Decanol solution

L2 Region with homogeneous, isotropic decanolic solution. 

From the vibrational structure in the monomer fluorescence spectrum of Py, the Ham-effect (54-58), information was obtained on the polarity of the surface where the excimer and dimer formation takes place. It appears that Py on silica/decanol resides in an environment similar to a homogeneous decanol solution (36), whereas for Py on dry silica a considerably higher polarity was found between that of methanol and water, see Fig. 8. For rever-sed-phase Si-C.jg in contact with methanol/water 3/1 (Section 4.2.3), it was concluded that Py finds itself in a nonpolar medium (21). 

Fig. 2.17. Surface pressure isotherm for 1-decanol solutions O -experimental data [36, 37] calculations from the von Szyszkowski equation (1), Frumkin equation (2), and aggregation model (3).

As experimental example, the dependencies of dynamic surface tensions for 1-decanol solutions as reported by Lin et al. [83, 84] are compared in Fig. 4.31 with the results calculated from the present aggregation model. 

Fig. 4.31 Dynamic surface tension for 1-decanol solutions, experimental results from Lin et al. [83, 84] for c = 6.3210 mol/1 (O) and c = 1.01810 mol/1 (O) dotted curves calculated for a Langmuir isotherm, solid curves correspond to the aggregation model with n = 2.5 and Fc< lO mol/m, according to Aksenenko et al. [65]...

The variety of explanations for a slower surface tension decrease, a case which is often experimentally observed, is very large and was summarised by Fainerman et al. (2001). One of the reasons for slower adsorption kinetics can be an inaccurate adsorption isotherm. As experimental example, the dynamic surface tensions for 1-decanol solutions by Lin et al. (1994) are compared in Fig. 25 with the results calculated from the aggregation model. 

Fontell studied the solubilization of n-decanol by NaDC (38). His phase diagram is redrawn in Fig. 55 and demonstrates that bile salt in adequate quantities produces a single liquid phase extending from pure water to pure decanol. Thus, bile salt not only solubilizes decanol in an aqueous solution (left side) but also solubilizes water in a decanol solution (right side). 

The influence of the presence of alcohols on the CMC is also well known. In 1943 Miles and Shedlovsky [117] studied the effect of dodecanol on the surface tension of solutions of sodium dodecyl sulfate detecting a significant decrease of the surface tension and a displacement of the CMC toward lower surfactant concentrations. Schwuger studied the influence of different alcohols, such as hexanol, octanol, and decanol, on the surface tension of sodium hexa-decyl sulfate [118]. The effect of dodecyl alcohol on the surface tension, CMC, and adsorption behavior of sodium dodecyl sulfate was studied in detail by Batina et al. [119]. 

Kawasaki et /. (1996) have used a supported membrane catalyst for extraction of erythromycin from its dilute, slightly alkaline aqueous solutions. 1-Decanol was used as an intermediate fluid membrane phase and a buffered acidic aqueous solution was used to strip the organic membrane. 

Sodium valproate has been determined in pharmaceuticals using a valproate selective electrode [13,14]. The electroactive material was a valproate-methyl-tris (tetra-decyl)ammonium ion-pair complex in decanol. Silver-silver chloride electrode was used as the reference electrode. The electrode life span was >1 month. Determination of 90-1500 pg/mL in aqueous solution by direct potentiometry gave an average recovery of 100.0% and a response time of 1 min. 

So far it has not been possible to measure the chemical potentials of the components in the mesophases. This measurement is possible, however, in solutions which are in equilibrium with the mesophases. If pure water is taken as the standard state, the activity of water in equilibrium with the D and E phases in the system NaC8-decanol-water is more than 0.8 (4). From these activities in micellar solutions, the activity of the fatty acid salt has sometimes been calculated. The salt is incorrectly treated as a completely dissociated electrolyte. The activity of the fatty acid in solutions of short chain carboxylates has also been determined by gas chromatography from these determinations the carboxylate anion activity can be determined (18). Low CMC values for the carboxylate are obtained (15). The same method has shown that the activity of solubilized pentanol in octanoate solutions is still very low when the solution is in equilibrium with phase D (Figure 10) (15). 

Figure 3. Growth of liquid crystalline filaments towards aqueous solution of sodium laurate (right) after it has been contacted with decanol (left) (46)...

Pyrene exclmer formation provides additional evidence.11 If pyrene and decanol are coadsorbed, one can observe the excimer-like emission at 470 nm growing In with the same kinetics as is seen in solution, ie.. 

Thus, the decanol coadsorption appears to increase significantly the dynamic excimer formation but the residual surface Inhomogeneity still prevents one from observing all the features of solution-like behavior. 

Ca by didecylphosphate dispersed in the organic, or membrane, phase. In a similar manner, incorporation of methyl tricaprylam-monium (Aliquat 336S) salts in polymer membranes produced CWEs for their respective anions (2J. A 60 (v/v) solution of Aliquat 336S in decanol was first converted to the desired anionic form via shaking... 

Succinylcholine solutions contained 0.05% (w/v) methyl- -hydroxybenzoate as stabilizer. Phenytoin (sodium salt) and decanol were supplied by Sigma (St. Louis, MO) other materials were tricaprylylmethylammoniura chloride or Aliquat 336S (General Mills Chemicals, Inc., Kankakee, IL). Solutions of sodium phenytoin were prepared by serial dilution while keeping both pH and ionic strength at constant values, 10 and 0.1 mol/1, respectively. The selectivity coefficients were determined at pH 10.0 and 0.1 mol/1 ionic strength, both adjusted with borax-NaOH buffer solution of pH 10.0. 

Five grams of Aliquat 336S were mixed with 5.0 g of decanol and equilibrated with ten separate 15 ml aliquots of 0.1 mol/1 sodium phenytoin solution in 20% (v/v) methanol. The organic phase was washed twice with distilled water and then centrifuged until a clear solution was obtained. 

As expected, the influence of added nonelectrolytes can be quite different depending on whether the added compound is likely to be located in the micelles or in the in-termicellar solution. The effect of normal alcohols has been studied in detail for potassium dodecanoate the CMC is lowered for all alcohols studied but the effect increases considerably in going from ethanol to decanol (cf. Fig. 2.7). Hydrocarbons, like cyclohexane, n-heptane, toluene, and benzene, have been found to lower the CMC for many surfactants. Strongly hydrophilic substances, like dioxane and urea, have small and complex effects. At higher concentrations they markedly increase the CMC or even inhibit micelle formation. Addition of another similar surface-active agent generally gives a CMC in between the CMCs of the two surfactants. 

Fig. 2.19 A-D. Solubility of decanol in solutions of (A) sodium octanoate (20 °C), (B) sodium deca-noate (40 °C), (C) sodium dodecanoate (40 °C) and (D) sodium tetradecanoate (40 °C). Curves a refer to right hand ordinate axes and curves b to left hand ordinate axes. (From Ref.86))...

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