Synthesis of Silica-Coated Uranium Oxide Nanoparticles by Surfactant-Templated Sol-Gel Process for Use as Catalysts

Uranium oxide (U₃O₈) nanoparticles were synthesized and coated in situ with porous, mesostructured silica using a modified sol-gel method for use as a catalyst. The catalytic property of coated U₃O₈ nanoparticles was evaluated by exposing them to an aqueous solution of benzene at 500 mg/l at room temperature. The presence of benzene was not detected by an ultraviolet (UV)-visible (UV-vis) spectrometer after 6 weeks of exposure to coated uranium oxide nanoparticles, indicating the particles' potential as a catalyst. Based on the results of the benzene destruction, it may be suggested that the coated U₃O₈ nanoparticle-based catalyst has the potential to destroy hydrocarbons, aromatics, and various toxic substances such as perchlorates and 1,4-dioxane from groundwater. However, further experiments are necessary to explore the full potential of the catalyst. Pluronic-123, n-butanol, and 2-propanol were used as surfactant, cosurfactant, and continuous phase, respectively, for the synthesis of the U₃O₈ nanoparticles, which were formed through nucleation, growth, and subsequent aggregation in the solution phase. The nanoparticles were coated in situ using an aqueous solution of tetraethyl orthosilicate. The coated particles were characterized using transmission electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, nitrogen physisorption, X-ray diffraction, and diffuse reflectance UV-vis spectroscopy. These measurements revealed that U₃O₈ particles ranging from 4- to 10-nm were distributed exclusively inside the silica matrix.