C. E. G. Ilha, A. Santos, J. Souzade
Oct 1, 2009
Citations
0
Influential Citations
26
Citations
Journal
Clean-soil Air Water
Abstract
The degradation reactions of two monoazo pigments, namely, Red 53:1 and Red 48:2, by Fenton, photo-Fenton and UV/H 2 O 2 systems have been studied. The efficiencies of the Fenton reactions increased with temperature, but the formation of solid agglomerates was observed when the reactions were carried out above 50°C indicating a coagulant action of Fe +2 or Fe +3 . Photo-Fenton reactions irradiated by sunlight presented the best rate constants for cleavage of the azo bond and the naphthalene rings. The UV/H 2 O 2 system exhibited the highest efficiency with respect to the consumption of H 2 O 2 . The presence of a carbonyl group in the ortho position of the naphthol ring hampered the oxidation of pigment Red 48:2 by hydroxyl radicals. This finding may be explained in terms of the acceptor character of the COOH group, and suggests the formation of a complex containing two six-membered rings between Fe +3 and the pigment molecule.