Direct spectroscopic speciation of the complexation of U(VI) in acetate solution.
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Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq).The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1).Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+).
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Affiliation: RER Consultants, Fuchsbauerweg 50, 94036 Passau, Germany.
ABSTRACT
Abstract: As a result of systematic UV-Vis absorption spectroscopy studies in the U(VI) acetate system, the single component spectrum of [UO2CH3COO](+) with characteristic parameters was evaluated and applied in quantitative deconvolution of multicomponent spectra. Free acetate concentrations were obtained by the use of geochemical and probabilistic modelling codes. A total of 51 UV-Vis spectra were collected in a wide range of experimental conditions where coordination of U(VI) by acetate ion was indicated by characteristic variations in the spectra structure as compared to UO2 (2+). Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq). The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1). Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+). No MeSH data available. Related in: MedlinePlus |
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Mentions: The quotient of species concentrations is obtained from the quantitative spectral deconvolutions, while the free acetate concentrations may be estimated on basis of the known total acetate concentration, the pH, and the pKA of acetic acid. These quantities are given in Table 2. A graphical summary is given in Fig. 8 where parameters from Table 2 are interpreted by a trend with fixed slope 1 according to Eq. (1). The formation quotient lg β11 for UO2CH3COO+ is defined as1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\lg \, \beta_{11} \, = \lg \frac{{[{\text{UO}}_{2} {\text{CH}}_{3} {\text{COO}}^{ + } ]}}{{[{\text{UO}}_{2}^{2 + } ]}} - \lg \, [{\text{CH}}_{3} {\text{COO}}]^{ - }$$\end{document}lgβ11=lg[UO2CH3COO+][UO22+]-lg[CH3COO]-where [A] denotes molar concentrations of species A.Fig. 8 |
View Article: PubMed Central - PubMed
Affiliation: RER Consultants, Fuchsbauerweg 50, 94036 Passau, Germany.
Abstract: As a result of systematic UV-Vis absorption spectroscopy studies in the U(VI) acetate system, the single component spectrum of [UO2CH3COO](+) with characteristic parameters was evaluated and applied in quantitative deconvolution of multicomponent spectra. Free acetate concentrations were obtained by the use of geochemical and probabilistic modelling codes. A total of 51 UV-Vis spectra were collected in a wide range of experimental conditions where coordination of U(VI) by acetate ion was indicated by characteristic variations in the spectra structure as compared to UO2 (2+). Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq). The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1). Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+).
No MeSH data available.