Investigation of Interactions between Sodium Dodecyl Sulfate and Crystal Violet in Aqueous Solution

Abstract

To study the interactions between the anionic surfactant sodium dodecyl sulfate in presence of cationic dye crystal violet and effect of increasing temperature on these interactions, both surface tension and conductometric techniques were used. The surface tension and the specific conductance values of dye-surfactant mixtures decreased when proportion of dye increased in the mixtures, in respect of the temperature. Furthermore, the results revealed that the critical micelle concentrations (CMC) have reflected a tendency towards decreasing in the values with increasing in both the proportion of the dye in the surfactant solutions and in the temperatures. Moreover, the interactions of dye-surfactant are spontaneous based on the negative values of standard Gibbs free energy changes of micelle formation (DG°_mic), for all systems. Significantly, the positive values of standard enthalpy micelle formation (DH°_mic), revealed that the interactions of dye-surfactant system are endothermic. Additionally, the entropy change of micellization formation (DS°_mic), is positive.