Separation Science and Technology, Vol.31, No.11, 1541-1553, 1996
Recovery and Concentration of Metal-Ions .3. Concentration and Temperature Effects in Multimembrane Hybrid System
The performance of the multimembrane hybrid system (MHS) made up of ion-exchange membranes and a bulk liquid membrane (DZEHPA in kerosene) has been examined. Fluxes and the separation between Zn(II), Mn(II), Cu(II), Co(II), and NI(II) sulfates have been studied as dependent on the concentration of aqueous phases and temperature. The results show a saturation of fluxes at increased concentrations of aqueous feed or strip solutions. The total limiting fluxes are similar to 1 x 10(-9) mol/cm(2)-s whereas the limiting fluxes for specific metal ions vary in the range from 6 x 10(-12) to 5 x 10(-10) mol/cm(2)-s. The effect of temperature on MHS transport results in an activation energy of 16 to 30 kJ/mol depending on the metal species. The optimum conditions for separating metals are determined by the concentration of a feed solution in the range from 0.001 to 0.01 M and the concentration of sulfuric acid in a stripping solution in the range from 0.01 to 0.5 M. Selectivity coefficients beta(Co+Ni)(Zn+Mn+Cu) calculated as the ratio of stationary fluxes amount to 30-40, and are practically constant in the 298 to 328 K temperature interval.
Keywords:SUPPORTED LIQUID MEMBRANE;EXCHANGE MEMBRANES;TRANSPORT;DIFFUSION;ACID;EXTRACTION;KINETICS;CATION;ZINC