with moisture indicator free of heavy metals
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Synonym: Silica gel
Properties
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Related Categories
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Adsorbents, Filter Aids and Drying Agents, Analytical Reagents, Analytical/Chromatography, Application Specific Reagents, Drying Agents,
More...
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InChI Key
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VYPSYNLAJGMNEJ-UHFFFAOYSA-N
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quality
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with moisture indicator free of heavy metals
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impurities
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≤0.025% soluble in chloroform
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loss
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≤2% loss on drying, 150 °C, 3 h
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particle size
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2-5 mm
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capacity
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≥25 % absorption capacity (water)
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bp
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2230 °C
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Silica gel is a granular, vitreous, porous form
of silicon dioxide made synthetically from sodium silicate. Silica gel
contains a nano-porous silica micro-structure, suspended inside a liquid.
Detailed description
Most applications of silica gel require it to be
dried, in which case it is called silica xerogel. For practical purposes,
silica gel is often interchangeable with silica xerogel. Silica xerogel is
tough and hard; it is more solid than common household gels like gelatin or agar. It is a naturally occurring mineral that is purified and
processed into either granular or beaded form. As a desiccant, it has an average
pore size of 2.4 nanometers and has a strong affinity for water molecules.
Silica gel is most commonly encountered in everyday
life as beads in a small (typically 2 x 3 cm) paper
packet. In this form, it is used as a desiccant to control
local humidity to avoid spoilage or degradation
of some goods. Because silica gel can have added chemical indicators (see below) and absorbs
moisture very well, silica gel packets usually bear warnings for the user not
to eat the contents.
Applications
Desiccant
In many items, moisture encourages the growth of
mold and spoilage. Condensation may also damage other items like electronics
and may speed the decomposition of chemicals, such as those in vitamin pills.
Through the inclusion of silica gel packets, these items can be preserved
longer.
Silica gel may also be used to keep the relative humidity (RH) 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 frequency, degrading the signal. It is common for a small
compressed air system (similar to a small home aquarium 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 compressor discharge flows through a bed
of silica gel beads. The silica gel adsorbs moisture from the air, preventing
damage at the point of use of the compressed air due to condensation or
moisture. The same system is used to dry the compressed air on railway
locomotives, where condensation and ice in the brake air pipes can lead to
brake failure.
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, syringes, drug test kits and hospital
sanitation kits.
Chemistry
In chemistry, silica gel is used in chromatography as a stationary phase. In column chromatography, the stationary phase is most often composed of silica gel
particles of 40–63 μm. 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. In this application, due to silica gel's polarity,
non-polar components tend to elute before more polar ones, hence the name normal phase
chromatography. However, when hydrophobic groups (such
as C18 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 to aluminium, glass,, or plastic sheets for thin layer
chromatography.
The hydroxy (OH) ,groups on the surface of silica
can be functionalized to afford specialty silica gels that exhibit unique,e
stationary phase parameters. These so-called functionalized silica gels are
also used in organic s,ynthesis and purification as insoluble reagents
and scavengers.
Chelating groups have also been covalently bound to
silica gel. These materials have the ability to remove metal Ions selectively
from aqueous media. Chelating groups can be covalently bound to polyamines that
have been grafted onto a silica gel surface producing a material of greater
mechanical integrity. Silica gel is also combined with alkali metals to form
a M-SG reducing agent.
Cat litter,
Silica gel is also used as cat litter,[8] by itself or in combination
with more traditional materials, such as clays including b,entonite. It is non-tracking and virtually
odorless.
Food additive
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 (GRAS), meaning it can be added to food
products without needing app,roval. Silica is allowed to be added to food in
the US at up to 2% as permitted under 21 CFR 172.4,,80. In the EU it can be in
up to 5% concentrations.
Listed use,s include: anticaking agent, defoaming
agent, stabilizer, adsorbent, carrier, conditioning agent, ch,illproofing
agent, filter aid, emulsifying agent, viscosity control agent, and
anti-settling agent.
1, 6×1, 2.5 kg in poly bottle
500, 6×500 g in poly bottle
PRICE
$129.36/KG OR $58.80/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
e-mail: emeabau@yahoo.com
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