Abstract

Introduction: The influence of polar organic solvent on the self-assembly of surfactants is of significant concern. Specifically, certain biological and technical processes required non-aqueous media to achieve optimal outcome. Aims: This work investigated the effect of an aprotic solvent (acetonitrile) on the micellization of benzethonium chloride (BZC) at 298.1-318.1.K at an interval of 5 K. Materials and Methods: The micellization of benzethonium chloride in ACN was studied with the aid of temperature controlled-water bath and electrical conductivity meter. The stock solution of BZC was prepared in redistilled-de-ionized water, and then in mixed varying volume percentages of ACN. Results: The values of the critical micelle concentration (CMCBZC) obtained at different temperatures in aqueous medium ranged from 2.885 to 3.486 moldm-3. When 5% v/v of ACN was added to the system, the values of the were 3.093 - 3.545 moldm-3 at 298.1 - 318.1 K. However, when the concentration of ACN was further increased to 10% v/v and 15% v/v, the process of micellization was depressed at different temperatures. The values of the Gibbs free energy (ΔGBZC, kJmol-1) were all negative, while the values obtained for the , were positive with variation in the degree of randomness at different volume percentages of ACN and temperatures. In addition, the values revealed that the system was on the overall, exothermic. Conclusion: The ACN adjusted the aggregation process in the context of co-solvent, and the thermodynamic data indicated that the ACN-BZC micelle can be utilized in water-non-aqueous based system.

Keywords: Benzethonium Chloride, Mixed solvent, Thermodynamic parameters, and Acetonitrile