Three-Phase Behavior in a Water/C(12)EO(8)/Propanol/Cyclohexane/Heptane System.
We studied the three-phase behavior and dissolution behavior of propanol (C(3)OH) in a water/C(12)EO(8)/C(3)OH/cyclohexane (c-C(6))/heptane (C(7)) system at 35 and 45 degrees C. Without C(12)EO(8), a three-phase region (IIIa) consisting of C(3)OH, aqueous (W), and oleic (O) phases exists between R(oil) (c-C(6)/c-C(6) + C(7)) = 0.2 and 0.3 (w/w) above 35 wt% C(3)OH. The C(3)OH phase originates from the W phase and becomes identical to the O phase with increasing R(oil). In the presence of C(12)EO(8), the three-phase region expands below 20 wt% C(3)OH. The surfactant phase behaves in two ways according to the role of C(3)OH. When R(oil) < 0.2, the D(p) phase forms a closed-loop miscibility gap with a W phase. The added C(3)OH acts as a lipophilic cosurfactant and a water-soluble cosolvent. When R(oil) > 0.3, a microemulsion (D) phase changes from water-rich to oil-rich in a chiral three-phase body. Most C(3)OH added acts as a lipophilic cosurfactant at R(oil) = 1. The two types of three-phase behavior are transformed into each other via region IIIa. C(3)OH cooperatively acts with C(12)EO(8) and a higher-order phase is formed. Copyright 1999 Academic Press.
Yamaguchi
S
Faculty of Informatics, Teikyo Heisei University, 2289 Uruido, Ichihara, Chiba, 290-0193, Japan