M$^+$/H$^+$ ion exchange behavior of the phosphoantimonic acids H$_n$Sb$_n$P$_2$O$_{3n+5}$. $x$H$_2$O (n=1,3) for M=Cs and other alkali metal ions

J.G. Decaillon (1) , Y. Andres (1) , J.C. Abbe (1) , M. Tournoux (2)

1 SUBATECH - Laboratoire de physique subatomique et des technologies associées
2 IMN - Institut des Matériaux Jean Rouxel

The sorptions of cesium and of other alkali metal ions have been studied by batch techniques; the data are well fitted using the Langmuir equation. The values of the various thermodynamic parameters associated to the ion exchange are reported (free energies, enthalpies, entropies, distribution coefficients Kd, selectivity coefficients Kc) and discussed; the ion selectivity, at infinite exchange on HSbP O (called H ) and on H Sb P O (called H ) varies according to the sequence 2 8 1 3 3 2 14 3 1 Cs . Rb . K . Na. The very negative values of DGCs/H Rb/H 8, and DG 8 are indicative of a preferential adsorption of Cs and 1 1 Rb higher in H than in H, by about one order of magnitude at low concentration level. The selectivity coefficients for Cs , 3 1 Rb on H vary linearly with the fractional exchange x¯ in solid (Kielland plot) suggesting a unique site of exchange. The 1 M Kielland plot for H can be described in terms of a multisite ion exchange model (two sites) in agreement with the number of 3 sites in the crystalline structure of K (homologous compound). Radiotracers have been used to estimate the parameters 3 Kd at low concentration levels. The results are discussed on the basis of the thermodynamic data together with the structures

Domaines: Chimie-Physique [physics.chem-ph]

J.G. Decaillon, Y. Andres, J.C. Abbe, M. Tournoux. M$^+$/H$^+$ ion exchange behavior of the phosphoantimonic acids H$_n$Sb$_n$P$_2$O$_{3n+5}$. $x$H$_2$O (n=1,3) for M=Cs and other alkali metal ions. Solid State Ionics, 1998, 112 (1-2), pp.143-152. ⟨10.1016/S0167-2738(98)00227-6⟩. ⟨in2p3-00006586⟩