Ionic structure in caustic aluminate solutions and the precipitation of gibbsite

Abstract

The structure of caustic aluminate solutions in relation to the precipitation of gibbsite was investigated using vibrational spectroscopy and molecular dynamics simulations. Results from the molecular dynamics simulations indicate that aluminate ions form clusters as a function of time and that these clusters are stabilised by sodium ions. While the method used has the limitation that bond formation is forbidden, the predicted clustering would certainly facilitate polyaluminate anion formation. It is proposed that observed additional bands in vibrational spectra of concentrated aluminate solutions, as compared with those of dilute solutions, result from vibrations of these clusters (and any polyaluminate ions which arise from them). The absence of spectral features characteristic of a distinct interfacial aluminate layer at the growing crystal surface is explained by clustering throughout the bulk solution, and the participation of such clusters (and polyanions) in the growth process.

References

1. R. J. Moolenaar, J. C. Evans and L. D. McKeever, J. Phys. Chem., 1970, 74, 3629.
2. N.-Y. Chen, M.-X. Liu, Y.-L. Cao, B. Tang and M. Hong, Sci. in China, Ser. B, 1993, 36, 32.
3. L. A. Myund, V. M. Sizyakov, M. K. Khripun and A. A. Makarov, Russian J. Gen. Chem., 1995, 65, 826; Zh. Obshch. Khim., 1995, 65, 911.
4. L. A. Myund, V. M. Sizyakov, K. A. Burkov, V. O. Zakharzhevskays and O. A. Borzenko, Russian J. Gen. Chem, 1995, 68, 1721; Zh. Obshch. Khim., 1995, 68, 1964.
5. J. W. Akitt and W. Gessner, J. Chem. Soc., Dalton Trans., 1984, 147.
6. J. W. Akitt, W. Gessner and M. Weinberger, Magn. Reson. Chem., 1988, 26, 1047.
7. D. S. Rossiter, P. D. Fawell, D. Ilievski and G. M. Parkinson, J. Cryst. Growth, 1998, 191, 521.
8. H. Saalfeld and M. Wedde, Z. Kristallogr., 1974, 139, 129.
9. E. R. Lippincott, J. A. Psellos and M. C. Tobin, J. Chem. Phys., 1952, 20, 536.
10. A. C. Hess, P. F. McMillan and M. O'Keefe, J. Phys. Chem., 1988, 92, 1785.
11. H. Liu, S. Huang and N. Chen, Trans. Nonferrous. Met. Soc. China, 1992, 2(3), 43.
12. N. Chen and H. Liu, J. Mol. Struct. (THEOCHEM.), 1994, 305, 283.
13. P. Sipos, P. M. May, G. T. Hefter and I. Kron, J. Chem. Soc., Chem. Commun., 1993, 2355.
14. D. Frenkel and B. Smit, Understanding Molecular Simulation, Academic Press, San Diego, CA, 1996.
15. M. P. Allen and T. D. Tildesley, Computer Simulation of Liquids, Oxford University Press, Oxford, 1997.
16. M. Levitt, M. Hirshberg, R. Sharon, K. E. Laidig and V. Daggett, J. Phys. Chem. B, 1997, 101, 5051.
17. A. Laaksonen, P. G. Kusalik and I. M. Svishchev, J. Phys. Chem. A, 1997, 101, 5910.
18. R. L. Mancera, A. D. Buckingham and N. T. Skipper, J. Chem. Soc., Faraday Trans., 1997, 93, 2263.
19. L. X. Dang, J. Am. Chem. Soc., 1995, 117, 6954.
20. A. Tongraar, K. R. Liedl and B. M. Rode, J. Phys. Chem. A, 1997, 101, 6299.
21. G. Woods, H. Watling and P. Smith, Analysis of Bayer type liquors by inflection point titrations, CSIRO Division of Mineral Products Confidential Report No IR/P-001, 1994.
22. S. Barlow, A. L. Rohl, S. G. Shi, C. M. Freeman and D. O'Hare, J. Am. Chem. Soc., 1996, 118, 75.
23. D. M. Heyes, J. Chem. Phys., 1981, 74, 1924.
24. A. S. Russell, J. D. Edwards and C. S. Taylor, J. Met., 1955, 7, 1123.
25. H. Watling, Appl. Spectrosc., 1998, 52, 250.
26. M. Moskovits and K. H. Michaelian, J. Am. Chem. Soc., 1980, 102, 2209.
27. S. K. Sharma and S. C. Kashyap, J. Inorg. Nucl. Chem., 1972, 34, 3623.
28. T. Allen, Particle size measurement, Chapman and Hall, London, 4th edn., 1990, p. 487.
29. P. D. Fawell and H. R. Watling, Appl. Spectrosc., 1998, 52, 1115.