Preparation of microcrystalline cellulose from rice straw under microwave irradiation

Crude cellulose was isolated from rice straw and then converted into microcrystalline cellulose (MCC) via partial hydrolysis. Both the isolation and partial hydrolysis were carried out under microwave. Rice straw was successively pretreated with alkaline and acid solutions before hydrolysis. Lignin and silica were almost removed but partial removal of hemicellulose in dilute alkali solution, and the residual hemicellulose was further removed in dilute acid solution. The total removal rates of hemicellulose, lignin and silica reached up 92.0%, 98.5%, and 96.8%, respectively. The cellulose content of 93.6 wt % in MCC was given by partial hydrolysis of crude cellulose isolated from rice straw. The comparison between microwave irradiation and traditional heating method was also investigated. Compared to traditional heating method, similar results were obtained while milder conditions, including shorter time and lower temperature, were required. An effective microwave-assisted and energy-efficient methodology using rice straw as the alternative source of cellulose fiber was developed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44901. © 2017 Wiley Periodicals, Inc.