Carbon filtering is a method of filtering that uses a bed of activated carbon to remove impurities from a fluid using adsorption.
Mechanism
Carbon filtering operates through
adsorption, where pollutants in the fluid to be treated are trapped within the pore structure
of a carbon substrate. The substrate consists of many carbon granules, each of which is highly
porous. Consequently, the substrate possesses a large surface area that can trap contaminants. Activated carbon is typically used in filters because it has been treated to have a significantly higher surface area than untreated carbon. One gram of activated carbon has a surface area exceeding 3,000 m² (32,000 sq ft).
Common uses
Carbon filtering is commonly used for water purification,
and industrial gas processing, for example the removal of
and
hydrogen sulfide from
biogas. It is also used in a number of other applications, including respirator masks, the purification of
sugarcane, some methods of coffee
decaffeination, and in the recovery of precious metals, especially gold. It is also used in
and in the
EVAP used in cars.
When filtering water, charcoal carbon filters are most effective at removing chlorine, particles such as sediment, volatile organic compounds (VOCs), taste and odor. They are not effective at removing minerals, salts, and dissolved inorganic substances.
Filters containing an Adsorption or catalyst such as charcoal (carbon) may also remove and gaseous pollutants such as volatile organic compounds or ozone.
Specifications
Each carbon filter is typically given a
micron rating that specifies the size of particle which the filter can remove from a fluid. Typical particle sizes which can be removed by carbon filters range from 0.5 to 50 μm. The efficacy of a carbon filter depends not only on its particle size, but also on the rate of flow of fluid through the filter. For example, if a fluid is allowed to flow through the filter at a slower rate, the contaminants will be exposed to the filter media for a longer amount of time, which will tend to result in fewer impurities.
See also
Further reading
