EXTRACTION OF LEAD(II) BY CYANEX-302 IN TOLUENE, EFFECT OF CYANEX-301ON THE EXTRACTION BY CYANEX-302

The extraction of Pb(II) from 1.0 M KCl media by the commercial extrac tant Cyanex 302 dissolved in toluene has been studied as a function of the total extractant concentration, the equilibrium pH and the total metal concentration. The influence of bis(2,4,4,-trimethylpentyl)dithi ophosphinic acid, one of the minor impurities of Cyanex 302 and also t he major component in Cyanex 301, on the extraction of lead has also b een examined by studying the extraction of the metal ion by Cyanex 301 . Experimental data have been treated numerically by means of the comp uter program LETAGROP-DISTR, and can be explained by assuming the extr action of the species PbR(2)(HR), PbL(2)(HL) and a mixed complex of st oichiometry PbLR(HR), HL being bis(2,4,4-trimethylpentyl)dithiophosphi nic acid, the active component of Cyanex 301 and HR standing for bis(2 ,4,4-trimethylpentyl)monothiophosphinic acid, the active component of Cyanex 302. The stoichiometric equilibrium constants of the extraction processes are also given.