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 Bin aqueous solution. Effects of annealing temperature were successfully elucidated and TiO2 NTs annealed at 300 degrees 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 degrees C due to the destruction of tubular structure, a decrease in the surface area and pore volume and phase transformation from anatase to ruffle. 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. (C) 2010 Elsevier B.V. All rights reserved.