Kinetic study of the manganese-based catalytic hydrogen peroxide oxidation of a persistent azo-dye

✍ Scribed by Chedly Tizaoui; Nazira Karodia; Mohsen Aburowais

• Publisher: Wiley (John Wiley & Sons)
• Year: 2009
• Tongue: English
• Weight: 220 KB
• Volume: 85
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/jctb.2293

✦ Synopsis

Abstract

BACKGROUND: The discharge of synthetic dyes by the textile industry into the environment poses concerns due to their persistence and toxicity. New efficient treatment processes are required to effectively degrade these dyes. The aim of this work was to study the degradation of a persistent dye (Drimarene Brilliant Reactive Red K‐4BL, C.I.147) using H~2~O~2~ oxidation catalysed by an Mn(III)‐saltren catalyst and to develop a kinetic model for this system.

RESULTS: Dye oxidation with H~2~O~2~ was significantly improved by the addition of the catalyst. As the pH was increased from 3 to 10, the oxidation rates increased significantly. The kinetic model developed in this study was found to adequately explain the experimental results. In particular, dye oxidation can be described at high pH by pseudo‐first‐order kinetics. A Michaelis–Menton type equation was developed from the model and was found to adequately describe the effect of H~2~O~2~ and catalyst concentrations on the apparent pseudo‐first‐order rate constant. Optimum catalyst and H~2~O~2~ concentrations of 500 mg L^−1^ and 6.3 g L^−1^, respectively, were found to give maximum reaction rates.

CONCLUSION: Catalytic H~2~O~2~ oxidation was found to be effective for the removal of persistent dye and the results obtained in this work are of significance for design and scale‐up of a treatment process. Copyright © 2009 Society of Chemical Industry