EDTA leaching of copper from contaminated soils: Experimental study and transport model application for parameters estimation

EDTA column’s extraction were performed on four artificially contaminated soils, followed by the percolation of pure water to ensure the removal of EDTA entrapped in soil. The investigated soils were characterized by a content of organic matter ranging from 1% to 25%. A mathematical model was developed for copper leaching from the soils. The correlation of experimental data shows that while the EDTA transport was not affected by the soil organic fraction, the simulated transport of Cu-EDTA complexes in solution exhibited a delay effect due to the chemical adsorption of such complexes onto the soil organic matter. The distribution coefficient (Kd), between the solid and liquid phases showed a logarithmic increase when the organic content of soil increased. The column’s hydrodynamic characteristics (αL) and the kinetic coefficients (k) of chelant extraction were estimated independently for each soil. A correlation of kinetic coefficients data versus soil’s organic content was also proposed: experimental data showed, in the investigated range, a logarithmic dependence of k on the organic content of soil.