Lanthanum-based perovskites as catalysts for the ozonation of selected organic compounds

Abstract

The ozonation of two model compounds (oxalic acid and dye C. I. Reactive Blue 5) was carried out in the presence of La containing perovskites prepared by the citrate method. With the exception of LaFe0.9Cu0.1O3, all samples are active in the catalytic ozonation of oxalic acid, some of them allowing fast degradation of the compound. The presence of lattice vacancies on the perovskites surface and tuning of oxidation ability by the B cation play a key role in oxalic acid removal. Sample LaCoO3 was considered the best catalyst in oxalic acid degradation; in addition to its high activity, no metal leaching was observed. Regarding colour removal from the dye solution, single ozonation was slightly more efficient than catalytic ozonation in the presence of LaCoO3. On the other hand, ozonation catalyzed by LaCoO3 improved the TOC removal, allowing almost complete mineralization of the solution after 3 h of reaction under the conditions tested.