Preparation of convertible cellulose from rice straw using combined organosolv fractionation and alkaline bleaching

Rice straw was employed to prepare microcrystalline cellulose (MCC). First, crude cellulose was isolated from rice straw using organosolv fractionation in the presence of mixed solvent composed of ethanol and H2O. Most hemicellulose and lignin were removed while little silica was not. Second, crude cellulose was bleached in Na2CO3/H2O2 mixed solution to remove residual silica as well as small amount of hemicellulose and lignin. After that, the removal rates of hemicellulose, lignin and silica reached up 91.5, 92.8 and 97.9%, respectively. Cellulose from rice straw was further converted into MCC in the presence of hydrochloric acid aqueous solution, and the cellulose content reached up to 92.4% in MCC. Infrared spectrometer (IR) and X-ray diffractometer (XRD) were used to characterize the structure of rice straw and its derived samples.