The uptake of radium by calcium silicate hydrates and hardened cement paste
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Jan Tits
, Kazuki Iijima , Erich Wieland and Gento Kamei
In the present study the interaction of Ra(II) with calcium silicate hydrates (C-S-H) as well as with fresh and degraded hardened cement pastes (HCP) has been investigated using batch-type sorption tests. Synthetic C-S-H phases with varying CaO:SiO2 (C:S)mol ratios, relevant to non-degraded HCP and degraded HCP, were prepared in the absence of alkalis (Na(I), K(I)) and in an alkali-rich artificial cement pore water (ACW). The Ra(II) sorption kinetics, the effect of the solid to liquid ratio and the C:S mol ratio on the Ra(II) uptake were investigated. In addition, the reversibility of Ra(II) sorption was tested using dilution tests. Comparison with data on the uptake of Sr(II) by C-S-H phases obtained from previous in-house studies showed that the same model concept could be applied to interpret the immobilization of Sr(II) and Ra(II) in these systems. Ra(II) sorption on C-S-H in the absence of alkalis could be interpreted in terms of a Ra2+-Ca2+ cation exchange model. The Ra2+-Ca2+ exchange selectivity coefficient, RaCaKC, was determined to be (6±4). There are indications that, in the presence of alkalis, the Ra(II) sorption by C-S-H phases can only be described with the help of an ion-exchange model involving Ra2+, Ca2+ and the monovalent alkalis.
The cation exchange model developed for C-S-H phases in the absence of alkalis was successfully applied to predict the sorption of Ra(II) on degraded HCP, assuming that the Ra(II) sorbs solely on the C-S-H fraction of the HCP. Model predictions and experimental data were found to agree well in view of the simplified sorption model used.
© Oldenbourg Wissenschaftsverlag
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Articles in the same Issue
- Preface Migration 2005
- Solubility measurement of zirconium(IV) hydrous oxide
- Solubility of ThO2·xH2O(am) and the formation of ternary Th(IV) hydroxide-carbonate complexes in NaHCO3-Na2CO3 solutions containing 0−4 M NaCl
- Ion interaction (SIT) coefficients for the Th4+ ion and trace activity coefficients in NaClO4, NaNO3 and NaCl solution determined by solvent extraction with TBP
- Leaching of neptunium from garnet- and murataite-based ceramics
- Coprecipitation of thorium and lanthanum with UO2+x(s) as host phase
- Rare Earth element (REE) incorporation in natural calcite: Upper limits for actinide uptake in a secondary phase
- Protonation of D-gluconate and its complexation with Np(V) in acidic to nearly neutral solutions
- Complexing properties of α-isosaccharinate: thorium
- Determination of the thermodynamic quantities of complexation between Eu(III) and carboxylic acids by microcalorimetry
- Potentiometric investigations on the interaction of humic acid with Cu(II) and Eu(III) ions
- Investigation of complexation of thorium by humic acid using chemically immobilized humic acid on silica gel
- Correlation between X-ray chemical shift and partial charge in Tc(IV) complexes: Determination of Tc partial charge in TcnOy(4n-2y)+
- Oxidation and dissolution rates of UO2(s) in carbonate-rich solutions under external alpha irradiation and initially reducing conditions
- On the stability of Pu(III) at different pH under non-inert conditions
- Reduction behavior of uranium in the presence of citric acid
- Leaching of zirconolite ceramics under H+ and He2+ irradiation
- Reduction of plutonium(VI) in brine under subsurface conditions
- Theoretical first step towards an understanding of the uranyl ion sorption on the rutile TiO2(110) face: A DFT periodic and cluster study
- Cm(III) sorption onto γ-Al2O3: New insight into sorption mechanisms by time-resolved laser fluorescence spectroscopy and extended X-ray absorption fine structure
- Modelling sorption data for the actinides Am(III), Np(V) and Pa(V) on montmorillonite
- Sorption of Cs, Ni, Pb, Eu(III), Am(III), Cm, Ac(III), Tc(IV), Th, Zr, and U(IV) on MX 80 bentonite: An experimental approach to assess model uncertainty
- The uptake of radium by calcium silicate hydrates and hardened cement paste
- Np(V)O2+ sorption on hydroxyapatite-effect of calcium and phosphate anions
- Uranium(VI) interaction with pyrite (FeS2): Chemical and spectroscopic studies
- Interaction of U(VI) with pyrite, galena and their mixtures: a theoretical and multitechnique approach
- Technetium sorption by stibnite from natural water
- Mechanisms of cesium sorption onto magnetite
- Sorption of cesium on granite under aerobic and anaerobic conditions
- Comparative study of cesium sorption on crushed and intact sedimentary rock
- The INE-Beamline for actinide research at ANKA
- Evaluation of the reversibility of iodide uptake by argillaceous rocks by the radial diffusion method
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- Interaction mechanisms of bacterial strains isolated from extreme habitats with uranium
- Biotransformation of plutonium complexed with citric acid
- Iodination of humic acid samples from different origins
- The fate of the epsilon phase (Mo-Ru-Pd-Tc-Rh) in the UO2 of the Oklo natural fission reactors
- Rhenium migration at the Maqarin natural analogue site (Jordan)
- Classic adsorption isotherms incorporated in modern surface complexation models: Implications for sorption of actinides
- Use of thermodynamic sorption models to derive radionuclide Kd values for performance assessment: selected results and recommendations of the NEA sorption project
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