Electrochimica Acta 52 (2007) 4161–4166 Indium tin oxide coated conducting glass electrode for electrochemical destruction of textile colorants J. Bandara ∗ , P.T. Wansapura, S.P.B.Jayathilaka Institute of Fundamental Studies, Photochemistry Group, Hantana Road, Kandy CP 20000, Sri Lanka Received 2 October 2006; received in revised form 17 November 2006; accepted 27 November 2006 Available online 18 December 2006 Abstract Galvanostatic oxidation of 5.0 × 10 -2 mM textile dyes such as Eosin Y (EY) and Orange II (Or II) was carried out on an indium tin oxide (ITO) coated glass anode in the presence of 1.0 × 10 -2 mM KCl solution at pH 4.0 and 6.0. The degradation results of EY were compared with that of highly stable azo dyes (Or II). EY dye solution with a concentration of 5.0 × 10 -2 mM is totally decolorized in 30 min at an electrical charge (Q) 0.067 A h dm -3 while 5.0 × 10 -2 mM Or II degraded in a little less than an hour at the same electrical charge density. The decay kinetics of dyes follows a pseudo first-order reaction. The degradation of dyes is faster in acidic pH values than in basic pH values. Electrochemical degradation results show significant decrease in chemical oxygen demand (COD) values after electrodegradation of textile dyes. The key advantage of the ITO conducting glass anode is that the deposition of polymeric materials on the anode surface during electro-degradation of textile dyes is absent and therefore the electrode fouling is not observed. Hence, the ITO anodes can be employed an extended period without loss of activity. © 2006 Elsevier Ltd. All rights reserved. Keywords: Orange II; Eosin; Electro-degradation; Azo dyes; Electrochemical destruction 1. Introduction A large amounts of colored wastewater containing unfixed dyestuff are released from dye-houses as a by-product from tex- tile dyeing operations. Synthetic textile dyes of the azo family represent an important part of the world production of synthetic dyes and are characterized by the presence of azo group. Azo dyes released without proper treatment represents about 15% of the total world production and azo dyes are resistant to bacterial activity [1,2]. The other most commonly used textile dye today is Eosin dyes, which are supposed to be resistant to bacterial activity [1]. Thus, the accumulation of those dyestuffs in nature is a growing concern related to the health impact. Therefore, the development of effective methods for their removal from water bodies is warranted. To solve the problem of highly colored wastewater, numerous attempts to decolorize textile effluents have been proposed. Dye wastewater is usually treated by physical or chemical treatment ∗ Corresponding author. Tel.: +94 81 2232002; fax: +94 81 2232131. E-mail addresses: jayasundera@yahoo.com, jayasund@ifs.ac.lk (J. Bandara). process. They include physical or chemical flocculation, elec- trofilteration, membrane filtration, electrokinetic coagulation [3–5]. Over the past few years, alternative methods for dye treat- ment have been investigated, including chemical oxidation with reagents such as: ozone, hydrogen peroxide, ozone/UV, hydro- gen peroxide/UV and Fenton’s reagent [6–10]. Other alternative techniques such as biological treatment [11–13], adsorption and precipitation [14–16] and reductive treatment [17–19] have applied successfully. For all the proposed techniques, great care has to be taken to keep the costs of such processes at reasonable levels and to avoid the formation of byproducts, which cause additional costs for secondary treatment or disposal. Among the remediation techniques described above, electro- chemical treatment is a very promising method for the reduction or decolorizing of toxic pollutants by decomposing the organic substances dissolved in wastewater. In recent years, anodic oxidation has been the focus of much research attention in wastewater treatment because of its high oxidation efficiency, fast reaction rate and ease of operation. It is important to select the proper electrode material, because the electrolytic products strongly depend on those materials as well as the operating con- ditions [20,21]. Selection of a proper electrode material is vital for an efficient and enduring operation of an electrode. It is well 0013-4686/$ – see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.electacta.2006.11.036