Structural and thermodynamical characterization of interfacial domains
The aim of this research was to investigate experimentally the two dimensional domains which occur between the oil and the water as soon as water, oil, surfactant and alcohol (or any cosurfactant) are mixed: the interest of such an investigation lies in the fact that it leads to direct determinations of physicochemical parameters characterising these domains. The precise knowledge of these quantities allows theoretical calculations of phase diagrams, this approach being very useful in chemically enhanced oil recovery simulators. First, the phase diagram of the ternary Hexanol/Heavy-Water/S.D.S. system has been determined. Then, a systematic study of the Deuterium N.M.R. signal of the heavy water, for the different compositions corresponding to the lamellar domain encountered, has been performed: all the variations observed within the whole set of data obtained have been explained in terms of a very simple hydration process: the S.D.S. molecules are completely hydrated by 8 water molecules while 5 (or 6) are sufficient for the alcohol. After having synthetised alpha deuterated molecules of hexanol and of S.D.S., the same series of experiments has been realised with these last: the whole set of results has then been considered within the frame of a fluctuation theory. This theoretical approach allowed the determination of the bending modulus k(c). This quantity is of primary importance in all the theories developed to account for the stability of chemical mixtures consisting of water and surfactant. The value determined (1.68kT) should be compared to the only one previously determined (1.66kT) for a similar system where the alcohol was the pentanol. This determination has been made for the whole set of compositions corresponding to the lamellar domain; the most fundamental result is that the bending modulus k(c) does not seem to vary when the bilayer composition is modified.
Bibliographic Reference: EUR 12916 EN (1990) 46 pp., MF, ECU 4
Record Number: 199011045 / Last updated on: 1994-12-01
Original language: en
Available languages: en