[Comparison on desorptive behavior of cadmium in phaeozem and burozem]

Desorptive behavior of Cd2+ was comparatively studied by the batch method on the two typical soils in northeast China. The results indicated that the two soils exhibit statistically significant sorption-desorption hysteresis. Phaeozem has a longer hysteresis period than the Burozem. The desorptive behavior of Cd2+ in the two tested soils was a rapid reactions, which could account for 90% of the Cd2+ equilibrium desorption within the first 30 min. Compared with the total adsorption, the desorptive percentage of the adsorped Cd2+ in the phaeozem and burozem was in a low extent, which was ranged within rate of 9.0% and 15.1% respectively. The desorptive rates of Cd2+ in the soils were increased with the higher concentrations of Cd2+ in the treatments, and decreased with the increasing desorptive amount and time. Soil properties had no significant effect on the desorptive rate decreasing. Freundlich equation was the optimal model to describe the desorptive isotherm of Cd2+, while the Elovich equation was the best model to describe Cd2+ desorption kinetics in the two soils.