ROLE OF SURFACE AREA IN KINETICS CADMIUM SORPTION IN CALCAREOUS SOILS

The relative activity of soils is intimately relating to their specific soil properties as well as by their mineralogical characterization; these properties largely determine the chemical behavior of the surface chemistry and its kinetic reactions. This work aimed to evaluate the contribution of some chemical properties of five calcareous soils (Typic calcids), varied in their total and active CaCO3, on cadmium (Cd2+) sorption characterization using kinetic approach. The obtained results revealed that empirical modified Freundlich (power function) and Elovich equations compared to other models tested best described kinetic data. The rate of Cd2+ sorption on used soils was highly positively correlated with the specific surface area of used soils through the simple correlation coefficient (r) takes place, multiple and stepwise regression analysis. For other soil parameters, results indicated that percent of clay contents, organic matter (OM) and total Cd2+ content were also influencing Cd+2 retention in used soils, these properties largely controlled the variations in rate constants of kinetic parameters of best fitted models and also the capacity factors of used models. The active CaCO3 content, which best fitted with the specific surface area, was negatively correlated and significant controlled the variations of kinetic parameters i.e. rate, and capacity factors of kinetic models. Through the obtained results, it could have suggested that adsorption followed by surface precipitation on active CaCO3 surfaces are the main mechanisms controlled Cd2+ retention and release.