Resumo

DIAZ-URIBE, Carlos; VERA, Kevin  e  VEGA, Dariana. DISCOLORATION OF ALIZARIN RED ON THIN FILMS OF FE (III)-TETRACARBOXYPHENYL PORPHYRIN DEPOSITED ON SILICON OXIDE. Iteckne [online]. 2020, vol.17, n.1, pp.49-55. ISSN 1692-1798.  https://doi.org/10.15332/iteckne.v17i1.2429.

Alizarin Red is a water soluble anthraquinone dye used extensively in the textile industry as a staining agent and is considered to be one of the most recalcitrantand durable pollutants. Fenton reaction can be used to destroy a wide variety of organic compounds: a ferrous ion reacts with hydrogen peroxide (H2O2) to form hydroxyl radical (HO•) which is a powerful oxidizing agent. The rate of this reaction could be increased when exposed o UV-vis light, this method is known as photo- assisted Fenton process and constitutes an attractive alternative of advance oxidation process. In this work, we studied the alizarin red dye photocatalytic discoloration through heterogeneous Photo-Fenton process induced by visible light; we used tetra (4-carboxyphenyl) porphyrin iron (III) adsorbed on silicon dioxide thin films. The characterization of the catalyst was carried out by UV-Vis, diffuse reflectance and IR-FT; The tests were carried out at three (3) pH values 1.0, 3.0 and 5.0; finally, the kinetic model described by Langmuir-Hinshelwood was used to obtain kinetic parameters for photo-discoloration process. The results showed that at pH = 1.0 highest alizarin red photo-discoloration percentage was reported; furthermore, after applied the pseudo-first order model, we obtained rate constants (k) for discoloration process that finds the highest k value was 1.1x10-2min-1. The hydroxyl radicals were detected by chemical trapping through indirect fluorescence of the 2-hydroxyterephthalic acid. Photo-Fenton processes based on heterogeneous catalysis systems solve part of these environmental problems providing an easy separation and recovery of the catalyst from the treated wastewater, wherein it is noncorrosive, and, besides, it is environmentally friendly.

Palavras-chave : Porphyrin; photo-fenton hydroxyl radical; alizarin red dye; visible light; catalysis.

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