Hydrothermal treatment and strontium ion sorption properties of fibrous cerium(IV) hydrogenphosphate

Abstract

Fibrous cerium hydrogenphosphate, CeP, has been treated hydrothermally in 1 mol dm^-3 phosphoric acid solution. CEP and its hydrothermally treated product, CeP(HT), have been characterized by X-ray powder diffractometry, scanning electron microscopy, solid-state ³¹P MAS NMR spectroscopy, FTIR spectroscopy, chemical and thermal analyses. A poorly crystalline fibrous CeP with a d-spacing of 1.1 nm converted into a highly crystalline CeP(HT) with platelet morphology by hydrothermal treatment. Solid-state ³¹P MAS NMR and FTIR measurements confirmed that one kind of phosphate (H₂PO₄) is present in CeP and two kinds of phosphate (HPO₄ , PO₄) are present in CeP(HT), in which the integrated intensity ratio of HPO₄ to PO₄ is 2:1. From chemical and thermal analyses, structural formulae for CeP and CeP(HT) are assumed to be CeO(H₂PO₄)₂ 2H₂O and Ce(HPO₄) (PO₄)_0.5(OH)_0.5 , respectively. The Na⁺ exchange capacity of CeP amounted to 4.5 mmol g^-1 at pH 11 while that of CeP(HT) was less than 1.0 mmol g^-1 in the pH range 2–12. The pH dependence of the metal ion distribution coefficients exhibited ideal ion-exchange behaviour on CeP while metal ion distribution coefficients on CeP(HT) scarcely depended on pH. The metal ion selectivities of CeP and CeP(HT) increased in the order: Na⁺<Ca²⁺<Sr²⁺ <K⁺ , and Na⁺<K⁺<Ca²⁺ <Sr²⁺ , respectively. The distribution coefficient for the Sr²⁺ ion of CeP(HT) was higher than that of CeP under hydrothermal conditions.

References

1. G. A. Alberti, M. A. Massucci and E. Torracca, J. Chromatogr., 1967, 30, 579.
2. G. A. Alberti, M. Casciola, U. Costantino and M. L. Luciani, J. Chromatogr., 1976, 128, 289.
3. G. A. Alberti, U. Costantino, F. Di Gregorio, P. Galli and E. Torracca, J. Inorg. Nucl. Chem, 1968, 30, 295.
4. G. A. Alberti, U. Costantino and L. Zsinka, J. Inorg. Nucl. Chem., 1972, 34, 3549.
5. K. H. Konig and E. Meyn, J. Inorg. Nucl. Chem., 1967, 29, 1153.
6. E. M. Larsen and W. A. Cilley, J. Inorg. Nucl. Chem., 1968, 30, 287.
7. R. G. Herman and A. Clearfield, J. Inorg. Nucl. Chem., 1975, 37, 1697.
8. T. Sasaki, Y. Komatsu and Y. Fujiki, Chem. Lett., 1981, 957.
9. N. Yamasaki, K. Yanagisawa, S. Kanahara, M. Nishioka, K. Matsuoka and J. Yamazaki, J. Nucl. Sci. Technol., 1984, 21, 71.
10. D. K. Bhattacharyya and N. C. Dutta, J. Mater. Sci., 1995, 30, 2248.
11. S. Ahrland and G. Carleson, J. Inorg. Nucl. Chem., 1977, 33, 2229.
12. A. Clearfield and G. D. Smith, Inorg. Chem., 1969, 8, 431.
13. N. J. Clayden, J. Chem. Soc., Dalton Trans., 1987, 1877.
14. A. N. Christensen, E. K. Andersen, I. G. K. Andersen, G. Alberti, M. Nielsen and M. S. Lehmann, Acta Chem. Scand., 1990, 44, 865.
15. N. J. Clayden, Solid State Ionics, 1987, 24, 117.
16. K. Nakashiro, Y. Ono, S. Nakata and Y. Morimura, Zeolites, 1993, 561.
17. L. Maistriau, Z. Gabelica, E. G. Derouane, E. T. C. Vogt and J. van Oene, Zeolites, 1991, 583.
18. K. Segawa, S. Nakata and S. Asaoka, Mater. Chem. Phys., 1987, 17, 181.
19. H. Hayashi, T. Iwasaki, T. Nagase, Y. Onodera and K. Torii, Solvent Extr. Ion Exch., 1995, 13, 1145.
20. F. H. Sweeton, R. E. Mesmer and C. F. Baes, Jr, J. Solution Chem., 1974, 3, 191.