Obtenção de celulose a partir de biomassa vegetal e resíduos industriais para posterior conversão a nanocelulose

Abstract

Vegetable fibers are lignocellulosic materials and can be extracted from natural sources or industrial waste, such as peels and straws, having in its composition mainly cellulose, hemicellulose and lignin, as well as small amounts of minerals. Cellulose and its modifications have been widely used in various industry sectors, such as food, pharmaceutical, materials and nanotechnology. This work aimed to extract cellulose fibers from plant biomass and industrial residues such as perennial ryegrass straw, acerola seed residue and oil palm mesocarp fiber, followed by the isolation of nanocellulose, in addition to chemical modification with maleic anhydride and its chemical and morphological characterizations. For cellulose extraction, basic and acid hydrolysis and bleaching processes were employed. Products obtained after processing such as cellulose and nanocellulose and their modified versions were evaluated and characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Transmission Electron Microscopy (MET). In the infrared spectra, bands referring to cellulose characteristic bonds were observed, such as O-H (3400 to 3300 cm-1), C-H (2904 cm-1), and β-1,4 (C-O) glycosidic bonds (C-O-C) groups (800-1100 cm-1). In the TEM image of the purified nanocellulose a needle-shaped morphology was observed, with a thickness in the order of 10 to 20 nm. The XRD results showed characteristic diffraction peaks of cellulose, according to the literature, around 16 ° and 22 °, thus confirming the results obtained in the infrared analysis. The thermogravimetric analysis results showed a main thermal event, characteristic of cellulose, at approximately 340 ° C. The results of this study showed that the extraction of cellulose and nanocellulose from biomass was easy to perform and reproducible, and environmental appeal.