| Autor: |
Mostafa A. Borhan El-Din, A. M. Habib, Hosny A. El-Daly |
| Rok vydání: |
2003 |
| Předmět: |
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| Zdroj: |
Dyes and Pigments. 57:197-210 |
| ISSN: |
0143-7208 |
| DOI: |
10.1016/s0143-7208(02)00161-4 |
| Popis: |
The kinetics of oxidation of the direct dye Durazol Blue 8G with H2O2 was studied spectrophotometrically in different media. An induction period was observed at the early stages of the reaction. The slowness of the oxidation reaction was a precursor of an autocatalytic behaviour. The absorbance A=f(t) curve has a sigmoid character with a point of inflection which is typical of autocatalytic reactions. The kinetic and activation parameters were determined at time tending to zero (t→0) and in the bulk for uncatalyzed and autocatalyzed reactions. The reaction followed zero-order kinetics with respect to [dye] and first-order kinetics with respect to [H2O2]. The reaction at t=0 followed a first-order kinetics for both [dye] and H2O2]. This means that the order as a function of the initial concentration was greater than that as function of time with respect to [dye]. This is an indication for the autocatalytic behaviour. The activation energy, E increases in the following order: phosphate buffer (pH > 8)=sodium tetraborate/NaOH buffer |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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