Equilibrium distribution of aromatic compounds between aqueous solution and coacervate of nonionic surfactants

Studies have been made of the equilibrium distribution of aromatic compounds between an aqueous solution and a coacervate of a nonionic surfactant, polyoxyethylene nonyl phenyl ether, which has an average ethylene oxide number of 10. Phase separation of the surfactant solution was attained by allowing it to settle at a temperature above the cloud point, and then the aromatic compounds were partitioned into the surfactant-rich phase from the solution in a form of the neutral species. The extraction behavior could be interpreted in terms of the acid dissociation constant as a function of the solution pH. It was found that organics which lower the cloud point to larger extent can attain higher extraction. Furthermore, the cloud-point extraction of phenol in a mixed surfactant system has been examined.