What is the difference between hydrated silica and precipitated silica?
Hydrated silica is a form of silicon dioxide, which has a variable amount of water in the formula. When dissolved in water, it is usually known as silicic acid. It is found in nature as opal(which has been mined as a gemstone for centuries), and in the cell walls of diatoms. It is also synthetically manufactured for use in toothpaste as an abrasive to assist in cleaning. Hydrated silica can be dehydrated to produce silica gel, which is used as a desiccant. It is also used in various paints and varnishes and in the production of beer.
Precipitated silica, on the other hand, is formed through a chemical reaction between silicon dioxide and an alkaline solution, such as sodium hydroxide. It is a finely divided, amorphous form of silica that is used in a range of applications, including tires, coatings, and industrial rubber products.
The primary difference between hydrated silica and precipitated silica lies in their manufacturing processes. Hydrated silica is produced through the precipitation of silicon dioxide from a solution and then modifying it with water. Precipitated silica, on the other hand, is produced by combining silicon dioxide and an alkaline solution in a reactor vessel.
Another key difference is the physical properties of the two materials. Hydrated silica has a higher specific surface area and a more porous structure, which makes it useful as a desiccant in applications where moisture control is important. Precipitated silica, on the other hand, has a lower specific surface area and a more uniform particle size distribution, which makes it useful as a reinforcing filler in rubbers and plastics.
In summary, while both hydrated and precipitated silica are forms of silicon dioxide, they differ in their manufacturing processes and physical properties. The choice between the two will depend on the specific application and desired performance characteristics.