Electrochemical treatment of pharmaceutical azo dye amaranth from waste water

The electrochemical behavior of pharmaceutical azo dye amaranth has been investigated in distilled water and Britton–Robinson buffer. One well-defined irreversible cathodic peak is observed. This may be attributed to the reduction of the –N=N– group. Calculation of the number of electrons transferred in the reduction process has been performed and a reduction mechanism proposed. Results indicate that the electrode process is diffusion controlled. The cathodic peak in the case of controlled potential electrolysis is found to reduce substantially with a decrease in color and absorbance. The reaction has first order kinetics with k value 5.75 × 10⁻² abs min⁻¹. The efficiency of different electrode materials (platinum and steel) for decolorisation is compared. Chemical oxygen demand (COD) decreases substantially from 2,680 to 96 ppm at platinum and to 142 ppm at steel. This translates to 97% COD removal at platinum and 95% at steel.