Banca de DEFESA: THIAGO ALVES DE ALBUQUERQUE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : THIAGO ALVES DE ALBUQUERQUE
DATE: 27/02/2025
TIME: 08:00
LOCAL: Auditório do DQ
TITLE:

TITANIUM-BASED INORGANIC MATERIALS APPLIED TO PEST CONTROL

KEY WORDS:

Aedes aegypti, photocatalysis, titanium dioxide, sol-gel

PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Foto-Química Inorgânica
SUMMARY:

Dengue is an arbovirus that has affected millions of people worldwide in recent decades, with the primary vector being the Aedes aegypti. It has four serotypes capable of causing clinical variations: classic dengue (CD), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS). Given the high impact, control methods, such as environmental sanitation, combating breeding sites through educational activities, and direct combat using chemical, physical, and biological agents, have been adopted. Direct combat consists of the use of insecticides and larvicides. Both deaths occur due to oxidative stress caused by increased Reactive Oxygen Species (ROS). Therefore, a new proposal for controlling the dengue vector is through heterogeneous photocatalysis, which is based on the incidence of photons with energy higher than the semiconductor bandgap, generating an electron-hole pair (e-/h+), in which h+ reacts with H2O, generating HO• radicals. Among the photocatalysts, TiO2 is the most widely used due to its advantages: high photooxidative potential, photostability, high chemical stability, resistance to photocorrosion, low cost, and nontoxicity. However, it has limitations, such as recombination between the e-/h+ pair and low activity in solar radiation due to its band gap. To solve these problems, some solutions are using SiO2 as support and incorporating Ag nanoparticles (NPs). Both strategies increase photocatalytic activity, reduce band gap energy, increase visible activity, and enable solar radiation. Therefore, photocatalysts based on TiO2, SiO2, and Ag were synthesized by the sol-gel method, which was pure titania, TiO2-SiO2, and TiO2-SiO2-Ag composites were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD), thermogravimetric analysis (TGA) and diffuse reflectance, which allowed us to verify the formation of the synthesized materials. The XRD of all samples showed standard peaks of the anatase phase of TiO2, which overlapped the SiO2 and Ag peaks, confirmed by the percentages and the decrease in the crystallite size. The FTIR confirmed the presence of Ti-O-Ti at 469-498 cm-1 for TiO2 and Ti-O-Si at 942 cm-1 for the TiO2-SiO2 and TiO2-SiO2-Ag composites. However, there was no Ag vibration. All photocatalysts were tested for decolorization of methylene blue (AM), showing a 98.3-99.5% decolorization rate for TiO2-SiO2 and TiO2-SiO2-Ag. Only TiO2-SiO2-Ag were tested against Aedes aegypti larvae, showing promising results regarding mortality, leaving most of them lethargic, which will require the test's or the photocatalyst's optimization.

COMMITTEE MEMBERS:
Interno - JOAO RUFINO DE FREITAS FILHO
Externa ao Programa - ***.096.204-** - LIDIANE MACEDO ALVES DE LIMA - UFRPE
Presidente - MONICA FREIRE BELIAN