Activated carbon (AC) a tasteless, solid, microcrystalline, non-graphitic form of black carbonaceous material with a porous structure [1-2], has been regarded as a unique and versatile adsorbent because of its extended surface area, microporous structure, high adsorption capacity, and high degree of surface reactivity [3-5]. AC is applied widely in a variety of fields such as food and chemical industries, wastewater treatment, solvent recovery, air pollution control and hydrometallurgy for the recovery of gold and silver.