Direct proton magnetic resonance cation hydration study of uranyl perchlorate, nitrate, chloride, and bromide in water-acetone mixtures

Abstract

A cation hydration number study has been carried out for solutions of UO2(C104)2, U02(N03)2, U02C12, and U02Br2 in water-acetone mixtures by the direct proton magnetic resonance (pmr) method. At temperatures below -85°, proton exchange is slow enough to permit the observation of separate pmr signals for bulk water molecules and water molecules in the U022+ solvation shell. In CIO4solutions, U022+ is hydrated by a maximum of four water molecules and complex formation is negligible. Bidentate complexing occurs with N03and the equilibrium quotient for the formation of the mononitrato complex is roughly an order of magnitude greater than that for the dinitrato complex. Complexing is evident in the Cland Brsolutions but spectral complexities prevented an unambiguous identification of the species.

Spectroscopic monitoring of spent nuclear fuel reprocessing streams: an evaluation of spent fuel solutionsviaRaman, visible, and near-infrared spectroscopy

“…The use of Raman spectroscopy to investigate the UO 2 (NO 3 ) 2 /nitric acid system is well established [3, 11-14, 31, 32], and experimental studies have indicated that several solution species exist for uranyl nitrate, including UO 2 (NO 3 ) + [14,[33][34][35][36][37], the neutral complex UO 2 (NO 3 ) 2 [14,37,38], and UO 2 (NO 3 ) 3 − [37,39]. We have measured solutions of spent commercial fuel in variable nitric acid solutions using Raman spectroscopy to probe the UO 2 -NO 3 interaction under fuel reprocessing conditions and identify spectral regions that can be used for the on-line monitoring of uranyl nitrate.…”

Investigation of Uranyl Nitrate Ion Pairs Complexed with Amide Ligands Using Electrospray Ionization Ion Trap Mass Spectrometry and Density Functional Theory

“…Complexes with n = 4 or 5 were the most prominent in the gas-phase spectra, an observation consistent with the fact that the dominant uranyl (VI) species in water is generally accepted to be the penta-aquo complex, 50,71 although early experiments indicated only four ligands present. 72 Studies by Van Stipdonk and co-workers 50,51 of gas-phase complexes of [UO 2 ] 2þ ligated with acetone/acetonitrile showed penta-coordinated uranyl complexes. Shamov and Schreckenbach 46 modeled aquo complexes using DFT that predicted stable penta-and hexa-aquo complexes and showed a structure for the hexa-aquo complex with H 2 O ligands bending out of the equatorial plane.…”

Vibrational spectra of discrete UO22+ halide complexes in the gas phase

“…Furthermore, multiple species are always present, as demonstrated by recent X-ray absorption spectroscopy measurements of uranyl chloride in an aqueous-acetonitrile solvent system [7], and probably explains why earlier NMR studies could not identify speciation either [8].…”