Removal of Indigo Carmine Dye from Synthetic Wastewater by Electrochemical Oxidation in a New Cell with Horizontally Oriented Electrodes

The electrochemical oxidation of a synthetic wastewater containing indigo carmine dye was investigated using a new cell with horizontally oriented electrodes. The study dealt with colour removal and chemical oxygen demand (COD) reduction using an array of Pb/PbO2 cylinders as anode and stainless steel screen as cathode in a batch recycle electrochemical unit. Operating variables such as current density, initial dye concentration, NaCl concentration, pH, and solution flow rate were investigated. The results indicate that complete decolourization and 88.2% COD reduction can be achieved under the optimum operating conditions. Kinetic study at different flow rates has shown that decolourization takes place through a first order diffusion controlled reaction. Energy consumption was calculated at different operating parameters. The use of horizontally oriented array of lead cylinders as anode has the potential of acting also as a built-in heat transfer facility to control the cell temperature especially in case of large scale cells where heat generation could adversely affect the process via increasing lead solubility and decreasing the current efficiency of Cl-2 generation.