Silica white, scientifically known as hydrated silica (SiO₂·nH₂O), is a non-toxic, tasteless, amorphous nano-scale inorganic powder material. Due to its white appearance, fine texture, and excellent properties such as high specific surface area, high activity, good reinforcement, thickening, and anti-adhesion, it has become an indispensable core additive in many industries such as rubber, plastics, coatings, and daily chemicals. Its performance is closely related to the preparation process. With the tightening of environmental policies and the demand for industrial upgrading, the preparation process of silica white is iterating and upgrading from the traditional high-pollution, high-energy-consumption mode to green, efficient, and refined directions.
At present, the mainstream preparation processes of silica white are mainly divided into precipitation method and fumed method. The precipitation method uses water glass (sodium silicate) and inorganic acids such as sulfuric acid and hydrochloric acid as raw materials, and prepares the product through neutralization precipitation, filtration, washing, drying, crushing and other processes. This process has low equipment investment, simple operation, and large output, accounting for more than 90% of the global silica white output, and is widely used in middle and low-end fields such as rubber and coatings. However, the traditional precipitation method has obvious shortcomings: a large amount of high-salt wastewater is generated during the production process, with large pollutant emissions, and the product has low specific surface area and insufficient activity, which is difficult to meet the needs of high-end fields.
The fumed method uses silicon tetrachloride, oxygen and hydrogen as raw materials to generate silica white through hydrolysis reaction in a high-temperature flame. Its products have high purity, large specific surface area, and good dispersibility, and their performance is far superior to that of precipitation method products, which are suitable for high-end fields such as high-end rubber, electronics, and biomedicine. However, the fumed method has the problems of high equipment investment, high energy consumption, and high production cost, which has been difficult to achieve large-scale popularization for a long time and is only used in high-end niche scenarios.
In recent years, the improvement of silica white preparation process has focused on two major directions: greenization and high performance. In terms of precipitation method optimization, wastewater recycling technology has been developed to recover salt substances from wastewater through membrane separation, evaporation crystallization and other processes to achieve zero wastewater discharge; new composite acids are used to replace single inorganic acids, and reaction parameters are optimized to improve the specific surface area and activity of products, narrowing the gap with fumed method products. In terms of fumed method upgrading, low-energy combustion technology has been developed to reduce reaction temperature and energy consumption; raw material ratio is optimized to improve product yield and reduce production cost.
At the same time, new preparation processes such as sol-gel method and microemulsion method are constantly emerging, which can prepare high-end silica white products with uniform particle size and controllable performance, suitable for harsh scenarios such as electronic packaging and high-end daily chemicals. With the in-depth development of green chemical concepts, the environmental protection upgrading and performance optimization of silica white preparation process not only solve the pollution pain points of traditional processes, but also promote its transformation from general-purpose additives to high-end functional materials, laying a solid foundation for the high-quality