The activated carbon is produced from various raw materials and,therefore, it presents different properties [20]. Apart from the raw material, the specific properties of the coal also depend on the particular activation process employed, which may be conducted by physical processes, by contact with a high temperature steam flow (800–1000 °C) or, by chemical with use of acids. The bulk density may be used in order to identify several activated carbon classes. The
macroporous carbon has a bulk density N1 cm3/g (pore space volume for gram of carbon). The mesoporous carbon has a bulk density in the range 0.85–1.0 cm3/g. Instead, the microporous carbon presents a value b0.85 cm3/g. Generally, macroporous or mesoporous carbons are used for the removal of large molecules while, microporous, are more suitable for the removal of small molecules