Obtenção de molibdatos de prata através do método sonoquímico para catálise do azul de metileno
The silver-based semiconductors belonging to the group of transition metal oxides have attracted significant attention because of their unique photosensitivity, which provides these materials with excellent photocatalytic activity mainly due to the effects of plasmon resonance. For the applicabil...
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| Formato: | Dissertação |
| Idioma: | por |
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Brasil
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/26425 |
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| Resumo: | The silver-based semiconductors belonging to the group of transition metal oxides
have attracted significant attention because of their unique photosensitivity, which
provides these materials with excellent photocatalytic activity mainly due to the effects
of plasmon resonance. For the applicability of these materials, the stability during reuse
is fundamental to avoid the generation of secondary residues. This dissertation
proposed to accomplish the study of the structural and morphological properties of
silver molybdates obtained by the sonochemical method for the reaction medium
between pH 1 and pH 8. Evaluating the application of molybdates through the reuse of
the powders obtained in the catalysis of methylene blue dye. The silver molybdate
powders were obtained by the sonochemical method and characterized by X-ray
diffraction (XRD), field emission electron microscopy (SEM-FEG), and UV-Visible
spectroscopy by diffuse reflectance to estimate the value of optical band-gap. The
catalytic activity on the methylene blue dye as well as the stability of the evaluated
powders were also evaluated. It was observed that the synthesized materials
crystallize in the structures Ag2Mo3O10.2H2O, Ag2Mo2O7 and Ag2MoO4, as a function
of the pH of the reaction medium. With the structures of Ag2Mo3O10.2H2O and
Ag2Mo2O7 presenting nanorod morphology, while the structures of Ag2MoO4 present
irregular micrometric morphology, with both structures obtained after the sonochemical
method presenting a high content of superficial silver precipitates. The complete
decolorization of the dye solution was obtained after 5 minutes exposure of the
Ag2Mo3O10.2H2O powders and 15 minutes of exposure of Ag2Mo2O7 without external
irradiation. The degradation of the methylene blue dye under UV irradiation was
observed for Ag2MoO4 structure, where complete discoloration of the MB dye was
observed after 60 minutes. There was no loss of catalytic efficiency of the powders
after 3 cycles of reuse. Indicating that the sonochemical method is effective in obtaining
stable silver molybdate powders for the catalytic application of the methylene blue dye. |
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