Síntese, caracterização e aplicação de compósitos de SnO2 e SnO2/Ag2O com pasta de cimento

Abstract

The production of new photocatalytic materials has gained a huge interest over the last few years as a promising strategy to mitigate human-caused environmental damage. Therefore, this work collaborates with the sustainable development of new materials for advanced applications in civil engineering. In this work, we prepared a composite of cement paste (water/cement ratio = 0.5) with a coating based on nanoparticles of SnO2 (SnO2/cement paste) and SnO2 decorated with Ag2O (Ag2O-decorating SnO2/cement paste) for photocatalytic applications. These coatings were produced through the hydrothermal synthesis process and characterized by different experimental techniques. The photocatalyst efficiency was evaluated in this study through the degradation of the methylene blue dye, with and without the presence of inhibitors, which allowed a more fundamental understanding of the reactive oxygen species that can cause the complete mineralization of this dye. This composite was also subjected to the Fenton-like process after being decorated with silver oxide for the degradation of methylene blue and methyl red dyes, individually and mixed. In addition, in this study, the effect of pH was also investigated using a pH variation between 2 and 6. The results of dye degradation obtained through the photo-Fenton process are clearly higher when compared to the reference photocatalysis. On the other hand, the decorated material significantly improved the degradation efficiency as the presence of silver oxide was increased and the pH of the solution was decreased. However, at pH 6 a selectivity was observed during the degradation of the dye mixture, giving preference to the degradation of methylene blue instead of methyl red.