SOLID-LIQUID EXTRACTION STUDIES OF ZN(II), CU(II) AND CD(II) FROM CHLORIDE MEDIA WITH IMPREGNATED RESINS CONTAINING MIXTURES OF ORGANOPHOSPHORUS COMPOUNDS IMMOBILIZED ON TO AMBERLITE XAD2

The solid-liquid extraction of Zn(II), Cu (II) and Cd(II) from chlorid e medium at 0.1 and 0.5 M ionic strength and 25 degrees C by impregnat ed resins containing mixtures of di(2-ethylhexyl)phosphoric acid (DEHP A=HL) and tri-n-octylphosphine oxide (TOPO=S) was studied. Impregnated resins containing TOPO and mixtures of DEHPA and TOPO, by direct adso rption of both extractants into a styrene/divinylbenzene macroporous s upport, Amberlite XAD2, using the dry impregnation method, were prepar ed. The distribution coefficients of Zn(II), Cu(II) and Cd(lI) were de termined as a function of pH, chloride concentration in the aqueous ph ase and extractant concentration (DEHPA and TOPO) in the resin phase a nd the data were analyzed graphically using the slope analysis method in terms of synergistic effect. Analysis of the results showed that th e extraction of these metal ions with resins containing mixtures of DE HPA and TOPO (XAD2-DEHPA-TOPO) can be explained assuming the formation of metal complexes in the resin phase with a general composition MCl( t)L(p)(HL)(q)S-s where p, t, a and q take different values depending o n the metal and the extractant concentration ratio in the resin phase ([HL](r)/[S](r)). Finally, a comparison between the extraction of Zn(I I), Cu(II) and Cd(II) in terms of the separation factors with Amberlit e XAD2-DEHPA-TOPO resins and using Amberlite XAD2-DEHPA resins was mad e.