Obtenção e caracterização de nanocristais de celulose a partir da coroa do abacaxi

• Autor(a) principal: Coutinho, Luana Venâncio [UNESP]
• Data de Publicação: 2018
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/203612; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2019-06-25/000916093.pdf
• topic: Nanocristais; Celulose; Hidrolise; Abacaxi; Nanopartículas

Currently, interest in the use of natural fibers has increased due to environmental concern and consequent search for sustainable and renewable materials. Brazil is the second largest pineapple's producer, and after it was used in the industry, it generates approximately 45% of its initial weight in wastes, mostly the peel and the crown, that are often inadequate dispose, causing environmental damage. The objective of this work was to use the crown of the pineapple (Ananas comosus) to obtain cellulose nanocristals from acid hydrolysis with sulfuric acid (H2SO4) and hydrochloric acid (HCl) and different reaction time and acid concentration, adding value with an application to the waste and collaborating to reduce the environmental pollution generated from its disposal. The pineapple crown was oven dried for 24 h at 60 ºC, grounded and subjected to the following chemical pretreatment steps to remove amorphous components: alkaline treatment (NaOH solution 4% (w/v), 1 h at 70 ° C), two bleaching steps (solution of 300 mL of 4% NaOH (w/v) and 30 mL of 30% (v/v) H2O2 for 3 h) and alkaline treatment with KOH (KOH solution 4% (w/v) in the ratio of 1: 20 (g/mL) for 1 h at 80 ° C) resulting in bleached cellulose (CB). The CB was characterized by scanning electron microscopy (SEM), thermogravimetry (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (DRX), and it was submitted to different acid hydrolysis conditions changing the reaction time (30 min, 1 h, 2 h e 3 h), acid's type (sulfuric and hydrochloridric) and acid concentration (20%, 36%, 50% e 64%), in order to obtain nanocellulose (NC). NCs were characterized by zeta potential, TGA, FTIR, XRD and transmission electron microscopy (TEM). Chemical pre-treatments were efficient in the removal of amorphous components, and increased the fiber whiteness and the ... (Complete abstract click electronic access below)