Banca de DEFESA: THYALLE TRINDADE DE ARAÚJO REZENDE

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : THYALLE TRINDADE DE ARAÚJO REZENDE
DATE: 11/12/2020
TIME: 09:00
LOCAL: Videoconferência pelo link: (a ser divulgado)
TITLE:

Study of Photocatalytical Degradation of Methylene Blue in the presence of WO 3 /SnO 2 /CuO Thin Films obtained by Dip Coating

KEY WORDS:

Thin films, WO 3 , SnO 3 , CuO, Photocatalysis, Dip coating.

PAGES: 97
BIG AREA: Engenharias
AREA: Engenharia de Materiais e Metalúrgica
SUMMARY:

Recently, the interest in materials with photocatalytic properties for the degradation of dyes from textile industries has been increasingly studied, since the incorrect disposal of these dyes causes serious environmental problems. The tungsten trioxide (WO 3 ) has a band gap of 2,7 eV which makes it a promising element for the absorption of photons in the visible spectrum range. Tin dioxide (SnO 2 ) is a band gap semiconductor equal to 3,6 eV with a high surface area, making it essential for the photocatalysis process. In turn, copper oxide (CuO) presents an expansion of the light spectrum from the ultraviolet to the visible regions due to its narrow band gap of 1,2 eV. In this work W, Sn and Cu based resins were synthesized by the complex polymerization method (MPC) for the production of thin films of WO 3 , SnO 2 , CuO and WO 3 /SnO 2 /CuO with 9 layers using the dip coating  technique. Two heat treatment pathways (Route 1 and 2) were used during the process of obtaining the nanocomposites, with all samples calcined at a temperature of 500 °C. The films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy with field emission (SEM-FEG), energy dispersion spectroscopy (EDS), spectroscopy in the region UV-Visible (UV-Vis) and wettability test. The XRD results confirmed the formation of orthorhombic, monoclinic and tetragonal crystalline structures, there was also the formation of a sub stoichiometric phase (WO 2,63 ) and tin tungstate in the route 2 nanocomposite, indicating chemical interaction between the interfaces. The images of the surface and the cross section of the thin films indicated regular morphologies with small porosity and uniform thicknesses. The contact angle measurements indicated that the nanocomposites remained hydrophilic even after UV irradiation and storage in the dark. The optical absorption spectra by UV-Vis characterized thin films as semiconductors. The photocatalytic activity was evaluated and the results showed that the films degrade the MB dye when exposed to UV and solar radiation. The maximum photocatalytic activity (89%) was obtained under sunlight and remained practically unchanged after six cycles of use, indicating that the nanocomposites studied are promising for degradation of MB dye.

BANKING MEMBERS:
Presidente - 1802888 - FABIANA VILLELA DA MOTTA
Externo à Instituição - MARIO GODINHO JUNIOR - UFG
Interno - 1883170 - MAURICIO ROBERTO BOMIO DELMONTE
Externo à Instituição - NEFTALÍ LENIN VILLARREAL CARREÑO - UFPel