Carbon filter: forms, working mechanism, application and life span

Carbon filter

A carbon filter is one of the most popular filters known to the world. It is also called activated charcoal which follows the principle of adsorption.


Adsorption is a process by which foreign materials in gases or liquid adhere to the solid surface via a Van der wall force. Once the adsorptive, adsorb to all the porous surface of adsorbing material, the adsorption stops and desorption begins. In that case, you need to change or recharge the filter.

Some of the common examples include

Activating a charcoal

  • Physical activation (heating, solvent extraction, etc.)
  • Chemical activation (acid, base, etc.)

Normal charcoal consists of uneven pores of various sizes. So to bring uniformity in the porosity and to increase the total surface area of the charcoal, it needs to be activated. This also helps to remove non-organic compounds such as water, tar, etc. from charcoal. The other advantage of activating carbon is that it can filter a large volume of fluid than normal carbon.

 Forms of carbon filter

  • Granular form
  • Carbon block
  • Radial flow carbon

Granular form carbon filter

Black form carbon filter



Since it is not compact, water can easily flow through this.

Since it is compactly arranged, water has to face more resistance

Less surface area in comparison to block form carbon filter

More surface area in comparison to granular form carbon filter

A radial flow carbon filter is a mixture of both granular and block forms of carbon.


  • Adsorption of volatile organic compounds such as ethanol, formaldehyde, butanol, acetic acid, etc., and also chlorine.
  • Adsorption of the residues of herbicides, pesticides, etc.
  • Useful to get rid of unpleasant taste and odor from air and water.
  • I have seen a carbon filter in respirator mask, oxygen concentrator, and water purification system that gives HPLC grade of water.
  • It is not good for filtering out heavy metals, dissolved inorganics, minerals, and salts.

Factors affecting the lifespan 

  • Quality of fluid (water and air):- If the fluid is not much polluted, carbon filters will last longer.
  • Size of filter:- More is the size of the filter, the more it can adsorb the molecules.


  • You cannot wash it with soap water.
  • You cannot recharge the filter for reuse. So, when it expires, it is better to replace it with a new one.  


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