SYNERGISTIC EFFECTS IN THE SOLVENT-EXTRACTION OF SOME DIVALENT METALSBY MIXTURES OF VERSATIC-10 ACID AND PYRIDINECARBOXYLATE ESTERS

Pyridinecarboxylate esters were found to cause appreciable synergistic shifts in the pH,, values for the extraction of some divalent base me tals by solutions of Versatic 10 acid in xylene. For n-octyl 3-pyridin ecarboxylate, the synergistic shifts decreased in the order Ni > Co > Cd > Cu approximate to Fe > Mn > Zn, and for the commercial extractant Acorga DS5443A in the order Ni > Cu > Co > Fe > Cd > Mn > Zn. No syne rgistic effects were observed for divalent lead, calcium and magnesium . On the basis of the pH,, values obtained, several possible practical metal separations are suggested. No loss of metal-loading capacity wa s found when the organic phases were contacted with 1 M sulphuric acid for prolonged periods at 30 degrees C. The effect of changes in the s tructure of a series of isomeric octyl pyridinecarboxylates is reporte d for one of the smaller cations studied (copper), as well as for one of the larger cations (cadmium).