Electrochemical decomposition of some azo dyes using Pt electrodes. Thermodynamic parameters for methyl red

Abstract

Azo compounds have been widely used in dye and pharmaceutical industries and are thus present in the waste water. Therefore treatment of water containing azo pollutants becomes a great necessity. In the present work, we have studied electrochemical-decomposition of azo indicators at different voltages ranging from 5 to 20 V. The azo compounds studied are: methyl red (MR), methyl orange (MO), eriochrome blackT (EBT), eriochrome blue black (EBB), and 1,2 pyridylazo-2 naphtol (PAN). The electrodecomposition products were characterized by UV/visible spectroscopy methods. The decomposition rates follow first order reactions and increase with increasing current. The studies indicate that electrodecomposition involves oxidation. The thermodynamics for electrochemical decomposition of MR were also evaluated at different pH. The acidic form of MR shows the highest decomposition rate than its basic form and follows different mechanism.