Síntese e caracterização dos fotocatalisadores SnO2, NiO e SnO2/NiO5%, aplicados na degradação do potencial poluente orgânico azul de metileno

Abstract

With the increase in industrial activity, the search for technologies that can solve environmental problems and increase the safety of natural resources has grown. In view of this, heterogeneous photocatalysis has been widely studied, with special attention to the improvement of environmental systems. The objective of this work was to investigate the SnO2 and NiO photocatalysts, in addition to the SnO2/NiO-5% heterojunction, which were synthesized by the precipitation and co-precipitation method. The surface, electronic and structural properties were determined by X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy (DRS/UV-vis), Infrared Absorption Spectroscopy (FTIR) and N2 physisorption analysis using the method B.E.T. The photocatalytic activity of the systems was evaluated through the photodegradation of methylene blue, a potential organic contaminant widely used by industries as a textile dye. A bandgap value of 2.38 eV for SnO2, 3.37 eV for NiO and 2.0 eV for SnO2/NiO-5% was observed, noting that the bandgap for the heterojunction exhibited a decrease compared to the oxides pure, which may be promising for activating this material with wavelengths in the visible range of the electromagnetic spectrum. In addition, the heterojunction presented a surface area value of 62.2 m2 /g-1 , higher than the individual. After 120 minutes of reaction in the presence of UV irradiation, the photocatalytic efficiency values of the materials were 54%, 32% and 15% for SnO2, SnO2/NiO-5% and NiO, respectively. The result showed that for SnO2 and SnO2/NiO-5% heterojunction, which are materials with similar properties, there was a greater efficiency compared to pure NiO. Also, due to the decrease of the main characteristic band of methylene blue, located at 664nm, the cleavage path of the chromophore structure was identified as the predominant photodegradation route present in the absorbance spectra of all photocatalysts. In general, it is worth mentioning that the literature presents few reports on the synthesis and use of the aforementioned systems in the photodegradation of contaminants, which drives the search for more studies. Demonstrating the feasibility of this investigation.