Nanoscale UO2 and novel complex U(IV)-sulphate phase formation from electrolytically reduced uranyl sulphate solutions
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D. Gil
Abstract
Three different processes have been explored to determine the ranges of U-concentration and acidity (pH-value) for nanocrystalline U2+x precipitation from electrolytically reduced uranyl sulphate solutions. Precipitation of U2+x nanoparticles aggregates was found to occur only in the narrow range of pH ∼ 4.5 to 5 and for U-concentrations of ∼10-6 to 10-7 M. The solid phase crystallized with the typical UO2- fcc structure and with a crystallite size ≤3 nm. The average aggregate size was mostly ≤80 nm. At higher U-concentrations, ranging from [U]∼10-1 M at pH∼1.5 to [U]∼5×10-4 M at pH∼4.9, formation of microscale precipitates of a novel complex U(IV)-sulphate phase occurred, which was characterized by SEM/EDX-WDX, ICP-OES and XRD-powder diffraction. The crystal structure was identified with an orthorhombic cell (space group Cmca ), with the following lattice parameters: a=1.9740(2) nm, b=1.3336(2) nm and c=2.0643(2) nm. Further composition analyses indicated a basic sulphate hydrate of the type Na3U(SO4)3(OH)·nH2O.
© by Oldenbourg Wissenschaftsverlag, München, Germany
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Articles in the same Issue
- A new value of 93Zr half-life
- Complexation of plutonium(IV) with fluoride at variable temperatures
- Determination of the stability constants of nitrate complexes of Np(V) and Pu(V) using CE-ICP-MS
- Nanoscale UO2 and novel complex U(IV)-sulphate phase formation from electrolytically reduced uranyl sulphate solutions
- Method validation in solvent extraction for 210Po determination from groundwaters
- Random coincidence summing of gamma rays and dead time count loss corrections in HPGe-detector based gamma ray spectrometry
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- Determination of rare earth and other trace impurities in high purity gadolinium oxide
