Titanium Dioxide 1D Nanostructures as Photocatalysts for Degradation and Removal of Pollutants in Water

Abstract

The oxidation of organic pollutants in water is the most reported application of a Titanium dioxide (TiO2) photocatalyst. During the last decade, photoreduction with TiO2 has also been explored but simultaneous capabilities for unmodified TiO2 have not been reported yet. Here, we reported on the fabrication of TiO2 nanorods using hydrothermal treatment and compared the effect of two different TiO2 powders as the starting material: P-25 and TiO2 sol–gel (N-P25 and N-TiO2, respectively) which were further calcined at 400 °C (N-P25-400 and N-TiO2-400). XPS and XRD analyses confirmed the presence of sodium and hydrogen titanates in N-P25, but also an anatase structure for N-TiO2. The specific surface area of the calcined samples decreased compared to the dried samples. Photocatalytic activity was evaluated using phenol and methyl orange for degradation, whereas 4-nitrophenol was used for photoreduction. Irradiation of the suspension was performed under UV light (λ = 254 nm). The results demonstrated that the nanorods calcined at 400 °C were more photoactive since methyl orange (20 ppm) degradation reached 86% after 2 h, when N-TiO2-400 was used. On the other hand, phenol (20 ppm) was completely degraded by the presence of N-P25-400 after 2 h. Photoreduction of 4-nitrophenol (5 ppm) was achieved by the N-TiO2-400 during the same period. These results demonstrate that the presence of Ti3+ and the source of TiO2 have a significant effect on the photocatalytic activity of TiO2 nanorods. Additionally, the removal of methylene blue (20 ppm) was performed, demonstrating that N-TiO2 exhibited a high adsorption capacity for this dye.