Photocatalytic Degradation of four Textile Azo Dyes in Aqueous TiO2 Suspensions: Practical Outcomes and Revisited Pathways

Author: Zayani Ghanem     Bousselmi Latifa   Pichat Pierre   Mhenni Farouk   Ghrabi Ahmed  

Publisher: Science and Technology Network Inc.

ISSN: 1203-8407

Source: Journal of Advanced Oxidation Technologies, Vol.9, Iss.1, 2006-01, pp. : 65-78

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Abstract

The non-biodegradability of textile wastewaters is mainly due to the presence of synthetic dyes. We have studied the photocatalytic degradation of four commercial (i.e. containing additives) azo dyes (viz. Yellow Cibacron FN-2R, Red Cibacron FN-R, Navy Erionyl R 180%, Everdirect Black VSF) in aqueous suspensions of TiO2 Degussa P25 under irradiation at 365 nm. Measurements performed were: the extent of dark adsorption; the kinetic variations in absorption, TOC and pH; the temporal formations of inorganic ions and carboxylates. In some cases, the effects of initial pH, TiO2 loading and dye concentration were determined. Aside from considerations regarding the practical outcomes, the results are exploited to revisit the photocatalytic degradation pathways of these types of dyes, particularly on the basis of organic chemistry fundamental mechanisms.