Abstract
In the present study, the conductometric and dye-solubilization techniques have been utilized to investigate the interaction between an anionic dye (acid yellow 23 [AY]) and a cationic surfactant (cetyltrimethylammonium bromide [CTAB]) in presence of organic (ethanol)/inorganic (NaCl) additives. From the conductometric method, two critical micelle concentrations (
) were found for AY + CTAB mixture in an aqueous system and the
values were found to undergo a change with the variation of AY concentrations. The
values of AY + CTAB systems were observed higher in the alcoholic medium, while the same was found to be lower in the NaCl solutions. The change in
of AY + CTAB systems shows an U-like curve with an increase of temperature. The negative free energy of micellization (
) for the AY + CTAB systems has indicated a spontaneous micelle formation in all of the cases studied. The enthalpy (
), as well as the entropy of micellization (
) for the AY + CTAB systems, were assessed and discussed with proper reasoning. Additionally, the enthalpy-entropy compensation parameters were also investigated and illustrated. The solubility of AY and
was observed to rise linearly with an increase in the concentration of CTAB/NaCl solution. The solubilization capacity (
) of AY, the molar partition coefficient (
) amongst the micellar and the aqueous phase, and free energy of solubilization (
) were evaluated and discussed in detail. The former parameters undergo an increase with an increase of NaCl concentrations.