title: Direct spectroscopic speciation of the complexation of U(VI) in acetate solution.
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 UO22+. Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO22+(aq). The molar absorption coefficient for the U(VI) monoaceto species was estimated asε418= 17.8 ± 1 dm3mol-1cm-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 lgβ11= 2.8 ± 0.3 of UO2(CH3COO)+.
authors.affiliation: RER Consultants, Fuchsbauerweg 50, 94036 Passau, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Meinrath
authors.affiliation: Department of Rare Earth, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Kwiatek
authors.affiliation: Department of Rare Earth, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Hnatejko
authors.affiliation: Department of Rare Earth, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Lis
keywords: Absorption spectra; Coordination chemistry; Stability constant; UV–Vis spectroscopy