This paper examines theoretically the conditions which favor enhanced extraction when a microemulsion phase containing a surfactant and a chelating agent is used as the solvent extraction organic phase. A general thermodynamic model of liquid-liquid distribution in reversed micellar systems is presented. The model treats the reversed micellar aggregates of the surfactant HA as a pseudophase and considers (a) the partition of a chelating extractant (HL) between the continuous organic phase and the reversed micellar pseudophase, (b) transfer of the metal ion Mz+into the continuous organic phase via reaction with HA monomers, (c) partition of the MZ+-HA complex between the continuous organic phase and the reversed micellar pseudophase, (d) reaction of the MZ+-HA complex with HL in the reversed micellar pseudophase, and (e) partition of the HL-containing complex between the reversed micellar pseudophase and the continuous organic phase. Quantitative expressions are derived that permit one to identify the chemical parameters that influence the liquid-liquid transfer process and therefore permit one to undertake the rational design of microemulsion formulations for specific applications.
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Chemical Engineering
- Process Chemistry and Technology
- Filtration and Separation