Electrolytic treatment of CI Acid Orange 7 in aqueous solution using a three-dimensional electrode reactor

A simulated wastewater containing the monoazo dye C.I. Acid Orange 7 was electrolytically treated using a three-dimensional electrode reactor equipped with granular activated carbon as particle electrode. The activated carbon fiber cathode was more effective than either a graphite or a stainless steel cathode due to its larger surface area which was beneficial to the electrogeneration of H2O2. Under the reaction conditions of 20 V and 3.0 g L-1 Na2SO4 at pH 3.0, decrease in the COD of up to 80%, and in the TOC by up to 72% were achieved and almost the complete decolorization of the dye was secured after 180 min electrolysis. Furthermore, decay of the dye followed a pseudo-first-order reaction in the first 60 min treatment. The three-dimensional electrode system generated more hydroxyl radicals than a two-dimensional system due to the formation of microelectrodes under applied high potential. (C) 2007 Elsevier Ltd. All rights reserved.