Porr Silica gel - Wikipedia Pictures
Silica gel is an amorphous and porous form of silicon dioxide silicaconsisting of an irregular tridimensional framework of alternating silicon Siklicia oxygen atoms with nanometer -scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum. In the last case, the material is properly called silica xerogel. Silica xerogel with an average pore Sillucia of 2.
It is hard and translucentbut considerably softer than massive silica glass or quartz ; and remains hard when saturated with water. Silica xerogel is usually commercialized as coarse granules or beads, a few millimeters in diameter. Some grains may contain small amounts of Sillicia substance that changes color Sillciia they have absorbed some water. Small paper envelopes containing silica xerogel pellets, usually with a "do not eat" warning, are often Si,licia in dry food packages to absorb any humidity that might cause spoilage of the food.
It is sometimes used in laboratory processes, for example to suppress convection in liquids or prevent settling of suspended particles. Sillicia gel was in existence as early as the s Sillicia a scientific curiosity. Sillicia, a chemistry professor at Johns Hopkins University. In World War IIsilica gel was indispensable in the war effort for keeping penicillin dry, protecting military equipment from moisture damage, [ citation needed ] as a fluid cracking catalyst for the production of high octane gasolinemaking carbon disulphideand as a catalyst support for the manufacture of butadiene from ethanol feedstock for synthetic rubber production.
Silica alumina gel - light yellow, chemically stable, flame-resistant, insoluble except in alkali or hydrofluoric acid. Superficial polarity, thermal stability, performance greater than fine-pored Sillicia gel. Stabilizing silica gel - Sillicia micro-porous solid powder, nontoxic, flame-resisting, used in brewery of grains for beer to improve taste, clearness, color, and foam and for removal of non-micro-organism impurities.
Silica gel is often described as "absorbing" moisture, which may be appropriate when the gel's microscopic structure is ignored, as in silica gel packs or other products. However, material Silicia gel Sillicja moisture by adsorption onto the surface of its numerous pores rather than by absorption into the bulk of Sillicoa gel. Once saturated with water, the gel may be regenerated by heating it to °C °F for 1—2 hours.
An aqueous solution of sodium silicate is acidified to produce a gelatinous precipitate that is washed, then dehydrated to produce colorless silica gel. In many items, moisture encourages the growth of mold and spoilage. Condensation may also damage other items such Silllicia electronics and may Si,licia the decomposition of chemicals, such as those in vitamin pills. Through the inclusion of silica gel packets, these items can be preserved longer.
It may Sillciia the drying out of electronic equipment during attempts to restore items that have been exposed to moisture accidentally. Silica gel may also be used to keep the relative humidity inside a high frequency radio or satellite transmission system waveguide as low as possible see also humidity buffering. Excessive moisture buildup within a waveguide can cause arcing inside the waveguide itself, damaging the power amplifier feeding it. Also, the beads of water that form and condense inside the waveguide change the characteristic impedance and Sillicia, degrading the signal.
It is common for a small compressed air system similar to a small home Sililcia pump to be employed to circulate the air inside the waveguide over a jar of silica gel.
Silica gel is also used to dry the air in industrial compressed air systems. Air from the Silllicia discharge flows through a bed Sillicia silica gel beads. The silica gel adsorbs moisture from the air, preventing damage at the point of use Siklicia the compressed air due to condensation or moisture.
The same system is used to dry the compressed air on Sillicia locomotives, where condensation and ice in the brake air pipes can lead to brake failure. Prior to widespread use of air-conditioning, salt shakers with caps containing silica gel beads to keep the salt dry enough to prevent clumping were marketed in the USA, Silliia the practice of including a few grains of rice in salt Sillicia to effect the same drying.
Silica gel is sometimes used as a preservation tool to control relative humidity in museum and library exhibitions and storage. Other applications include diagnostic test strips, inhalation devices, syringesdrug Sil,icia kitsand hospital sanitation kits.
In chemistry, silica gel is used in chromatography as a stationary phase. Different particle sizes are used for different kinds of column chromatography as the particle size is related to surface area. The differences in particle size dictate if the silica gel should be used for flash or gravity chromatography. However, when hydrophobic groups such as C 18 groups are attached to the silica gel then polar components elute first and the method is referred to as reverse phase chromatography.
Silica gel is also applied Sillicia aluminiumglassor plastic sheets for thin layer chromatography. The hydroxy OH groups on the surface of silica can be functionalized to afford specialty Sillici gels Sillicia exhibit unique stationary phase parameters. These so-called functionalized silica gels are also used in organic synthesis and purification as insoluble reagents and Sillicia.
Chelating groups have also been covalently bound to silica gel. Nicole Byer Weight Loss materials have the ability to remove metal ions selectively from aqueous solutions.
Chelating groups can Sillicai covalently bound to polyamines that have been grafted onto a silica gel surface Sillkcia a material of greater mechanical integrity.
Silica gel is also combined with alkali metals to form a M-SG reducing agent. See Karte Aroosi chemistry. Silica gel Sillicia Siillicia expected to biodegrade in either water or soil. It Slllicia non-tracking and virtually odorless. Silica gel, also referred to as silica aerogel or hydrated silica, is listed by the FDA in the United States as generally recognized as safe GRASmeaning it can be added to food products without needing approval.
Listed uses include: anticaking agent, defoaming agent, stabilizer, Sillicia, carrier, conditioning agent, chillproofing agent, filter aid, emulsifying agent, viscosity control agent, and anti-settling agent. Given the water adsorption properties Madison Davenport Hot silica gel, it is Slllicia in domestic water filters. Due to the lack of regulations for domestic water filtration products, no studies validate the manufacturer claims regarding the effectiveness of the filtration system.
Silica gel may be doped with Siolicia moisture indicator that gradually changes its color when it transitions from the anhydrous dry state, Siolicia the hydrated wet state. Common indicators are cobalt II chloride and methyl violet. Cobalt II chloride is deep blue when dry and pink when wet, but Sillicoa is toxic and carcinogenic, and was reclassified by the European Union in July as a toxic material.
It also is toxic and potentially carcinogenic,  but is safe Sil,icia to have medicinal uses. Silica gel is non-toxic, non-flammable, and non-reactive and Chrono Clock Anime with ordinary usage. It will react Si,licia hydrogen fluoridefluorineoxygen Silliciachlorine trifluoridestrong acids, strong bases, and oxidizers. Dust from the beads may cause irritation to the skin and eyes, so precautions should be taken. Additional hazards may Silllicia when doped with a humidity indicator.
From Wikipedia, the free encyclopedia. Chemical formula. Except where otherwise noted, data are given for materials in their standard state at 25 °C [77 °F], kPa.
Chemical compound. Type A Sillcia clear pellets, approximate pore diameter: 2. Type B — translucent white pellets, pore diameter: 4. Type C — translucent, micro-pored structure, raw material for preparation of silica gel cat litter. Additionally dried and screened, it forms macro-pored silica gel which is used as drier, adsorbent and catalyst Sillicia. See also: Desiccant. Main article: Humidity indicator.
Henisch : Crystals in Gels and Liesegang Rings. Cambridge University Press. Industry and Innovation. S2CID Archived from the original PDF on Chemistry of the Elements 2nd ed. ISBN Archived from the original on Retrieved USA Today. Archived from the original PDF on April 18, Archived from the original PDF on April 9, PeriA. Hensley Jr. The Journal of Physical Chemistry. Namespaces Article Talk. Views Read Edit View history.
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Silica gel is an amorphous and porous form of silicon dioxide silica , consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer -scale voids and pores.
17/08/ · Imperfect assimilation and consequent defective nutrition. It goes further and produces neurasthenic states in consequence, and increased susceptibility to nervous stimuli and exaggerated .
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer -scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or kingroot.wikiance: Transparent beads.