Complexation of Ni(II) by α-isosaccharinic acid and gluconic acid from pH 7 to pH 13

Warwick, Peter; Evans, Nicholas D.M.; Hall, Tony; Vines, Sarah

doi:10.1524/ract.91.4.233.19971

Cited by 35 publications

(43 citation statements)

References 8 publications

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“…The stoichiometry and the stability constants of the Np(IV)-GLU complexes forming in the conditions of the experiment were determined in accordance with the Schubert method [1,4,6,8]. The method is based on the analysis of the effect of increasing ligand concentration on the sorption of a metal/radionuclide on a solid phase.…”

Section: Determination Of the Stoichiometry And Stability Constants Omentioning

confidence: 99%

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Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions: sorption studies

Rojo¹,

Tits²,

Gaona³

et al. 2013

Radiochimica Acta

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The complexation of Np(IV) with gluconic acid (GLU) under alkaline conditions was investigated in the absence of Ca by carrying out a series of sorption experiments. The decrease of Np(IV) sorption on the sorbing material at increasing concentrations of GLU was interpreted as the formation of Np(IV)-GLU aqueous complexes. The modelling of experimental data according to the Schubert method [1] confirmed the formation of a complex with a Np : GLU ratio 1 : 1. The stoichiometry of the complex Np(OH)4GLU− was proposed based on the experimental observation that no proton exchange occurred during the course of the complexation reaction and that Np(OH)4(aq) was the predominant hydrolysis product in the absence of GLU. A log * β 1,4,1 0 = −2.92 ± 0.30 for the formation reaction Np4+ + 4H2O + GLU−⇔Np(OH)4GLU− + 4H+ was calculated based on the conditional stability constants determined from sorption experiments and using the Np(IV) thermodynamic data selected in the NEA reviews [2]. Linear free energy relationships (LFER) confirmed that the stoichiometry and stability of the Np(IV)-GLU complex characterized in this work are consistent with data available for Th(IV)-, U(IV)- and Pu(IV)-GLU complexes.

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Section: Determination Of the Stoichiometry And Stability Constants Omentioning

confidence: 99%

“…The Schubert method [e.g. 1,4,6,8] was applied to determine the stoichiometry and the stability constants of the Np(IV)-GLU complexes. The resulting thermodynamic data were compared with data available for other An(IV)-GLU complexes.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions: sorption studies

Rojo¹,

Tits²,

Gaona³

et al. 2013

Radiochimica Acta

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“…They also could be sorbed onto the HCP surface with a competing effect on anionic RN uptake. The influence of organics such as isosaccharinic acid (ISA), the most important degradation product of cellulose, on the behaviour of cationic fission products and actinides has already been studied in cementitious solution and materials [6][7][8][9][10][11]. The sorption of ISA on undegraded HCP surface has already been observed and measured [12], and its competing effect on anionic species sorption onto HCP has already been observed [13].…”

Section: Introductionmentioning

confidence: 99%

Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands

Pointeau¹,

Coreau²,

Reiller³

2008

Radiochimica Acta

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To cite this version:I. Pointeau, N. Coreau, Pascal E. Reiller. Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands. Radiochimica Acta, R Oldenbourg Verlag GMBH, 2008, 96 (6) .0), corresponding to the decalcification of the calcium silicate hydrate (C-S-H) phases. The behaviour of anionic RN seems to be correlated to the evolution of calcium concentration and is opposed to the evolution of sulphate concentration in solution which could have a competing effect. Comparison is done with the behaviour of caesium and uranium(VI), which is a cationic RN but has a major negative hydrolysed species at high pH. As awaited, the uranium(VI) behaviour is very different from purely anionic RN one in accord with spectroscopic analyses from literature works. The R d values have also been measured for the organic ligands isosaccharinate (ISA) and EDTA. The uptake of ISA can be important and competing effect with the sorption of SeO 3 2− has been evidenced in HCP suspensions as a function of the ISA concentration.

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“…Also, isosaccharinic acid (ISA) and similar polyhydroxylated carboxylic acids, will be formed by the anaerobic, alkaline degradation of cellulose. ISA is highly complexing and can cause significant increases in radionuclide solubility at high pH [1]. The repository will not be homogenous and there are likely to be areas of reducing and oxidising potential.…”

Section: Management Of Technetium Waste Before Disposalmentioning

confidence: 99%

“…Corrosion of waste-containing steel canisters will lead to the gradual formation of reducing conditions. Thus, the behaviour of radionuclides likely to be in the waste must be understood in the context of this chemistry [1].…”

Section: Introductionmentioning

confidence: 99%

The fate of Tc in a UK intermediate-level nuclear waste repository

Evans

Hallam

Aldridge

et al. 2008

WIT Transactions on Ecology and the Environment

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In the UK, tetraphenylphosphonium bromide (TPPB) has been used to remove technetium prior to disposal from some waste-streams by forming TPPBTc floc. If this floc were to be disposed of in a cementitious repository the TPPBTc would degrade by alkaline hydrolysis to triphenylphosphonium oxide, or by radiolysis to triphenylphosphine, releasing the Tc into solution. Its chemistry would be dominated by TcO 4 in aerobic waters and sparingly soluble TcO 2 (s) in anaerobic. Repository heterogeneity could mean that both Tc(VII) and Tc(IV) are present simultaneously. If TcO 4 -migrates into reducing conditions, ligands in the waste may complex with Tc during reduction to form water-soluble complexes. Also possible, is increased Tc solubility when organic ligands react with TcO 2 (s). Comparisons of Tc solubilities at high pH starting from TcO 2 and from TcO 4 -reduced in the presence of ligands were made. With EDTA and NTA no difference was observed, suggesting that Tc(IV)-ligand complexes were formed. For ISA and gluconic acid the Tc solubility starting from TcO 4 -was higher than in systems with TcO 2 as the starting point. This suggests that the TcO 4 -was not reduced to TcO 2 , but an intermediate oxidation state complex was formed, e.g. Tc(V). The conditional stability constant for the Tc(IV)-gluconic acid complex has been determined to be log β = 26.6 ± 0.2.

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Complexation of Ni(II) by α-isosaccharinic acid and gluconic acid from pH 7 to pH 13

Abstract: SummaryNickel reactions with gluconic acid (Gl) and

Cited by 35 publications

References 8 publications

Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions: sorption studies

Thermodynamics of Np(IV) complexes with gluconic acid under alkaline conditions: sorption studies

Uptake of anionic radionuclides onto degraded cement pastes and competing effect of organic ligands

The fate of Tc in a UK intermediate-level nuclear waste repository

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