Banca de DEFESA: TOMAZ RODRIGUES DE ARAÚJO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : TOMAZ RODRIGUES DE ARAÚJO
DATE: 07/03/2024
TIME: 10:00
LOCAL: Sala do Meeeting - virtual
TITLE:

SYNTHESIS OF ZnFe₂O₄-Fe₂O₃-ZnO NANOCOMPOSITE VIA MICROWAVE-ASSISTED SELF-COMBUSTION AND GREEN SYNTHESIS USING JATOBA WASTE (Hymenaea Courbaril L.)

 

 

KEY WORDS:

nanocomposite; ZnFe₂O₄-Fe₂O₃-ZnO; Green synthesi; Microwave-assisted self-combustion; Jatobá wood wast

PAGES: 120
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

The goal of this work was to enhance the textural, morphological, physical, structural, and crystalline properties of the ZnFe₂O₄-Fe₂O₃-ZnO nanocomposite using residues (phytochemicals from the liquid phase and lignocellulosic materials from the solid phase) originating from the processing of jatobá wood, which exhibits high production, low added value, and few technological applications. For this purpose, the following syntheses were used: microwave-assisted self-combustion and adapted green synthesis. The residues (liquid and solid phases) used were extracted through a hot process at various temperatures, and the liquid part was used in microwave-assisted self-combustion by replacing water with 50% and 100%; meanwhile, the solid part was used in adapted green synthesis as a structure and pore director.The characterization techniques used were X-ray diffraction, scanning electron microscopy (SEM-EDS and SEM-FEG), thermogravimetric and proximate analysis, calorific value, and thermal capacity; density by helium gas; contents of cellulose, hemicellulose, lignin, and phenolics; infrared, Raman, and ultraviolet-visible spectrophotometry; diffuse reflectance; Mossbauer; magnetic properties; in addition to particle size by dynamic light scattering (DLS) and specific surface area and pore size volume (BJH).Furthermore, analyses of the extraction process yield and syntheses were conducted. Regarding the results: The extraction yields were approximately 2% (by mass) for the aqueous extract and over 70% (by volume) for the solubles. The immediate analysis shows moisture content below 20%, high percentages of volatiles, low ash content, and fixed carbon. The raw and post-extraction residues exhibit specific heat ranging from 950.13 to 9091.98 cal/g°C and thermal capacity ranging from 2,433.10 to 2,504.03 cal/°C. The formation of ZnFe₂O₄-Fe₂O₃-ZnO occurred via the green synthesis route, while ZnFe₂O₄-Fe₂O₃ was formed through microwave-assisted self-combustion, along with the ZnFe₂O₄ phase. The crystallite size was from 14.2 to 26.39 nm, crystallinity from 40.39 to 57.45 % and band-gap from 1.48 to 2.46 eV. The microscopies show diverse morphologies with signs of cavities and channels oriented in accordance with the fiber orientations. The liquid part of the waste (used in the self-combustion synthesis) provided a specific area between 80.41 and 99.74 cm².g⁻¹ (approximately 100% increase), while the solid waste provided a maximum increase of 49%. The solid residues from jatobá in the green synthesis of nanocomposites yielded stable structures with low ferromagnetic properties and high magnetization, consistent for applications in devices subjected to alternating magnetic fields.In summary, the results showed the formation of the ternary nanocomposite (ZnFe₂O₄-Fe₂O₃-ZnO), demonstrating a technological application capable of adding value to this class of lignocellulosic waste.

COMMITTEE MEMBERS:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externo ao Programa - 1674707 - MARCO ANTONIO MORALES TORRES - UFRNExterno ao Programa - 6347420 - MARCUS ANTONIO DE FREITAS MELO - UFRNExterna ao Programa - 1979301 - RENATA MARTINS BRAGA - UFRNExterno à Instituição - DENER DA SILVA ALBUQUERQUE - IFRN
Externo à Instituição - GILVAN PEREIRA DE FIGUEREDO - IFMA