Hydrolysis of Uranyl(VI) in Acidic and Basic Aqueous Solutions Using a Noncomplexing Organic Base: A Multivariate Spectroscopic and Statistical Study

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• 作者：Fabienne Quile虁s ; Chinh Nguyen-Trung ; Ce虂dric Carteret ; Bernard Humbert
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：April 4, 2011
• 年：2011
• 卷：50
• 期：7
• 页码：2811-2823
• 全文大小：1274K
• 年卷期：v.50,no.7(April 4, 2011)
• ISSN：1520-510X

文摘

In the field of actinide aqueous chemistry, this work aims to resolve some controversy about uranyl(VI) hydroxide species present in basic aqueous solutions. We revisit the Raman, IR, and UV鈭抳isible spectra with two new approaches. First, Raman, IR and UV data were recorded systematically from aqueous solutions with the noncomplexing electrolyte (C₂H₅)₄NNO₃ at 25 掳C and 0.1 MPa ([U_total] = 0.005鈭?.105 M) in H₂O and D₂O over a wide range of 鈭抣og mH(D)⁺ between 2.92 and 14.50. Second, vibrational spectra (IR and Raman) of basic solutions in H₂O and D₂O were analyzed using the Bayesian Positive Source Separation method to estimate pure spectra of individual species. In D₂O solutions, the new spectroscopic data showed the occurrence of the same species as those in H₂O. As observed for the wavenumber of the symmetric stretching mode, the wavenumber characteristic of the O鈺怳鈺怬 antisymmetric stretching mode decreases as the number of OH(D)^{鈭?/sup> ligands increases. These kinds of data, completed by (1) analysis of the signal widths, (2) persistence of the apparent exclusion rule between IR and Raman spectra of the uranyl species stretching modes, and (3) interpretation of the absorption UV鈭抳isible spectra, allow discussion of the chemistry, structures, and polynuclearity of uranyl(VI) species. In moderate basic solutions, the presence of two trimers is suggested. In highly basic solutions ([OH鈭?/sup>] 鈮?3 M), the two monomers UO₂(OH)₄2鈭?/sup> and UO₂(OH)₅3鈭?/sup> are confirmed to be in good agreement with earlier EXAFS and NMR results. The occurrence of the UO₂(OH)₆4鈭?/sup> monomer is also suggested from the more basic solutions investigated.}