Non-dispersive solvent extraction of alkali metals with the dicyclohexano 18 crown 6:: Evaluation of mass transfer coefficients

The aim of this study is both to check the feasibility of the membrane contactor for the extraction of alkali metals with the dicyclohexano 18 crown 6 as extractant and to obtain informations about the mass transfer of these metals. The influence of tube and shell side hydrodynamics on extraction rates is studied. High aqueous flow rates flowing inside the tubes increase extraction efficiency, on the other hand the organic diffusion layer seems to have a less important role on the mass transfer. Initial extraction rate order follows the order of the extraction equilibrium. The mass transfer coefficients of alkali cation are calculated by performing an unsteady state material balance and compared with values calculated by the resistance in series model and by a steady state model.