NONIDEAL BEHAVIOR OF MIXED MICELLES IN IONIC END NONIONIC SURFACTANT SYSTEMS

The behaviour at mixing of some cationic surfactants, such as alkylpyridinium halides with polyethoxylated nonionic surfactant was investigated. The surface tension of mixed surfactant systems in aqueous solution as a function of the mole fraction of the ionic surfactant in solution was determined at various temperatures. The critical micelle concentration of the mixed system and the maximum surface excess at the air - solution interface were calculated from the surface tension isotherms. The mole fraction of the ionic surfactant in the mixed micelle and the interaction parameter were obtained from the experimental surface tension data, using the regular solution theory.