Rapid Communication: Evidence for the Existence of Complexes between Th(IV) and α-Isosaccharinic Acid under Alkaline Conditions

Vercammen, Karlien; Glaus, Martin A.; Loon, Luc R. Van

doi:10.1524/ract.1999.84.4.221

Cited by 26 publications

(22 citation statements)

References 9 publications

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“…Wieland et al [19] studied the sorption of Th(IV) on hardened cement past under similar conditions and found a significant effect of α-ISA on the sorption of Th(IV) in the range 10" 5 M < [a-ISA] < ΙΟ" 2 M. The data could be explained by the formation of a 1:2 Th-ISA complex. The formation of a 1:2 complex is in good agreement with recent observations that in presence of Ca(II), ISA forms 1:2 complexes with Th(IV), Ca being part of the complex [21] and with studies of the coordination between Al(III), aldarate ligands and Ca(II) [22], In the absence of Ca(II), a 1:1 complex between Th(IV) and α-ISA is formed [21], Based on these findings, and because ACW-I contains ~2 mM Ca(II), the data for pure α-ISA were analysed assuming that a 1:2 complex between Th and α-ISA is formed (n = 2). The solid line in Fig.…”

Section: Resultssupporting

confidence: 91%

Degradation of Cellulosic Materials under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate Level Radioactive Waste. Part III: Effect of Degradation Products on the Sorption of Radionuclides on Feldspar

et al. 1999

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Cellulose / Isosaccharinic acid / Complexation / Sorption / Radionuclides SummaryThe effect of degradation products of different cellulosic materials on the sorption behaviour of Th(IV), Eu(III) and Ni(II) on feldspar at pH 13.3 was studied. For all three metals, a decrease in sorption could be observed with increasing concentration of organics in solution. For Th(IV), a-ISA is the effective ligand present in the solutions of degraded cellulose, independent on the type of cellulose studied. For Eu(III), α-ISA is the effective ligand in the case of pure cellulose degradation. In the case of other cellulosic materials, unknown ligands cause the sorption reduction. For Ni(II), also unknown ligands cause sorption reduction, independent on the type of cellulose studied. These unknown ligands are not formed during alkaline degradation of cellulose, but are present as impurities in certain cellulosic materials.

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Section: Resultssupporting

confidence: 91%

Degradation of Cellulosic Materials under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate Level Radioactive Waste. Part III: Effect of Degradation Products on the Sorption of Radionuclides on Feldspar

et al. 1999

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“…The thermodynamic complexation constants (K and K Ca ) associated to Eqs. (2) and (3) can be written as (note that the nomenclature for equilibrium constants has been slightly modified compared to [6]):…”

Section: Resultsmentioning

confidence: 99%

“…between a few safety-relevant nuclides and ISA [5][6][7]. Apparent stability constants (sometimes also known as conditional stability constants) reduce the stoichiometric relation between the metal and the ligand and additional reactants to a simple metal-ligand interaction.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, it is not a priori clear, whether these results can be applied to the pH range of interest in the present work. The influence of Ca on the formation of complexes between Th(IV) and ISA at pH 12.8 and 13.3 has recently been shown [6]. Through high performance ion exchange chromatography (HPIEC) and batch sorption experiments, these authors demonstrated that (i) in the absence of Ca, 1:1 Th:ISA complexes are formed and (ii) in the presence of Ca, 1:2:2 Th:ISA:Ca complexes are formed.…”

Section: Introductionmentioning

confidence: 99%

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Complexation of Th(IV) and Eu(III) by α-isosaccharinic acid under alkaline conditions

Vercammen¹,

Glaus²,

Loon³

2001

Radiochimica Acta

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The complexation of Th(IV) and Eu(III) by α-isosaccharinic acid (ISA) has been studied in the pH range from 10.7 to 13.3 by batch sorption experiments, and the influence of Ca on the complexation was investigated. Sixteen data sets -each determined at variable ISA concentrationsare used to determine the stoichiometry of the complexation reactions and the stability constants. Based on best-fit analysis of the sorption data, it is postulated that 1:1 Th:ISA complexes are formed in the absence of Ca according to the complexation reaction: Th + ISA (ThISA) −4H + 4H with log K = −10.1 at I = 0.3 M. In the presence of Ca, the sorption data can be interpreted best by a mixed-metal complex, according to the complexation reaction: Th + 2ISA + Ca (Th(ISA) 2 Ca) −4H + 4H with log K Ca = −3.6 at I = 0.3 M. There are no indications that Ca participates in complexes of ISA with Eu. The sorption data suggest that 1:1 Eu:ISA complexes are dominant in the pH range from 10.7 to 13.3 according to the complexation reaction: Eu + ISA (EuISA) −4H + 4H with log K = −30.6 at I = 0.3 M. It is important to note that the stoichiometric numbers and stability constants proposed here are not independent of the hydrolysis reactions of the two metal cations. Thus, the same hydrolysis data as used here have to be applied in speciation calculations with the ISA complexation data for Eu(III) and Th(IV).

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“…Only very limited reliable data are available for isosaccharinate (ISA -) complexes of thorium. Two types of data that are available for this system are 1) those that are based on sorption experiments under alkaline conditions [2][3][4][5][6] and 2) those based on liquid-liquid extractions [7,8]. The data based on sorption experiments have recently been reviewed by Hummel et al [1] who concluded that the entire data can be represented by [Th(OH) 4 (aq) + ISA -= Th(OH) 4-x (ISA -xH ) +xH 2 O; Th(OH) 4 (aq) + 2ISA -+ Ca 2+ = CaTh(OH) 4-2y (ISA -yH )(aq) + 2yH 2 O] and that the values of x and y in the above reactions cannot be determined by standard thermodynamic methods.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Model for ThO2(am) Solubility in Isosaccharinate Solutions

Rai¹,

Yui

Moore

et al. 2009

J Solution Chem

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Rapid Communication: Evidence for the Existence of Complexes between Th(IV) and α-Isosaccharinic Acid under Alkaline Conditions

Cited by 26 publications

References 9 publications

Degradation of Cellulosic Materials under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate Level Radioactive Waste. Part III: Effect of Degradation Products on the Sorption of Radionuclides on Feldspar

Degradation of Cellulosic Materials under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate Level Radioactive Waste. Part III: Effect of Degradation Products on the Sorption of Radionuclides on Feldspar

Complexation of Th(IV) and Eu(III) by α-isosaccharinic acid under alkaline conditions

Thermodynamic Model for ThO2(am) Solubility in Isosaccharinate Solutions

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