Cellulose nanocrystals from Siam weed: Synthesis and physicochemical characterization

Abstract

The use of biomass for the development of environmentally friendly and industrially useful materials is still attracting global interest. Herein, cellulose nanocrystals were prepared from Siam weed. The production steps involved dewaxing the biomass sample, bleaching treatment, alkali treatment and acid hydrolysis. The resulting cellulose nanocrystals were characterized using Fourier transformed infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) technique. Chemical composition results showed that Siam weed contained 39.6% cellulose, 27.5% hemicellulose, 28.7% lignin and 4.2% extractive. FTIR spectrum confirmed the presence of cellulose and absence of lignin and hemicellulose while XRD analysis revealed that the cellulose nanocrystals have crystallinity index of 66.2% and particle size of 2.2 nm. TGA revealed that thermal stability of raw Siam weed is lower than that of its cellulose nanocrystals due to the presence of the non-cellulosic component with lower temperature of degradation. SEM revealed that degradation of cellulosic chain had occurred. TEM confirmed that the crystal size is in the nanoscale with an average size <100 nm. DLS data revealed a nanocellulose with an average hydrodynamic size of 213 nm and a zeta potential at −9.57 mV.