ORIGINAL PAPER Electrochemical oxidation of Acid Yellow 1 using diamond anode J. Rodriguez Æ M. A. Rodrigo Æ M. Panizza Æ G. Cerisola Received: 29 September 2008 / Accepted: 20 March 2009 / Published online: 3 April 2009 Ó Springer Science+Business Media B.V. 2009 Abstract The electrochemical oxidation of a synthetic wastewater containing Acid Yellow 1 on boron-doped dia- mond was investigated. The inﬂuence of applied current (0.5–3 A), dye concentration (1–3 g L -1 ), temperature (25–40 °C) and ﬂow-rate (75–300 L h -1 ) on colour removal and current efﬁciency was evaluated. It was demonstrated that the complete decolourization and COD removal were achieved in any experimental conditions indicating that the electrochemical oxidation on BDD electrodes is a suitable method for treatment of wastewaters polluted with synthetic dyes. In particular it was found that the decay of Acid Yellow 1 follows a pseudo-ﬁrst-order kinetic and the oxidation rate was favoured by increasing current and ﬂow-rate, while it was almost unaffected by solution temperature. Keywords Boron-doped diamond anode  Electrochemical oxidation  Decolourisation  Dyes 1 Introduction Large amounts of coloured wastewaters are produced annually world-wide, not only by textile industries but also by other industrial operations such as printing, coffee absorption, yeast preparation and edible oil reﬁnery [1]. Even if the wastewaters contain low concentration of dye, they present strong colour and turbidity and their dis- charge is particularly troublesome because of its negative visual impact. Decolouration of efﬂuents is a well-known technical problem and therefore the research is devoted to ﬁnd an effective treatment capable of solving this problem. Physical and chemical methods such as coagulation [2, 3], electro-coagulation [4–6], ﬂocculation [7], adsorp- tion [8], Fenton’s process [9, 10], ozonation [11, 12] and combined processes [13, 14] have demonstrated to be effective, however, some of these methods present impor- tant drawbacks as sludge problems, high investment, elevated operational costs, or pollution problems from residual compounds. As an alternative, electrochemical oxidation appears to be a promising method to solve the environmental prob- lems caused by discharge of dye efﬂuents [15–22]. Many electrode materials have been tested for electro- chemical treatment of dye solutions, including Iridium or Ruthenium oxide [23–25], PbO 2 [26, 27], Pt [19, 28] SnO 2 [29] but high current efﬁciency, even about 100%, was obtained only using boron-doped diamond (BDD) anode [30–34]. In fact, using BDD, which presents an extremely high overpotential for oxygen evolution and an inert surface with low adsorption properties, the organic compounds are incinerated to CO 2 by electrogenerated hydroxyl radicals from water discharge [35]: 2H 2 O ! 2HO  þ 2H þ þ 2e  ð1Þ The aim of this work was to study the electrochemical oxidation of a synthetic dye solution containing Acid J. Rodriguez (&) Department of Chemical Engineering and Materials, University of Cagliari, Piazza D’Armi I, 09123 Cagliari, Italy e-mail: j.rodriguez@dicm.unica.it M. A. Rodrigo Chemical Engineering Department, Faculty of Chemistry, University of Castilla-La Mancha, Campus Universitario s/n, 13071 Ciudad Real, Spain M. Panizza  G. Cerisola Department of Chemical and Process Engineering, University of Genoa, P.le Kennedy, 1, 16129 Genoa, Italy 123 J Appl Electrochem (2009) 39:2285–2289 DOI 10.1007/s10800-009-9880-8