Résumé
Malonamides have shown a lot of features that made them worthy candidates for further investigations to assess their possible use in the process of recycling of spent nuclear fuels. Most of these processes are based on thermodynamic performances especially on the separation factor between targeted elements against impurities. However, kinetics of mass transfer are studied and optimized later. The aim of the current studies is to set up an innovative process approach established on kinetics control to separate metals.The kinetics of palladium, neodymium and iron extraction from nitric acid media by malonamides have been studied using single drop technique. The experiments have been carried out with three different malonamides substituted either by butyl, hexyl or tetradecyl chains in order to determine the effect of their structure on the extraction kinetics of each metal . Global transfer constants (KM) from aqueous phase to organic phase have been determined for the three metals with each extractant. The kinetics of neodymium extraction is the fastest in comparison with that of palladium and iron. Furthermore, neodymium extraction shows a similar kinetic behavior in the presence of palladium or in absence. In regard to iron, the kinetic behavior does not depend on the malonamide topology. These results appear very promising and open prospects to clarify the relationship between mass transfer kinetics for a given ion(s)/extractant system and the molecular phenomena which intervenes in each phase during the transfer process, with a focus on the coordination chemistry of the ion. Also, after a preliminary technical and methodological set-up phase conducted on malonamide systems, well known at the laboratory [3], studies will focus on processes relevant for future back-end nuclear fuel cycle, especially on some problematic fission products, such as ruthenium.