Activated carbon is a carbon that has been specially treated. It involves heating organic raw materials (such as fruit shells, coal, wood, etc.) under an oxygen-free condition to reduce non-carbon components (this process is called carbonization), and then reacting with gases, causing the surface to erode and form a highly developed microporous structure (this process is called activation). Since the activation process is a microscopic one, i.e., the surface erosion of a large number of carbon molecules is point-wise erosion, it results in the activated carbon surface having numerous tiny pores. The diameter of the micropores on the surface of activated carbon is typically between 2 to 50 nm, and even a small amount of activated carbon has a vast surface area, with the surface area per gram ranging from 500 to 1500 m². All applications of activated carbon are almost based on this characteristic.