Interaction of Hexafluoroacetylacetone with Metals and Their Alloys in the Medium of Supercritical Carbon Dioxide in the Processes of Equipment Decontamination

In the course of treatment of stainless steel with supercritical CO₂ containing -diketones in combination with pyridine and water, these agents react mainly with the oxide films. Therefore, in industrial use of such media, e.g., for decontamination of the equipment, the corrosion is expected to be low. Under these conditions, uranium does not dissolve from the surface of metallic uranium, and iron does not dissolve from the surface of pure metallic iron. In treatment of a copper or nickel surface with supercritical CO₂ containing -diketons and modifiers, both the oxide film and metals are involved in the reaction. It is presumed that water facilitates ionization of the complexing agent, and pyridine (or another amine with pK _a 5-6) creates a medium favorable for complexation. Furthermore, pyridine molecules may be incorporated in the complex as additional ligands.