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ACTIVATED
CARBON is an industrial chemical used for air
and water filtration and purification which is produced by the activation
of coconut shell charcoal, wood, fruit kernels or sawdust.
Activation is the process of removing
hydrocarbons adhering to the carbon material by means of
chemical or thermal treatment This is usually done in a rotary
kiln, where the charcoal is heated to a temperature of 800-1000oC in an atmosphere
of superheated steam. The reaction between the steam and charcoal
takes place at the internal surface, allowing the breakdown
and removal of hydrocarbons, thus producing a highly developed
network of tunnels and pores that are ideal sites for ADSORPTION.
Under a
scanning electron microscope the pores appear like a porous
bath sponge. |
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HOW
IT WORKS One gram of
activated carbon is said to have the surface area of a 1,200
square meters- a large as a football field!
It is this vast internal surface that gives activated carbon
its unique ability to adsorb a wide range of compounds from
both the gas and liquid phases. Once the targeted compound is
in contact with the activated carbon, it diffuses into its pores
and is locked in place by weak Van de Waals forces. The process
of transferring molecules from the gas or liquid phases onto
a solid surface is called ADSORPTION.
Pores in activated carbon vary in size and can be classified
into three types: micropores which are less than 20 nm; mesopores
which are 20-200 nm and macropores which are 200 nm and above.
The meso and macropores are the tunnels that lead to the micropores.
When used for air or water purification
activated carbon works on the same principal as a sieve – polluted
air or liquid is sent through a screen of activated carbon
that absorbs toxic matter.
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AMONG THE CONTAMINANTS EFFECTIVELY REMOVED
BY ACTIVATED CARBON are: arsenic, asbestos, benzene, atrazine, carbon
tetrachloride, chlorine, chlorobenzene, chromium, copper, ethylbenzene,
ethylene dibromide, heloketones, hexachlorobutadiene, hydrogen sulfide,
iron, mercury, dichlorobenzene, radon, pentachlorophenol, styrene,
toluene, xylenes, zinc and trichloroethylene.
Why Coconut Shell AC is Superior vs. Other AC?
Demand for Coconut Shell Activated Carbon is projected
to grow with stricter environmental legislation and the rise in
living standards requiring improved air and water purification.
Activated carbon can be made from a wide variety of
materials, among them wood, coal, sawdust, sugar cane bagasse and
fruit kernels. However, activated carbon manufactured from coconut
shells is considered superior to those obtained from other sources
mainly because of its micropore structure - majority
of the pores having a diameter of less than 2 nanometers!
This makes it more effective for the adsorption of
gas/vapour, for the removal of color and odor compounds and for
solvent recovery.
In addition to this, coconut shell activated
carbon has high adsorption capabilities and low ash content. Its
intrinsic hardness and abrasion resistance make coconut shell carbons
ideal for use in gold recovery.
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