homogeneous and biphasic, respectively. Carbon flow analysis revealed that 1 kg of corn stalk (CS) yielded 111.9 g of lignin with the homogeneous pretreatment (lignin yield: 60.0%), while 149.8 g of lignin was obtained with the biphasic pretreatment (lignin yield: 80.3%). Biphasic pretreatment yielded the lignin with higher activity (more β-O-4 bond content). Additionally, 210.4 g and 267.0 g of glucose were obtained from the enzymatic hydrolysis of homogeneously and biphasically pretreated CS, respectively, where glucose yields were 53.0% and 67.2%, respectively. Fourier Transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were employed to verify the component fractionation results. The Hansen solubility parameter and combined severity factor analysis were used to evaluate the effects of various factors on component fractionation. Nuclear magnetic resonance and mechanistic analyses were performed to explore the process of component fractionation. Overall, we discovered that biphasic pretreatment was significantly better than homogeneous pretreatment in component fractionation, including component recovery and lignin activity.