Indirect electrochemical oxidation of reactive blue 19 dye as a model organic substrate: Role of anode material and oxidants electrochemically generated

The indirect electrochemical oxidation (IEO) of Reactive Blue 19 has been studied at boron-doped diamond (BDD) and Ru_0.3Ti_0.7O₂/Ti anodes by applying 25, 50 and 75 mA cm^-2 in presence of NaCl as supporting electrolyte. Results: clearly showed that electrochemical degradation of dye was achieved via electrogenerated species (hydroxyl radicals and active chlorine), obtaining higher removal efficiencies of color (100% for both anodes) and organic matter from solution (from 30 up to 60% for Ru_0.3Ti_0.7O₂/Ti and from 65 up to 80% for BDD). In order to understand the key role of oxidants, active chlorine species were also determined, achieving different concentrations of dissolved Cl₂, HClO, ClO^-, chlorite, chlorine dioxide and chlorate at both anodes, as a consequence of experimental conditions used as well as the nature of electrode material employed. For BDD, the IEO was more effective due to the effective production of ^•OH radicals as well as HClO and ClO^- species that favor the degradation of organic matter. The results are discussed on the light of existing literature.