Electrochemical oxidation of Norfloxacin (NOR) in sodium sulphate media has been comparatively studied in an undivided and in a divided electrolytic cell both containing either a boron doped diamond (BDD) or a novel Sb-doped SnO 2 ceramic anode under galvanostatic operation. The electro-oxidation was found to occur with first order kinetics mainly when using both anodes. The results showed the great oxidizing power of BDD in relation to the ceramic anode to convert NOR and all the intermediate accumulated into CO 2. In the case of the BDD, although a 92 % of TOC abatement was achieved, the complete mineralization was not possible probably due to the carboxylic acids still present in solution. On the contrary, for the ceramic electrode, which presented a maximum value of TOC removal of about 63 %, the total mineralization of the aromatic oxidation intermediates was not reached under the experimental conditions. The use of a membrane divided cell showed positive aspects in terms of molecule degradation, degree of mineralization and current efficiency since prevents the intermediate products formed during the NOR oxidation process from being reduced on the cathode.

The properties of the ceramic electrodes make them interesting for electrochemical advanced oxidation processes (EAOPs), destined to the elimination of emergent or refractory contaminants, as an alternative to boron-doped-diamond (BDD) electrodes. The oxygen discharge potential (E O2 ) for the ceramic electrodes decreases as the sintering temperature increases, being these values higher than that observed for the Pt electrode and smaller than that for the BDD electrode. This result in a highest rate of 2 COD removal for the electrode sintered at 1050 ºC comparing with the rest of ceramic electrodes under potentiostatic operation. On the other hand, in galvanostatic mode, the performance of the different ceramic electrodes in terms of the degradation of Norfloxacin, used as tested antibiotic, was similar.Comparing the behavior of the ceramic electrode sintered at 1250 ºC and that of the BDD electrode at an applied potential of 3V, it is inferred that although both present similar values in terms of the degradation of Norfloxacin, the rate of removal of the chemical oxygen demand is higher in the case of the BDD.

Electrochemical oxidation of β-blocker atenolol (ATL, 100 ppm) at different applied current densities (33, 50 and 83 mA•cm -2 ) using a reactor divided by an ion-exchange membrane and an undivided one was investigated. Two types of anodes were used for this purpose: a boron-doped diamond (BDD) anode and new low-cost ceramic electrodes made of tin dioxide doped with antimony (Sbdoped SnO2). Degradation was assessed using a high performance liquid chromatography, while mineralization by measuring total organic carbon (TOC) dissolved in sample. Except for the lowest current density, ATL was completely 2 degraded for both reactors and electrodes. The highest percentage of TOC eliminated (89%) was obtained at the highest applied current density with the BDD electrode in the divided reactor. The presence of the cation-exchange membrane prevented the reduction of both the electrogenerated oxidizing species and the oxidized organic compounds and enhances the electro-oxidation kinetic reaction.In order to study the influence of the supporting electrolyte, three different concentrations of sodium sulfate (0.014, 0.05 and 0.1 M) were tested in the undivided reactor with both electrodes. The results showed that an increase in the concentration of the supporting electrolyte improves the mineralization of ATL for the BDD electrode and, on the contrary, worsens for the ceramic electrode.Accelerated service life tests were carried out for the ceramic electrode at 100 mA•cm -2 in 0.5 M H2SO4. Ecotoxicity tests using marine bacteria (Vibrio Fischeri) revealed that no toxic by-products were formed in any case.

Novel Sb-doped SnO2 ceramic electrodes sintered at different temperatures, are applied to the degradation of Reactive Black 5 in both divided and undivided electrochemical reactors. In the undivided reactor the discoloration of the solution took place via the oxidation of RB5 dye, without the corresponding reduction in the chemical oxygen demand for the ceramic electrodes. However, in the divided one, it was possible to achieve the discoloration of the solution while at the same time decreasing the chemical oxygen demand through the ·OH-mediated oxidation, although the chemical oxygen demand degradation took place at a slower rate.

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