How is Low Sodium Type Colloidal Silica/Silica Sol prepared?

In the vast field of materials science, Low Sodium Type Colloidal Silica plays an important role in many industries such as coatings, casting, and textiles due to its unique physical and chemical properties. This article will explore the preparation process of this high-performance material and introduce its transformation process from raw materials to finished products.

The first step in preparing Low Sodium Type Colloidal Silica is to select suitable raw materials. The main raw materials are silicon tetrachloride (SiCl₄), water (H₂O), and hydrogen (H₂) and oxygen (O₂) as catalysts. These raw materials must undergo strict quality control to ensure the purity and performance of the final product. In the pretreatment stage, the raw materials usually need to be purified to remove impurities. In particular, silicon tetrachloride, due to its high reactivity and potential toxicity, must be operated under closed and safe conditions to ensure production safety and environmental friendliness. The core step in preparing Low Sodium Type Colloidal Silica is the gas phase hydrolysis reaction, which is usually carried out in a special reactor that can accurately control parameters such as temperature, pressure and gas flow. In the reactor, silicon tetrachloride gas is mixed with hydrogen and oxygen in a certain proportion and undergoes a hydrolysis reaction under high temperature conditions. The reaction equation can be roughly expressed as: SiCl₄ + 2H₂O → SiO₂ + 4HCl. In actual industrial production, the reaction conditions are more complicated, involving multiple steps and intermediates. By precisely controlling the reaction conditions, such as temperature, pressure and gas composition, silica particles with uniform particle size and good dispersion can be generated. In order to obtain low sodium products, specific additives must be added during the reaction or specific post-treatment processes must be used to reduce the sodium content in the final product. After the reaction is completed, the resulting mixture needs to undergo separation and purification steps to extract colloidal silica, which usually includes filtering, washing, drying and other steps. During the filtration process, the silica particles are separated from the unreacted raw materials and by-products by a suitable filter medium, and then the silica particles are washed multiple times to remove residual impurities and salt. Finally, the washed particles are dried to obtain the final low-sodium colloidal silica product.

The preparation process of Low Sodium Type Colloidal Silica is a complex and delicate process involving multiple steps and control of key parameters. By continuously optimizing the preparation process and improving the production technology level, higher quality and lower sodium content colloidal silica products can be produced to meet the growing market demand.