Micellisation of Binary Mixtures of Surfactants Na-Deoxycholate-Na-Decyl Sulfate and Na-Hyodeoxycholate-Na-Decyl Sulfate in Water Solutions: Rational Development of the Thermodynamic Model for the Excess Gibbs Energy (GE)
Micellisation of the binary mixtures: sodium decylsulphate (NaDS) - sodium deoxycholate (NaDC) and sodium decyl sulphate (NaDS)- sodium hyodeoxychlolate (NaHDC) is examined, in consideration with the different molar fractions of the monomers (x=0.1 - x=0.9). In bile acids, the OH groups attached to steroid skeletons are spatially ecraned, while the sulphate group of NaDS is not ecraned. Thus, NaDC and NaHDC in relation to NaDS have different coordination numbers, in the micelle pseudophase. On the basis of stereochemical analysis, rational design shows that the excess Gibbs energy (GE) of formation of the binary mixed micelle throughout the whole composition range can be described with two-parameter Margules function, while the GE function from the regular solution theories is applicable only in the narrow interval of the bile salts molar fractions (x=0.5 - x=0.8). Coefficient of activity (hypothetical) of the infinitely diluted mixed micelle of NaDS in the presence of NaDC shows significant thermodynamic stabilisation of decyl sulphate ions in comparison with the infinitely diluted hypothetical mixed micelle with NaHDC. Probably this stabilisation of decyl sulphate ions is due to the cooperative binding of NaDS by parallel OH groups of NaDC.
Compounds
#
Formula
Name
1
C10H21NaO4S
Sodium decyl Sulfate
2
C24H39NaO4
sodium hyodeoxycholate
3
C24H39NaO4
sodium deoxycholate
4
ClNa
sodium chloride
5
H2O
water
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.