What is silica gel
Silica gel is an amorphous form of silicon dioxide, which is synthetically produced in the form of hard irregular granules (having the appearance of crystals) or hard irregular beads. A micro porous structure of interlocking cavities gives a very high surface area (800 square meters per gram). It is this structure that makes silica gel a high capacity desiccant. Water molecules adhere to the gels surface because it exhibits
a lower vapor pressure than the surrounding air. When equilibrium of equal pressure is reached, no more adsorption occurs. Thus the higher the humidity of the surrounding air, the greater the amount of water that is adsorbed before equilibrium is reached. It is in these higher humidity conditions (above 50% Relative Humidity) that stored or in-transit items are susceptible to damage.
The beauty of silica gel is the physical adsorption of water vapor into its internal pores. There is no chemical reaction, no by products or side effects. Even when saturated with water vapor, silica gel still has the appearance of a dry product, its shape unchanged.
Silica gel is also known as amorphous silicon dioxide with the chemical formula SiO2.It is used as a drying agent to absorb the moisture in its surroundings. It is very poisonous and can cause sever damages to the human body when eaten. It looks like beads because it is a crystalline solid like glass. In fact glass has the same chemical formula as silica gel.
Standard white silica gel is referred to as being non-indicating. As it adsorbs moisture it remains physically unchanged. Non-indicating silica gel is cheap and effective, available loose in bulk packs or packed in sachets. Self-indicating silica gels have a moisture sensitive additive added to the basic silica gel. This indicator
changes color as moisture is adsorbed thus giving a visual indication as to the activity level of the silica gel.
Related posts:
Leave a Reply