Isolation and characterization of cellulose nanofibrils from wheat straw using steam explosion coupled with high shear homogenization

Cellulose nanofibrils of diameter 10-50 nm were obtained from wheat straw using alkali steam explosion coupled with high shear homogenization. High shear results in shearing of the fiber agglomerates resulting in uniformly dispersed nanofibrils. The chemical composition of fibers at different stages were analyzed according to the ASTM standards and showed increase in alpha-cellulose content and decrease in lignin and hemicellulose. Structural analysis of steam exploded fibers was carried out by Fourier Transform Infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). Thermal stability was higher for cellulose nanofibrils as compared to wheat straw and chemically treated fibers. The fiber diameter distribution was obtained using image analysis software. Characterization of the fibers by AFM, TEM, and SEM showed that fiber diameter decreases with treatment and final nanofibril size was 10-15 nm. FT-IR, XRD, and TGA studies confirmed the removal of hemicellulose and lignin during the chemical treatment process. (C) 2010 Elsevier Ltd. All rights reserved.