Characterization of homoionic Fe{sup 2+}-type montmorillonite: Potential chemical species of iron contaminant

Journal Article · Wed Aug 15 00:00:00 EDT 2007 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2007.06.002· OSTI ID:21043805

Kozai, Naofumi ^[1]; Inada, Koichi; Adachi, Yoshifusa; Kawamura, Sachi; Kashimoto, Yusuke; Kozaki, Tamotsu; Sato, Seichi ^[2]; Ohnuki, Toshihiko ^[1]; Sakai, Takuro; Sato, Takahiro; Oikawa, Masakazu ^[3]; Esaka, Fumitaka; Mitamura, Hisayoshi ^[4]

---

1. Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan)
2. Division of Energy and Environmental Systems, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)
3. Department of Advanced Radiation Technology, JAEA, Takasaki, Gunma 370-1292 (Japan)
4. Division of Environment and Radiation Sciences, JAEA, Tokai, Ibaraki 319-1195 (Japan)

Fe{sup 2+}-montmorillonite with Fe{sup 2+} ions occupying cation exchange sites is an ideal transformation product in bentonite buffer material. In our previous study on preparation and characterization of Fe{sup 2+}-montmorillonite, the montmorillonite sample that adsorbed Fe{sup 2+} ions on almost all of the cation exchange sites was prepared using a FeCl{sub 2} solution under an inert gas condition [N. Kozai, Y. Adachi, S. Kawamura, K. Inada, T. Kozaki, S. Sato, H. Ohashi, T. Ohnuki, T. Banba, J. Nucl. Sci. Technol. 38 (2001) 1141]. In view of the unstable nature of iron(II) chemical species, this study attempted to determine the potential contaminant iron chemical species in the sample. Nondestructive elemental analysis revealed that a small amount of chloride ions remained dispersed throughout the clay particles. The chloride ion retention may be due to the adsorption of FeCl{sup +} ion pairs in the initial FeCl{sub 2} solution and the subsequent containment of the Cl{sup -} ions that are dissociated from the FeCl{sup +} ion pairs during excess salt removal treatment. Two explanations are advanced for the second process: the slow release of the remaining Cl{sup -} ions from the collapsed interlayer of the montmorillonite, and the transformation of a minor fraction of the remaining FeCl{sup +} ion pairs to iron(III) hydroxide chloride complexes having low solubility. - Graphical abstract: The distribution of Si (left) and Cl (right) in homoionic Fe{sup 2+}-type montmorillonite prepared under an inert gas atmosphere by a conventional method using a FeCl{sub 2} solution. A small fraction of chloride ions remained dispersed throughout the clay. This paper mainly discusses the potential contaminant iron chemical species in this sample other than Fe{sup 2+} ions.

• OSTI ID: 21043805
• Journal Information: Journal of Solid State Chemistry, Vol. 180, Issue 8; Other Information: DOI: 10.1016/j.jssc.2007.06.002; PII: S0022-4596(07)00225-3; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
BENTONITE
CHLORINE IONS
CONTAINMENT
HIGH-LEVEL RADIOACTIVE WASTES
ION EXCHANGE
ION PAIRS
IRON CHLORIDES
IRON COMPLEXES
IRON HYDROXIDES
IRON IONS
MONTMORILLONITE
SOLUTIONS