Determination of solubilization of phenol at coacervate phase of cloud point extraction

When the temperature of a nonionic surfactant solution is over the cloud point, the solution separates into two phases, a dilute phase and a coacervate phase. The solute that originally exists in the solution will unevenly partition into those two phases, which is known as cloud point extraction (CPE). For determination of the solubilization of phenol in micelles of surfactant solution, the concentration of free solute unassociated to micelles in the dilute phase was determined. It was a constant at certain temperature. The result was re-verified by titration experiments. Therefore, the solubilization in the coacervate phase can be determined experimentally. The result was compared with the solubilizaton in micelles, which showed that the solublization in the coacervate phase was different from that in micelles. This can be attributed to different structures of micelles in dilute phase and in coacervate phase. (C) 2002 Elsevier Science B.V. All rights reserved.