Activated carbon is an absorbent obtainable in the forms of small black grains, spheres pellets or powder and is used for purifying air, gas and liquid. It is also used in recovery of precious metals from ores and as a catalyst. It is differs from graphite by having a random imperfect structure which is highly porous over a broad range of pore sizes from visible cracks and crevices to molecular dimensions. Activated carbon has the strongest physical adsorption forces or the highest volume of adsorbing porosity.The characteristic of the activated carbon is an extensive network of interior pores of near molecular dimensions. The surface is 2.272 x 105_7.336 x 106 sq. ft. per pound, equivalent to 151 acres of surface per pound.Internal surface area of the activated carbon can be determined by the adsorption of nitrogen. The organic molecules are much larger than a nitrogen molecule and as the pores are of molecular dimensions it is possible for a sieving action to take place.