Investigation of the Removal of Several Micropollutants Presenting Different Ozone Reactivities from Natural Potable Water Matrix by the Application of Ozonation with the Use of SiO2 and Al2O3 as Catalysts

Abstract

The aim of this study was to investigate the correlation between solid materials and micropollutants, aiming to enhance the removal of the latter during the application of the ozonation process. For that purpose, two solid materials (SiO2 and Al2O3) presenting catalytic activity were used for the removal of eight micropollutants from natural potable water, containing them either separately or in a mixture, by ozonation. The studied micropollutants, presenting different physicochemical properties, are atrazine, ibuprofen, p-CBA (ozone-resistant compounds), benzotriazole, caffeine (with moderate ozone reactivity), carbamazepine, fluoxetine, paracetamol (easily oxidized by ozone). The residual concentrations of carbamazepine, paracetamol, and fluoxetine were found to be lower than 5.9 μg/L, 1.2 μg/L, and 15.5 μg/L, respectively, after 1 min of oxidation time in all studied systems. In contrast, benzotriazole and caffeine removal was enhanced by the addition of catalysts; in both cases the best catalyst was SiO2. Regarding the ozone-resistant compounds, both examined materials enhanced the removal of ibuprofen and p-CBA; however, the best was found to be SiO2 and Al2O3, respectively. In contrast, Al2O3 cannot be considered as an effective catalyst for the removal of atrazine, which presents chemical affinity only with SiO2 and for this reason it can be removed to a higher extent by its presence. Similar results were observed in the study of the mixture, although in this system, the residual concentration of all micropollutants was found to be under the detection limit after the application of catalytic ozonation.