Speaker
Description
The increasing demand of carbon-neutral and low-cost energy has caused nuclear energy as an essential element in the overall composition of the current global power supply. Accompanied by the high-speed development of nuclear energy, the environmental problems associated with used nuclear fuel have aroused great attention. The spent fuel produced by modern light water reactors, over 98.5% of the components are mainly composed of U, Pu and lanthanides (Lns). However, it still contains less than 1wt % of minor actinides (MA) including Am, Np and Cm, which are responsible for long-standing radiotoxicity. In order to improve the long-term management safety of nuclear waste, the partitioning-transmutation strategy (P&T) was emerged and recognized as a viable global option. The proposed P&T initially partitioned the transuranic elements and long-lived fission products by the PUREX process using solvent extraction, and which was subsequently subjected to neutron bombardment for transmutation them into short-lived nuclides. For the realization of P&T strategy, the initial separation of Lns(III) from Ans(III) is an inevitable prerequisite. This is due to the fact that some lanthanide isotopes with large neutron cross sections can hinder the efficient transmutation of minor actinides.
In this work, the four novel hydrophilic soft-hard hybrid N,O-donor ligands with 2,6-pyridine dicarboxamide (DAPy) and 2,9-diamide-1,10-phenanthroline (DAPhen) skeletons were firstly designed and synthesized for selective binding of Ans(III) in aqueous phase. The known TODGA was used as lipophilic extractant for coordination of Lns(III) in organic medium. A biphasic competitive extraction for separation of Ans(III)/Lns(III) was developed using the present hydrophilic masking agents and the lipophilic TODGA extractant. The stability constants of complexes of Lns (III) with preferred DAPhen in nitric acid medium were determined through UV-Vis spectroscopic titration. To gain insight into the complexation mechanism of the present DAPhen ligands to Ans(III), DFT calculations, 1H NMR titration, luminescence titration, ESI-HRMS, and FT-IR analyses were further employed to investigate the coordination mode and bonding properties of DAPhen ligands with various Lns(III).