Adsorption and Desorption of Cd, Cr, Ni and Pb in Soils Pre-Loaded with Their Maximum Adsorption Capacity of These Heavy Metals.

The pollution of the environment and in particular of the soil compartment has been marked as a major socio-environmental problem, especially when it refers to the accumulation of certain chemicals in the soil. Identifying the mechanisms of adsorption, if the process tends to be specific or electrostatic, or knowing the behavior of certain metals while others are already previously adsorbed can contribute to the development of techniques to minimize environmental problems caused by the release of waste rich in heavy metals on soils previously contaminated. The soils selected for this experiment belong to the dominant soil classes of Minas Gerais State. Soil horizons A and B with contrasting characteristics in terms of chemical and physical, were sampled and classified as Alfisol - PVA Oxisol - AVL and Red - LV, Cambisol - CX and Quartz - RQ. Samples of these soils received doses equivalent to their maximum adsorption capacities (MAC) for Cd, Cr, Ni and Pb and were kept incubated for 30 days. After that, adsorption of these metals was conducted for each soil using concentrations of 0, 0.5, 1 and 1.5 times the maximum adsorption capacity previously determined for each metal and soil. Results showed that Cr and Pb were retained strongly as compared to Cd and Ni and, in general the formers displaced the latters in all soils.