Coordination Chemistry of Actinide Nitrates with Cyclic Amide Derivatives for the Development of the Nuclear Fuel Materials Selective Precipitation (NUMAP) Reprocessing Method

Abstract

Nuclear fuel recycling is one of promising options to resolve current issues arising from energy security and nuclear wastes. Chemical separation called reprocessing aims to recover recyclable nuclear fuel materials from spent fuels, and also to reduce the volume of high-level radioactive wastes. Even today, solvent extraction is extensively employed as a principal method for reprocessing, while there are also several safety and security concerns arising from use of large amount of organic solvents and potential isolation of highly purified (namely [a]

Effects of coordinating heteroatoms on molecular structure, thermodynamic stability and redox behavior of uranyl(vi) complexes with pentadentate Schiff-base ligands

“…Hence, the complexation between UO 2 2+ and organic ligands has been widely studied. [1][2][3][4][5][6][7][8][9][10][11][12][13] Pearson's Hard and So Acids and Bases (HSAB) principle is quite useful to describe preferential interactions between specic metal ions and coordinating atoms of ligands and to design organic molecules selectively coordinating with a target metal ion, 14,15 although this principle is rather empirical. In the HSAB principle, UO 2 2+ is classied as a hard acid, 14,15 and therefore, generally tends to more strongly interact with hard bases like N, O and F, compared with soer ones such as heavier congeners like P, S, and Cl.…”

Machine-Learning-Guided Identification of Coordination Polymer Ligands for Crystallizing Separation of Cs/Sr

“…To separate the duo, we propose to identify ligands that can selectively coordinate to Sr over Cs, or vice versa. The complex should be extending compounds such as coordination polymers (CPs) to ensure a complete solid–liquid phase separation, convenient for large-scale application. − Now the scientific question boils down to this: which ligand binds to one cation significantly more strongly than the other? To answer this question, one naturally turns to the Cambridge Structural Database (CSD), as it compiles a large amount of data of coordination compounds. , For a given ligand (L) available in the CSD, an assessment of its selective coordinative capability entails comparing its coordination parameters toward Sr and Cs, assuming that both complexes have preregistered structural data there .…”

Crystal Structures of Ce(IV) Nitrates with Bis(2-pyrrolidone) Linker Molecules Deposited from Aqueous Solutions with Different HNO3 Concentrations

“…Indeed, both [Pu–O–Pu] 6+ and [Pu(NO 3 ) 6 ] 2– species have been found previously in the crystal structures of K 4 [Pu 2 (μ-O)Cl 4 (NO 3 ) 6 ]·H 2 O and A 2 [Pu(NO 3 ) 6 ] [A = NH 4 + , NEt 4 + , NBu 4 + , IC 5 H 4 NH + , and cationic Pu(IV) complexes], − respectively. This point has a critical impact to decide the detailed conditions of our NUMAP reprocessing for spent nuclear fuels, because the stoichiometry of L required for crystallization of [Pu–O–Pu] 6+ is different from that of [Pu(NO 3 ) 6 ] 2– as demonstrated in the present work for Ce(IV).…”

“…31−33 We employed this nature to develop a simple and versatile reprocessing method for nuclear fuel recycling, namely, nuclear fuel materials selective precipitation (NUMAP). 34 In contrast, Zr 4+ does not exhibit such behavior even after loading L despite the same valence with An 4+ . 33 Now, a question arises: how does Ce 4+ behave in HNO 3 (aq) through the addition of L?…”

“…At higher acidity, the hydrolysis of M 4+ tends to be suppressed. Indeed, (NH 4 ) 2 [Ce(NO 3 ) 6 ] deposits from a concentrated HNO 3 (aq). , The analogous hexanitrato An(IV) complexes (An = Th, U, Np, Pu), [An(NO 3 ) 6 ] 2– , were isolated from HNO 3 (aq) as crystalline deposits with appropriately selected counter cations like monovalent alkaline metals and quaternary ammonium ions. − Recently, we have found that bis(2-pyrrolidone) derivatives (L) shown in Chart afford sparingly soluble [An(NO 3 ) 6 ] 2– salts, where an anhydrous H + is adopted for charge compensation despite deposition from HNO 3 (aq). − We employed this nature to develop a simple and versatile reprocessing method for nuclear fuel recycling, namely, nuclear fuel materials selective precipitation (NUMAP) . In contrast, Zr 4+ does not exhibit such behavior even after loading L despite the same valence with An 4+ …”