The spectral study of azo dye and cationic surfactant interaction in ethanol-water mixture

Abstract

The interaction of the azo dye methyl red (MR) with dodecyl trimethyl ammonium bromide (DTAB) has been studied by the spectrometric methods through the azo-hydrazone tautomeric behaviour of MR for a series of the ethanol–water system (0.1, 0.2, 0.3 and 0.4 volume fractions of ethanol) at room temperature. The critical micelle concentration was determined using the conductometric technique with the increased ethanol volume, influenced by the solvent polarity and the architectural flexibility of methyl red. The azo form of methyl red brings the electrostatic interaction with the cationic surfactant through the adsorption phenomenon. The binding parameters were calculated with the aid of a modified Benesi–Hildebrand equation.

Keywords

• molar absorptivity
• binding constant
• standard gibbs energy