Effect of additives in photocatalytic degradation of commercial azo dye Lanaset Sun Yellow 180This paper is published as part of the themed issue of contributions from the 7th European Meeting on Solar Chemistry and Photocatalysis: Environmental Applications held in Porto, Portugal, June 2012

The photocatalytic degradation of the commercial dye Lanaset Sun Yellow 180 was studied in the presence and absence of the different additives used in the dye's formulation. The experiments were performed with Degussa P25 as received and doped with Fe (Fe-TiO 2 ) and a new catalyst synthesized by our research group (ECT-1023). The best efficiency was achieved with Fe-TiO 2 . With this catalyst, the formation of a photoactive complex was observed between the dye and Fe atoms of the catalyst surface that accelerated degradation. FTIR studies revealed that the complex was formed by interaction between the dye's carbonyl groups and the atoms of the metal. In mixtures of the dye containing citric acid or acetate, degradation was notably inhibited with the catalysts Fe-TiO 2 and ECT-1023 because of the formation of carboxylates on their surface. This inhibitory effect was neutralized when all the additives were present in the solution. Toxicity analyses indicated that intermediates were not toxic. Thus, the photocatalytic methods seem to be optimal for the decolourization of wastewaters containing this dye. This study has shown the effect of certain additives and the formation of complex Fe 3+ -dye in photocatalytic degradation of the dye Sun Yellow 180.