Mild Mechanochemical Pretreatment of Wheat Straw for High Exergy Efficiency to Promote Efficient Enzymatic Hydrolysis and Saccharification

Abstract

This study proposed a new strategy for simultaneous catalytic conversion of wheat straw with a deep eutectic solvent-assisted ball milling method at high solid content (20%) conditions, thereby improving monosaccharide yield and exergy efficiency. After mechanical shearing by ball milling, the crystallinity of wheat straw was reduced and the porosity increased by 12.7%. Meanwhile, 13C NMR and 2D HSQC NMR demonstrated that low DES loadings in this strategy can still effectively cleave β-O-4 bonds and reduce hydrogen-bond strength within cellulose molecules and LCC. Pearson correlation coefficient matrix analysis showed that increased pores from mechanical shearing and DES-induced delignification significantly promoted the saccharification rate. After 72 h of enzymatic hydrolysis, the monosaccharide concentration reached 30.7 g/L, 6.1 times that of the control. The overall exergy efficiency of wheat straw pretreated by the mechanochemical process reached 85.7%, indicating that the proposed strategy is suitable for monosaccharide production while maintaining low exergy loss and has great application potential in sustainable biorefining plants.