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Use of Titanium Dioxide Photocatalysis on the Remediation of Model Textile Wastewaters Containing Azo Dyes

Author(s): Enrico Mendes Saggioro | Anabela Sousa Oliveira | Thelma Pavesi | Cátia Gil Maia | Luis Filipe Vieira Ferreira | Josino Costa Moreira

Journal: Molecules
ISSN 1420-3049

Volume: 16;
Issue: 12;
Start page: 10370;
Date: 2011;
Original page

Keywords: photocatalytic degradation | semiconductor | photocatalysis | azo dyes | TiO2 | TiO2 reuse

The photocatalytic degradation of two commercial textile azo dyes, namely C.I Reactive Black 5 and C.I Reactive Red 239, has been studied. TiO2 P25 Degussa was used as catalyst and photodegradation was carried out in aqueous solution under artificial irradiation with a 125 W mercury vapor lamp. The effects of the amount of TiO2 used, UV-light irradiation time, pH of the solution under treatment, initial concentration of the azo dye and addition of different concentrations of hydrogen peroxide were investigated. The effect of the simultaneous photodegradation of the two azo dyes was also investigated and we observed that the degradation rates achieved in mono and bi-component systems were identical. The repeatability of photocatalytic activity of the photocatalyst was also tested. After five cycles of TiO2 reuse the rate of colour lost was still 77% of the initial rate. The degradation was followed monitoring the change of azo dye concentration by UV-Vis spectroscopy. Results show that the use of an efficient photocatalyst and the adequate selection of optimal operational parameters may easily lead to a complete decolorization of the aqueous solutions of both azo dyes.
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Tango Jona
Tangokurs Rapperswil-Jona