Research on Craft Optimization of Wheat Straw Pretreatment

Background: Lignocellulose resources are abundant, but the utilization rate is very low, and wheat straw is one of them. The main reason is that the compact structure of lignin limits the conversion and utilization of cellulose and hemicellulose. Objectives: Thus, optimizing the pretreatment process of wheat straw is one of the effective means to improve the conversion rate. Methods: Firstly, the pretreatment method of wheat straw was optimized, and the optimal pretreatment method was determined by the analysis components of wheat straw before and after pretreatment and the enzymatic hydrolysis and saccharification experiments. On this basis, the pretreatment conditions were optimized to further improve the hydrolysis efficiency of wheat straw; Finally, Scanning Electron Microscopy was used to characterize the surface structure of wheat straw before and after pretreatment to verify the pretreatment effect again. Results: In this study, 2% H₃Cit + 1% H₂O₂ was selected to pretreated wheat straw finally. This method removed lignin relatively mildly while retained cellulose and hemicellulose components well; the mixed sugar content in the enzymatic hydrolysis solution was 91 mmol/L (glucose 53 mmol/L, xylose 38 mmol/L). The experimental results of pretreatment optimization showed that the total amount of glucose and xylose in the hydrolysate of pretreated wheat straw was highest, which could reach 97 mmol/L, under the conditions of pretreatment temperature of 120 ℃, liquid ratio of 1:11 and time of 50 min; The results of scanning electron microscopy showed that the surface of the wheat straw pretreated by the method in this study had fractures, roughness and hollow, and the lignin was effectively removed. The relatively mild pretreatment method adopted in this study effectively removed the lignin of wheat straw, at the same time retained the cellulose and hemicellulose components well, improved the utilization rate of wheat straw. It provided a favorable basis for the improvement of wheat straw fermentation utilization and comprehensive utilization efficiency, and laid a foundation for the efficient transformation of wheat straw biomass resources.