Otimização do processo de obtenção de nanocristais de celulose a partir do caroço de manga

Abstract

With the increase in world population, the demand for agro-industrial products has been also increasing. Processing is a way of adding economic value to the raw materials of agroindustry. However, there is a large accumulation of waste, as in the case of mango processing, with 40 to 60% of residues, which can be used to add value to the agribusiness. The Tommy Atkins mango is the main variety produced in Brazil, and its seed corresponds to 25% of the fruit weithg. Starch, tannic acid, fatty material and lignocellulosic fibers are the components of the mango seed. The seed tegument is composed of polymer chains, such as cellulose, lignin, hemicellulose, pectin, among others. Cellulose is the most abundant polymer in nature and used on an industrial scale, mainly on paper and textiles. Nanometric particles have also been of industrial interest for their properties that confer rigidity to biocomposites. In this strand, the production of cellulose nanocrystals from the Tommy Atkins mango residue was proposed, based on experimental planning. For this, a pretreatment (acetosolv pulping followed by bleaching) was carried out, which guaranteed 97.2% reduction of lignin, a major component of the amorphous cellulose region, and increased crystallinity by almost 84%. The bleached fibers were submitted to acid hydrolysis, and different reaction conditions were evaluated. The experimental planning variables were: acid concentration (for H3PO4 and H2SO4/HCl) and time. The TEM images, the aspect ratio (length / diameter ratio) and yield indicated treatment 10 (45.0 / 6.1% v / v 60 min) of process 2 (with H2SO4/HCl) as the best hydrolysis condition.