Banca de DEFESA: TANARA CAROLINE NUNES NICÁCIO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : TANARA CAROLINE NUNES NICÁCIO
DATE: 31/07/2023
TIME: 09:00
LOCAL: Sala virtual (videoconferência)
TITLE:

Effect of zinc and nickel doping on the photocatalytic and antimicrobial properties of hydroxyapatite

KEY WORDS:

Hydroxyapatite, doping, co-doping, photocatalysis, antimicrobial activit.

PAGES: 100
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
SPECIALTY: Cerâmicos
SUMMARY:

Nanostructured hydroxyapatite (HAp) has been studied in advanced technologies in the catalytic area and in the field of biomedicine, such as drugs and protein transporters. In this work, HAp nanoparticles were synthesized by microwave-assisted hydrothermal method and doped with different concentrations of zinc and nickel ions. The samples were characterized by the X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR) and by field emission scanning electron microscopy (FEM-FEG), respectively. Optical properties were estimated in the UV-Vis region to calculate the gap energy value. The hydrothermal method used in this work proved to be efficient for obtaining HAp nanoparticles. The XRD patterns together with the structural refinement, showed the HAp formation for all samples, which corresponds to the hexagonal crystalline structure. There was no secondary phase formation, indicating that doping was successful. The FTIR spectra indicated that Zn2+ and Ni2+ doping in the HAp network did not change the vibrational modes of the main HAp functional groups. The SEM-FEG micrographs illustrated an agglomeration of the particles with the increase in the percentage of dopant ions in the structure, presenting nanorod formats. The gap energy of HAp doped and co-doped with zinc and nickel varied between 5.75 eV and 3.26 eV. The photocatalytic properties through the degradation of methylene blue dye (MB) under UV and solar irradiation were investigated, as well as the antimicrobial activity against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. The results of the photocatalytic activity indicated 66.81% degradation of the MB dye under UV irradiation for the H5Z sample and 97.85% degradation when subjected to solar irradiation. To analyze the reuse applicability of the photometers, the samples were submitted to three cycles of reuse. The H5Z sample showed 55% efficiency after reuse cycles. The antimicrobial activity results showed that the H5Z, H5Z5N, H10Z5N and H15Z5N samples showed an inhibition zone of 18.5; 14.5; 18 and 17mm, respectively, against gram negative bacteria (Escherichia coli), indicating the antibacterial effect of samples with higher percentages of zinc in the synthesized HAp structure. The samples did not show antimicrobial action against S.aureus bacteria.

COMMITTEE MEMBERS:
Presidente - 1802888 - FABIANA VILLELA DA MOTTA
Interno - 1883170 - MAURICIO ROBERTO BOMIO DELMONTE
Externa ao Programa - 1452833 - MARIA CELESTE NUNES DE MELO - UFRNExterna à Instituição - ANA PAULA DE AZEVEDO MARQUES - UNIFESP