Electrochemical decolorization and removal of indigo carmine textile dye from wastewater

Abstract

The present paper discusses an integrated electrochemical decolorization/degradation treatment procedure of indigo carmine dye, which comprises electrocoagulation, electrooxidation and advanced electrochemical oxidation using the electro-Fenton process. The electrocoagulation process is performed by sacrificial iron electrodes, the indirect electrooxidation process by dimensionally stable Ti/Pt and graphite electrodes in NaCl electrolyte solution, and the electro-Fenton process by iron electrodes and added amounts of H2O2. All electrochemical experiments are conducted in the same electrochemical cell with the same apparent electrode surface and inter-electrode distance. The three different electrochemical processes are discussed, their efficiencies compared and evaluated. The initial dye concentration of 100 mg l-1 was fast and efficiently removed in only a few minutes of electroprocessing time. The electro-Fenton treatment is the fastest, most efficient and economical process operated at very low current densities of 0.33 and 0.66 mA cm-2 and consuming only 4.75×10-3 and 5.23×10-3 kWh m-3 of treated solution respectively. The electrocoagulation treatment with iron electrodes and the electrooxidation process with Ti/Pt electrodes conducted at applied current densities of 5 mA cm-2 consumed 0.511 and 0.825 kWh m-3 of treated solution respectively. The proposed procedure is a safe, economical and efficient method for removal of indigo carmine dye from aqueous solutions and dye house effluents. © 2014 Global NEST Printed in Greece. All rights reserved.