Obtenção de celulose e nanocelulose a partir de resíduo do beneficiamento de coco (cocos nucifera) pré-tratado por hidrólise subcrítica

Abstract

New changes in the suppliers industry are being studied in order to insert the introduction of new materials and manufacturing processes that meet new efficiency and environmental demands. The use of lignocellulosic materials becomes an attractive option for industries that seek sustainable development, since they are renewable, biodegradable and low cost sources. Converting lignocellulosic biomass into chemical components of interest and, from them generating new products, have been the focus of many researches. In this scenario, the present research used in natura coconut husk, submitted to the hydrolysis process with subcritical water in order to obtain, from the hydrolyzed liquid fraction, fermentable sugars and, from the solid residue, cellulose and nanocellulose. For the pretreatment by subcritical hydrolysis, the studied variables were temperatures of 200, 230 and 260°C, water/solids mass ratio of 10 and 20, pressure of 15 MPa and total reaction time of 15 minutes. The temperature of 260°C and flow rate of 20 mL/min showed the highest yield of reducing sugars of 4.70 ± 0.64 g/100g of coconut shell. From the thermogravimetric analysis and the derivative of thermograms (DTG), the contents of cellulose, hemicellulose and lignin present in the in natura sample were determined and they were submitted to pre-treatment, where it was possible to verify that the remaining residues still had cellulose, demonstrating a possibility of reuse. From the remaining residues of the subcritical treatment, cellulose was obtained through the bleaching process and the cellulose nanocrystals (CNC) through acid hydrolysis. It can be concluded, through Fourier transform infrared spectrophotometry (FTIR) and X-ray diffraction (DRX), the efficient isolation of cellulose and nanocellulose, which could be obtained with high crystallinity. Therefore, residues from in natura coconut shell have potential for reuse in a wide range of applications, making it an attractive option, promoting the rational use of natural resources.