Electrochemically induced mineralization of organics by molecular oxygen on boron-doped diamond electrode

Electrocatalysis in wastewater treatment: recent mechanism advances

“…Indeed, hydrogen peroxide was detected on BDD during electrolysis of 1M HClO 4 . 45,46 In the presence of organic compound, hydroxyl radicals are involved in organics oxidation (indirect oxidation), as it has been proposed by Feng and Johnson. 33 Therefore, recent studies have been performed using BDD anodes in order to understand better the mechanisms, kinetic and hydroxyl radicals which mediate the oxidation processes in the vicinity of the electrode surface.…”

“…45 Helmut Baltruschat (Universität Bonn, Germany), along with Christos Comninellis (Ecole Polytechnique Fédérale de Lausanne, Switzerland) and colleagues showed that organics mineralization on BDD electrodes does not only involve hydroxyl radicals but also molecular oxygen present in air/oxygen-saturated aqueous organic solutions. The direct evidence for this process was found during EO of an acetic acid (AA) solution saturated with isotopically labelled 18 O.…”

“…In this way, Comninellis, Baltruschat, and colleagues proposed an original and additional mechanism for the electrochemically induced oxidation of organic compounds via molecular oxygen dissolved in aerated solutions on BDD electrodes, as shown in Figure 2. 45 This activation of the reaction with molecular oxygen proceeds most likely through the sequence of reactions that are initiated by HO…”

“…A similar mechanism of activation had been previously observed by radiolysis of hydrocarbons (RH), when it was found that during the ionizing irradiation of an aqueous solution of organic compounds (with X or g rays), molecular oxygen enhances the oxidation processes. 45 This occurs via addition of molecular oxygen to an organic free radical (R • ) resulting in the formation of an organic peroxy radical (RO • 2 ), which can participate in subsequent reactions. The organic free radical (R • ) is formed via the dehydrogenation of hydrocarbons (RH) initiated by HO…”

“…These findings lend further evidence to the importance of the nature of the electrode material and represent a new approach to the electrochemical oxidation mechanism. [45][46][47][48] For this reason, these recent results open new avenues in the study of the EO mechanisms, so as to optimize such processes. Future developments will rely upon the close collaboration of electrochemists, engineers, and chemists to ensure the effective application and exploitation of EO techniques to control important water pollutants using the advances in electrocatalysis.…”