Abstract:

Monodisperse spherical SiO₂ particles were successfully synthesized in 2-propanol-H₂O-NH₃ system by the microwave hydrothermal method using ammonia as catalyst. To investigate the influences on the size of spherical SiO₂ particles, factors such as ammonia concentration, reaction temperature, stirring intensity and reactants mol ratio have been studied. The orthogonal experiments were carried out. The as-prepared SiO₂ particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and differential thermal analysis (DTA). The results indicated that the size of SiO₂ particles increased greatly with the increase in ammonia concentration, temperature and reactants mol ratio, but increased slightly with the increase in stirring intensity. Monodisperse spherical SiO₂ particles were amorphous with perfect sphere and uniform size. Hydroxyl was detected in SiO₂. Kinetic parameters were calculated, and finally the reaction rate equation of dehydrated hydroxyl was obtained.

Key words: Monodisperse spherical SiO₂ particle, Microwave hydrothermal method, Amorphous, Reaction rate