Banca de DEFESA: MYLLENA KELY PEREIRA FERREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : MYLLENA KELY PEREIRA FERREIRA
DATE: 30/08/2024
TIME: 13:00
LOCAL: Modo Remoto
TITLE:

PHOTOCATALYTIC AND PHOTOELETROCHEMICAL EVALUATION OF Nb2O5-xAg AND POTENTIAL DEGRADATION OF REACTIVE DYE

KEY WORDS:

POAs; Sun light; water treatment; semiconductor; green hydrogen; photoelectrocatalysis.

PAGES: 100
BIG AREA: Engenharias
AREA: Engenharia Química
SUMMARY:

Water contamination through the inappropriate release of dye residues can result in irreparable effects on human life and the environment. Especially synthetic dyes with azo groups, due to their toxicity and carcinogenicity. Conventional methods are ineffective in removing this pollutant. Alternatively, photocatalytic degradation using semiconductors is considered an ecological and economical alternative for the mineralization of dyes. Furthermore, photoelectrocatalysis also emerges as an alternative process that can be integrated into wastewater treatment, allowing the simultaneous generation of an alternative energy source, which is green hydrogen. Among semiconductors, niobium oxide stands out as the most available semiconductor in Brazil. Despite its numerous advantages, Nb2O5, the most thermodynamically stable state of the niobium-oxygen system, has a narrow light absorption range, being activated mainly under ultraviolet radiation. Therefore, this work aimed to prepare heterostructured niobium oxide semiconductors with silver nanoparticles (Ag) for photocatalytic application in the degradation of reactive blue dye 109 and photoelectrochemical studies for possible photoelectrocatalytic applications. Nb2O5 was obtained using Pechini's methodology and the heterostructures were obtained from the chemical reduction of the mineral salt, AgNO3, in different proportions, corresponding to the composites 21Nb2O5/Ag and 32Nb2O5/Ag. The synthesized materials were characterized by XRD, FTIR, DRS UV-Vis and SEM. The photocatalytic tests were conducted using a lamp that simulates the solar spectrum and the degradation efficiency was investigated using UV-Vis. The orthorhombic crystalline structure of Nb2O5, as well as the formation of metallic Ag on its surface, was confirmed. Furthermore, the morphology revealed particles of irregular sizes and shapes, agglomerated and with an interconnected porous structure. After 120 minutes, 32Nb₂O₅/Ag demonstrated significantly superior photocatalytic performance than Nb2O5 with approximately 94% dye removal at a concentration of 5 mg L⁻¹, compared to only 9% achieved by Nb2O5. After this result, the influence of the dye concentration, the amount of catalyst and pH variation were also variables investigated. The photoelectrochemical responses were obtained by CV, LSV, chronoamperometry, EIS and Mott-Schottky curves, through the deposition of the materials on an ITO plate using the dip-coating method. The photocurrent results and charge transfer carrier efficiency of the heterostructures were superior to Nb2O5. These results suggest that decorations such as Ag nanoparticles made in Nb2O5 have expanded their use, becoming a promising material for photocatalytic and photoelectrocatalytic applications.

COMMITTEE MEMBERS:
Interna - 2275848 - ELISAMA VIEIRA DOS SANTOS
Presidente - 2941160 - JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
Externa ao Programa - ***.673.134-** - JUSSARA CÂMARA CARDOZO - UFRN
Externo à Instituição - PIERRE BASILIO ALMEIDA FECHINE