Activated carbon is a type of carbon widely used to filter pollutants in water and air, and its essence is also a type of carbon. However, the biggest difference between activated carbon and other ordinary charcoal is its larger surface area, similar to the difference between popcorn and corn kernels.

Activated carbon has many small pores at the nm level, and the surface area of one gram of activated carbon can even exceed 3000 square meters. One gram of inactive charcoal has a surface area of only 2.0-5.0 square meters.

There are two ways to produce activated carbon. 1. Physical activation involves placing carbonized raw materials into high-temperature oxidizing gas, which reacts with carbon atoms and some impurity atoms to create pores. 2. Chemical activation, allowing carbonized materials to be immersed in chemicals such as acids, strong alkalis, etc. Acids or strong bases can react with impurities, corroding carbonized materials and creating many pores.

So why do we call some substances "active"? Literally, 'activity' refers to a property that has vitality, activity, and is easily reactive. The "activity" of activated carbon here refers to its large surface area, strong adsorption ability, and easy adsorption of small particles and molecules. Therefore, we believe that materials like activated carbon that are easy to absorb energy or substances from the external environment are "active". For example, activated alumina is also loose and porous, with a large surface area. It is not only a good catalyst and catalyst carrier, but also a strong water removal agent.