Lead(II) removal in discontinous systems by carbon activated by phosphoric acid and vapor

Adsorption of heavy metal cations by activated carbon is dependent on the capacity of the material in promoting adsorption and the time needed to reach equilibrium. Carbon samples were previously activated either by phosphoric acid treatment at 400 degrees C or by steam at 800 degrees C. The results of Pb(II) adsorption by these activated carbons have shown that equilibrium was typically reached within the first 5 min of contact between carbon and metal solution, with a maximum adsorption capacity higher than 69 mg g(-1) for the vapor-activated sample. Temperature influences the sorption capacity, which corresponds to an endothermic process. Lead(R) retention is more pronounced at high temperature and low pH.