silica gel


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silica gel,

chemical compound. It is a colloidal form of silicasilica
or silicon dioxide,
chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white.
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, and usually resembles coarse white sand. It may be prepared by partial dehydration of metasilicic acid, H2SiO3. Because it has many tiny pores, it has great adsorptive power. It is used as a drying agent, as a catalyst or catalyst carrier, and in purifying various substances. Silica aerogelaerogel,
any of a group of extremely light and porous solid materials; the lightest is less than four times as dense as dry air. Aerogels are produced from certain gels (see colloid) by heating the gel under pressure, which causes the liquid in the gel to become supercritical
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 is fully dehydrated silica gel; it is very porous and is often used in insulation, e.g., for refrigerators.

Silica Gel

 

the desiccated gel of polysilicic acid; a solid hy-drophilic sorbent. By composition, silica gel is silicon dioxide (silica), and by structure, a highly porous body composed of extremely minute, accreted spherical particles.

In the manufacture of silica gel, a solution of sodium or potassium silicate (water glass) is first acted upon by hydrochloric or sulfuric acid. The congealed product is then broken into pieces, rinsed with water, dried, ground, fractionated, and roasted to remove all moisture. Commercial silica gel is available in grains or globular granules 5-7 to 10-2 mm in size. Various brands of silica gel have a mean effective pore diameter of 20–150 angstroms and a specific surface of 102-103 m2/g.

Silica gel is used to absorb water vapor and the vapors of organic solvents. It is also used for the absorptive purification of nonpolar liquids and for the separation of alcohols, amino acids, vitamins, and antibiotics in gas and liquid chromatography. Macroporous silica gel serves as a catalyst base.

REFERENCE

Kol’tsov, S. I., and V. B. Aleskovskii. Silikagel’, ego stroenie i khimiches-kiesvoistva. Leningrad, 1963.

silica gel

[′sil·ə·kə ¦jel]
(inorganic chemistry)
A colloidal, highly absorbent silica used as a dehumidifying and dehydrating agent, as a catalyst carrier, and sometimes as a catalyst.

silica gel, synthetic silica

A form of silica which adsorbs moisture readily; used as a drying agent.

silica gel

A form of porous silica used as a desiccant. It is used as a drying or moisture-absorbing agent in packing and sometimes in avionics themselves.

silica gel

An absorbent form of silicon dioxide often wrapped in small packets that is shipped with equipment to absorb moisture. Silica gel packets are desiccants.

Don't Throw Them Away
Silica gel packets can be used to remove odors in a gym bag. Stored in a box of photos, they can prevent them from sticking to each other, and they can extend the life of razors by eliminating moisture. A wet phone can be dried out if placed in a jar filled with the gel bags. See silicon dioxide.


Silica Gel Packets
These commonly found desiccants are small beads of silica gel inside paper packets.
References in periodicals archive ?
The sub-fraction H5 eluted with n-hexane: EtOAc (4: 6) was further purified over silica gel column using a gradient of n-hexane: EtOAc, to get compound 2 (30 mg).
Complete dissolution of silica gel (>90%, which is within the limit of the analytical accuracy) was achieved with a ratio of 1 :200 and higher (Fig.
65 g) by repeated silica gel column chromatography, eluted with different hexane-dichlorometane mixtures.
A controlled amount of silica gel (100, 200, 300, 400, and 500 mg) was dispersed into PAN solution in THF.
In the last 6 months, preliminary metallurgical tests have been conducted by a clay processing engineer who found that the silica gel substance was easily removed by a simple, low-cost washing procedure that may become a proprietary technology.
The commonly used physical adsorbents for adsorption refrigeration systems are activated carbon, silica gel and zeolite.
The gel was dried at 125[degrees]C for 30 min affording a dry, pale yellow lead thiolate doped silica gel precursor.
Their range of dew-point hygrometers are used for a variety of compressed air applications around the world, including compressed air systems, dessicant and rotary wheel dryers, fluid beds, refrigerant membranes and silica gel.
Pamela Jones, Harlow, Essex THE bag of silica gel that you get with your next electronics purchase should not be thrown out.
The researchers further fractionated the neutral fractions using normal phase chromatography with silica gel.
Now, a new method that involves small plastic containers filled with silica gel can keep all your food as fresh as when you bought it and, in some cases, even fresher; and finding the right merchandising strategy can help freshen sales, too.
The highly moisture resistance of the coating was clearly evidenced by putting several color-variable silica gel particles coated with polysilsesquioxane sol into water.