Evaluation and comparison of micro/nanocellulose extracted from Arundo, Kenaf and Miscanthus

Cellulose can be isolated from the lignocellulosic fibers and then depolymerized to give rise to nanocrystalline cellulose (CNC), an extraordinary nanometer-scale bio-based material with applicability in diverse technological areas. However, not all cellulose hydrolyze to the point of being converted to nanometric size after the reaction is finished. Despite being more fractionated when compared to the initials fibers, these particles are still a few micrometers long, which are denominated microcrystalline cellulose (MCC). In this context, the aim of this work was to extract, characterize and compare micro/nanocellulose obtained from three different lignocellulosic biomasses, Arundo (Arundo donax L.), Kenaf (Hibiscus cannabinus L.) and, Miscanthus (Miscanthus × giganteus Greef et Deu.). The MCC/CNC from the crop’s stems were produced via an alkaline pre-treatment with additional chlorinefree bleaching followed by acid hydrolysis. Along the process phases, the fiber composition was quantified, being the obtained MCC/CNC characterized: particle size analysis with polarized optical microscopy (POM) and Atomic Force Microscopy (AFM); crystallinity with X-ray Powder Diffraction (XRD); thermal analysis with Differential Calorimeter (DSC) and thermogravimetric Analyzer (TGA); chemical composition with Fourier-transform Infrared Spectroscopy (FTIR). The MCC/CNC extraction was successfully completed, as demonstrated by FTIR spectra. The Kenaf fibers were the ones that showed the smallest initial particle size, and the same happened for its MCC/CNC particles. XRD data showed a rise in crystallinity values in peaks corresponding to cellulose as expected after treatments and acid hydrolysis. Thermal analysis showed that Miscanthus MCC/CNC start to thermal degradation at lower temperatures.