Evaporation rates of water from water-in-oil microemulsions

Abstract

We have used a gravimetric technique to measure the rate of evaporation of water from water-in-dodecane microemulsions stabilised by AOT. Evaporation rates were measured under controlled gas flow conditions for a series of different microemulsion drop sizes and concentrations. Even for microemulsion samples where the equilibrium vapour pressure of water is similar to that of pure water, the evaporation rates are slower by more than an order of magnitude. The measured rates for the different microemulsion compositions are found to be approximately consistent with a model in which it is assumed that diffusion of the water microemulsion drops through the microemulsion to the surface is rate limiting. The subsequent processes of transfer of water across the liquid/vapour surface and the stagnant vapour space are not rate limiting.

References

1. K. J. Beverley, J. H. Clint and P. D. I. Fletcher, Phys. Chem. Chem. Phys., 1999, 1, 149.
2. K. J. Beverley, J. H. Clint, P. D. I. Fletcher and S. Thubron, Phys. Chem. Chem. Phys., 1999, 1, 909.
3. S. E. Friberg, B. Yu, J. W.-P. Lin, E. Barni and T. Young, Colloid Polym. Sci., 1993, 271, 152.
4. S. E. Friberg, T. Young, R. A. Mackay, J. Oliver and M. Breton, Colloids Surf. A, 1995, 100, 83.
5. S. Hamdan, Y. Y. Dai and F. B. H. Ahmad, Oriental J. Chem., 1997, 13, 111.
6. S. Hamdan, F. B. H. Ahmad, Y. Y. Dai, K. Dzulkefly and K. H. Ku Bulat, J. Dispersion Sci. Technol., 1999, 20, 415.
7. R. Aveyard, B. P. Binks, S. Clark and J. Mead, J. Chem. Soc., Faraday Trans. 1, 1986, 82, 125.
8. E. Keh and B. Valeur, J. Colloid Interface Sci., 1981, 79, 465.
9. See, for example, P. W. Atkins, Physical Chemistry, Oxford University Press, Oxford, 5th edn., 1994, p. 795.
10. Selected values of properties of hydrocarbons and related compounds, ed. C. W. Haas, Thermodynamic Research Center AP144 Hydrocarbon Project, Thermodynamics Research Center, Texas A&M University, Texas, 1978.
11. P. Alexandridis, J. F. Holzwarth and T. A. Hatton, J. Phys. Chem., 1995, 99, 8222.
12. K. Kon-No and A. Kitahara, J. Colloid Interface Sci., 1971, 35, 409.
13. J. Biais, L. Oldberg and P. Stenius, J. Colloid Interface Sci., 1982, 86, 350.
14. M. Ueda and Z. A. Schelly, Langmuir, 1988, 4, 653.
15. C. H. Chew and M. K. Wong, J. Dispersion Sci. Technol., 1991, 12, 495.
16. P. D. I. Fletcher, A. M. Howe and B. H. Robinson, J. Chem. Soc., Faraday Trans. 1, 1987, 83, 985.
17. W. J. Albery, R. A. Choudhery, N. Z. Atay and B. H. Robinson, J. Chem. Soc., Faraday Trans. 1, 1987, 83, 2407.
18. W. Nitsch, P. Plucinski and J. Ehrlenspiel, J. Phys. Chem., 1997, 101, 4024.
19. W. Jost, Diffusion in Solids, Liquids, Gases, Academic Press Inc., New York, 1952, p. 37.