Banca de DEFESA: HELOISE OLIVEIRA MEDEIROS DE ARAÚJO MOURA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : HELOISE OLIVEIRA MEDEIROS DE ARAÚJO MOURA
DATA : 24/07/2019
HORA: 14:00
LOCAL: Auditório do CCET
TÍTULO:

INVESTIGATING THE EFFECT OF PRETREATMENTS ON THE STRUCTURE OF LIGNOCELLULOSIC BIOMASSES FOR THE ISOLATION OF HIGH-REACTIVITY CELLULOSES

PALAVRAS-CHAVES:

Biomass, Cellulose, Combined pretreatment, Peak deconvolution, Accessibility, Biorefinery

PÁGINAS: 104
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Orgânica
ESPECIALIDADE: Química dos Produtos Naturais
RESUMO:

The lignocellulosic biomass is composed of cellulose, hemicellulose and lignin strongly bonded to each other and stands out as a highly available and promising raw material for conversion processes. Cellulose has been widely studied in literature as a renewable source for the production of chemical platforms, molecules of great importance for the biorefinery industry capable of being converted into the most diverse chemical compounds used in today's society. However, the efficient separation of cellulose is still challenging due to the recalcitrant nature of the biomass. Thus, this work aims to evaluate the efficiency of the combined acid/peroxide-alkaline (APA) pretreatment, the ultrasound cavitation (US) and the association of both methods (USA + PA) under different conditions in increasing the accessibility of common residual biomasses in the Brazilian Northeast: sugarcane bagasse (Saccharum officinarum), corn cob (Zea mays) and prickly pear pseudostem (Opuntia ficus-indica L. Mill.), as well as on the crystallinity changes of the celluloses that will be isolated later. For this, the peak deconvolution of X-ray diffraction (XRD) data was compared to the absorption bands generated by the Fourier transform infrared spectroscopy (FTIR) analysis of the samples, in order to evaluate the effectiveness of the APA treatment under conditions already found in the literature and in a new methodology with ultrasonic assisted acidic step (US). The evaluation of the polymorphism and inferred crystallinity parameters showed that cavitation made possible the production of a more accessible biomass under milder conditions of acid treatment (30 min, 90 °C) for removing hemicellulose and with shorter time (60 min) of the delignification step (peroxide-alkaline) for sugarcane bagasse and prickly pear pseudostem samples. The deconvolution methodology was also applied to the derived thermogravimetric curves (DTG) and was successful for separating the overlapping mass loss events and in the determination of the mass content of lignocellulosic fractions by calculating the area under each degradation curve, with precision and accuracy comparable to the standard characterization method for these biomasses.

MEMBROS DA BANCA:
Externa à Instituição - LEILA MARIA AGUILERA CAMPOS - UNIFACS
Presidente - 1805556 - LUCIENE DA SILVA SANTOS
Interna - 1569526 - RENATA MENDONÇA ARAUJO
Interna - 1149440 - ROSANGELA DE CARVALHO BALABAN