KINETIC BEHAVIOR OF SOME AZO DYES DECOLORIZATION BY VARIATION OF ZINC OXIDE AND TITANIUM DIOXIDE CONCENTRATIONS

The decolorization of three monoazo dyes (acid orange 7, direct orange 34, and methyl orange), one diazo dye (direct yellow 86) and one tetraazo dye (direct red 80) were mediated by n-type semiconductors as ZnO and TiO2 under pseudo-first order conditions at 30 ºC. The decolorization rate constants...

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Bibliographic Details
Published in:Química Nova 2018-03, Vol.41 (3), p.268-272
Main Authors: Silva, Wallace, Monezi, Natalia, Leão Neto, Vanildo, Takashima, Keiko
Format: Article
Language:English
Subjects:
CHEMISTRY, MULTIDISCIPLINARY
first-order rate constant
heterogeneous photocatalysis
TiO2
ZnO
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Summary:The decolorization of three monoazo dyes (acid orange 7, direct orange 34, and methyl orange), one diazo dye (direct yellow 86) and one tetraazo dye (direct red 80) were mediated by n-type semiconductors as ZnO and TiO2 under pseudo-first order conditions at 30 ºC. The decolorization rate constants of these azo dyes were determined, varying the semiconductor concentration for the majority of them from 1.0 to 10.0 g L-1. In general, the highest rate constants were displayed for ZnO. This work elucidates that the decolorization capacity depends on the charge, structure, and adsorption of the azo dye on the semiconductor surface as well as the agglomeration of the photocatalyst particles.
ISSN:0100-4042
1678-7064
DOI:10.21577/0100-4042.20170172