Electrochemical degradation of Congo red from aqueous solution: Role of graphite anode as electrode material

Abstract

The present work has been carried out to study the mechanism of electrochemical degradation of Congo red dye. Electrolysis has been carried out in a single-chamber electrochemical cell having graphite anode and platinum cathode in the presence of KCl as supporting electrolyte under amperostatic conditions. The potential across the electrodes has been adjusted so that a constant 30 mA current passed through the cell. The effect of various operating parameters such as current density, initial dye concentration, nature of supporting electrolyte KCl, pH and electrode materials, on electrochemical degradation of Congo red dye has been investigated. The decolourization efficiency was assessed through UV-Visible studies which are supported by a percentage reduction in Chemical Oxygen Demand (COD). Kinetic studies indicate that decolourization takes place through a second order diffusion controlled reaction. Energy consumption has been calculated. It is observed from Fourier transform infrared spectroscopy (FTIR) and mass spectra that Congo red dye has been degraded to small molecules. Results indicate that electrochemical degradation of Congo red by using low-cost graphite electrodes proves to be an efficient method at an optimum current density of 1.805 mA cm-2.