A simple way of catching a big fat element: plutonium from radioactive waste by a task specific ionic liquid.

Uranium (U) and plutonium (Pu) contents in nuclear materials must be maintained to a definite level in order to get the desired performance of the fuel inside the reactor. Therefore, high accuracy and precision is an essential criterion for the determination of U and Pu. We already reported the voltammetric determination of Pu in the presence of U in fast-breeder-test-reactor (FBTR) fuel samples, but interfacial, coupled chemical reactions between U(IV) and Pu(IV) enhance the peak-current density of U(VI) reduction and thus make voltammetry unsuitable for the quantitative determination of U in the presence of Pu. Thus, developing a voltammetric method for the simultaneous determination of U and Pu is highly challenging. Herein, we report the simultaneous voltammetric determination of U and Pu in 1 M sulfuric acid (HSO) on a poly(3,4-ethylenedioxythiophene) (PEDOT)-poly(styrenesulfonate) (PSS)-modified glassy-carbon (GC) electrode (PEDOT-PSS/GC). The modified electrode shows enhanced performance compared with bare GC electrodes. The peak-current density for U(VI) reduction is enhanced in the presence of Pu(IV), but it attains saturation when [Pu]/[U] in solution is maintained ≥2. Hence, under these circumstances, the variation of Pu concentration no longer influences the U(VI)-reduction peak, and thus the quantitative determination of U in the presence of Pu is possible. No interference is observed from commonly encountered impurities present in FBTR fuel samples. This method shows accuracy and precision comparable to those of the biamperometry method. High robustness, fast analysis, simultaneous determination, reduced radiation exposure to the analyst, and ease of recovery of U and Pu from analytical waste makes it a suitable candidate to substitute the presently applied biamperometry method.

The selective separation of uranyl ions from an aqueous solution is one of the most important criteria for sustainable nuclear energy production. We report herein a known, but unexplored extractant, tetraalkyl urea, which shows supreme selectivity for uranium in the presence of interfering thorium and other lanthanide ions from a nitric acid medium. The structural characterization of the uranyl complex (UO2X2·2L, where X = NO3(-), Cl(-) and Br(-)) by IR, NMR and single crystal X-ray diffraction provides insight into the strong interaction between the uranyl ion and the ligand. The origin of this supreme selectivity for uranyl ions is further supported by electronic structure calculations. Uranyl binding with the extractant is thermodynamically more favourable when compared to thorium and the selectivity is achieved through a combination of electronic and steric effects.

A monoamide, N,N'-dioctyl, α-hydroxy acetamide, shows unusual extraction properties towards trivalent lanthanide and actinide ions above 3 M HNO3. The extracted ions could be quantitatively back extracted using 0.5 M HNO3. This amide shows negligible extraction towards Sr(II) and Ru(III) ions, making it advantageous over other reported extractants. The structures of Sm(III) and Eu(III) nitrate compounds show that the metal ion is surrounded by three of the ligands, one nitrate and one water molecule. The ligand acts as a neutral bidentate ligand and bonds through the amido and hydroxyl oxygen atoms.

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