Chemical activation is achieved by degradation or dehydration of the raw material structure, which is usually sawdust. The most popular activation chemical is phosphoric acid, although zinc chloride is also still used by some manufacturers. The raw material and dehydration reagent are mixed into a paste, dried and carbonized in rotary furnaces at 600°C.
Chemical activation process: activation by acid oxidation
When phosphoric acid is the activating agent, the carbonized product is further heated above 800°C during which stage the carbon is oxidized by the acid. The activated product is washed with water to recover the acid and then dried. The recovered acid is concentrated back to the required concentration for reuse. The activity of the final products mainly depend on the amount of activating agent, furnace temperature and residence time.