Effect of annealing temperature on the characteristics, sonocatalytic activity and reusability of nanotubes TiO2 in the degradation of Rhodamine B

Titanium dioxide nanotubes (TiO2 NTs) were synthesized via combined sol–gel and hydrothermal method and annealed at various temperatures. The morphology and crystalline structures of the prepared TiO2 NTs were characterized using scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), X-ray diffraction (XRD) and surface area analyzer. The sonocatalytic activity of the prepared TiO2 NTs was evaluated based on sonocatalytic degradation of Rhodamine B in aqueous solution. Effects of annealing temperature were successfully elucidated and TiO2 NTs annealed at 300 °C had the highest surface area and pore volume. Its sonocatalytic activity could increase by a factor of 3.7 times as compared to the conventional TiO2 powder. Sonocatalytic activity of the annealed TiO2 NTs decreased with increasing annealing temperature above 300 °C due to the destruction of tubular structure, a decrease in the surface area and pore volume and phase transformation from anatase to rutile. Reusability study did not reveal any significant drop in the efficiency for 4 successive cycles under investigation. The morphology, catalyst composition, specific surface area, pore size and pore volume were also investigated after each catalytic cycle.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Annealing temperature influenced characteristics and activity of TiO2 NTs. ▶ The catalyst annealed at 300 °C showed the highest Rhodamine B degradation. ▶ Elucidation of sonocatalytic behaviors based on characteristics. ▶ Ultrasonic irradiation slightly changed the morphology of TiO2 NTs. ▶ TiO2 NTs retained high catalytic activity after the fourth catalytic cycle.