Removal of Brilliant Yellow Azo Dye from Wastewater by Electrocoagulation in a Cell of Improved Design

Removal of brilliant yellow azo dye from wastewater by electrocoagulation was carried out using a cell with Al helical coil whose external surface acts as an anode, and its internal surface acts potentially as a cooler to control the cell temperature. This is important in the case of large-scale cells which use high currents and low electrolyte conductivity where accumulated heat decreases the rate of electrocoagulation. The helical coil anode was enclosed between two Al cylindrical screen cathodes. Variables studied were current density, initial dye concentration, solution pH, solution temperature, NaCl concentration, and magnetic stirring rate. Most of the variables were found to have opposing effects on the % dye removal. Under the optimum conditions, a maximum of 92% dye removal was obtained in 90 min using a current density of 3 mA/cm(2), pH 5-6, an initial dye concentration ranging from 10 to 75 ppm, and NaCl concentration of 30 g/L. Electrical energy consumption ranged from 3.258 to 313.3 kW center dot h/kg of dye removed depending on the operating conditions.