Banca de DEFESA: GEILSON NASCIMENTO BARROS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GEILSON NASCIMENTO BARROS
DATE: 24/12/2025
TIME: 07:00
LOCAL: Auditório da UAF
TITLE:

Structural, Optical, and Magnetic Properties of NiO Nanoparticles Synthesized by Green Coprecipitation Using Tomato Juice.

 

KEY WORDS:

Green synthesis. Nanoparticle. Co-precipitation. Physical Properties.

PAGES: 119
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

A strategic approach combining green synthesis with the coprecipitation method was employed to obtain nickel oxide (NiO) nanoparticles (NPs). In the main synthesis (Sample 3), tomato juice was used as a biological agent, whose rich biomolecular composition acted synergistically as chelating, stabilizing, and morphology-modifying agents, as confirmed by the characterization results. Owing to its high water content (~94%), the use of tomato juice eliminated the need for distilled water in the precursor solution, contributing to a more sustainable synthesis route. Two control samples were prepared for comparison: Sample 1, synthesized without a biological agent, and Sample 2, synthesized using a 98% concentrated lycopene extract to isolate its interaction with Ni2+ and O2− ions during NiO formation. All samples were calcined at temperatures ranging from 350 °C to 650 °C, in 100 °C increments, and characterized by Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM–EDS), X-ray Diffraction (XRD), Ultraviolet–Visible Spectroscopy (UV–Vis), and Vibrating Sample Magnetometry (VSM). XRD analysis confirmed the formation of the NiO phase in Sample 3, with crystallite sizes between 11.54 nm and 51.74 nm, indicating effective chelation up to 550 °C. SEM observations revealed improved nanoparticle dispersion at lower temperatures and the development of pseudo-octahedral structures at 650 °C. UV–Vis results suggested the presence of amorphous carbonized organic matter in Sample 3,as no systematic reduction in the optical band gap was observed with increasing calcination temperature. VSM measurements showed a ferromagnetic contribution superimposed on antiferromagnetic behavior in all samples, with Sample 3 exhibiting the lowest magnetic parameters (H_c, M_r, and M_s). Overall, the results demonstrate that the biomolecular matrix of tomato juice is a promising agent for achieving enhanced control over the structural and magnetic properties of NiO nanoparticles.

 

COMMITTEE MEMBERS:
Presidente - 2341246 - KENNEDY LEITE AGRA
Externo ao Programa - 1733054 - LINCOLN RODRIGUES SAMPAIO DE ARAUJO - UFCGExterno ao Programa - 1702795 - RENILTON CORREIA DA COSTA - UFCGExterna à Instituição - KAROLINE OLIVEIRA MOURA - UFPB