Toward the large-scale continuous synthesis of flaky barium sulfate

Abstract

The conventional barium sulfate used in foundation cosmetics encountered some problems, such as poor extendibility over the skin, insufficient adhesion to the skin, and another uncomfortable feeling after using it. To overcome these disadvantages, flaky (plate-like) barium sulfate with a large particle size was proposed (Japanese Patent Laid-open No. 41718/1983). Flaky barium sulfate has a specific crystal structure with a relatively high area ratio compared to the other morphology of barium sulfate, and barium sulfate with a flake shape also has unique optical characteristics like shading properties and a smoother feeling. Therefore, flaky barium sulfate can be used in foundation cosmetics to give an excellent skin feel instead of conventional barium sulfate products. However, producing such barium sulfate involves several complicated processes due to the requirement of post-treatment of the crude products, such as heat treatment or washing with mineral acid. However, removing the crude products after such a post-treatment is complex, and developing the desired shape is insufficient. Given this situation, this thesis aims to explore one efficient approach to low energy consumption in the mass production of flaky barium sulfate that satisfies the abovementioned requirements. This thesis involves the synthesis of flaky barium sulfate and using numerical simulation to analyze the influence of fluid dynamics in the chemical reactor on the synthesis process and properties of Barium sulfate:
1. Four different types of reactors, including high-speed shear mixer, simple stirred tank reactor, Taylor-Couette reactor, and ultrasonic reactor, were applied to the small-scale synthesis of barium sulphate. The experiments were carried out in different reactors to obtain the target product by adjusting the operation process parameters, such as reactant concentration, reaction temperature, reactor parameters (rpm, volt), feed flow rate, and others.
2. The morphology and particle size of the products were characterized using a field emission scanning electron microscope and a particle size analyzer. After comparing the products prepared using different reactors, the results show that the Taylor-Couette reactor has an obvious advantage in the synthesis of flaky barium sulfate. Therefore, the Taylor-Couette reactor was determined for the large-scale production of flaky barium sulfate.
3. With the help of ANSYS Fluent, the hydrodynamics generated in Taylor-Couette reactors were captured. The visual descriptions of the fluid mechanisms give insights on the influence of hydrodynamics on the properties of barium sulfate.
Overall, this masterwork provides a feasibility study of application of the Taylor-Couette reactor to synthesize flaky barium sulfate, providing an essential platform for further industrial application. Future research on the characteristics and application of Taylor-Couette reactors in the industry will be expanded further.

Date of Award	Nov 2024
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Guang Li (Supervisor) & Xiaogang Yang (Supervisor)