Activated carbon is defined as carbon that has been heated or otherwise treated to increase its adsorptive capacity.
The key property of activated carbon is adsorption, which allows gases and chemicals to adhere to millions of microscopic pores on the internal surface area of the material. Adsorption should not be confused with absorption (spelled with a B). Adsorption is the adhesion of molecules from a gas or liquid (adsorbate) to a surface of a material (adsorbent). Absorption is the process in which a molecule (the absorbate) permeates or is dissolved by a liquid or solid (the absorbent). So Adsorption is a surface adhesion phenomenon while absorption utilizes the total volume of the material to capture the absorbent.
“Activating” carbon is the process of making the carbon high in surface area to facilitate adsorption.
Adsorption opens a world of opportunity for industrial applications. Activated carbon is used to filter water, purify gas, and is even used as an ingredient in prescription medicines.