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The preparation of nano-sized TiO 2 by microemulsion method is one of the more popular methods in recent years. W/O microemulsion is a thermodynamically stable system composed of water, oil and surfactant. Water is encapsulated by a single layer of surfactant to form a micro-water pool, dispersed in the oil phase, and the ultra-fine particles are controlled by controlling the size of the micro-pod. The size of the nanoparticles due to the size of the micro-pools can be effectively limited by the size of the micro-pools. The key to microemulsion technology is to prepare microemulsions with uniform microscopic size, controllability and stability. The microemulsion method is expected to prepare monodisperse nano-TiO 2 micropowder, but reducing the cost and reducing the agglomeration or the two problems that need to be solved by the microemulsion method, it is estimated that it takes a long time to produce nano-scale TiO 2 in the industry by microemulsion method. .
The advantages of the liquid phase method are wide source of raw materials, low cost, simple equipment, normal temperature reaction, no danger, easy process control, and convenient mass production. However, the liquid phase method tends to cause the local concentration of the material to be too high, the particle size and shape are not uniform, and because the nano TiO 2 particles are small, the specific surface area is large, and the surface energy is extremely high, the drying and calcination processes are likely to cause agglomeration between the particles, which is characterized by hard Reunion makes the product dispersibility worse, affecting the use effect and application range of the product.
Nano-TiO 2 powder, especially rutile powder, surface treatment, a key step in the industrial production of TiO 2 nanoparticles essential. One of the reasons is that due to the polarity of the nano-TiO 2 powder, it is easy to agglomerate in a polar medium, or the excess free energy per unit area is increased, the surface tension is increased, the surface binding energy is increased, and the TiO 2 particles are agglomerated. At this time, the motor potential is relatively high. These TiO 2 agglomerates can be further dispersed only by using those having a greater wetting force than the solid particles, i.e., a free energy low treatment agent at the liquid-solid interface. Therefore, in order to increase the wetting force, the free energy of the liquid-solid interface is further reduced, the electric double layer is thickened, and the TiO 2 with the same charge is mutually repelled, thereby improving the dispersion of the TiO 2 particles and making them excellent. The performance is fully utilized; the second reason is that the photochemical properties of nano-TiO 2 are stable, but they may also be powdered when used for a long time in the atmosphere. Therefore, after surface treatment, the light resistance and weather resistance can be improved. The method of surface treatment and the degree of coating directly affect the scope of application and application effects. At present, the conventional surface treatment measures are that the surface is coated with an inorganic film or (and) an organic film to avoid agglomeration of the nano TiO 2 powder and improve the light resistance and weather resistance of the nano TiO 2 .
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