Applied Catalysis B: Environmental 115–116 (2012) 107–116 Contents lists available at SciVerse ScienceDirect Applied Catalysis B: Environmental jo ur n al homepage: www.elsevier.com/locate/apcatb Finding the best Fe 2+ /Cu 2+ combination for the solar photoelectro-Fenton treatment of simulated wastewater containing the industrial textile dye Disperse Blue 3 Ricardo Salazar a , Enric Brillas b , Ignasi Sirés b,∗ a Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, USACh, Casilla 40, Correo 33, Santiago, Chile b Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain a r t i c l e i n f o Article history: Received 8 November 2011 Received in revised form 12 December 2011 Accepted 15 December 2011 Available online 24 December 2011 Keywords: Anthraquinonic dyes Boron-doped diamond anode Metal catalysts Solar photoelectro-Fenton Wastewater treatment a b s t r a c t The performance of the solar photoelectro-Fenton (SPEF) process with Fe 2+ and Cu 2+ as metal co-catalysts and its application to the treatment of solutions simulating Disperse Blue 3 (DB3) dye bath effluents of a Chilean textile company are reported in this paper. The trials were carried out with 2.5 l solutions using a solar pre-pilot plant containing an electrochemical reactor with a 20 cm 2 BDD anode and air- diffusion cathode, coupled to a 600 ml solar photoreactor. DB3 solutions with 0.1 M Na 2 SO 4 at pH 3.0 were electrolyzed to assess the effect of the applied current density, catalyst nature and concentration and dye content on the decolorization rate, dye removal and total organic carbon (TOC) abatement. The SPEF treatments using 0.5 mM Fe 2+ + 0.1 mM Cu 2+ led to the quickest degradation kinetics, mainly due to the concomitant action of UV photolysis and the generated oxidizing hydroxyl radicals on the organic molecules and/or their Cu(II) and Fe(III) complexes. Based on the identification of up to 15 aromatic by- products by GC–MS, a reaction scheme for DB3 degradation has been proposed. The progressive color and TOC removal of DB3 solutions were due to various changes undergone by the initial anthraquinonic structure, including the modification/addition of auxochromes giving 6 anthraquinonic by-products and its cleavage to yield compounds with 2 aromatic rings due to intermolecular cyclization or 1 aromatic ring mainly in the form of phthalic acid derivatives. Upon cleavage of these aromatics, maleic, oxalic, oxamic, pyruvic and acetic acids were formed. NO 3 - ions were released to a larger extent than NH 4 + ions. The great efficacy of SPEF with Fe 2+ and Cu 2+ was demonstrated for simulated wastewater containing DB3 and industrial surfactants and additives at 50 mA cm -2 , allowing their total decolorization and almost overall mineralization in only 150 and 360 min, with an energy consumption of 11.0 and 26.4 kWh m -3 , respectively. © 2011 Elsevier B.V. All rights reserved. 1. Introduction The contamination of water bodies by man-made organic chem- icals is definitely a critical issue that the recent water framework directives are trying to address in order to ensure good water qual- ity status and healthy ecosystems [1]. Although major attention is paid to persistent and emerging pollutants, especially if they are likely to show endocrine disrupting activity, water pollution by synthetic dyes is also of great concern due to the large world- wide production of dyestuffs. Dyes are extensively used by many industries, mainly in the textile dyeing process, which produces highly contaminating spent dyeing baths containing unreacted dyes, surfactants and additives washed out from the fabric [2]. As ∗ Corresponding author. Tel.: +34 934021223; fax: +34 934021231. E-mail address: i.sires@ub.edu (I. Sirés). a result, the water resources become seriously threatened from the aesthetic and toxicological standpoint, with proven toxic and mutagenic effects [3], which justifies the need for more effective water treatment technologies. Researchers have mainly focused on the removal of azo dyes from water, since they account for about 70% of the world dye production [4]. However, the intro- duction of synthetic fibres has led to the appearance of some niche markets that require the use of other classes of dyes. For exam- ple, disperse anthraquinone dyes such as Disperse Blue 3 (DB3) are neutral species that keep their pre-eminent position for dyeing polyester fibres [5], but their removal from waters has been much less explored. Since textile wastewaters are toxic, mostly non-biodegradable and resistant to destruction by conventional physicochemical methods, better technologies have been developed to deal with them [6]. Particularly, the advanced oxidation processes (AOPs) have shown an extraordinary ability to reduce their impact. The 0926-3373/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.apcatb.2011.12.026