Macro- and microspectroscopic study of Nd (III) uptake mechanisms in hardened cement paste

Environmental Science & Technology
P MandalievE Wieland

Abstract

Cement is an important component in repositories for low-level and intermediate-level radioactive waste. Nd uptake by hardened cement paste (HCP) has been investigated with the aim of developing a mechanistic understanding of the immobilization processes of trivalent lanthanides and actinides in HCP on the molecular level. Information on the microstructure of HCP, the Nd distribution in the cement matrix, and the coordination environment of Nd in these matrices was gained from the combined use of scanning electron microscopy (SEM), synchrotron-based micro-X-ray fluorescence (micro-XRF), micro-X-ray (micro-XAS), and bulk-X-ray absorption spectroscopy (bulk-XAS) on Nd doped cement samples. The samples were reacted over periods of time between 15 min and 200 days. SEM and micro-XRF investigations suggest preferential Nd accumulation in rims around "inner"-calcium silicate hydrates (C-S-H). The EXAFS data indicate that the coordination environment of Nd taken up by HCP was dependent on reaction time. Changes in the structural parameters derived from EXAFS support the idea of Nd incorporation into the structure of C-S-H phases. The Nd binding mechanisms proposed in this study have implication for an overall assessment of the safe di...Continue Reading

References

Aug 22, 2001·Journal of Synchrotron Radiation·M Newville
Apr 23, 2004·Journal of Synchrotron Radiation·Matthew A MarcusRobert E Sublett
Jun 29, 2004·Journal of Colloid and Interface Science·Thorsten StumpfThomas Fanghänel
Sep 24, 2004·Environmental Science & Technology·Michel L SchlegelPascal Reiller
Jun 22, 2005·Journal of Synchrotron Radiation·B Ravel, M Newville
Mar 15, 2006·Waste Management·Barbara Lothenbach, Erich Wieland
May 2, 2006·Environmental Science & Technology·M VespaA M Scheidegger
Jun 22, 2006·Environmental Science & Technology·Silvia StumpfThomas Fanghänel
Apr 7, 2007·Environmental Science & Technology·M VespaA M Scheidegger

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Citations

Aug 14, 2012·Analytical and Bioanalytical Chemistry·Daniel R FröhlichTobias Reich
Oct 30, 2015·Environmental Science & Technology·Lucile DezeraldAndrés Saúl
Sep 20, 2016·Journal of Hazardous Materials·Amitava Roy, Julia A Stegemann

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