Water oleate system

For soap/alcohol combinations — g will depend not only on the soap counter ion but also on the alcohol/soap ratio. Furthermore, when a certain alcohol/soap ratio is exceeded (=2 for the potassium oleate system) S becomes Independent of the water content of the lamellar phase. This condition applies for Inverse structures and the water/pentanol/potassium oleate inverse micellar system will be examined for the structure determining ratio in Table I. 

The mean polar head group area in a water/decanol/potassium oleate system is approximately 26 A for an alcohol/soap molecular ratio of 2.l — For the soap alone an area of 36.0 3 was found. Assuming a linear relationship a value of 22 A is obtained for the decanol. This value will be used also for the pentanol. The volume, chain length and area can now be estimated ... 

The o c experimental results for the water/pentanol/potas-slum oleate system (18,19) show that a pentanol/potasslum oleate molecular ratio of 5.5 and lower should give a premlcellar aggregate/lamellar liquid crystal transition instead of the pre-micellar aggregate/Inverse micelle transition at high alcohol/ soap ratios. 

The H20- -dodecane-l-hexanol-potassium oleate system has also aroused scientific curiosity. Previously reported SANS data indicate that this system manifests itself as a collection of water droplets in oil with a droplet size of about 100 A. The results of a cryo-TEM analysis are presented in Fig. 9. 

In a series of papers published a few years ago (39-41), Shah and co-workers reported data gained from correlated conductivity, birefringence, interfacial tension and NMR investigations performed on water-hexadecane systems using potassium oleate and hexanol as... 

Fig. 7. Variations of the low frequency permittivity with increasing water mass fraction in water-hexadecane systems using potassium oleate and 1-hexanol combined with the mass ratio 3/5, for different values of p, the hexa-decane mass fraction. Temperature T = 25°C.

FIG. 15 Water-hexadecane system (Table 2). DSC-ENDO spectra of the upper isotropic phase of biphasic samples with increasing water concentration of the sample as a whole. Curve 1 Ctoi = 0.372, the first appearance of a birefiingent liquid crystalline lens. Curve 2 Ct = 0.388. Curve 3 Ct = 0.419. Curve 4 Melting endotherms of the Uquid crystalline bottom mesophase of a sample with Ct , = 0.419. AH and AHb are the thermal contributions of the n-hexanol and the water-K-oleate-hexanol mixture, respectively. (From Ref. 23.) Curve 5 DSC-ENDO spectrum of the ternary mixture n-hexanol-K-oleate-water. The proportions between surfactant and cosurfactant are the same as those used to formulate the four-component W/O microemulsions. 

If the third substance dissolves in both liquids (and the solubility in each of the liquids is of the same order), the mutual solubility of the liquids will be increased and an upper C.S.T. will be lowered, as is the case when succinic acid or sodium oleate is added to the phenol - water system. A 0 083 molar solution of sodium oleate lowers the C.S.T. by 56 -7° this large effect has been applied industrially in the preparation of the disinfectant sold under the name of Lysol. Mixtures of tar acids (phenol cresols) do not mix completely with water at the ordinary temperature, but the addition of a small amount of soap ( = sodium oleate) lowers the miscibility temperature so that Lysol exists as a clear liquid at the ordinary temperature. 

In a study of the adsorption of soap and several synthetic surfactants on a variety of textile fibers, it was found that cotton and nylon adsorbed less surfactant than wool under comparable conditions (59). Among the various surfactants, the cationic types were adsorbed to the greatest extent, whereas nonionic types were adsorbed least. The adsorption of nonionic surfactants decreased with increasing length of the polyoxyethylene chain. When soaps were adsorbed, the fatty acid and the aLkaU behaved more or less independently just as they did when adsorbed on carbon. The adsorption of sodium oleate by cotton has been shown independently to result in the deposition of acid soap (a composition intermediate between the free fatty acid and the sodium salt), if no heavy-metal ions are present in the system (60). In hard water, the adsorbate has large proportions of lime soap. 

The influence of cosurfactant structure is best illustrated by using various isomeric alcohols with the same chain length. This is shown in Figure 4 for the system water, benzene, potassium oleate and amylic alcohols (25). The mass ratio of potassion oleate to COH is 3 5 and the temperature was 22°C. 

Figure 4. Phase diagrams of the system water benzene potassium oleate/an lic alcohols (a)...

Variation of k with for the system water/hexadecane/potassium oleate/hexanol. 

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. 

A nonpolar solubilizate such as hexane penetrates deeply into such a micelle, and is held in the nonpolar interior hydrocarbon environment, while a solubilizate such as an alcohol, which has both polar and nonpolar ends, usually penetrates less, with its polar end at or near the polar surface of the micelle. The vapor pressure of hexane in aqueous solution is diminished by the presence of sodium oleate m a manner analogous to that cited above for systems in nonpolar solvents. A 5% aqueous solution of potassium oleate dissolves more than twice the volume of propylene at a given pressure than does pure water. Dnnethylaminoazobenzene, a water-insoluble dye, is solubilized to the extent of 125 mg per liter by a 0.05 M aqueous solution of potassium myristate. Bile salts solubilize fatty acids, and this fact is considered important physiologically. Cetyl pyridinium chloride, a cationic salt, is also a solubilizing agent, and 100 ml of its A/10 solution solubilizes about 1 g of methyl ethyl-butyl either m aqueous solution. 

Dixit and Biswas124 dealt with the relationship between H+ an OH- concentrations and adsorption of an anionic collector on a mineral surface and its flotability. They used the system zircon-Na oleate. If Na oleate is dissolved in water the following equilibrium sets up ... 

Figure 7. The onset of Inverse mlcelllzatlon In the pentanol solution In the water, pentanol (C5OH), potassium oleate (KOL) system (V) was changed to a small degree at the addition of decane (0) but to a pronounced degree by benzene ( ) (Reprinted with permission from ref. 23. Copyright 1978 Academic Press.)...

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