EXTRACTION STUDIES OF ZN(II), CU(II) AND CD(II) WITH IMPREGNATED AND LEVEXTREL RESINS CONTAINING DI(2-ETHYLHEXYL)PHOSPHORIC ACID (LEWATIT-1026 OC)

Impregnated resins are an alternative approach to the usual techniques for the recovery of metal ions, such as solvent extraction and ion ex change resins. This paper presents the results of the extraction of Zn (II), Cu(II) and Cd(II) from nitrate and chloride solutions at 0.1 M i onic strength and 25-degrees-C by the Levextrel impregnated resin Lewa tit 1026 Oc containing di(2-ethylhexyl)-phosphoric acid (DEHPA). The d istribution coefficients were determined as a function of both pH and ionic medium and the data were analyzed graphically, using the slope a nalysis method, and numerically using the program LETAGROP-DISTR. Anal ysis of the results shows that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin ph ase have a general composition ML2(HL)(q), where q takes different val ues depending on the metal. An extraction reaction is proposed and the extraction constants of the species are given. The adsorption of DEHP A molecules on the styrene/divinyl benzene macroporous support is due to weak extractant-support interactions, as indicated by FTIR spectros copy. Furthermore, it is also shown that the ability of the extractant towards Zn(II), Cu(II) and Cd(II) changes in the solid support, in co mparison with organic solvents. Finally, a comparison is made between the extraction of Zn(II), Cu(II) and Cd(II) with Lewatit 1026 Oc resin s and impregnated resins prepared by direct adsorption of DEHPA into A mberlite XAD2 (XAD2-DEHPA resins).