Interaction of Phenol Red with cetyltrimethylammonium bromide in aqueous solution

This paper studies the interaction of anionic dye Phenol Red with cationic surfactant cetyltrimethylammonium bromide in aqueous solution and its influence on the formation of cetyltrimethylammonium bromide micelles for the first time. We obtain a series of thermodynamic parameters of the interaction by establishing a reasonable physical model of the association. Moreover, an in-depth study on the variation in the absorption spectrum finds that the value of absorbance at the maximum absorption peak changes regularly with increase in the cetyltrimethylammonium bromide concentration. By establishing the micellisation models and measuring the changes in electrical conductivity with different cetyltrimethylammonium bromide concentrations, the critical micelle concentration values are obtained, which are essentially the same as the range of concentrations of regular change in absorbance, which shows that the formation of the cetyltrimethylammonium bromide micelles have an impact on the association interaction between Phenol Red and cetyltrimethylammonium bromide. All these data and phenomena illustrate a strong interaction between Phenol Red and cetyltrimethylammonium bromide.