Title : Elimination of sulfamethoxazole using ozone in the presence of catalytic films on iron and nickel base
Emerging pollutants are compounds of different classes, where could find pesticides, drug pharmacists, personal care products, flame retardants, plasticizers, and nanoparticles. Their presence has been quantified in effluents of wastewater plants from different hospitals, principally with a high concentration of pharmaceutical compounds. In other countries of Latin America for example Brazil, Venezuela, Argentina, Colombia, and Ecuador have been detected the presence of sulfamethoxazole was higher than the Predicted No Effect Concentration for health determined a few years ago through the United States Environmental Protection Agency.
In the present study, the degradation of sulfamethoxazole (SX) carried out by ozone in the presence of different catalytic films on the base of Ni, Fe, and Fe:Ni [50:50] synthesized by means of the Ultrasonic Spray Pyrolytic technique (USP)) varying a nozzle size up to 2.5 to 14 mm. The HPLC results showed a total removal of the initial compound by direct reaction with molecular ozone, while the catalyst effect showed in the decomposition of the ozonation intermediates. The catalyst’s activity and selectivity depend on the chemical structure of the treated compound, as well as the catalyst films used in ozonation. In this study, the combined catalyst Fe:Ni [50:50] with a very small concentration (a precursor concentration of 0.1 mol/L) was more effective in the decomposition of ozonation intermediates.
As preliminary results may be seen the greatest crystal agglomerates are produced with a nozzle size of 14 mm, which remarks a significant impact of this parameter on the crystal structure and morphology of the catalyst surface. The HPLC chromatograms of the SX behavior in the ozonation process, where we can observe lower concentrations of SX in the presence of the FexOy:NiO[50:50] combined catalyst at the beginning of the treatment, marking the catalytic effect. The FexOy:NiO[50:50] catalyst showed greater catalytic activity and stability during ozonation, with the removal of 100 % of the SX compounds during 60 minutes of treatment, while the treatment with FexOy, NiO, and O3-conv achieves major by-products formation.
When analyzing the degree of mineralization obtained by measuring TOC for the two systems: conventional and catalytic processes during 60 min of ozonation. Finally, it’s possible to appreciate which method is more effective for the elimination of sulfamethoxazole in an aqueous solution model. The combined catalyst Iron/Nickel system had a major mineralization with only six films prepared at 0.1 mol/L concentration, in comparison with the conventional ozonation. This effect in the catalytic activity could be due to the major formation of oxidizing species (ROS) during the decomposition reaction of ozone.