Estudo da degradação fotocatalítica do azul de metileno na presença de filmes finos de WO3/SnO2/CuO obtidos via Dip Coating
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 (WO3) has a band gap of 2,7 eV which makes it...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/46455 |
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| Resumo: | 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 (WO3)
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 (SnO2) 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 WO3, SnO2, CuO and WO3/SnO2/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 (WO2,63) 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. |
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