This work experimentally investigates the colour and Chemical Oxygen Demand (COD) removal of effluents containing: Trypan Blue (TB); Orange G (OG) dye using the two most common electrode materials – Mild Steel (MS) and Aluminium (Al). Effects of the time of electrotreatment, solution pH, electrode material, current density and initial dye concentration on decolourisation and COD reduction are reported. MS electrodes show better colour removal efficiency event at lower cell current efficiency compared with Al electrodes and are able to achieve up to 90–98% removal in less than 60 min. Removal efficiency is higher in the case of TB compared with OG irrespective of electrode material due to higher electrostatic attraction between TB molecules and metal hydroxide sludge. Higher current density enhances colour removal even though pH elevation (approaching close to zero point charge) rate is higher. COD reduction is found to be about 10-20% lower than colour diminution measured spectrophotometrically suggesting different mechanisms of dye removal involved during EC.
Keywords: electrocoagulation, trypan blue, orange G, decolourisation, COD reduction, adsorption capacity, chemical oxygen demand, dye effluent, textile dyes, wastewater treatment, colour removal