How is Sodium Colloidal Silica/Silica Sol prepared?

Sodium Colloidal Silica is a colloidal solution of highly dispersed silica particles suspended in water, in which sodium ions act as stabilizers and play a key role in the solution. The unique physical and chemical properties of this material have been widely used in many fields such as coatings, casting, ceramics, papermaking, textiles and medicine.

The preparation of Sodium Colloidal Silica is mainly based on the acidification reaction of sodium silicate (water glass). In this process, the sodium silicate solution undergoes hydrolysis and polycondensation under acidic conditions to generate silica particles with uniform particle size distribution, which are stably suspended in water to form a colloidal solution. By controlling the reaction conditions, such as acidification rate, temperature, pH value and stirring intensity, the size, distribution and stability of the colloidal particles can be regulated.

Before the preparation begins, high-purity sodium silicate is selected as the raw material to ensure that its impurity content is low to ensure the quality of the final product, and an appropriate amount of acid solution (such as hydrochloric acid, sulfuric acid, etc.) is prepared as a catalyst for the hydrolysis reaction. Slowly drop the sodium silicate solution into the continuously stirred acid solution, or slowly drop the acid solution into the sodium silicate solution to avoid excessive local reaction. During the dropping process, strictly control the dropping speed and stirring intensity to ensure uniform reaction. As the reaction proceeds, the solution gradually becomes turbid, indicating that silica particles begin to form. After the reaction is completed, the resulting colloidal solution is aged at a certain temperature for a period of time to allow the particles to grow further and stabilize. During the aging process, the particle size distribution and colloidal stability of the particles can be optimized by controlling the temperature and time. The aged colloidal solution may contain unreacted raw materials or by-products, so it needs to be filtered and washed. Large particle impurities are removed by filtration, and then washed with deionized water for multiple times to remove residual ions and organic matter. According to the use requirements, the washed colloidal solution can be concentrated to increase its solid content. Adjust the solution parameters such as pH value and viscosity as needed to meet the application requirements of different fields.

The preparation of Sodium Colloidal Silica/Silica Sol is a complex and delicate process that requires strict control of conditions in each link. By optimizing the preparation process, silica sol products with uniform particle size distribution and good stability can be produced, providing strong support for the development of various industries.