Preparation and Characterisation of Cellulose Nanocrystal from Sugarcane Peels by XRD, SEM and CP/MAS 13C NMR

Abstract

Sugarcane peels are agro-waste resources discarded before taking the sugarcane juice. In the present study, cellulose nanocrystal was isolated from sugarcane peel by sulphuric acid hydrolysis. Two pretreatments, alkaline treatment and bleaching with acidified sodium chlorite, were applied. Sulphuric acid hydrolysis was performed at 450C for 45 min using 64% concentrated sulphuric acid. The resulting cellulose nanocrystal (CNC) of the sugarcane peel was characterised by studying the surface morphology using scanning electron microscope (SEM). X-ray diffraction (XRD) was studied to identify the crystalline nature of the CNC. CP/MAS 13C solid-state NMR was used to evaluate the purity and molecular structure of the CNC. The SEM image of the nanocrystal showed that the bundles of fibre were separated into individual CNC, with the size decreasing to a nanosize indicating an effective removal of the amorphous region. XRD diffraction pattern showed that the CNC possessed the cellulose crystalline configuration with crystallinity index of 99.2% and crystallite particle size dimension of 5.56 nm. The NMR spectra of the CNC revealed that all the signals have six carbon atoms of cellulose and the disappearance of several signals also indicated the disruption of the amorphous region. The results revealed effective synthesis of CNC from sugarcane peel, suggesting the leaching of the amorphous domain, apparent crystallinity and purity of the CNC. The cellulose nanocrystal prepared is considered to be a potent material for various industrial applications.