The uptake of radium by calcium silicate hydrates and hardened cement paste

Tits, J.; Iijima, Kazuki; Wieland, Erich; Kamei, Gento

doi:10.1524/ract.2006.94.9-11.637

Cited by 31 publications

(9 citation statements)

References 12 publications

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“…Interestingly, increasing U(VI) uptake by C-S-H with increasing Ca concentration is in contrast to previous observations on Sr and Ra binding to C-S-H phases [3,9] which showed a decreasing uptake with increasing aqueous Ca concentration. Interestingly, increasing U(VI) uptake by C-S-H with increasing Ca concentration is in contrast to previous observations on Sr and Ra binding to C-S-H phases [3,9] which showed a decreasing uptake with increasing aqueous Ca concentration.…”

Section: Effect Of Ph and Ca Concentration On The U(vi) Sorption Isotcontrasting

confidence: 99%

Uranium(VI) Uptake by Synthetic Calcium Silicate Hydrates

et al. 2008

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The immobilization of U(VI) by C-S-H phases under conditions relevant for the cementitious near field of a repository for radioactive waste has been investigated. C-S-H phases have been synthesized using two different procedures: the "direct reaction" method and the "solution reaction" method.The stabilities of alkaline solutions of U(VI) (presence of precipitates or colloidal material) were studied prior to sorption and co-precipitation tests in order to determine the experimental U(VI) solubility limits. These U(VI) solubility limits were compared with the U(VI) solubilities obtained from thermodynamic speciation calculations assuming the presence of combinations of different solid U(VI) phases. The solid phase controlling U(VI) solubility in the present experiments was found to be CaUO 4 (s).The U(VI) uptake kinetics and sorption isotherms on C-S-H phases with different C:S ratios were determined under various chemical conditions; e.g., sorption and co-precipitation experiments and different pH's. U(VI) was found to sorb fast and very strongly on C-S-H phases with distribution ratios (R d values) ranging in value between 10 3 L kg -1 and 10 6 L kg -1 . Both sorption and co-precipitation experiments resulted in R d values which were very similar, thus indicating that no additional sorption sites for U(VI) were generated in the co-precipitation process. Furthermore, C-S-H synthesis procedures did not have a significant influence on U(VI) uptake. The U(VI) sorption isotherms were found to be non-linear, and further, increasing Ca concentrations resulted in increasing U(VI) uptake. The latter observation suggests that U(VI) uptake is controlled by a solubility-limiting process, while the former observation further indicates that pure Ca-uranate is not the solubility-limiting phase. It is proposed that a solid solution containing Ca and 2 2 UO + could control U(VI) uptake by C-S-H phases.

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Section: Effect Of Ph and Ca Concentration On The U(vi) Sorption Isotcontrasting

confidence: 99%

Uranium(VI) Uptake by Synthetic Calcium Silicate Hydrates

et al. 2008

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“…The uptake of 55 Fe onto C-S-H phases and TiO 2 can be expressed in terms of a K d value (distribution coefficient), which is commonly used to quantify the partitioning of a radiotracer between solid and liquid phase in case of linear sorption. The K d value is defined as follows: meaning that water is disregarded in the mass calculations (Tits et al, 2006b). Isotherm data are presented as the quantities of Fe sorbed per kg solid (dry weight of C-S-H) versus the Fe equilibrium concentration.…”

Section: Sorption Experimentsmentioning

confidence: 99%

“…The interlayer was found to also expose hosting sites for radionuclide uptake. The uptake potential of C-S-H phases has been studied for several radionuclides, such as Zn(II) (Ziegler et al, 2001), U(VI) (Harfouche et al, 2006;Tits et al, 2011), Eu(III) (Pointeau et al, 2001;Schlegel et al, 2004), Sr(II) (Tits et al, 2006a), Ra(II) (Lange et al, 2018;Olmeda et al, 2019;Tits et al, 2006b), Np(IV) (Gaona et al, 2011;Tits et al, 2014), and Nd(III) (Mandaliev et al, 2010a;Mandaliev et al, 2010b).…”

Section: Introductionmentioning

confidence: 99%

Fe(III) uptake by calcium silicate hydrates

Mancini

Wieland

Geng

et al. 2020

Applied Geochemistry

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…In this contribution we complement the studies of Lange et al [40] on the uptake of Ra with calculations regarding the incorporation of Sr. Previous studies of Tits et al [41,42] indicate significant difference in the uptake of Ra and Sr by C-S-H, with uptake of Sr being two orders of magnitude lower. The measured Kc values (selectivity constants) for the cation exchange reactions are shown in Fig.…”

Section: Retention Of Ra and Sr By Cementitious Materialsmentioning

confidence: 85%

Modeling of Nuclear Waste Forms: State-of-the-Art and Perspectives

et al. 2020

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Computational modeling is an important aspect of the research on nuclear waste materials. In particular, atomistic simulations, when used complementary to experimental efforts, contribute to the scientific basis of safety case for nuclear waste repositories. Here we discuss the state-of-the-art and perspectives of atomistic modeling for nuclear waste management on a few cases of successful synergy of atomistic simulations and experiments. In particular, we discuss here: (1) the potential of atomistic simulations to investigate the uranium oxidation state in mixed-valence uranium oxides and (2) the ability of cementitious barrier materials to retain radionuclides such as 226Ra and 90Sr, and of studtite/metastudtite secondary peroxide phases to incorporate actinides such as Np and Am. The new contribution we make here is the computation of the incorporation of Sr by C-S-H (calcium silicate hydrate) phases.

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The uptake of radium by calcium silicate hydrates and hardened cement paste

Cited by 31 publications

References 12 publications

Uranium(VI) Uptake by Synthetic Calcium Silicate Hydrates

Uranium(VI) Uptake by Synthetic Calcium Silicate Hydrates

Fe(III) uptake by calcium silicate hydrates

Modeling of Nuclear Waste Forms: State-of-the-Art and Perspectives

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