SOLUBILIZATION OF 1-ALKANOLS IN IONIC MICELLES MEASURED BY PIEZOELECTRIC GAS SENSORS

The partition coefficients of 1-alkanols (1-butanol to 1-heptanol) bet ween ionic micelles and water, expressed in the mole ratio scale (K-N) and in the mole fraction scale (K-X), were measured at 25 degrees C b y using polymer-coated piezoelectric gas sensors. While K-N is constan t over the concentration range measured, K-X decreases with increasing mole fraction of the 1-alkanols in micelles. It is demonstrated that K-N is equal to the value of K-X at infinite dilution. The thermodynam ic analysis shows that the micellar palisade supplies the solubilizati on site for 1-alkanols and is less lipophilic than hydrocarbons and 1- alkanols. The dependence of the partition coefficient on the chain len gth of the cationic surfactants is explained in terms of the micellar electrostatic potential change on solubilization.