ABSTRACT

The micellization behaviour of the long-chain carboxylates: sodium octanoate (NaC8), sodium decanaote (NaC10), potassium decanoate (KC10), caseium decanoate (CsC10) and sodium dodecanoate (NaC12) in aqueous solutions were studied using electrical conductivity measurements between the temperatures 278.15 and 328.15 K. By using the pseudo-phase separation model and Gibbs-Helmholtz equation, the thermodynamic parameters for the micellization process were obtained from the temperature dependence of the critical micelle concentration, CMC, and the degree of micelle ionization, a. The heat capacities of micellization, Amiccpo, estimated from the temperature dependence of enthalpy of micellization, AmicHo, were correlated with the size of the non-polar solvent's accessible surface area, which is removed from the contact with water during micellization. In all investigated systems, results suggest that the micelle core is still in contact with water molecules.

Compounds

#	Formula	Name
1	C8H15NaO2	sodium octanoate
2	C10H19NaO2	sodium decanoate
3	C12H23NaO2	sodium dodecanoate
4	C10H19KO2	potassium decanoate
5	H2O	water
6	C10H19CsO2	cesium decanoate

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1 5	Electrical conductivity, S/m ; Liquid	Temperature, K; Liquid Molality, mol/kg - 1; Liquid	Pressure, kPa; Liquid	Liquid	Alternating current cell with electrodes	93
POMD	2 5	Electrical conductivity, S/m ; Liquid	Temperature, K; Liquid Molality, mol/kg - 2; Liquid	Pressure, kPa; Liquid	Liquid	Alternating current cell with electrodes	90
POMD	5 6	Electrical conductivity, S/m ; Liquid	Temperature, K; Liquid Molality, mol/kg - 6; Liquid	Pressure, kPa; Liquid	Liquid	Alternating current cell with electrodes	102
POMD	5 4	Electrical conductivity, S/m ; Liquid	Temperature, K; Liquid Molality, mol/kg - 4; Liquid	Pressure, kPa; Liquid	Liquid	Alternating current cell with electrodes	114
POMD	3 5	Electrical conductivity, S/m ; Liquid	Temperature, K; Liquid Molality, mol/kg - 3; Liquid	Pressure, kPa; Liquid	Liquid	Alternating current cell with electrodes	96

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Thermodynamics of the micellization process of carboxylates: A conductivity study

Medos, Z.[Ziga], Bester-Rogac, M.[Marija]

ABSTRACT