Banca de DEFESA: JOSE LUCAS DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JOSE LUCAS DA SILVA
DATE: 27/02/2026
TIME: 13:30
LOCAL: Auditório da UAF
TITLE:

Synthesis of Iron Oxide Nanoparticles with Mandacaru via Green Coprecipitation

KEY WORDS:

nanoparticles, iron oxides, green synthesis, mandacaru.

PAGES: 106
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUBÁREA: Física da Matéria Condensada
SUMMARY:

reen synthesis methods have become increasingly common in the production of nanoparticles (NPs) due to the ability of organic compounds to control the particle nucleation rate, enabling controlled sizes and morphologies, as well as adapting traditional synthesis processes to make them less harmful to the environment. This work proposes the use of an adapted coprecipitation method for the green synthesis of NPs, employing the pulp of the mandacaru fruit (Cereus jamacaru) as a reducing and controlling agent in the synthesis of iron oxides. The objective of this study is to identify the morphological, magnetic, structural, and optical effects resulting from the addition of mandacaru fruit pulp during the synthesis process. For comparison purposes, a control sample without the extract was prepared under the same experimental conditions. Both samples were calcined at 350, 450, 550, and 650 °C. The results for the samples containing mandacaru indicate a nanoscale particle size ranging from 21 to 34 nm and the direct formation of hematite (α-Fe₂O₃). In contrast, the iron nanoparticles synthesized without the pulp exhibit two distinct phases up to 450 °C—hematite and maghemite (γ-Fe₂O₃)—as well as particle sizes ranging from 26 to 38 nm. The samples synthesized with mandacaru exhibit predominantly antiferromagnetic behavior with surface ferromagnetism, whereas the control sample shows ferrimagnetic behavior up to 450 °C. The green route also enabled nonlinear modulation of the band gap (Eg), while in the conventional route Eg evolved linearly. This work preliminarily concludes that the mandacaru extract acts as a reducing/stabilizing agent, modulating the structural pathway, the surface magnetic domain, and the Eg of the nanoparticles, resulting in α-Fe₂O₃ with high phase purity and controllable crystallinity.

COMMITTEE MEMBERS:
Externa à Instituição - KAROLINE OLIVEIRA MOURA - UFPB
Presidente - 2341246 - KENNEDY LEITE AGRA
Externo ao Programa - 1702795 - RENILTON CORREIA DA COSTA - null