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Direct spectroscopic speciation of the complexation of U(VI) in acetate solution.

Meinrath G, Kwiatek D, Hnatejko Z, Lis S - Monatsh. Chem. (2014)

Bottom Line: 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)(+).

View Article: PubMed Central - PubMed

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)(+).

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Experimental U(VI) spectrum obtained at pH 2.24 and total acetate concentration (CH3COO(H/Na)) of 0.059 mol dm−3. Under those conditions, the monoacetato species is a minor component only
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Fig5: Experimental U(VI) spectrum obtained at pH 2.24 and total acetate concentration (CH3COO(H/Na)) of 0.059 mol dm−3. Under those conditions, the monoacetato species is a minor component only

Mentions: The single component spectrum of UO2(CH3COO)+ (Fig. 4) is applied to the experimental spectra given in Fig. 1. The physical and chemical parameters of these samples are summarised in Table 2 together with results of a spectral deconvolution using the mean value spectra of UO22+ and UO2CH3COO+ from Fig. 4. Examples of this deconvolution are given in Figs. 5, 6 and 7 for three spectra with widely varying ratio of the U(VI) species concentrations. These spectra illustrate the power of the single component spectrum given in Fig. 4 to quantitatively interpret U(VI) solutions with widely varying physico-chemical conditions.Table 2


Direct spectroscopic speciation of the complexation of U(VI) in acetate solution.

Meinrath G, Kwiatek D, Hnatejko Z, Lis S - Monatsh. Chem. (2014)

Experimental U(VI) spectrum obtained at pH 2.24 and total acetate concentration (CH3COO(H/Na)) of 0.059 mol dm−3. Under those conditions, the monoacetato species is a minor component only
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4495045&req=5

Fig5: Experimental U(VI) spectrum obtained at pH 2.24 and total acetate concentration (CH3COO(H/Na)) of 0.059 mol dm−3. Under those conditions, the monoacetato species is a minor component only
Mentions: The single component spectrum of UO2(CH3COO)+ (Fig. 4) is applied to the experimental spectra given in Fig. 1. The physical and chemical parameters of these samples are summarised in Table 2 together with results of a spectral deconvolution using the mean value spectra of UO22+ and UO2CH3COO+ from Fig. 4. Examples of this deconvolution are given in Figs. 5, 6 and 7 for three spectra with widely varying ratio of the U(VI) species concentrations. These spectra illustrate the power of the single component spectrum given in Fig. 4 to quantitatively interpret U(VI) solutions with widely varying physico-chemical conditions.Table 2

Bottom Line: 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)(+).

View Article: PubMed Central - PubMed

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