Silica Drying Agent

Silica drying agent is a substance that is made from sodium silicate. It is commonly available as silica gel, although it is actually a solid, granular substance that looks like small pellets or tiny pebbles. Silica itself is a naturally occurring substance that is subjected to purification and processing resulting in silica drying agent.

When used as a desiccant, silica drying agent has a pore size of about 2.4 nanometers, and it has the ability to attract and absorb water molecules.

The most familiar from of silica drying agent are the packets commonly found in commercially available packages containing food items, electronics, or any other item that has to be protected from moisture. These packets of silica drying agent or desiccants are used to control humidity in packages, preventing the spoilage and degradation of items that are sensitive to moisture.

The qualities of silica

The silica in silica drying agent has a very high surface area, and this gives it the ability to absorb water to a considerable degree. This makes silica drying agent ideally suited for use as a desiccant.

Silica drying agent also has the unique ability to be restored to its former absorbent capacity. When the gel has reached its saturation point, simply heating it for two hours at a temperature of 120 °C will restore it to its former condition.

Some types of silica drying agent may pop when it has absorbed enough water. This is caused by the breaking of the silica grains when they come in contact with water.

Although usually colorless, some types of silica drying agent are mixed with either ammonium tetrachlorocobaltate or cobalt chloride. This results in a silica drying agent that changes color from blue to pink when moisture is absorbed.

Using silica as a desiccant

Silica drying agent is commonly used in items where moisture is likely to cause problems such as:

• mold growth
• spoilage
• condensation

Condensation is particularly damaging to electronic items and certain food items. Moisture that condenses in electronic equipment can damage or cause a short circuit in sensitive components, and cause deterioration in the quality of certain food items. By adding a few silica drying agent packets into a package, these products can be protected from much of the damaging effects of moisture.

Common applications for silica drying agents

Some common uses of silica drying agents are:

• for controlling relative humidity in storage and display facilities
• for use in diagnostic strips
• as an ingredient in inhalation devices
• in sanitation kits used in hospitals

Another common usage of silica drying agent is the drying of air in compressed air systems used in transport and industry. This usage is commonly seen in heavy machinery, hydraulic systems, and train brakes, where excessive moisture and condensation can cause a malfunction of the compressed air system. For these applications, the silica drying agent absorbs excess moisture that is present in the air, preventing any moisture related damage at key points of the equipment.

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