The critical micelle concentration (cmc) of a novel surfactant, 3-p- nonylphenoxy-2-hydroxypropyltrimethyl ammonium bromide was deteimined by measuring the surface tension. The effects of salinity, pH, and temperature on cmc were studied. The results revealed that the novel surfactant had higher surface activity than traditional cationic surfactants. The cmc of the surfactant was strongly dependent on the salinity, while it was moderately affected by the pH value and complicatedly affected by the temperature. The experimental results could be satisfactorily explained by thermodynamic calculations.

Key words: SURFACTANTS, SURFACE TENSION, QUATERNARY AMMONIUM COMPOUNDS, MICELLE, THERMODYNAMIC FUNCTION