Banca de QUALIFICAÇÃO: MAXWELL GOMES DA SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MAXWELL GOMES DA SILVA
DATE: 19/07/2023
TIME: 14:00
LOCAL: Remoto
TITLE:

Synthesis and characterization of superparamagnetic nanoparticles and mathematical modeling of the microchannel magnetophoresis process.

KEY WORDS:

Magnetic nanoparticles, reverse coprecipitation, partial oxidation, thermal decomposition, magnetophoresis, computational fluid dynamics.

PAGES: 140
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Operações Industriais e Equipamentos para Engenharia Química
SPECIALTY: Operações de Separação e Mistura
SUMMARY:

Magnetic iron oxide nanoparticles have attracted great interest from researchers because of their vast application potential that ranges from magnetic recording, magnetic resonance imaging (MRI), and drug delivery to ferrofluids, catalysis, and separation processes. Magnetite (Fe 3 O 4 ) is one of the phases of iron oxide with the greatest magnetism, which is composed of cations Fe 2+ and Fe 3+ in a 2:1 molar ratio. Magnetite nanoparticles can be synthesized by several methods which must be selected according to the type of application since the conditions and precursors employed are determining factors for properties such as morphology, size distribution, phase composition, and magnetization. In this work, superparamagnetic magnetite nanoparticles were synthesized by reverse coprecipitation using Fe 2+ and Fe 3+ ions and by partial oxidation of Feions 2+ . The magnetic precipitates were characterized by infrared spectroscopy, Raman spectroscopy, X-ray diffraction, vibrating sample magnetometry, dynamic light scattering, scanning electron microscopy, and thermal analysis. The thermal stability of the particles in air was evaluated and a study of thermal decomposition kinetics was carried out using a model-based approach. The results showed that both methods produced nanoparticles with superparamagnetic properties at room temperature with diameters of 10 and 30 nm and saturation magnetizations of 35 and 64 emu/g. The particles showed very different thermal stability with respect to oxidation and phase change. The kinetic parameters of thermal decomposition were estimated and the kinetic model fit showed a good correlation with the experimental data (R 2 = 0.988). A computational fluid dynamics model coupled with a discrete element model was implemented in MATLAB ® using the Eulerian-Lagrangian approach to simulate the magnetophoresis of magnetic nanoparticles in a microchannel. The magnetic force acting on the system was simulated from a magnetic field model based on the charge model. The magnetization and particle size distribution data obtained experimentally were used as model parameters during the simulations. The results demonstrated that the model is capable of predicting different scenarios of particle trajectory change according to changes in the magnetic field gradient inside the channel. Thus, the results obtained can be used for the analysis of conditions and designs of microdevices for separation processes involving
magnetic particles.

COMMITTEE MEMBERS:
Externo à Instituição - ANDERSON ALLES DE JESUS - UFMA
Interno - 3304882 - CARLOS EDUARDO DE ARAÚJO PADILHA
Presidente - 1584174 - DOMINGOS FABIANO DE SANTANA SOUZA
Interno - 1547970 - JACKSON ARAUJO DE OLIVEIRA