Selective recognition of uranyl ions from bulk of thorium(iv) and lanthanide(iii) ions by tetraalkyl urea: a combined experimental and quantum chemical study

Abstract

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.

Insight into Speciation and Electrochemistry of Uranyl Ions in Deep Eutectic Solvents

“…After uranyl ion addition, there was no shift in −NH 2 and −OH stretching frequencies with respect to that of reline, which suggested no direct bonding of either −NH 2 or −OH groups of urea and choline chloride, respectively, with uranyl ion. However, the carbonyl stretching frequency is shifted to ∼42 cm –1 downward from 1660 to 1618 cm –1 , indicating a direct interaction of the uranyl group with the carbonyl group of urea. − Peaks observed at ν = 1472 cm –1 (CH 3 ), 1081 cm –1 (CH 2 ), 1005 cm –1 (ν COH), 952 cm –1 (ν as CCO), and 864 cm –1 (ν s N–CH 3 ) in reline and uranyl-added reline confirmed that the choline groups remain unaffected . There were additional peaks at 920 and 830 cm –1 in uranyl-added reline which correspond to the asymmetric (ν as ) and symmetric stretching (ν s ) of UO 2 2+ group, respectively.…”

Achieving highly efficient and selective cesium extraction using 1,3-di-octyloxycalix[4]arene-crown-6 in n-octanol based solvent system: experimental and DFT investigation

“…The above methodology was earlier reported to produce good correlation with the experimental results. [54][55][56] Finally, binding free energy of the metal binding reactions was calculated using following reaction scheme:…”

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

“…The original concept of this precipitation‐based method is strongly related to yellowcakes such as diuranate salts or uranyl peroxide , . Even today, there are also several research activities of precipitation‐based reprocessing or separation methods with similar concept to ours …”