Adsorption and displacement of the cadmium ion in savannah soils

摘要

Cadmium is commonly found in industrial and urban residues, sewer sludge and fertilizers, and when disposed in the soil can represent risks of pollution of the soil and water. This study aimed to analyze the adsorption and movement of cadmium in Red Latosol, Red Argisol, Red Nitosol and Quartzarenic Neosol found in cultivated áreas in the State of Goiás. In order to quantify the adsorbed cadmium, 5 mL of oven-dried soil were stirred in beaker, for 24 h, with 50 mL of CaCl2.2H2O (0.01 mol L-1) solution containing different quantities of cadmium (0.10, 1.80, 19.00, 46.60 and 105.70 mg L-1). In the trial of the transport of Cd in soil columns a displacement solution of 105.70 mg L-1 was used. Sorption of Cd was evaluated by potential and linear models of the Freundlich isotherm and the retardation factor (R) and hydrodynamic dispersion coefficient (D) were adjusted by minimizing the sum of squares of deviations between the experimental and simulated breakthrough curve. Both isothermal and linear potential and the adjustment of the transport parameters D and R showed a good fit for describing the adsorption and the displacement of Cd in the different studied soils. The Quartzarenic Neosol showed lower retention of Cd in comparison to other classes of soil, and therefore more vulnerable to contamination of groundwater, followed by the Latosol, Argisol and Nitosol.