Selective Separation Between Uo22+ And Pu4+ By Novel Tetradentate Chelate Phenanthroline Diamide Ligand In 1-Octanol

In the traditional spent nuclear fuel reprocessing process, tri-n-butyl phosphate (TBP) combined with reducing agents is employed for co-extraction of UO(2)(2+)and Pu4+ and their separation from each other, which makes the system very complicated and also brings phosphorus pollution problems. Herein, a series of environmentally friendly tetradentate phenanthroline-diamide ligands in line with the "CHON" principle were synthesized and applied to the selective separation between UO22+ and Pu4+ in 1-octanol system. The sifted ligand, N,N'-diethyl-N,N'-diphenyl-2,9-diamide-1,10-phenanthroline (Et-Ph-DAPhen), can co-extract UO22+ and Pu4+ under high acidity, but hardly extract Pu4+ under low acidity, which substantiates the applicability of this extraction system for selective separation of UO22+ from Pu4+. The novel scheme achieving the separation without any reductant but only by adjusting the acidity of the aqueous phase will simplify the separation process and improve the existing scheme. The coordination chemistry research of the ligand with UO22+ and Pu4+ confirms that the ligand generates both M: L = 1:1 and 1:2 complexes with Pu4+ but only M: L = 1:1 complex with UO22+. The coordination ability of ligand with shorter carbon chains is slightly stronger than that with longer chains. The ligands and diluents in line with the "CHON" principle will be helpful to reduce environmental pollution and pressure of subsequent waste treatment. No reducing agent process contributes to simplify the operation steps and reduce the complexity of the process. The coordination chemistry offers further comprehension of the separation mechanism and guides the synthesis of efficient separation ligands.