Reversed micelle formation in a model liquid-liquid extraction system

The formation of reversed micelles and the roles of extractant and extracted complexes were investigated in the Cyanex923/n-heptane/H2SO4 system. Interfacial tension (gamma), electrical conductivity (kappa), and water content measurements showed that Cyanex923 had a tendency to self-assemble, forming reversed micelles. The changes in electrical conductivity with concentration of H2SO4 in the organic phase (CH2SO4,(0)) exhibited an S-type curve: a correlation was found between the change in electrical conductivity and the water content as a function of CH2SO4,(0),. The changes of electrical conductivity were mainly induced by the components and microstructure in the organic phase, while the conversion of extracted complex also resulted in the changes of components and microstructure in the organic phase. Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) were used to characterize the organic phases and sizes of the reversed micelles, respectively. The extractant and extracted complexes, such as Cyanex923 center dot H2SO4, were involved in the formation of reversed micelles. (C) 2008 Elsevier Inc. All rights reserved.