Photodegradation mechanism of metronidazole on nanostructured material type SBA-15/TiO2

Abstract

The water quality to supply the human population has been a growing concern throughout the planet, as well as wastewater treatment. In this context, the photodegradation of the antibiotic metronidazole (MTZ) in aqueous solution was evaluated on nanostructured SBA-15/TiO2 under UV irradiation. The structural and optical characterization of SBA-15/TiO2 indicated the formation of a structure similar to the SBA-15 molecular sieve with band gap energy (Eg) equal to 3.23 eV. The photodegradation of MTZ on SBA-15/TiO2 indicated that the concentration was reduced by 87.70 % after 200 min of irradiation, with 75.52 % of degradation after the third reuse cycle. Comparatively, the photodegradation rate was 63.39 % and 56.7 % for commercial TiO2 (P25) and synthesized TiO2 (NP-TiO2), respectively. The effect of radical scavengers at 10-4 mol L-1 concentration demonstrated that inhibition of radicals O2•- and •OH reduces photodegradation by 76.73 % and 86.13 %, respectively. The photodegradation byproducts analysis by LC-MS indicated that the photodegradation of MTZ begins by oxidation of C-OH by radical O2•- and hydroxylation of the imidazole ring. Through chemical actinometry was obtained 10.6 % of the radiation emitted by UV lamps in the photodegradation process. Furthermore, the degradation of MTZ on SBA-15/TiO2 had a cost-effective $ 21.05 m-3 and was better than that of the other powders studied in this work.