Partitioning of minor actinides: Effects of gamma irradiation on the extracting capabilities of a selected calixarene-based picolinamide ligant

The ligand [3-N-(6-carboxymethylpicolinamide)propyloxy]calix[6]arene (1) has been selected among a series of calixarene-based picolinamide ligands as a possible candidate to be used in a small-scale process for the An/Ln separation under the option of the advanced reprocessing of irradiated nuclear fuel. In this frame, due to the high radioactivity of the nitric solutions to be treated, the behaviour of the ligand under irradiation conditions is undoubtedly of key importance. Liquid–liquid extraction tests were performed, in order to ascertain the extracting capabilities of the calixarene ligand 1 before and after g-irradiation. A wide range of absorbed doses was investigated, and the tests were performed both in reactive and inert (N2) atmosphere. The determination of distribution coefficients for actinides and lanthanides, and of the separation factors between elements of the two families was carried out by using g-spectrometry (as for 241Am and 152Eu) and ICP-mass spectrometry (MS) (as for all the lanthanides of interest). Contrarily to what observed in the case of other previously and currently studied ligands [Baaden, M., Berny, F., Muzet, N., Troxler, L., Wipff, G., 2000. In: Lumetta, G., Rogers, R., Gopolan A. (Eds.), Calixarenes for Separation. A.C.S. Symposium Series No. 757. American Chemical Society, Washington, DC, pp. 45–55], the extraction efficiency (distribution coefficients) of the calixarene ligand 1, increases by a factor of 2–10 after g-irradiation on a significant range of absorbed doses.