Removal of lead from water samples by sorption onto powdered limestone

Bench scale batch adsorption experiments were performed, aiming at the removal of the Pb2+ ions from aqueous solutions and water samples by fine powdered Limestone (LS) as an effective inorganic sorbent, which is inexpensive, widespread, and cheap. The main parameters (i.e., solution pH, sorbent and lead concentrations, stirring times, and temperature) influencing the sorption process, in addition to the effect of some foreign ions, were investigated. The results obtained stated that the sorption of Pb2+ ions onto LS is well described by Freundlich model and deviated from that of Langmuir over the concentration range studied. Under the optimum experimental conditions employed, the removal of ca. 100% of Pb2+ ions was attained. The procedure was successfully applied to the removal of lead from aqueous and different natural water samples. Moreover, the adsorption mechanism is suggested.