STATISTICAL-MECHANICAL TREATMENT OF REACTIVE SOLVENT-EXTRACTION

A statistical mechanical lattice model of a reactive solvent extractio n process involving two phase liquid-liquid ion exchange is presented. It is applied to literature data on the extraction of aliphatic carbo xylic acids by quaternary ammonium salts. The Helmholtz free energy of the system is constructed and minimised subject to the constraints of mass balance and electroneutrality. The equations defining the equili brium conditions have been solved numerically for a range of interacti on parameters and hence the equilibrium concentrations of the various partitioned species are obtained. These interaction parameters are com pared with experiment. The intuitive notion that the extent of partiti on is dominated by electrostatic solute-extractant interactions is sho wn to neglect various other interactions that may, in some systems, be important. (C) 1997 Elsevier Science B.V.