The combined method to synthesis silica nanoparticle by Stöber process

To get the controlled size and monodispersed silica nanoparticle is a popular topic since its broad applications are in a lot of fields such as biological medicine, military project, catalyst, and chip industry. The Stöber process was often used to prepare silica nanoparticle because of its low cost and easy operation. Here, the combined method of microchannel and microwave was proposed to accelerate the rate of both nucleation and growth reactions, which is important to the dimension and uniformity of the monodispersed silica nanoparticle. It was found that the particle size ranging from 15 to 400 nm was achieved by varying the concentration of TEOS and NH₄OH with the combined method of microchannel-mixed (MC) and microchannel-microwave (MM). X-ray powder diffraction, Fourier transform infrared spectroscopy, dynamic light scattering, and scanning electron microscopy were used to characterize all the particles. Compared with the MC way, it showed a larger particle size and narrower distribution under the same operating condition experiment with the MM method due to the higher reaction rate of the nucleation and growth. When the concentration of NH₄OH is 0.2 M, the size range of produced particles for the MC method is 17.7–28 nm comparing to the MM method is 151–213 nm. Besides, the higher yield of the silica nanoparticles was obtained by the MM method than the MC way because of the better mass and heat transfer. When the concentration of TEOS is 0.25 M, the yield of silica produced by the MC method is 70–77% comparing to the data of 87–92% by the MM combined method. The results of this paper may have important implications for developing the productivity of the industry.