Silica Gel Properties

Silica Gel Properties

Silica gel allows it to absorb water readily. It has a very high porosity, around 800 m²/g. Therefore it is useful as a desiccant (drying agent). It can reduce the relative humidity around 40% in a closed space. Once the silica gel reached its maximum absorption level, it will stop absorbing moisture. But we can be regenerated (dried) by heating it for 1.5 hours per liter (about 1 dry quart measure or about 30oz weight) to 150°C (300°F)  in a thick-walled Pyrex dish.

Silica gel is non-toxic, non-flammable and chemically unreactive. Regeneration of Silica Gel is possible by heating the crystals in an oven. The oven temperature of not more than 300° F (149° C) for approximately three hours or until the crystals turn blue or transparent white. 

By heating in a microwave oven dehydrating the desiccant may also be accomplished. Heat the crystals for three-minute intervals until the color change occurs by using a 900-watt oven. For small purposes, we can re-use silica gel by re-heating it with Oven.

The actual amount of time required will depend upon the oven wattage. Spreading the desiccant in a bread pan in a shallow layer will speed the process. Heating to 325° F (149° C) or more, or using a microwave oven over 900 watts can damage the gel and render it unable to absorb moisture.

Silica Gel has a very strong affinity for water and will adsorb it in preference to most other substances. It is also a good adsorbent for HC1, gasoline-range hydrocarbons, CO2, C12, Sulphur and nitrogen compounds, aromatics, and many others.

Silica Gel is widely using in many industries for a large number of applications where a high capacity desiccant or selective adsorbent is required. It is used for different purposes in different forms. For example, if the purpose is cargo protection, cargo desiccant is there. If the purpose is medicine protection, oxy-guard is there. We can choose it based on our application.