EVALUATION AND OPTIMIZATION OF THE FACTORS AFFECTING NONIONIC SURFACTANT-MEDIATED PHASE SEPARATIONS

The technique of extracting and concentrating hydrophobic species from water via nonionic surfactant micelle-mediated phase separations was examined. The effect on extraction efficiency, solute distribution coefficient, and phase volume ratio of pertinent experimental parameters such as surfactant hydrophobicity, pH and ionic strength, equilibration time and temperature, centrifuge time, and analyte and surfactant concentration was systematically evaluated. Surfactant hydrophobicity, which was studied by monitoring the extraction parameters observed for two homologous series of poly-(oxyethylene glycol) monoethers, appeared to be the dominant factor along with solution pH for those solutes possessing either an acidic or a basic functionality. The use of poly(oxyethylene glycol) monooctyl ether (C8E3) in the cloud point procedure led to very good extraction efficiency and concentrating ability for most solutes, achieving extraction recoveries of 88-99% for a series of chlorinated phenols. The general trends observed as a function of changes in the experimental conditions should be applicable to those cloud point extraction systems that utilize other nonionic surfactants. The optimized procedure was also demonstrated for the extraction of some other substituted phenols and anilines.