Interactions between dye Orange II and three cationic surfactants

Interactions between an anionic dye,Orange Ⅱ and three cationic surfactants with different head groups,N-cetyl-trimethyl ammonium bromide,N-cetyl-hydroxyethyl dimethyl ammonium bromide,and N-cetyldihydroxyethyl-methyl ammonium bromide,were studied in aqueous solutions by using UV-Vis spectroscopy.The absorbances of Orange Ⅱ aqueous solutions with a surfactant are obviously lower than those without a surfactant and the absorbance increases with the increase of the concentration of the surfactant.The results showed that Orange Ⅱ has strong interactions with the cationic surfactants.The critical micelle concentrations of the surfactants and the interaction constants between the dye and the surfactants were estimated from the UV-Vis measurements.It was showed that the interaction of N-cetyl-dihydroxyethyl-methyl ammonium bromide with Orange Ⅱ is stronger than that of N-cetyl-trimethyl ammonium bromide and N-cetyl-hydroxyethyl dimethyl ammonium bromide is weaker than N-cetyl-trimethyl ammonium bromide.