Hydration and hydrolysis of samarium (III) in montmorillonite clay: a neutron diffraction study

O. V. Sobolev (1) , L. Charlet (1) , G. J. Cuello (2) , A. Gehin (1) , J. Brendle (3) , Nicolas Geoffroy (1)

1 LGIT - Laboratoire de Géophysique Interne et Tectonophysique
2 ILL - Institut Laue-Langevin
3 LMPC

Neutron diffraction with isotopic substitution was carried out at room temperature on hydrated samples of Sm montmorillonite, prepared at pH = 4 and 8, in order to find out whether Sm is present as aqueous Sm(OH)3o, Sm3+, or intermediate hydrolyzed species, and how it is linked to the clay surface. It was found that the number of hydrogen atoms (5.5 ± 2.0) nearest to Sm3+ at pH = 4 is equal to or even slightly smaller than that of oxygen atoms (7.5 ± 1.0). This means that Sm3+ is bound to the clay surface and it is probably partially hydrolyzed. This result is very close to those obtained earlier for Yb3+ and Nd3+, despite the different methods of sample preparation and the different mineralogy of the samples.

O. V. Sobolev, L. Charlet, G. J. Cuello, A. Gehin, J. Brendle, et al.. Hydration and hydrolysis of samarium (III) in montmorillonite clay: a neutron diffraction study. Journal of Physics: Condensed Matter, 2008, 20 (10, article n° 104207), pp.NIL_42-NIL_46. ⟨10.1088/0953-8984/20/10/104207⟩. ⟨insu-00335680⟩