Activated carbon filters treat water using a process called adsorption. When water passes through activated carbon, the carbon acts like a sponge with a large surface area, absorbing contaminants from the water. In simple terms, activated carbon exerts a magnetic-like pull on specific impurities, attracting and trapping them in the pores of its surface area.
Dissolved impurities migrate from the liquid to the areas of the pores where the attraction is strongest. Contaminants are absorbed because the attraction on the carbon surface is much stronger than the attraction that kept them dissolved in the liquid. After that, the filtered water flows to the next stage of filtration (if there is one).
As for chlorine and other chemicals that cannot attach to carbon, activated carbon filters use chemical reactions to eliminate these contaminants. Activated catalytic carbon is more reactive than regular carbon and chemically alters chlorine molecules, converting them into chlorides.
GAC filters are ideal for water purification because:
They are porous, cheap and easy to use as an absorbent
They have a larger useful surface area per gram than any other material that can be used for physical adsorption
They are not as restrictive as carbon block filters, thus allowing water to flow through the carbon at a faster rate
They have a longer lifespan
Activated carbon can be reactivated, unlike the disposable powdered particles in carbon block filters
