Study on the Semi-Dynamic Leaching Characteristics of CD Contaminated Soils Solidified/Stabilized with Phosphate under the Condition of Acid Rain

pH values significantly affect leachability of stabilized/solidified heavy metals contaminated soils. The diffusion coefficient (D-e) and the retardation factor (R-d) are essential for quantitative assessment of the impact of stabilized/solidified contaminated soils on surrounding environment. Diffusion of Cd leached from a new binder stabilized/solidified Cd-contaminated soil are investigated in this research. A series of tests including desorption test and semi-dynamic leaching test conduct to determine the obvious diffusion coefficient (D-obs) and the R-d, respectively. Desorption test results show that leached concentrations of Cd increase with the increase of its initial concentrations and a desorption curve fit well in the Freundlich desorption/adsorption model. The semi-dynamic leaching test results show that the accumulated heavy metal mass has a linear-relationship with time on a logarithmic scale. The results demonstrate that the D-obs of Cd calculated at 2.11x10(-12), the retardant factor of Cd determined as 109.7 and the D-e is therefore determined as 2.32x10(-10) m(2)/s.