Abstract
Correlation between phase behavior and the interfacial tension at oil/water interface, γo-w, has been studied in a three-phase region of CnH2n+1 (OCH2CHCH3) 3 OSO3M/C8H17 (OCH2CH2) 2 OH/brine/oil system (n=12, 16; M=1/2Ca, Na). γo-w reaches its minimum, γmino-w, in the midst of the three-phase region consisted of water, surfactant and oil phases, and γrmino-w attains to ultralow value 10-4-10-5mN·m-1. γmino-w decreases with an increase in the hydrocarbon chain length of surfactant or with a decrease in that of oil. The effect of salinity on γmino-w is also discussed.
