Evaluation of new ceramic electrodes based on Sb-doped SnO2 for the removal of emerging compounds present in wastewater

Abstract

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. For this purpose, new ceramic electrodes based on Sb-doped SnO2 have been developed. Sb-doped tin oxide electrodes have been obtained through mechanical mixing of raw materials and sintering of dry-pressed specimens. Different sintering temperatures (1050 °C to 1250 °C) were considered. The electrochemical behavior of the resulting electrodes has been compared to that exhibited by Pt and BDDs electrodes. The oxygen discharge potential (EO2) 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 COD removal for the electrode sintered at 1050 °C 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 °C and that of the BDD electrode at an applied potential of 3 V, 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.