Improvement and Characterization in Enzymatic Hydrolysis of Regenerated Wheat Straw Dissolved by LiCl/DMAc Solvent System

Lithium chloride (LiCl)/N,N-dimethylacetamide (DMAc) solvent system was used to dissolve native and pretreated wheat straw materials in order to promote the enzymatic hydrolysis process. The dissolution ratio of wheat straw in LiCl/DMAc solvent system increased when dilute sulfuric acid or ethanol-sulfuric acid mixture pretreatment was conducted before dissolution. The materials regenerated from LiCl/DMAc solution exhibited obvious changes in structure and morphology, as revealed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The cellulose and xylan digestibilities of regenerated materials were improved obviously. The cellulose digestibilities of materials regenerated from native and pretreated wheat straw by dilute sulfuric acid and ethanol-sulfuric acid mixture were 61.8, 81.2, and 84.4 %, respectively, with 25 FPU of cellulase and 187 IU of xylanase after 96 h. These values were significantly higher than the digestibilities of 0, 33.2, and 57.5 % obtained from corresponding materials before dissolution. Dissolution treatment of wheat straw by LiCl/DMAc solvent system provides an alternative method for efficient enzymatic hydrolysis.