Photo-Fenton oxidation of phenol with Fe(III)-tetra-4-carboxyphenylporphyrin/SiO2 assisted with visible light

• Hydroxyl radicals were generated by TCPPFe/SiO2 under visible light irradiation.
• pH 2.8 is the optimal in the photo-oxidation process.
• Hydroquinone, catechol and benzoquinone were main products of the photo-oxidation process.

In this work we studied the photo-Fenton oxidation of phenol in aqueous solution using tetra(4-carboxyphenyl)porphyrin iron (III) adsorbed on silicon dioxide (TCPPFe/SiO2) under irradiation of visible light for the generation of hydroxyl radicals. The TCPPFe/SiO2 was synthesized by the Alder's method and, it was characterized by spectrophotometry UV–vis, FT-IR and electron paramagnetic resonance (EPR). The hydroxyl radicals were detected by chemical trapping through indirect fluorescence of the 2-hydroxyterephthalic acid. The secondary products of the phenol photo-oxidation were analyzed by High Pressure Liquid Chromatography (HPLC) where hydroquinone, catechol and benzoquinone were identified as main products. Finally, we determined and compared the kinetic parameters of the photo-oxidation process using a pseudo-first order model.

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