Degradation of Monoazo Pigments Red 53:1 and Red 48:2 by Fenton,Photo‐Fenton and UV/Peroxide Reactions |
| |
| Authors: | Clóvis E G Ilha Antônio J M G dos Santos Jurandir R SouzaDe |
| |
| Institution: | Laboratório de Química Analítica e Ambiental, Instituto de Química, Universidade de Brasília Brasília‐DF, Brazil. |
| |
| Abstract: | The degradation reactions of two monoazo pigments, namely, Red 53:1 and Red 48:2, by Fenton, photo‐Fenton and UV/H2O2 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/H2O2 system exhibited the highest efficiency with respect to the consumption of H2O2. 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. |
| |
| Keywords: | Fenton reaction Photo‐Fenton reaction Pigment degradation UV/H2O2 system Water treatment |
|
|
