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Selenite and selenate uptaken in ettringite: Immobilization mechanisms, coordination chemistry, and insights from structure
AbstractAlthough ettringite is a crucial material in terms of Se immobilization, the immobilization mechanisms, atomic configuration, and intercolumn structure of Se sorbed in ettringite are unclear. The immobilization mechanism of Se oxoanions was evaluated through structural insight into ettringite. It is contrasting between SeO32− and SeO42− in chemical property of the solid residues after immobilization. The oxoanion exchange with structural SO42− is the main mechanism for immobilization of SeO42−. In contrast, SeO32− is easily immobilized to form inner-sphere complexes in ettringite. In addition, it is necessary to reveal the SeO32− complexation sites for understanding the mechanisms in immobilization of SeO32−. Based on the characterization results with the bond valence theory, the location sites of sorbed SeO32− in ettringite structure were proposed. The results obtained in this work are relevant to the understanding of Se and its isotopes immobilized in cement or alkaline environments, especially for nuclear waste management.
Graphical abstract
HighlightsThe immobilization mechanisms of SeO32− and SeO42− in ettringite are different.Sorption of SeO32− will remove structural water molecules in ettringite.SeO32− could form some inner-sphere complexes in the ettringite structure.The EXAFS and bond valence theory was applied to determine the sorption mechanism.The atomic configuration of ettringite surface was proposed after sorption of SeO32−.
Selenite and selenate uptaken in ettringite: Immobilization mechanisms, coordination chemistry, and insights from structure
AbstractAlthough ettringite is a crucial material in terms of Se immobilization, the immobilization mechanisms, atomic configuration, and intercolumn structure of Se sorbed in ettringite are unclear. The immobilization mechanism of Se oxoanions was evaluated through structural insight into ettringite. It is contrasting between SeO32− and SeO42− in chemical property of the solid residues after immobilization. The oxoanion exchange with structural SO42− is the main mechanism for immobilization of SeO42−. In contrast, SeO32− is easily immobilized to form inner-sphere complexes in ettringite. In addition, it is necessary to reveal the SeO32− complexation sites for understanding the mechanisms in immobilization of SeO32−. Based on the characterization results with the bond valence theory, the location sites of sorbed SeO32− in ettringite structure were proposed. The results obtained in this work are relevant to the understanding of Se and its isotopes immobilized in cement or alkaline environments, especially for nuclear waste management.
Graphical abstract
HighlightsThe immobilization mechanisms of SeO32− and SeO42− in ettringite are different.Sorption of SeO32− will remove structural water molecules in ettringite.SeO32− could form some inner-sphere complexes in the ettringite structure.The EXAFS and bond valence theory was applied to determine the sorption mechanism.The atomic configuration of ettringite surface was proposed after sorption of SeO32−.
Selenite and selenate uptaken in ettringite: Immobilization mechanisms, coordination chemistry, and insights from structure
Guo, Binglin (author) / Sasaki, Keiko (author) / Hirajima, Tsuyoshi (author)
Cement and Concrete Research ; 100 ; 166-175
2017-07-10
10 pages
Article (Journal)
Electronic Resource
English
| British Library Online Contents | 2017
| British Library Online Contents | 2017
| British Library Online Contents | 2017
Characterization of the intermediate in formation of selenate-substituted ettringite
| Online Contents | 2017