Banca de QUALIFICAÇÃO: HELOISE OLIVEIRA MEDEIROS DE ARAUJO MOURA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : HELOISE OLIVEIRA MEDEIROS DE ARAUJO MOURA
DATE: 08/09/2023
TIME: 15:00
LOCAL: Auditório do CCET
TITLE:

Innovative methodologies in the concept of biorefinery for the analysis and derivatization of lignocellulose.

KEY WORDS:

Biomass; Biorefinery; Characterization; Design of experiments; Carboxymethylcellulose; Cellulose dissolution.

PAGES: 120
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Polímeros e Colóides
SUMMARY:

Lignocellulose biorefinery is considered an industry analogous to oil refinery, with the potential to meet the demand for renewable fuels, chemicals and materials in the near future. However, compositional characterization processes of potential lignocellulosic sources, in addition to treatment and heterogeneous conversion of extracted cellulose are some of the main limitations for expanding the diversity of products that can be obtained with high efficiency in biorefineries. In this work, a series of innovative methodologies were developed with focus on optimizing the processes of this industry. A new composition characterization method via peak deconvolution of differential thermogravimetric curves (DTG) was applied to in natura biomass and pulps from corn cob (CC) and sugarcane bagasse (SB), in comparison to the standard method, with high precision (standard deviation <1.58) and accuracy (standard error <5.74x10^-2, R²>0.9993 and F>750,926). In addition, the new method made it possible to assess treatment efficiency and reactivity of cellulose. Then, the optimization of heterogeneous synthesis of carboxymethylcellulose (CMC), one of the most commercially important cellulose derivatives, was carried out from these residual celluloses by a D-Optimal experimental design with 28 experiments. Analysis of variance (ANOVA) and response surface methodology (RSM) results proved with high precision and accuracy (F=67.27; p-value<0.0001; R²=0.928; standard deviation=7.0x10^-4) that the residual celluloses extracted are promising to produce CMC under milder conditions in comparison to literature, yielding about 300% (w/w) of water-soluble CMC. Finally, a zinc molten salt hydrate was used as solvent and reaction system for one-pot carboxymethylation of cellulose in homogeneous medium, in a novel, more efficient and environmentally friendly process. Carboxymethylation was proven after just 30 min of reaction by solubility tests and spectroscopic analyses, as well as the complexation of Zn²⁺ by carboxylate groups. X ray diffraction and microscopic results proved this is a nanomaterial (10-36 nm) organized in a crystalline cubic microstructure formed by the aggregation of nanoparticles. Thus, the nanoZnCMC is the first cellulose-based biocoordination polymer reported in literature. This material potential high-tech applications, thus opening a new chapter for studies in the homogeneous synthesis of innovative materials from renewable sources.

COMMITTEE MEMBERS:
Externo ao Programa - 1913849 - EDGAR PERIN MORAES - nullInterno - 1803692 - FABRICIO GAVA MENEZES
Presidente - 1805556 - LUCIENE DA SILVA SANTOS
Interno - 1958858 - LUIZ HENRIQUE DA SILVA GASPAROTTO
Interna - 2413537 - POLLYANA SOUZA CASTRO