Materiais de óxido de nióbio para fotodegradação de contaminantes emergentes

Abstract

The treatment of water resources on the planet is a fundamental action for the maintenance of fauna and flora, especially marine ones. However, human development, and the requirement to meet the demands of certain industry sectors such as the pharmaceutical and textile industries, results in the generation of effluents rich in persistent organic pollutants (POPs), which, depending on their chemical nature, can interfere with several chemical processes in these environments, such as photochemical processes in cases of chemical species that absorb UV-Vis radiation, such as RhodamineB and Amiloride. The presence of these pollutants in water leads to significant impacts on the ecosystem in which they are located, which makes it necessary to study mechanisms to combat or reduce the harmful effects resulting from these chemical species in the water environment. One way to treat these effluents is through the photodegradation process, which consists of exciting a semiconductor with UV-Vis radiation that promotes the degradation of chemical species at the system's solid-liquid interface. Niobium oxide (Nb2O5) has been presented as a promising material for use in this process. Therefore, the objective of the present work was to synthesize, characterize and evaluate the photocatalytic capacity of Nb2O5 materials in their pseudohexagonal phase (TT-Nb2O5) obtained from different precursors, niobium pentachloride and niobium ammonium oxalate, by the method of microwave hydrothermal (HM). Among the materials of interest, the sample of Nb2O5 prepared from niobium pentachloride, proved to be inactive, while the Nb2O5 prepared from the precursor niobium ammonium oxalate, showed promising results in the photodegradation of the pollutants in question, with constant kinetics of the processes, at least 8.61 times greater than Rhodamine-B alone and 6.75 times greater than Amiloride alone, leading to complete degradation of amiloride in 30 minutes. Furthermore, the results obtained in photodegradation indicate that the precursor residues are functional groups, which contributes to the photocatalysis mechanism.