The preparation of activated carbon generally involves physical
or chemical activation methods. In physical activation, the raw
material is first pyrolysed under inert atmosphere at a temperature
above 400 ◦C, followed by activation with gases such as steam or
carbon dioxide at a temperature above 600 ◦C. In chemical activation,
the raw material is first impregnated by activating agents such as H3PO4, KOH or ZnCl2, followed by thermal activation to create
the pore structure. The chemical activation usually has higher carbon
yield and better developed pore structure than the physical
activation