DISTRIBUTION STUDIES OF ZN(II), CU(II) AND CD(II) WITH LEVEXTREL RESINS CONTAINING DI(2,4,4-TRIMETHYLPENTYL)PHOSPHINIC ACID (LEWATIT TP80784)

The use of physically immobilized reagents on macroporous polymeric su pports has been presented as an alternative approach, for the recovery of metal ions, to the usual techniques such as solvent extraction and ion exchange. 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 Levextrel impregnated resin Lewatit TP807'84 containing di(2,4,4-trimethylpentyl)phosphinic acid (DTMPPA). The distribution coefficient was determined as a function of both pH and ionic medium and the data were analyzed graphically using the slop e analysis method and numerically using the program LETAGROP-DISTR. An alysis of the results showed that the extraction of these metal ions c an be explained assuming the formation of metal complexes in the resin phase with a general composition ML(2)(HL)(q), where q takes differen t values depending on the metal studied. An extraction reaction is pro posed and the extraction constants of the species are given. The adsor ption of DTMPPA molecules on the styrene/divinyl benzene macroporous s upport seems to be the result of weak extractant-support interactions, as evidenced by FTIR spectroscopy. Nevertheless, it is also shown tha t the extraction ability of the extractant towards Zn(II), Cu(II) and Cd(II) does not suffer from the presence of the solid support, in comp arison with its ability to extract these metals using organic solvents . Finally, a comparison between the extraction of Zn(II), Cu(II) and C d(II) by Amberlite XAD2-DTMPP resins and using Lewatit TP807'84 resins is made.