Shear turbulence controllable synthesis of micro particles in a turbulent Rankine vortex flow reactor – mechanism and applications

Abstract

A large amount of attention has been paid to the approaches of synthesis micro/nano particles. In comparison with other methods such as hydrothermal treatment or self-assembly method, shear controllable methods have been attractive in recent study. Shear controllable synthesis has the advantages of precise control, high mass transfer rate and variable properties of synthesized production. In order to promote research in this area, we have developed a reactor, a counter swirling flow reactor, which can improve the mixing performance and mass transfer rate several times than conventional mixing tank.
This dissertation involves numerical simulations and micro/nano particle synthesis. First, we focus on the computational fluid dynamics inside the reactor. By using the ANSYS Fluent, hydrodynamic characteristics are captured giving a general concept of the underlying mechanisms. We highly concentrate on the shear turbulence at high Reynolds number, because the shear rate is the key factor in determining the size, particle size distribution and morphology of the production. Meanwhile, empirical formulas are given for better describing the relationship between hydrodynamics and synthesised particles.
Second, the effects of shear rate induced by both hydrodynamics and ultrasound irradiation under different experimental conditions have been illustrated. Because of the simplicity of the hydrolysis and condensation reaction of Tetraethyl orthosilicate (TEOS), amorphous nature and simple kinetics analysis, synthesis of SiO2 is chosen as the experiment object. The spherical mesoporous SiO2 nanoparticles are widely applied in Adsorption, catalysis, photoluminescence and biomedicine. However, particle size and morphology controllable technologies do not meet the industrial requirements. Based on the above discussion, it can be postulated that the characteristics of mesoporous SiO2 nanoparticles can be affected by local shear turbulence. To reveal the exact influence of the local shear turbulence on production, several analysis methods have been adopted, such as Scanning Electron Microscopy image, N2 adsorption–desorption isotherm measurement, Fourier transform infrared spectroscopy and particle size analysis.
Overall, the results of the work give an insight into the shear controllable synthesis process, which can provide a platform for further industrial synthesis. Future works of study on the mechanism and application of shear controllable synthesis of silica will be studied in much greater detail.

Date of Award	Jul 2022
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Xiaogang Yang (Supervisor) & Hao Chen (Supervisor)