Adsorption of lead (Pb) in weathered tropical soil (Ribeira Valley region - Brazil)

ABSTRACT Lateritic soils have been widely used in the construction of landfill base liners for solid waste disposal. On the other hand, there is little practice in the use of cambisols (less clayey) for this finality. The use of local soil for the construction of liners in order to waterproof and retain contaminants represents an alternative to control this type of contamination. Thus, the objective of this study was to determine the physical and chemical properties of a cambisol collected in the city of Eldorado (Ribeira Valley) and to evaluate the ability of this soil to adsorb lead (Pb). The contamination of soil and water by Pb is a worldwide problem, and in the Ribeira Valley the contamination by Pb is common in specific areas mainly due to inadequate mining waste disposal. The efficiency of Pb adsorption by the cambisol was indirectly proportional to the concentrations of Pb in solution. When the initial concentration of 20 mg/L was used, the adsorption percentage of Pb was 92.5% and when the initial concentration was 100 mg/L, the adsorption rate was 81.7%. In addition to the retention of Pb, this soil presented the following characteristics which are favorable for using soils in the construction of liners: a silt loam (a high plasticity clay, CH), with liquid limit (LL) of 57%, plasticity index (PI) of 33%, oxidizing medium and the predominance of negative charges on the surface of the colloidal particles. Thus, it is concluded that this tropical soil (cambisol) exhibits characteristics that allow it to be used as a liner in the disposal of residues containing Pb.