Cyclic Freeze-thaw Treatment on Enzymatic Saccharification of Lignocellulose (Wheat Straw) and its Synergism Effect with Alkali

Freeze-thaw pretreatment (FT) is an inexpensive and environmentally friendly method for treating lignocellulose. After cyclic FT treatment, the cellulose conversion rate of wheat straw increased by 67.35% compared to the untreated group, reaching 70.10%. After freeze-thaw and alkali treatment, wheat straw’s cellulose conversion rate reached a maximum of 97.04%, and it achieved 52.92% under the typical winter temperature of −20°C. Alkali increases wheat straw’s enzymatic saccharification capability. Cyclic FT deconstructed the crystalline area by breaking hydrogen connections between cellulose polymer chains, reducing polymerization. The greatest surface roughness of wheat straw (5.83 Ra/nm) was 24 times that of untreated, and the secondary cell wall delaminated due to lignin redistribution, which increased glucose output. This study helps develop cost-effective lignocellulose pretreatment techniques.