Decolorization of textile dyes by the electrocoagulation method

Dyes are common pollutants in a large variety of industrial wastewaters, and the treatment of these wastes has been extensively studied by coagulation. For the removal of pollutants from the wastewaters, different techniques have been used and electrocougulation is one of the widely used methods. This process is very effective in removing organic pollutants including dyestuff wastewater. The aims of this study were to detect the effects of the operating parameters, such as current density, electrolyte concentration, dyestuff concentration, and pH of solution on decolorization and chemical oxygen demand (COD) removal of wastewater containing three different dyes in same solution by direct current electrocoagulation. The amount of dye removed was found by chemometric method to the synthetic dye mixtures. In this study synthetic dye mixture which include disperse blue 56 (DB 56), C.I. Acid Violet 90 (AV 90) and basic yellow 28 (BY 28) were used for electrocougulation (EC) process with iron electrodes. In the presence of these three dye molecules, the optimum pH was found to be 6, optimum NaCl concentration was 3000 mg/L and optimum current density was 8.66 mA/cm2. Under these conditions in the case of 100 mg/L-1 each dye concentration at room temperature and 2.2 cm interelectro distance the color removal efficiency was reached 98.29% for AV 90, 96.07% for BY 28 and 87.24% for DB 56 in 15 minutes time duration. Dye concentration dependent highest COD removal efficiency was detected at 150 mg/L dye concentration around 88.7%.