Zinc(II) extraction from phosphoric media by bis(2,4,4-trimethylpentyl)-dithiophosphinic acid (CYANEX 301)

The extraction of Zn(II) from phosphoric acid media (0.4-7.3 M) by the commercial reagent CYANEX 301 in toluene has been studied. Experimental results have been treated graphically and numerically, and the formation of the species ZnR2, where HR is bis(2,4,4-trimethylpentyl)dithiophosphinic acid, in the organic phase has been proposed. Values of the conditional extraction constant, which increases with the phosphoric acid concentration, are given.