Separation and Isolation of radionuclides by the displacement chelating chromatography

Abstract

The review of results of the REE and TRU separation studies is given using the method of the displacement chelating chromatography performed in the Laboratory for Radioactive Elements Chromatography with the Frumkin Institute of Physical Chemistry and Electrochemistry of the Russian Academy of Sciences. The mathematical description of the chelating chromatographic systems is given in general terms. The sorption property study of some sorbents manufactured to date is performed. It is shown that no effective REE separation occurs on the mono-dispersed sorbents of the 0.5-0.75 mm grain size on account of the substantial contribution of the internal diffusion leading to the broadening of fronts and the formation of "tails". Meanwhile on the mono-dispersed sorbents of the 0.3 mm grain size the effective separation does occur and the minimum mixing zone volume is observed. The complex formation effect on the change in the selectivity of differently charged ions was studied. It was found that for mono-and protonated complexes the complete inversion of the selectivity is possible; however for the bi-nuclear complexes the selectivity inversion could be merely partial due to the formation of mixed isotherms. Techniques for the separation of high grade REE and TRU preparations from solutions of different composition including the spent nuclear fuel processing solutions have been developed.