Studies On Preparation And Technology Of Silica Microspheres And Nano-Ceria

The properties of a material are closely related to its morphology and size.Usually,the morphology and size of the material determine its application.The silica microspheres have a large specific surface area,stable physical and chemical properties,easy surface modification,and a wide particle size distribution.It has a wide range of application prospect.Cerium dioxide has good catalytic and ultraviolet absorption,and it has better performance at nanoscale.However,there are still many challenges in controlling the morphology and size of materials and preparing products with uniform particle size,good dispersibility,high yield and low cost.In this thesis,the template method and modified sol-gel method were used to prepare monodispersed silica microspheres with uniform size,large specific surface area and high yield,and explored the influence of various factors on the final product.The precipitation method and the combustion method were used to prepare flake nanometer cerium oxide and light nanometer cerium oxide.The prepared cerium oxide nanosheets had good dispersibility and good UV shielding effect.The main contents are as follows:?1?Monodisperse silica microspheres prepared by template method.Using cetyltrimethylammonium bromide as a template,ethyl orthosilicate as a silicon source,and diethanolamine as a catalyst,monodisperse silica microspheres with different particle sizes were successfully synthesized.We explored the effects of temperature,cetyltrimethylammoniumbr omide,ethyl orthosilicate,and diethanolamine on the microsphere morphology and particle size of silica through a series of characterization methods.The experimental results show that the particle size of the silica microspheres decreases with the increase of temperature,cetyltrimethylammonium bromide,and diethanolamine,and increases with the increase of ethyl orthosilicate.Monodisperse silica microspheres with a diameter of200 nm³?m,a surface area of 835 m²·g^-1,and an average pore diameter of 2.3 nm.The formation mechanism of monodisperse silica microspheres was studied.The prepared silica microspheres have potential application value in the fields of drug loading,rubber reinforcement,cosmetics and so on.?2?Monodisperse silica microspheres prepared by modified sol-gel method.Mono-dispersed silica microspheres were prepared by using modified sol-gel process with ethyl orthosilicate as the silicon source,anhydrous ethanol and deionized water as the mixed solvent,and triethylenetetramine as the catalyst.Effects of temperature,the ethanol/deionized water,the concentration of triethylenetetramine,the concentration of ethyl orthosilicate,and the inorganic salt on the microsphere appearance and particle size of monodispersed silica.The experimental results show that the diameter of the silica microspheres decreases with the increase of deionized water/ethanol,the concentration of triethylenetetramine decreases,the temperature decreases,and the orthosilicic acid As the concentration of ethyl ester increased,the amount of potassium chloride increased,and monodispersed silica microspheres with a particle size of about 230 nm to 1.5?m were obtained,The monodisperse silica microspheres was investigated and discussed,Silica microspheres were prepared by small-scale pilot scale experiments,up to 500 g.?3?Preparation and properties of cerium dioxide nanosheets.With cerium nitrate hexahydrate as the cerium source and triethylenetetramine as the precipitant,the cerium dioxide nanosheets were prepared by the precipitation method without a template.The experimental results were compared with the products on the market in terms of characterization and properties.As a result,the shape,size,particle size,dispersibility,and intensity of UV absorption of the nanosheets are much higher than those on the market.In this experiment,triethylenetetramine is more stable than the traditional synthesis using ammonia,which reduces the particle size of cerium dioxide,makes the synthesized nano-cerium oxide difficult to agglomerate,has good dispersibility,effectively reduces the reaction temperature,and also makes the synthesis method It has operating procedures simple,low energy consumption,easy control and provides the possibility for the synthesis of nanometer cerium oxide in a large amount,this chapter is a small-scale experiment.The purpose is to provide data and market comparison for industrial production.?4?Study on preparation and properties of light porous nano cerium oxide.Using cerium nitrate hexahydrate as the cerium source and ascorbic acid as the complexing agent,a lightweight porous nano-cerium dioxide was prepared by the combustion method.The effect of the complexing agent on the lightweight nano-cerium dioxide was explored.n?Ce?NO₃?₃·6H₂O?:n?C₆H₈O₆?=10:4,research have shown that this method can obtain nano-cerium oxide without precipitant and surfactant,light and porous,color adjustable,larger than the surface,synthetic The process is simple,low cost of preparing raw materials,environmentally friendly,low equipment requirements,high production efficiency,good reproducibility,and easy industrial production.