Original scientific paper
Published in: Holistic Approach Environ. 7(2017) 1, pp. 3 – 14
Paper reference number: HAE-132
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EFFECTS OF CONCENTRATION AND UV RADIATION WAVELENGHTS ON PHOTOLYTIC AND PHOTOCATALYTIC DEGRADATION OF AZO DYES AQUEOUS SOLUTIONS BY SOL-GEL TiO₂ FILMS

Veronika Marinović^*, Davor Ljubas^**, Lidija Ćurković^**

^* Forensic Science Centre “Ivan Vučetić”, Zagreb, Croatia

^** Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia

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ABSTRACT

The photocatalytic and photolytic degradation of anionic azo dyes Methyl Orange and Congo Red dye aqueous solutions was investigated in glass reactors with/without TiO₂ films that were irradiated with UV light. Two nanostructured sol-gel TiO₂ films were prepared by means of the dip-coating technique with and without of polyethylene glycol (PEG) as a structure-directing agent. Experiments were carried out by varying the concentration of dyes, TiO₂ films and sources of UV radiation. The concentrations of dyes were 0.0125 mmol L^-1, 0.025 mmol L^-1 and 0.05 mmol L^-1; the wavelengths of the incident ultraviolet light were predominantly 254 (UV-C) and 365 nm (UV-A). In the presence of TiO₂ film UV-C radiation showed higher degradation efficiency for both dyes than UV-A radiation. Also, UV-C radiation without TiO₂ photocatalyst was capable of degrading both dyes, while UV-A radiation alone did not show a potential for dyes degradation. Higher photoactivity showed TiO₂ film with addition of PEG.

Keywords: UV radiation, TiO₂ film, Congo red dye, Methyl Orange dye, photocatalysis, photolysis
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