Fluid extraction of metals of metalloids

[0011] Specific examples of the method of the present invention for extracting various heavy metals, noble metals and metalloids from media, especially acidic media, are provided below. The present invention also relates to specific examples of methods for extracting radioactive metals such as uranium from acidic solutions. I. Extraction fluid

[0012] Suitable fluids and / or supercritical fluids for use in the present invention include carbon dioxide, nitrogen, nitrous oxide, methane, ethylene, propane and propylene. It has been found that since carbon dioxide has moderate chemical constants (Tc=31°C, Pc=73atm), and it is chemically inert (i.e., carbon dioxide will not explode even under supercritical conditions, the extraction process is absolutely safe), so regardless of Fluids are particularly useful for both subcritical and supercritical fluid extraction. Carbon dioxide is also the preferred solvent for use due to its abundance and relative cheapness.

[0013] The phase

[0052] All experiments in this paper use laboratory-grade supercritical fluid extraction equipment, as described above and shown in Figure 1. This example concerns the extraction of Hg, Cu, Cd, Pb, Zn, As, Sb, Se and U ions from various acidic media. The acidic media tested included 0.1M hydrochloric acid solution, 1.0M hydrochloric acid solution, 0.1M nitric acid solution, 1.0M nitric acid solution, 0.05 sulfuric acid solution and 0.5 sulfuric acid solution. All metal and metalloid ions were extracted from acidic solutions each containing about 10 μg / ml metal or metalloid ions. Uranyl ion U(VI) is prepared from analytical grade uranyl nitrate. All other metal solutions were prepared from AAS standard solutions.

[0053] The extractant fluid used in this example comprised supercritical carbon dioxide. The chelating agent was di-2,4,4-trimethylpentyldithiophosphinic acid supplied by Cytec Industries of New Jersey, which was used without further purification. Supercritical ca

[0062] This embodiment involves the extraction of Hg, Cu, Cd, Pb, Zn, As, Sb, Se and U ions from acidic medium, using supercritical carbon dioxide and monothiophosphinic acid. The acidic media tested included 0.1M hydrochloric acid solution, 1.0M hydrochloric acid solution, 0.1M nitric acid solution, 1.0M nitric acid solution, 0.05M sulfuric acid solution and 0.5M sulfuric acid solution. All metal and metalloid ions were extracted from acidic solutions each containing about 10 μg / ml metal or metalloid ions. Uranyl ion U(VI) is prepared from analytical grade uranyl nitrate. All other metal solutions were prepared from AAS standard solutions. The extraction method is the same as described in the aforementioned "fluid extraction method".

[0063] The extractant fluid used in this example comprised supercritical carbon dioxide mixed with di-2,4,4-trimethylpentylmonothiophosphinic acid. Di-2,4,4-trimethylpentylmonothiophosphinic acid was supplied by Cytec Industries of New Jersey