What is silica gel?

Issuing time:2022-11-09 16:58

Silica gel is a highly active adsorption material, usually prepared by reacting sodium silicate and sulfuric acid and undergoing a series of post-treatment processes such as aging and acid foaming. Any solvent, non-toxic, tasteless, chemically stable, does not react with any substances except strong alkali and hydrofluoric acid.

The main component of silica gel is silicon dioxide, which is an amorphous machine-made product made of sodium silicate and sulfuric acid in silica. It is made into granular or beaded form after washing and processing minerals that exist in nature.

Its structure is very similar to a sponge, with interconnected pores forming a capillary adsorption system with a huge surface area, which can absorb and retain water vapor. Under the condition of 100% humidity, it can absorb and condense water vapor equivalent to 40% of its own weight.

As a desiccant, the average pore size of silica gel is 24 angstroms (length unit), it can still absorb moisture even when the temperature is greater than 105 ℃, but when the temperature is greater than 38 ℃, its moisture absorption rate begins to decrease, and its optimum moisture absorption When the temperature is 21℃--32℃, even when the relative humidity is higher than 60%--90%, the relative humidity in the container can be maintained at 40%.

The two characteristics of silica gel make it widely used in the packaging industry, namely non-toxic and non-corrosive, and it is approved by the US FDA agency for use in the food and pharmaceutical industries.

Its main features

High adsorption performance, good thermal stability, stable chemical properties, high mechanical strength, etc. The main reason why silica gel is widely used all over the world is that it is non-toxic, harmless and non-corrosive. At the same time, after the silica gel adsorbs water, the water can be removed by thermal desorption. The temperature for desorption of additional heat is preferably controlled at 120-180 degrees Celsius, and for blue silica gel, it is preferably controlled at 100-120 degrees Celsius. The moisture content of the regenerated silica gel Generally, it can be put into use again under 2%.

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