Electrogeneration of hydrogen peroxide and regeneration of iron on cross-linked glassy carbon cathodes

The electrochemical process known with the name of electro-Fenton, which is based on the fast and non-selective action of the hydroxyl radical, is made for decomposition, in the presence of fe rrous ions in acidic pH, of hydrogen peroxide, produced in situ, through the reduction of molecular oxygen dissolved on carbon cathodes. The simultaneous and continuous regeneration of ferrous ions allows to counteract the rapid decay of the concentration of hydroxyl radicals, enabling the achievement of very high yields with limited consumption of reagents and low sludge production. The oxygen reduction reaction, due to the poor solubility of this gas in the aqueous medium, is controlled by diffusion and favored by the use of three - dimensional electrodes, which are character ized by a high reactive surface. In the present work , we used as the cathode, a reticulated vitreous carbon electrode (RVC), a microporous material characterized by a rigid honeycomb, an d with a strong chemical and thermal resistance, which combined with high specific surface area, low density and moderate cost make it an especially attractive electrode material. In particular, we carried out, separately, electrogeneration of hydrogen peroxide and regeneration of ferric ions tests, evaluating the influence of several parameters and proceeding to a comparison with the carbon electrodes which are currently recognized to have the best performances. To this purpose we performed electrolysis under galvanostatic conditions, by using a reactor with two compartments, equipped with a cationic membrane as the separator. The obtained results showed that the RVC presents good production of hydrogen peroxide, also in air flow, only lower to those obtained with gas diffusion cathodes, which are little influenced by the operating conditions. In the case of iron regeneration, this has proven to be a highly effective material with fast and total regenerations , little influenced by temperature and pH.