Kinetics of separating multicomponent mixtures by nondispersive solvent extraction: Ni and Cd

A model for nonsteady metals separation using nondispersive solvent extract ion presented explicitly accounts for selective separation of multicomponen t solutions and concentration of separated components in a back-extraction phase. The separation process comprises extraction and back-extraction step s carried out in two different hollow-fiber modules, connected through the organic phase, together with three homogenization tanks. The model is based on a set of coupled differential equations describing mass balances of met allic solutes in the fluid phases. To be applied in its simplest form, if r equires the knowledge of three characteristic parameters, two parameters re lated to the chemical reactions, and one mass-transport parameter. The latt er describes the mass-transport rate through pores of the hollow-fiber memb rane filled with the organic phase. The mathematical model was checked agai nst the kinetic results of the separation of Cd/Ni mixtures working with hi gh-concentration solutions and obtaining the characteristic parameters of t his system.