Dye-Surfactant Complex Formation at Low Surfactant Concentration

Abstract

Alizarin Red S CARS), an anthraquinoid dye, forms anionic moiety in aqueous solution. The complex formation of ARS was studied with the cationic surfactant cetyltrimethylammoniurn bromide (CTAB) in aqueous environment at low surfactant concentrations. The complex was studied with the help of UV -Visible spectroscopy and FTIR technique. Method of continuous variation was applied to check the complex formation. 1 : 1 complex formation was evident from the experimental results. Equilibrium complex formation constant was determined at room temperature and also at five different temperatures. Different thermodynamic parameters, 6G, 6H and 6S were also calculated. 6H was calculated using Van't Hoff plot. Structure of the complex was proposed by taking FTIR spectrum of the complex and its correlation with the FTIR spectra of ARS and CT AB.