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Air Purifiers, Cleaners & Ionizers
Reviews, Comparisons & Buying Guide

Carbon Air Filters: What They Are,
How they Work and the Difference in Carbon Filters

Carbon filtering is a method of filtering that uses a piece of activated carbon to remove contaminants and impurities, utilizing chemical adsorption. When a material adsorbs something, it attaches to it by chemical attraction. The huge surface area of activated charcoal gives it countless bonding sites. When certain chemicals pass next to the carbon surface, they attach to the surface and are trapped.

Each piece of carbon is designed to provide a large section of surface area, in order to allow contaminants the most possible exposure to the filter media. One pound (454g) of activated carbon contains a surface area of approximately 100 acres (1 km/kg). This carbon is generally activated with a positive charge and is designed to attract negatively charged water contaminants. Carbon filtering is commonly used for water purification, but is also used in air purifiers.

There are two predominant types of carbon filters used in the filtration industry: powdered block filters and granular activated filters. In general, carbon block filters are more effective at removing a larger number of contaminants, based upon the increased surface area of carbon.

Activated Carbon

Activated carbon, also called activated charcoal or activated coal, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions. The word activated in the name is sometimes substituted by active. Due to its high degree of microporosity, just one gram of activated carbon has a surface area in excess of 500 m (or about 2 tennis courts), as determined typically by nitrogen gas adsorption. Sufficient activation for useful applications may come solely from the high surface area, though further chemical treatment often enhances the adsorbing properties of the material. Activated carbon is usually derived from charcoal. Properties of activated carbon include:

  • Has a capacity for virtually any vapor contaminant; it will adsorb some of almost any vapor.
  • Has a large capacity for organic molecules, especially solvents.
  • Will adsorb and retain a wide variety of chemicals at the same time.
  • Has an extremely large capacity to catalytically destroy ozone, a major component of smog.
  • Works well under a wide range of temperature and humidity conditions.
  • Adsorbs odors and chemicals preferentially to moisture. It is not a desiccant and will release moisture to adsorb chemicals.
  • Can be used as a carrier of one material to attract and hold or react with another material.
  • Is inert and safe to handle and use.

Activated carbon can be enhanced and impregnated and/or custom blended to be a more specialized adsorbant. For instance, Airpura Air Cleaners offers a super impregnated carbon blend where the problems are formaldehyde or ammonia based.

The Amount of Carbon Matters

Activated carbon adsorbs to it's surface. When there is no more surface left to adsorb to the carbon, it is depleted of its capability to be effective. Large amounts of carbon will last longer then small amounts because it has larger amounts of surface area for adsorption. Also, depending on amounts of pollutants being adsorbed, a small amount of carbon can be depleted within weeks making it useless.Airpura Air Cleaners offer either a 18 or 26 pound carbon bed.

The Thickness of Carbon Matters

The more contact time carbon has with a pollutant, the better chances of it adsorbing it. The thicker the carbon filter the better the adsorption. If the pollutant has to go through a long maze of activated carbon, it's chances are better of being adsorbed. That means that thin carbon filters that are used in inexpensive air purifiers are not very effective at removing chemicals, fumes and odors from the air.

Coconut Shell Activated Carbon

Coconut shell carbon's superior level of hardness makes them cleaner than most other carbons and gives them longer life expectancy. This, combined with their high activity level, makes them well suited for use in any kind of carbon filter or system. Aside from general air purification and deodorization, our coconut shell carbons are also very effective in solvent recovery applications.

Acid Washed Granular Coconut Shell Activated Carbon, like its name, comes from the coconut shell that has been undergone steam activation process to create its activated carbon form. During activation, it creates millions of pores at the surface of the carbon thus increasing the total surface area. Activated carbon pores can be divided into three general sizes:

  • Micro-pores (diameter in the range of less than 2 nm)
  • Meso-pores (diameter in the range of 2 - 25 nm)
  • Macro-pores (diameter in the range of above 25 nm)

Coconut shell carbon has mainly micro-pores to meso-pores, and due to its unique distribution of pores diameter, coconut shell activated carbon are very popular in the gas phase purification and potable water purification industries. Airpura Air Cleaners use Coconut Shell Carbon.

Anthracite Carbon

Anthracite is a hard, compact variety of mineral coal that has a high lustre. It has the highest carbon count and contains the fewest impurities of all coals, despite its lower calorific content. Anthracite is the highest of the metamorphic rank, in which the carbon content is between 92% and 98%. The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapors when heated below their point of ignition. Anthracite ignites with difficulty and burns with a short, blue, and smokeless flame. Anthracite carbon is best for exhaust fumes, burning wood or petrochemicals. Airpura offers Anthracit Carbon as an option.

Airpura Commercial HEPA and Carbon Air Cleaners

Airpura Commercial Air Cleaners with True HEPA and CarbonAirpura is a completely new air cleaner with all the design improvements lacking in other similar technology systems. Airpura design principles include a simplified unobstructed air flow for quieter more efficient performance and reduced noise. The prefilter can be vacuumed through the mesh for easy monthly maintenance, then replaced every 12 months. Two special microbial (bacteria and viruses) suppressing filters help to protect the hefty 18 or 26 pound carbon bed. Felt gaskets are used to seal the filter chamber, eliminating rubber seal off gassing. The metal capped HEPA filter removes the possibility of any plastic vapors from non-metal caps.

Airpura uses a powerful, variable speed integrated fan/motor, letting you choose the rate you clean your air from super quiet to premium power filtering with 560 CFM capacity. With Airpura's effective pressure sealed filter chamber, all air is filtered; NO particles or gases escape. Other systems allow leakage and can't achieve the claimed 99.97% HEPA efficiency. And, Airpura offers the cleanest air, using superior quality true HEPA and activated carbon (special carbon blends are available) with optional UV sterilization to deliver truly clean air for home, office and industrial applications. Airpura is available in eight models and three colors: Cream, white and black. more info

Find the Right Air Purifier for
Your Unique Problem or Application

It's no mystery that the air inside our homes, offices and nearly every building we enter is contaminated with toxic air pollution problems. But wading through the plethora of air purification technologies and models to make our living and working space free of pollution can be a daunting task, especially with the misinformation presented by so many salespeople and web sites. There are many different air purification technologies and air filters on the market, but no one air purifier technology can solve every air pollution problem, which is why we carry different brands. For help determining which air purifier is right for you, click on one of the below links or call us toll free at 866-875-4386 (US and Canada).

Air Purifiers: by Problem - by Technologyby Brand - Air Purifier Buying Guide 

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