Metal extraction from the artificially contaminated soil using supercritical CO2 with mixed ligands

Supercritical fluids have good penetrating power with a high capacity to dissolve certain solutes in the fluid itself, making it applicable for soil cleaning. Supercritical CO2 along with mixed ligands has been used for cleaning artificially contaminated soil. The extraction of metal from the soil was successful, and the molar ratio of ligands to the extracted metal was as low as 3. Complicated structures with a large surface area of the real soil seemed to cause the lower efficiency. Reduced efficiency was also observed over time after the sample preparation, indicating the possibility of chemisorption of the metal ion onto the soil. The use of supercritical CO2 with dissolved mixed ligands was sufficient to extract metal from the soil.

► Supercritical CO2 with adequate ligands was efficient to extract metals from soil.
► The mole ratio of ligands to metal extracted could be as low as 3.
► Cleaning efficiency of real soil from the field was lower.