Batch studies for the investigation of the sorption of the heavy metals Pb2+ and Zn2+ onto Amizour soil (Algeria)

Soils play an important role in the control of metallic cations in the environment. Therefore, knowledge of the adsorption properties of soil is crucial in understanding and solving pollution problems. The aim of this paper is to study lead and zinc adsorption, onto an Algerian soil sample, as a function of the reaction time, pH, ionic strength and metal concentration. The adsorption of lead and zinc onto soil was investigated on batch equilibrium adsorption experiments. Results show that the amount of lead and zinc adsorbed increases with increasing pH and initial concentration. For pH, this increase is due to the change of the surface charge and to the hydrolysis of the adsorbing metals. The high ionic strength reduces the adsorption capacity. The competition with electrolyte and the decrease of metal activities can explain this behaviour. The adsorption isotherms allow the determination of the affinity order of metals for the surface of the soil sample as such: Zn2+ < Pb2+. The equilibrium data fit well with Langmuir and Freundlich models.