Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process

Calcium silicate hydrate (CSH) is a main component of cement-based material required for constructing the geological repository. As in many countries, since the repository in Japan is constructed below water table, we must consider the interaction of radionuclide with cement materials altered around...

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Autores principales:	Yuichi NIIBORI, Masayuki NARITA, Akira KIRISHIMA, Taiji CHIDA, Hitoshi MIMURA
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2014
Materias:	radioactive wastes europium calcium silicate hydrates fluorescence emission spectra Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/7203b68aebae409aa50a8b248e8ac61d
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spelling	oai:doaj.org-article:7203b68aebae409aa50a8b248e8ac61d2021-11-26T06:09:52ZFluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process2187-974510.1299/mej.2014tep0027https://doaj.org/article/7203b68aebae409aa50a8b248e8ac61d2014-08-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/1/4/1_2014tep0027/_pdf/-char/enhttps://doaj.org/toc/2187-9745Calcium silicate hydrate (CSH) is a main component of cement-based material required for constructing the geological repository. As in many countries, since the repository in Japan is constructed below water table, we must consider the interaction of radionuclide with cement materials altered around the repository after the backfill. Using fluorescence emission spectra, so far, the authors have investigated the interaction of Eu(III) (as a chemical analog of Am(III)) with CSH gels as a secondary mineral formed without drying process, considering a condition saturated with groundwater. However, in such fluorescence emission behaviors, a deexcitation process of OH vibrators of light water and a quenching effect caused by Eu-Eu energy transfer between Eu atoms incorporated in the CSH gel must be considered. This study examined the fluorescence emission behavior of Eu(III) sorbed on CSH gels, by using La(III) (non-fluorescent ions) as a diluent of Eu(III). Furthermore, CSH samples were synthesized with CaO, SiO2, and heavy water (D2O) as a solvent in order to avoid the obvious deexcitation process of OH vibrators of light water. In the results, the peak around 618 nm was split into two peaks of 613 nm and 622 nm in the cases of Ca/Si=1.0 and 1.6. Then, the peak of 613 nm decreased with increment of Eu(III)/La(III) ratio. This means that the relative intensity of 613 nm is useful to quantify the amount of Eu(III) incorporated in CSH gel. Besides, the decay behavior of the fluorescence emission did not depend on the Eu/La concentration ratio. That is, such a quenching effect is neglectable. Additionally, the fluorescence emission spectra of Eu(III) showed that the state of Eu(III) depended on Ca/Si ratio of CSH. This suggested that there was several sites in CSH to incorporate Eu(III). When CSH is altered, whole cementitious material in repository must be altered forming cracks and leaching some calcium compositions. Therefore, the adsorptive capacity of CSH might also play a key role to retard the migration of nuclides released from the waste body. This study mentioned the fundamental behaviors on the interaction of radionuclides and the altered CSH around the repository.Yuichi NIIBORIMasayuki NARITAAkira KIRISHIMATaiji CHIDAHitoshi MIMURAThe Japan Society of Mechanical Engineersarticleradioactive wasteseuropiumcalcium silicate hydratesfluorescence emission spectraMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 1, Iss 4, Pp TEP0027-TEP0027 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	radioactive wastes europium calcium silicate hydrates fluorescence emission spectra Mechanical engineering and machinery TJ1-1570
spellingShingle	radioactive wastes europium calcium silicate hydrates fluorescence emission spectra Mechanical engineering and machinery TJ1-1570 Yuichi NIIBORI Masayuki NARITA Akira KIRISHIMA Taiji CHIDA Hitoshi MIMURA Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
description	Calcium silicate hydrate (CSH) is a main component of cement-based material required for constructing the geological repository. As in many countries, since the repository in Japan is constructed below water table, we must consider the interaction of radionuclide with cement materials altered around the repository after the backfill. Using fluorescence emission spectra, so far, the authors have investigated the interaction of Eu(III) (as a chemical analog of Am(III)) with CSH gels as a secondary mineral formed without drying process, considering a condition saturated with groundwater. However, in such fluorescence emission behaviors, a deexcitation process of OH vibrators of light water and a quenching effect caused by Eu-Eu energy transfer between Eu atoms incorporated in the CSH gel must be considered. This study examined the fluorescence emission behavior of Eu(III) sorbed on CSH gels, by using La(III) (non-fluorescent ions) as a diluent of Eu(III). Furthermore, CSH samples were synthesized with CaO, SiO2, and heavy water (D2O) as a solvent in order to avoid the obvious deexcitation process of OH vibrators of light water. In the results, the peak around 618 nm was split into two peaks of 613 nm and 622 nm in the cases of Ca/Si=1.0 and 1.6. Then, the peak of 613 nm decreased with increment of Eu(III)/La(III) ratio. This means that the relative intensity of 613 nm is useful to quantify the amount of Eu(III) incorporated in CSH gel. Besides, the decay behavior of the fluorescence emission did not depend on the Eu/La concentration ratio. That is, such a quenching effect is neglectable. Additionally, the fluorescence emission spectra of Eu(III) showed that the state of Eu(III) depended on Ca/Si ratio of CSH. This suggested that there was several sites in CSH to incorporate Eu(III). When CSH is altered, whole cementitious material in repository must be altered forming cracks and leaching some calcium compositions. Therefore, the adsorptive capacity of CSH might also play a key role to retard the migration of nuclides released from the waste body. This study mentioned the fundamental behaviors on the interaction of radionuclides and the altered CSH around the repository.
format	article
author	Yuichi NIIBORI Masayuki NARITA Akira KIRISHIMA Taiji CHIDA Hitoshi MIMURA
author_facet	Yuichi NIIBORI Masayuki NARITA Akira KIRISHIMA Taiji CHIDA Hitoshi MIMURA
author_sort	Yuichi NIIBORI
title	Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
title_short	Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
title_full	Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
title_fullStr	Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
title_full_unstemmed	Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
title_sort	fluorescence emission behavior of eu(iii) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process
publisher	The Japan Society of Mechanical Engineers
publishDate	2014
url	https://doaj.org/article/7203b68aebae409aa50a8b248e8ac61d
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_version_	1718409783171612672

Fluorescence emission behavior of Eu(III) sorbed on calcium silicate hydrates as a secondary mineral formed without drying process

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