Banca de DEFESA: MAXWELL GOMES DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MAXWELL GOMES DA SILVA
DATE: 11/08/2023
TIME: 14:00
LOCAL: Virtual
TITLE:

Synthesis and application of superparamagnetic nanoparticles in the microchannel magnetophoresis process: experimental study and fluid dynamic modeling

KEY WORDS:

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

PAGES: 155
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, and drug delivery to ferrofluids, catalysis, and separation processes. Magnetite (Fe3O4) is one of the phases of iron oxide with the greatest magnetism, which is composed of cations Fe2+ and Fe3+ in a 2:1 molar ratio. Magnetite nanoparticles can be synthesized by several methods which must be selected according to the type of application. In this work, superparamagnetic Fe3O4 nanoparticles were synthesized by reverse coprecipitation and partial oxidation of Feions2+. 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 the model-based approach. The results showed that the nanoparticles produced exhibited superparamagnetic properties at room temperature with mean diameters of 10 and 30 nm and saturation magnetizations of 35 and 64 emu/g for the samples synthesized by reverse coprecipitation and partial oxidation of Fe2+ ions, respectively. The magnetic nanoparticles obtained by reverse coprecipitation presented higher thermal stability than the nanoparticles synthesized by partial oxidation of Fe2+ ions. The kinetic parameters of thermal decomposition were estimated and the kinetic model fit showed a good correlation with the experimental data (R2 = 0.988). To evaluate the application potential of the synthesized particles, magnethophoresys experiments were carried out in a Y-Y type microchannel fabricated by 3D printing technology. Different separation profiles were obtained at different conditions of magnetic field gradient inside the device. a computational fluid dynamics model coupled with a discrete element model was implemented in MATLAB® using the Eulerian-Lagrangian approach to simulate the magnetophoresis process. The magnetic force acting on the system was simulated from a magnetic field model based on the charge model. The experimental saturation magnetization and particle size distribution data were used as model parameters for simulations. The results demonstrated that the model is capable of predicting different scenarios of particle trajectory changes according to variations in the magnetic field gradient inside the channel. In addition, the fluid dynamics model was validated with the experimental data and presented coherent results, which make it useful for understanding the characteristics of the process, as well as in the optimization of operating conditions and design of new microdevices.

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