PRECONCENTRATION OF CADMIUM, COBALT, COPPER, NICKEL AND ZINC BY SOLVENT-EXTRACTION INTO METHYL ISOBUTYL KETONE WITH 1,5-BIS [1-(2-PYRIDYL) ETHYLIDENE] THIOCARBONOHYDRAZIDE AND 1,5-BIS [PHENYL-(2-PYRIDYL) METHYLENE] THIOCARBONOHYDRAZIDE

The synthesis, physicochemical properties and interactions of two new thiocarbohydrazones, namely 1,5-bis[l-(2-pyridyl) ethylidene] thiocarb onohydrazide (APTH) and 1,5-bis[phenyl-(2-pyridyl) methylene] thiocarb onohydrazide (BPTH) have been studied as well as the use of both compo unds as extracting reagents. These thiocarbohydrazones form yellow com plexes with bivalent metal ions, and these are extractable into methyl isobutyl ketone. Conditions for quantitative extraction of Cd(II), Co (II), Cu(II), Ni(II) and Zn(II) are established from a critical study of the effect of pH, shaking time, reagent concentration in the organi c phase, ionic strength and volume ratio of aqueous to organic phase.