Nonaqueous Liquid-Liquid Extraction. Extraction of Zinc and Cadmium from Ethylene Glycol Solution of Bromide by Trioctylphosphine Oxide

The distribution of zinc between toluene phasecontaining trioctylphosphine oxide (TOPO) and nonaqueous ethylene glycol phase containing either hydrogen or alkali bromide has been investigated by using zinc-65 and cadmium-115 m. The distribution ratio, D fromethylene glycol phase reached a maximum value at about 0.1 N of hydrogen bromide for zinc and at about 0.4 N for cadmium. This shows that zinc bromide complexes are considerably more stable in ethylene glycol phase than in aqueous phase. In the zinc-hydrogen or alkali bromide-TOPO system, the complex ZnBr2.2TOPO may occur in toluene phase, while in the cadmium-hydrogen bromide-TOPO system, such acid com-plexes as HCdBr3.1TOPO and H2CdBr3•rTOPO are probably formed in the toluenephase. Under the conditions of the experiment, only mononuclear zinc and cadmium complexes appear to exist in the two phases