Binding constants and partial molar volumes of primary alcohols in sodium dodecylsulfate micelles
The densities of methanol, ethanol, 1-propanol, 1-butanol and 1-hexanol were measured in aqueous solutions of sodium dodecylsulfate at 25/sup 0/C. The partial molar volumes of the alcohols at infinite dilution in the aqueous surfactants solutions were calculated and discussed using a mass-action model for the alcohol distribution between the aqueous and the micellar phase. The partial molar volumes of the alcohols in the aqueous and in the micellar phases, and the ratios between the binding constant and the aggregation number, were calculated. The partial molar volume for all the alcohols in micellar phase is 10 cm/sup 3/-mol/sup -1/ smaller than that in octane. This can be related to the strong hydrophilic interaction between the head groups of the alcohol and the micellized surfactant. From the extrapolated values of the distribution constant and the partial molar volumes in the aqueous and micellar phases, the standard partial molar volume of heptanol in micellar solutions was found to decrease with increasing surfactant concentration. The standard free energy of transfer of alcohols from water to micelles was rationalized in terms of hydrophilic and hydrophobic contributions. A model is proposed in which the empty space around each solute is assumed to be the same in the gas and liquid phases, and is used to explain the behavior of micelles in the presence of amphiphilic solutes.
- Research Organization:
- Universit di Palermo, Italy
- OSTI ID:
- 6762507
- Journal Information:
- J. Solution Chem.; (United States), Vol. 15:8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BUTANOLS
BINDING ENERGY
ETHANOL
HEXANOLS
METHANOL
PENTANOLS
PROPANOLS
APPARENT MOLAL VOLUME
DENSITY
DISPLACEMENT FLUIDS
FREE ENERGY
MATHEMATICAL MODELS
MICELLAR SYSTEMS
ORGANIC SULFUR COMPOUNDS
PARTIAL MOLAL VOLUME
SODIUM SULFATES
SOLUBILITY
SURFACTANTS
ALCOHOLS
ALKALI METAL COMPOUNDS
ENERGY
FLUIDS
HYDROXY COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SODIUM COMPOUNDS
SULFATES
SULFUR COMPOUNDS
THERMODYNAMIC PROPERTIES
400201* - Chemical & Physicochemical Properties