Size-tunable synthesis of monodisperse thorium dioxide nanoparticles and their performance on the adsorption of dye molecules

We report a facile method to synthesize monodisperse, uniform and size-controllable thorium dioxide nanoparticles via a hydrothermal precursor synthesis and a subsequent calcination treatment. Highly uniform spherical precursor nanoparticles with a tunable diameter of 38-274 nm and monodisperse irregular precursor nanoparticles with a size range of 20-45 nm can be successfully synthesized using thorium nitrate pentahydrate, urea and glycerol as the metal source, nucleation agent, and size-controlling agent, respectively. The chemical composition, growth process, and size control of the precursor nanoparticles have been systematically investigated, and a probable formation mechanism of these nanoparticles was also proposed. Calcination of precursor nanoparticles at 800 degrees C leads to the formation of uniform thorium dioxide nanoparticles without any morphological deformation. Furthermore, the size and shape effects of thorium dioxide nanoparticles on the uptake of dye molecules have been studied. The corresponding adsorption behaviors of as-prepared samples can be elucidated very well by the nitrogen adsorption-desorption analysis.