Isolation of Cellulose from Wheat Straw and Its Utilization for the Preparation of Carboxymethyl Cellulose

Cellulose was isolated from wheat straw by the combined pretreatment including dilute acid hydrolysis, ethanol extraction, and alkaline H2O2 delignification. The effects of varying the parameters on carboxymethylation on isolated cellulose were investigated. Furthermore, the chemical structure of carboxymethyl cellulose (CMC) prepared from wheat straw was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope analysis. The isolated cellulose is mainly composed of cellulose without hemicellulose and with minors of lignin and ash. The optimal conditions for carboxymethylation were base concentration, 20%; reaction temperature, 70°C; reaction time, 2 h; mass ratio of etherifying agent to cellulose, 1.75. Under the optimized conditions, CMC with high degree of substitution (0.88) and low viscosity (18 mPa·s) was synthesized. Chemical structural characterization showed the feasibility of the preparation of CMC from wheat straw. The constituents of wheat straw would be maximally utilized by the proposed method.