SOLID-LIQUID DISTRIBUTION STUDIES OF DIVALENT METALS FROM NITRATE MEDIA USING IMPREGNATED RESINS CONTAINING A BIFUNCTIONAL ORGANOPHOSPHOROUS EXTRACTANT (O-METHYL-DIHEXYL-PHOSPHINE-OXIDE O'-HEXYL-2-ETHYL PHOSPHORIC-ACID)

The present paper presents the results of the extraction of Zn(II), Cu (II) and Cd(II) from 0.1 M NaNO3 at 25 degrees C by impregnated resins containing a bifunctional extractant, incorporating phosphine oxide a nd phosphoric acid diester funcionalities, O-methyl-dihexyol-phosphine -oxide O'-hexyl-2-ethyl phosphoric acid (HL). Solvent impregnated resi ns have been prepared by direct adsorption of I-IL into the styrene/di vinylbenzene macroporous support, Amberlite XAD2, by using the dry imp regnation method. The adsorption of HL, on the styrene/divinylbenzene macroporous support is shown by FTIR spectroscopy to be the result of only weak extractant-support interactions. The distribution coefficien t of Zn(II), Cu(II) and Cd(II) was determined as a function of pH and extractant (HL) concentration in the resin phase and the data were ana lyzed graphically using the slope analysis method and numerically usin g the program LETAGROP-DISTR. The composition of the extracted species in the resin phase has been determined. Analysis of the results showe d that the extraction of these metal ions can be explained assuming th e formation of metal complexes in the resin phase with a general compo sition ML(p)(NO3)(t)(HL)(q) where p, t, q take different values depend ing on the metal. An extraction reaction is proposed and the extractio n constants of these species are given.