An Efficient Strategy for Enhancing Glucose Recovery of Wheat Straw by Ionic Liquid Combined Ball Milling Pretreatment

The wheat straw (WS) recalcitrant nature resulting from its compositions and structures hinders the bioconversion of WS into glucose. In this study, a clean and efficient ionic liquid combined ball milling (IB) pretreatment was established to overcome structural barriers of WS, thus enhancing the accessibility and glucose recovery of WS. The proposed strategy has several advantages, including (i) the cellulose nanofibers (CNF) were directly obtained from WS by means of ionic liquid pretreatment; (ii) the dense fiber structure of CNF was rapidly destroyed by ball milling, thus increasing the cellulose accessibility; and (iii) the method can realize the fractionation of cellulose, hemicellulose, and lignin under mild process. Under optimal conditions, a maximal of 89.3% delignification and 92.5% hemicellulose removal was obtained with IB pretreatment, leading to glucose yield of 6.75 times that of raw WS. The samples before and after pretreatment were characterized by FTIR, TGA, XRD, SEM, and TEM. The results clearly confirmed that IB pretreatment could simultaneously remove lignin and hemicellulose, reduce the cellulose crystallinity, and change the morphology of cellulose, resulting in higher glucose yield.

Automated summary

A new method of ionic liquid combined ball milling pretreatment was established for wheat straw, which directly extracted cellulose nanofibers and improved the solubility and glucose recovery of wheat straw by destroying the fiber structure.