Actinide extraction by complexon solutions in supercritical and liquid carbon dioxide

Published data as well as original experimental results on actinide extraction by complexon solutions in liquefied and supercritical carbon dioxide, obtained in KRI, are presented. The dependences are analyzed of uranium, plutonium, neptunium and americium extraction by acidic (carboxylic and phosphororganic acids), neutral (alkyl-phosphates, alkylphosphonates, alkylaryl-phosphinoxides, alkylarylcarbomoylphosphinoxides, crown ethers, and polyethyleneglycol ethers) and chelating extractants and by their mixtures in supercritical and liquefied carbon dioxide. The experimental data showed that the main processes in the course of extraction of metals in carbon dioxide only slightly differ from those proceeding at liquid extraction. However, it was found that CO2 is not an inert diluent and carbon acid forming in aqueous phase equilibrium with CO2 affects the processes in liquefied and supercritical CO2. These series of studies performed allowed determination of the important directions of further investigations on complex-formation and extraction in the CO2 media