THE LOCALIZATION OF HEAVY-METALS IN SEWAGE TREATED SOILS - COMPARISON OF THERMODYNAMICS AND EXPERIMENTAL RESULTS

The localization of heavy metals in soils is usually performed with chemical reagents associated in sequential extraction procedures. Our aim was to investigate the action of some of these reagents from a thermodynamic point of view. The thermodynamics indicate the limits of the localization of heavy metals in soils with chemical reagents, due to the transfer of metals from one compartment to the other and/or the effect of acidity. Some experiments with chemical reagents commonly used to extract two compartments (hydrogen peroxide for organic matter and hydroxylamine for iron oxyhydroxides) indicate that the limitation for hydrogen peroxide is due to cations transfer and for hydroxylamine to the effect of acidity.