A general and facile method to prepare uniform gamma-alumina hollow microspheres from waste oil shale ash

摘要

A combined process was proposed for the utilization of waste oil shale ash (OSA) in the production of well-shaped Al_2O_3:Eu hollow microspheres. A urea-based homogeneous precipitation technique in the presence of colloidal carbon spheres as hard templates followed by a subsequent heat treatment process was employed for reducing the Al_2O_3:Eu hollow microspheres. XRD results demonstrate that all the diffraction peaks of the samples can be well indexed to the pure phase of γ-Al_2O_3. TEM and SEM images indicate the shells of the uniform hollow spheres whose diameters are about 400 nm. The as-prepared hollow Al_2O_3:Eu microspheres show a strong red emission corresponding to the ~5D_0-~7F_2 transition of the Eu~(3+) ions under 226 nm excitation, which might find potential applications in fields such as light phosphor powders, advanced flat panel displays, and biological labeling. The results obtained in the mentioned method prove that the oil shale ash (OSA) can be used for production of aluminum nanoparticles.