Recovery and Concentration of Metal Ions. III. Concentration and Temperature Effects in Multi membrane Hybrid System

Abstract

The performance of the multi membrane hybrid system (MHS) made up of ion-exchange membranes and a bulk liquid membrane (D2EHPA 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 ～1 × 10^?9 mol/cm^2.s whereas the limiting fluxes for specific metal ions vary in the range from 6 × 10^?12 to 5 × 10^?10 mol/cm²-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 β^Zn+Mn+Cu _Co+Ni calculated as the ratio of stationary fluxes amount to 30–40, and are practically constant in the 298 to 328 K temperature interval.