Alkaline hydrothermal synthesis of homogeneous titania microspheres with urchin-like nanoarchitectures for dye effluent treatments

The heterogeneous photocatalysis technique to treat dye effluents demands micrometer-sized titania aggregates with one-dimensional nanostructures, which possess high photocatalytic activity and at the same time facilitate the catalyst-recovery from a slurry system. In this study, the solution remained after interactions between metallic Ti and hydrogen peroxide was subjected to an alkaline hydrothermal treatment. Microspheres with extremely uniform sizes of ca. 2 mu m in diameter were achieved after a subsequent proton exchange followed by calcination in air. The microspheres were urchin-like aggregates of radially assembled nanowires, which consisted of chain-like anatase single crystallites with an average diameter of 20-25 nm. The homogeneous microspheres calcinated at 600 degrees C possessed a surface area of 45.4 m(2)/g and exhibited an excellent activity to assist photodegradation of rhodamine B in water, which is significantly higher than that of P25 titania nanoparticles. Because of the much easier recovery of the photocatalyst, the homogeneous microspheres synthesized herein may find practical applications in efficient photocatalytic treatments of dye effluents. (C) 2011 Elsevier B.V. All rights reserved.