Antimony-doped tin dioxide ceramics used as standalone membrane electrodes in electrofiltration reactors enhance the oxidation of organic micropollutants

Abstract

In the present work, microporous ceramics made of antimony-doped tin dioxide produced using a facile synthesis procedure were evaluated during the degradation of norfloxacin in a novel electrofiltration process. The antimony-doped tin dioxide ceramics were used as standalone electrodes accomplishing a dual function: as anodes and microfiltration membranes. The simultaneous generation of hydroxyl radicals and permeation of the electrolyte through the ceramic electrodes favors the effective utilization of their high active area in the degradation of organic compounds. The progress of the electrofiltration process was compared with that of a conventional flow electrolysis reactor using the ceramic electrodes and boron-doped diamond. By changing from a conventional flow reactor to an electrofiltration configuration, the effective utilization of the generated hydroxyl radicals is evidenced by the delayed transition from electrochemical-to mass transfer-controlled degradation rates. Evaluation of intermediate and by-product concentrations confirms the formation of acetate ions as a prior stage in the mineralization pathway using both types of electrodes. After 4 h of electrolysis, norfloxacin degradation rates of 98.3% and mineralization degrees of 82% were attained using the antimony-doped tin dioxide anodes at the highest permeate flow of 60 mL min −1 , approaching the outstanding performance of commercial boron-doped diamond electrodes. - Standalone Sb-doped SnO2 electrodes oxidize organic micropollutants - Microporous Sb-doped SnO2 plays a dual role as a membrane and as an electrode - Electrofiltration improves the effective use of • OH radicals in NOR oxidation. - Electrofiltration increases removal and mineralization of NOR - NOR removal degrees close to those achieved with BDD are obtained.