Sorption study of strontium onto hydrated cement phases using a sequential desorption method

Iwaida, Takeshi; Nagasaki, Shinya; Tanaka, Satoru

doi:10.1524/ract.2000.88.8.483

Cited by 23 publications

(7 citation statements)

References 4 publications

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“…Similar observations were reported by Sugiyama and Fujita [15]. Iwaida et al [14] explained the observed effect qualitatively by an increase in the zeta potential of the C-S-H surfaces which was attributed to the neutralisation of SiO − sites by Ca(II) ions. From sequential desorption experiments with H 2 O, NH 4 -acetate and EDTA, the same authors concluded that Sr(II) sorbs on different sites of C-S-H and that a small portion of the Sr(II) replaces Ca(II) in the CaO sheets of the C-S-H structure.…”

Section: Introductionsupporting

confidence: 86%

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Strontium binding by calcium silicate hydrates

Tits

Wieland

Müller

et al. 2006

Journal of Colloid and Interface Science

100

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Section: Introductionsupporting

confidence: 86%

“…Iwaida et al [14] determined the Sr(II) uptake by C-S-H phases with varying C:S ratios. The authors observed a significant decrease in the distribution ratio (R d ) with increasing Ca:Si (C:S) ratio of the C-S-H phases.…”

Section: Introductionmentioning

confidence: 99%

Strontium binding by calcium silicate hydrates

Tits

Wieland

Müller

et al. 2006

Journal of Colloid and Interface Science

100

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“…Various studies have been carried out to examine different aspects of the sorption behavior of Sr on a variety of solid materials [2][3][4][5][6][7][8][9][10][11][12][13]. Whereas the sorption behavior of Sr 2+ on kaolinite was investigated in a limited number of studies [14][15][16][17], our literature survey did not yield information *Author for correspondence (E-mail: talalshahwan@iyte.edu.tr).…”

Section: Introductionmentioning

confidence: 99%

Characterization of Sr²⁺uptake on natural minerals of kaolinite and magnesite using XRPD, SEM/EDS, XPS, and DRIFT

Shahwan¹,

Erten²

2005

Radiochimica Acta

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Sr2+ / Kaolinite / Magnesite Summary. The sorption behavior of Sr 2+ ions on natural minerals rich in kaolinite and magnesite was studied using SEM/EDS, XPS, XRPD, AAS/AES and DRIFT techniques. Quantitative analysis of the XPS data shows that magnesite is more effective in Sr 2+ uptake than kaolinite. DRIFT spectra and XRPD patterns indicate that the structures of both minerals were not affected upon Sr 2+ sorption. Intercalation of DMSO in kaolinite lamellae aiming at increasing the interlayer space did not significantly enhance the sorption capacity of the clay towards Sr 2+ probably due to the lack of a negative charge on the accessible sites. EDS mapping indicated that while the sorbed Sr is equally distributed on surface of natural kaolinite, it was associated -to a larger extent -with the regions richer in Mg in the case of natural magnesite. Comparing the uptake mechanisms of natural magnesite with that of pure MgCO 3 , it was seen that while natural magnesite sorbed Sr 2+ mainly through an ion exchange type mechanism, the formation of SrCO 3 coprecipitate was detected on the surface of the MgCO 3 at higher loadings.

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“…In the past decades several studies have reported uptake measurements with radiostrontium on cementitious materials (e.g., – ). In all these studies the distribution coefficient ( K d ) between crushed hardened cement paste (HCP) and highly alkaline cement pore waters was found to be lower on altered ( K d ∼10 −3 -10 −2 m 3 kg −1 ) – than on unaltered cementitious materials ( K d ∼0.1 m 3 kg −1 ) , suggesting that Ca may exert an influence on Sr uptake.…”

Section: Introductionmentioning

confidence: 99%

“…Sr binding in the complex cement matrix is still poorly understood. Sorption studies on single cement minerals indicate that Sr is taken up by calcium silicate hydrates (C-S-H) ,, and (Na+Al) substituted C-S-H (e.g., ). Strongest uptake, however, was reported under experimental conditions where AFt (Al 2 O 3 -Fe 2 O 3 -tri) phases are allowed to form or in ettringite-containing systems , .…”

Section: Introductionmentioning

confidence: 99%

Strontium Uptake by Cementitious Materials

Wieland

Tits

Kunz

et al. 2007

Environ. Sci. Technol.

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Wet chemistry experiments and X-ray absorption fine structure (XAFS) measurements were carried out to investigate the immobilization of nonradioactive Sr and 85Sr in calcite-free and calcite-containing Portland cement. The partitioning of pristine Sr between hardened cement paste (HCP) and pore solution, and the uptake of 85Sr and nonradioactive Sr were investigated in batch-type sorption/desorption experiments. Sr uptake by HCP was found to be fast and nearly linear for both cements, indicating that differences in the compositions of the two cements have no influence on Sr binding. The partitioning of pristine Sr bound in the cement matrix and 85Sr between HCP and pore solution could be modeled in terms of a reversible sorption process using similar Kd values. These findings allow 85Sr uptake to be interpreted in terms of an isotopic exchange process with pristine Sr. Sr K-edge EXAFS measurements on Sr doped HCP and calcium silicate hydrate (C-S-H) samples reveal no significant differences in the local coordination environments of pristine Sr and Sr bound to the cement matrix upon sorption. The first coordination sphere consists of five to six oxygen atoms located at a distance of about 2.6 A, which corresponds to Sr-O distances in the hydration sphere of Sr2+ in alkaline solution. Sr binds to the cement matrix via two bridging oxygen atoms located at a distance of about 3.6 A. No further neighboring atoms could be detected, indicating that Sr is taken up as a partially hydrated species by HCP. Wet chemistry and spectroscopic data further indicate that Sr binding to C-S-H phases is likely to be the controlling uptake mechanism in the cement matrix, which allows Sr uptake by HCP to be predicted based on a Ca-Sr ion exchange model previously developed for Sr binding to C-S-H phases. The latter finding suggests that long-term predictions of Sr immobilization in the cementitious near field of repositories for radioactive waste can be based on a simplified sorption model with C-S-H phases.

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Sorption study of strontium onto hydrated cement phases using a sequential desorption method

Cited by 23 publications

References 4 publications

Strontium binding by calcium silicate hydrates

Strontium binding by calcium silicate hydrates

Characterization of Sr²⁺uptake on natural minerals of kaolinite and magnesite using XRPD, SEM/EDS, XPS, and DRIFT

Strontium Uptake by Cementitious Materials

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Sorption study of strontium onto hydrated cement phases using a sequential desorption method

Cited by 23 publications

References 4 publications

Strontium binding by calcium silicate hydrates

Strontium binding by calcium silicate hydrates

Characterization of Sr2+uptake on natural minerals of kaolinite and magnesite using XRPD, SEM/EDS, XPS, and DRIFT

Strontium Uptake by Cementitious Materials

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Characterization of Sr²⁺uptake on natural minerals of kaolinite and magnesite using XRPD, SEM/EDS, XPS, and DRIFT