Adsorption of Pb (II) from aqueous solution onto charcoal and activated carbon

Adsorption of Pb (II) in aqueous solution on charcoal and activated carbon made from oak wood and coal, respectively, was examined in batch system. The activated carbon had higher surface area and higher porosity than the charcoal. Adsorption of Pb (II) was greatly increased as the particle size was decreased for the charcoal, whereas it was not changed for activated carbon. The amount of Pb (II) adsorbed on the charcoal was found to be proportional to the external surface area of the charcoal. The charcoal ash exhibited an attractive force toward Pb (II) in the aqueous solution, whereas the activated carbon ash had no such effect. Adsorption sites of the charcoal were supposed to be minerals exposed on the external surface, while those of the activated carbon would be carboxylic, lactonic and phenolic groups.