Catalytic studies for the abatement of emerging contaminants by ozonation

Abstract

BACKGROUND Pharmaceutical industry generates a large amount of liquid effluents rich in toxic compounds that reach natural water streams, if improperly degraded, being a threat for ecosystems. In this context, ozonation appears as an interesting alternative to conventional treatments. This work aims to study the effect of this technology aided by two ceramic catalysts (the laboratory Mn-Ce-O and the commercial N-150) on the degradation of a mixture of two contaminants: sulfamethoxazole and diclofenac. RESULTS: The presence of the catalysts had no significant impact on pharmaceuticals removal when compared with single ozonation. However, both materials increased the amount of COD removed per mg of ozone applied (0.10 mgCODremoved mg−1O3 and 0.067 mgCODremoved mg−1O3 for catalytic and single ozonation, respectively). The performance of Mn-Ce-O was very dependent upon the solution pH whereas no significant pH impact was detected for N-150. The generalized kinetic model (GKM) was able to satisfactorily describe the lumped kinetic mechanism concerning COD abatement. Moreover, no differences in the degradation results were observed for the Mn-Ce-O system when comparing two types of waters (ultrapure and natural) used to dissolve the pharmaceutical compounds. Importantly, the presence of the solid catalyst improved ozone usage and reduced the effluents' toxicity. CONCLUSION Although work has been published regarding the removal of single emerging contaminants, the analysis of mixtures is not so frequent. The use of Mn-Ce-O truly enhances COD degradation revealing its potential as heterogeneous catalytic material to improve ozone action on pollutants. © 2015 Society of Chemical Industry