Adsorption site of Cs+ in bentonite: Determination by EXAFS

M. Nakano, K. Hara, K. Kawamura, K. Amemiya

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

This study elucidated the location where Cs atoms resided at the solid-water interface in smectite hydrates that composed bentonite using EXAFS spectroscopy. Samples were prepared by adding 4ml of a 0.1M CsCl solution to 2g dry weight of suspended KunipiaF bentonite at pH 3.9, 7.1, and 9.8. The Cs K-edge absorption was measured in transmission mode at a synchrotron, Spring-8, Japan, using a Si(311) monochromator at room temperature for the wet paste and air-dried compacted samples. Data were analyzed with the program TECHXAS. The structural parameters were determined by a two-oxygen-shell fit using the ab initio program FEFF6 and ATOMS code. EXAFS analyses have suggested that for air-dried samples the first shell consisted of about 5O at a distance of 3.19-3.20 Å, and the second shell consisted of about 7O at a distance of 3.59-3.60 Å. For the wet paste, the first shell was observed at a distance of 3.15-3.16 Å with the coordination number of about 7O. The second shell consisted of about 6O at a distance of 3.59-3.60 Å. Debye-waller factors of the first oxygen shells were 0.021 and 0.04 Å2 for the air-dried and wet paste samples, respectively. For the second oxygen shells they were 0.039 and 0.052 Å2, respectively. Based on coordination numbers and Debye-waller factors, it concluded that the adsorption sites of Cs+ on smectite hydrates were positioned near the edge of the oxygen hexagonal cavity of the siloxane sheets on basal surface, and appeared between two aluminol sheets at fractured sections, assuming that the first shells were formed by oxygen of inter-layer water, and that the second shells consisted of oxygen forming clay minerals. Furthermore, in the wet paste Cs ions were considered to form incomplete inner-sphere-like complexes and to roam freely in inter-layer water in smectite.

Original languageEnglish
Title of host publicationProceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM
EditorsG. Benda, F. Sheil
Pages623-627
Number of pages5
Volume1
DOIs
Publication statusPublished - 2003
Externally publishedYes
Event9th International Conference on Environmental Remediation and Radioactive Waste Management - Oxford, United Kingdom
Duration: Sep 21 2003Sep 25 2003

Other

Other9th International Conference on Environmental Remediation and Radioactive Waste Management
CountryUnited Kingdom
CityOxford
Period9/21/039/25/03

Fingerprint

bentonite
shell
adsorption
oxygen
smectite
air
water
clay mineral
cavity
spectroscopy
ion

ASJC Scopus subject areas

  • Waste Management and Disposal

Cite this

Nakano, M., Hara, K., Kawamura, K., & Amemiya, K. (2003). Adsorption site of Cs+ in bentonite: Determination by EXAFS. In G. Benda, & F. Sheil (Eds.), Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM (Vol. 1, pp. 623-627) https://doi.org/10.1115/ICEM2003-5000

Adsorption site of Cs+ in bentonite : Determination by EXAFS. / Nakano, M.; Hara, K.; Kawamura, K.; Amemiya, K.

Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM. ed. / G. Benda; F. Sheil. Vol. 1 2003. p. 623-627.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Nakano, M, Hara, K, Kawamura, K & Amemiya, K 2003, Adsorption site of Cs+ in bentonite: Determination by EXAFS. in G Benda & F Sheil (eds), Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM. vol. 1, pp. 623-627, 9th International Conference on Environmental Remediation and Radioactive Waste Management, Oxford, United Kingdom, 9/21/03. https://doi.org/10.1115/ICEM2003-5000
Nakano M, Hara K, Kawamura K, Amemiya K. Adsorption site of Cs+ in bentonite: Determination by EXAFS. In Benda G, Sheil F, editors, Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM. Vol. 1. 2003. p. 623-627 https://doi.org/10.1115/ICEM2003-5000
Nakano, M. ; Hara, K. ; Kawamura, K. ; Amemiya, K. / Adsorption site of Cs+ in bentonite : Determination by EXAFS. Proceedings of the International Conference on Radioactive Waste Management and Environmental Remediation, ICEM. editor / G. Benda ; F. Sheil. Vol. 1 2003. pp. 623-627
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title = "Adsorption site of Cs+ in bentonite: Determination by EXAFS",
abstract = "This study elucidated the location where Cs atoms resided at the solid-water interface in smectite hydrates that composed bentonite using EXAFS spectroscopy. Samples were prepared by adding 4ml of a 0.1M CsCl solution to 2g dry weight of suspended KunipiaF bentonite at pH 3.9, 7.1, and 9.8. The Cs K-edge absorption was measured in transmission mode at a synchrotron, Spring-8, Japan, using a Si(311) monochromator at room temperature for the wet paste and air-dried compacted samples. Data were analyzed with the program TECHXAS. The structural parameters were determined by a two-oxygen-shell fit using the ab initio program FEFF6 and ATOMS code. EXAFS analyses have suggested that for air-dried samples the first shell consisted of about 5O at a distance of 3.19-3.20 {\AA}, and the second shell consisted of about 7O at a distance of 3.59-3.60 {\AA}. For the wet paste, the first shell was observed at a distance of 3.15-3.16 {\AA} with the coordination number of about 7O. The second shell consisted of about 6O at a distance of 3.59-3.60 {\AA}. Debye-waller factors of the first oxygen shells were 0.021 and 0.04 {\AA}2 for the air-dried and wet paste samples, respectively. For the second oxygen shells they were 0.039 and 0.052 {\AA}2, respectively. Based on coordination numbers and Debye-waller factors, it concluded that the adsorption sites of Cs+ on smectite hydrates were positioned near the edge of the oxygen hexagonal cavity of the siloxane sheets on basal surface, and appeared between two aluminol sheets at fractured sections, assuming that the first shells were formed by oxygen of inter-layer water, and that the second shells consisted of oxygen forming clay minerals. Furthermore, in the wet paste Cs ions were considered to form incomplete inner-sphere-like complexes and to roam freely in inter-layer water in smectite.",
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N2 - This study elucidated the location where Cs atoms resided at the solid-water interface in smectite hydrates that composed bentonite using EXAFS spectroscopy. Samples were prepared by adding 4ml of a 0.1M CsCl solution to 2g dry weight of suspended KunipiaF bentonite at pH 3.9, 7.1, and 9.8. The Cs K-edge absorption was measured in transmission mode at a synchrotron, Spring-8, Japan, using a Si(311) monochromator at room temperature for the wet paste and air-dried compacted samples. Data were analyzed with the program TECHXAS. The structural parameters were determined by a two-oxygen-shell fit using the ab initio program FEFF6 and ATOMS code. EXAFS analyses have suggested that for air-dried samples the first shell consisted of about 5O at a distance of 3.19-3.20 Å, and the second shell consisted of about 7O at a distance of 3.59-3.60 Å. For the wet paste, the first shell was observed at a distance of 3.15-3.16 Å with the coordination number of about 7O. The second shell consisted of about 6O at a distance of 3.59-3.60 Å. Debye-waller factors of the first oxygen shells were 0.021 and 0.04 Å2 for the air-dried and wet paste samples, respectively. For the second oxygen shells they were 0.039 and 0.052 Å2, respectively. Based on coordination numbers and Debye-waller factors, it concluded that the adsorption sites of Cs+ on smectite hydrates were positioned near the edge of the oxygen hexagonal cavity of the siloxane sheets on basal surface, and appeared between two aluminol sheets at fractured sections, assuming that the first shells were formed by oxygen of inter-layer water, and that the second shells consisted of oxygen forming clay minerals. Furthermore, in the wet paste Cs ions were considered to form incomplete inner-sphere-like complexes and to roam freely in inter-layer water in smectite.

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