Banca de DEFESA: FERNANDA YUKARI DE SOUZA SAKUMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : FERNANDA YUKARI DE SOUZA SAKUMA
DATE: 31/01/2022
TIME: 14:00
LOCAL: remota
TITLE:

CELLULOSE NANOFIBRIL AND MICROSILIC FILMS FROM AÇAÍ WASTE WITH HIGH SURFACE REACTIVITY

KEY WORDS:

Euterpe oleraceae. Microparticles. Lignocellulosic fibers. Silicon.

PAGES: 50
BIG AREA: Ciências Agrárias
AREA: Recursos Florestais e Engenharia Florestal
SUMMARY:

The açaí production chain generates large amounts of waste comprising cellulosic fibers and seeds, with potential for the development of bioproducts. The objective of the work was to develop biodegradable films through combining two materials obtained from açaí waste, cellulose nanofibrils and silica microparticles. The fibers were submitted to alkaline treatments with sodium hydroxide (NaOH) and bleaching with oxygen peroxide (H2O2). The nanocellulose was produced through mechanical defibrillation of the fibers, with five passes in the Supermasscolloider grinder. Three compositions of the waste were submitted to the production of microsilica: a) seeds + lignocellulosic fibers; b) lignocellulosic fibers; and c) seeds. The samples were sequentially submitted to the following procedures: treatment with (2N) HCl; heat treatment at 650 °C for 3 h; treatment with (6N) HCl to form sodium silicate (‎Na2SiO3) with magnetic stirring in 2.5N NaOH solution, forming the gel with the addition of sulfuric acid (H2SO4); and oven drying. Cellulose nanofibril films were produced with different concentrations of microsilica (2.5%, 5% and 10%) by the casting method. The following characterizations were performed: scanning electron microscopy for fibers (SEM); transmission electron microscopy for nanofibrils; Fourier transform infrared spectroscopy, thermogravimetry, SEM with energy dispersive spectroscopy and X-ray diffraction for microsilicas; and contact angle and physical properties of the films. Cellulose nanofibrils with approximately 30 nm in diameter were obtained. The fiber fraction of the residue showed low combustion efficiency, detection of high silicon concentration associated with the typical globular microstructures of the fiber of the açaí waste, with SiO2 functional group of predominant occurrence and in the tetragonal form and low content of degraded mass in an inert atmosphere, with no maximum degradation peaks above 100°C. The seed and seed fractions with fibers showed typical cellulose diffractograms and peaks of maximum degradation, indicating high levels of organic components in their composition. However, silicon and silica were detected at low concentrations. The additions of 5% and 10% of silica (fiber fraction) or minerals (seed and fiber fractions) caused a decrease in the contact angle. The opposite was observed for 2.5%. The microsilica of the fibers increased the water absorption and permeability of the films. The minerals from the other two fractions decreased the water absorption of the films, but increased the permeability. It was concluded that the fibers of the açaí waste are suitable as raw material for both the production of cellulose nanofibrils and crystalline microsilica. The combination of these products generates sustainable films of high reactivity. The addition of ash composed of multiple minerals decreased the hydrophilicity of the cellulose films.

BANKING MEMBERS:
Externa à Instituição - CARLA PRISCILLA TÁVORA CABRAL
Externo à Instituição - JARDEL PINTO BARBOSA
Presidente - 2410727 - LINA BUFALINO
Interno - 1134991 - THIAGO DE PAULA PROTASIO