Pentanol system

FIG. 8.13 Two representations of a portion of the phase diagram for the water-benzene-potassium oleate-pentanol system. The unshaded regions represent homogenous solutions, (a) Redrawn, with permission, from S. Friberg and I. Burasczeska, Prog. Colloid Polym. Sci., 63, 1 (1978). (b) Redrawn, with permission, from C. U. Herrmann, U. Wurz, and M. Kahlweit, In Solution Chemistry of Surfactants, Vols. 1 and 2 (K. L. Mittal, Ed.), Plenum, New York, 1979. 

Riggio, R., H. E. Martinez, and H. N. Solimo, Densities, Viscosities, and Refractive Indexes for the Methyl Isobutyl Ketone + Pentanols Systems Measurements and Correlations. J. Chem. Eng. Data, 1986 31, 235-238. 

For microemulsion system (hexanol system), since it contains water spheres in a continuous oil medium, the addition of water forms more spherical droplets. The continuous medium is still an oil phase and therefore, the electrical resistance is maintained at a high value in the range of lO-- ohms (70). However, for cosolubilized system (pentanol system), as the amount of water is increased, the average distance between alcohol molecules as well as between water molecules would change and this consequently would influence the hydrogen bonding ability of water and alcohol molecules, which in turn would influence the chemical shift of the resonance peak. Moreover, as one adds more and more water in cosolubilized system, it becomes more electrically conducting and, hence exhibits a continuous decrease in the electrical resistance (70). 

Figure 3. W/S pseudoternary diagrams at T = 21.5 °C ( in volume) of the water-dodecane-SDS-pentanol system. Top W/S = 1 bottom W/S = 1.4. L, Lg, and L designate respectively an isotropic phase, a birefringent phase and a flow birefringent liquid phase.

The demixing curves in the W/S pseudoternary diagrams for the hexanol and pentanol systems have been calculated according to the above theoretical treatment. These lines have been determined in the following way. The calculation of the state equation is applied to a dilution line along such a line the inverse micelles have a constant radius R. The micelles contain the whole water (volume Vw), the surfactant (volume V ) and a part of the alcohol V. The rest of alcohol is in the oil continuous phase. We suppose that the alcohol-oil ratio in the continuous phase is constant and is equal to k. Besides, in the calculation of the micellar radius R one assumes that the surfactant and the alcohol molecules which are situated at the interface have a constant area per chain s. In mos of the previous studies s has been found constant and equal to 25 A2. This value is taken equal for the alcohol and surfactant chains. Consequently ... 

In our model a critical radius Rc appears its value is 52 A in the pentanol system. Then in each W/S plane a critical dilution line corresponding to such a radius is obtained. Its location depends on the W/S ratio. As this ratio decreases, the critical line lies at a lower alcohol content. In the case, where the critical dilution line is below the "lamellar" demixing line, the phase diagram is expected to be similar to that observed with the hexanol system for which the interactions are not predominant. This is the case of the pseudoternary sections defined by a W/S ratio less than 1.1. Besides this provides an explanation for the simultaneous disappearance of the regions X, V, XI, XII. 

Figure 5. Comparison between experimental (full line) and calculated (dashed line) demixing curves in the oil rich region of the hexanol and pentanol systems. is the experimental critical point. P-E is the theoretical critical point.

The phase diagrams of two quaternary mixtures made of sodium dodecylsulfate (SDS)-water-dodecane and hexanol (system A) or pentanol (system B) have been investigated in detail [22,23]. In both cases, sections of the three-dimensional diagram with constant water/surfactant ratio have been examined. These cuts were chosen because they allow a good description of the oil region and also because the water/SDS ratio, termed X in the following, fixes the size of the droplets in the inverse microemulsion phase and the thickness of the bilayers in the oil-rich lamellar phase. In the description of the quaternary mixtures, we emphasize the details of the evolution of the phase equilibria as X is varied. We have focused our attention not only on the characterization and the location of the boundaries of the various phases but also on the equilibria between the phases. 

Figure 15 shows the effect of added salt on the stability of the three oil-rich phases L2, L, and L3.0 found in the section A = 1.55 of the phase diagram of the water-dodecane-SDS-pentanol system at low alcohol content. The three phases still exist at very high... 

Wisniak, J. Tamir, A. Association effects in the methanol - 1-pentanol system J. Chem. Eng. Data 1988,33,432-434... 

Scheme 13.4 Model of a microemulsion droplet in the water/CTAB-ethyl-methylimidazo-lium hexylsulfate/toluene-pentanol system.

Here, the apparent self-diffusion coefficient D pp of the alcohol in the ternary system can be measured by the NMR spin-echo technique [6]. is the selfdiffusion coefficient of the alcohol within or associated with the micelles and the corresponding value in the aqueous pseudophase it is approximated by measuring the self-diffusion coefficient in the binary D20-pentanol system. As is much smaller than the partition coefficient p can be approximated by... 

It turns out that virtually no ethanol is partitioned into the micelles (p 0), whereas NMR measurements suggest that p is about 0.4 in the case of 1-pentanol solutions with 8 mass % of alcohol (for more details, see Ref. [6]). The enzymatic activity measurements also lead to the conclusion that no ethanol is incorporated in the micelles. For the 1-pentanol system, a quantitative interpretation is more delicate. 

Other studies considered specifically the effect of the alcohol on the kinetics of micelle formation/break-down.92>i i -i 2 Spectacular changes of the relaxation time T2 were evidenced. Note, however, that the three relaxation processes expected for a mixed surfactant + alcohol system were evidenced and investigated for only the tetradecyltrimethy-lammonium bromide (TTAB)/l-pentanol system. ... 

Figure 3.12 TTAB/pentanol systems variation of the relaxation time associated with the pentanol exchange with the pentanol concentration at constant [pentanol]/[TTAB] molar concentration ratio (+) 0.5 ( ) 1.0 and (x) 2. Reproduced from Reference 166 with permission of Elsevier/Academic Press.

Figure 8 Ternary phase diagram of the water-sodium dodecylsulfate-l-pentanol system (T = 25°C). Li and Lj are, respectively, the region of direct solubilization and the region of inverse solubilization. Cl is the channel connecting L, and L2. D is the region of monophasic lamellar liquid crystals. 

Mihaila, G. Ababi, V Onu, R Luca, C. Liquid-vapor equilibrium of the cyclohexanone - 1-pentanol system [Rom]. Rev. Chim. (Bucharest) 1979, 30, 533-555. 

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