Extraction of Zinc from Water into Nitrobenzene Using Strontium Dicarbollylcobaltate in the Presence of Valinomycin

Emanuel Makrlík^a* and Petr Vaňvura^b

^a* Corresponding author: Faculty of Applied Sciences, University of West Bohemia, Husova 11, 306 14 Pilsen, Czech Republic
E-mail: Petr.Vanura@vscht.cz
^b Prague Institute of chemical Technology, Technická 5, 166 28 Prague 6, Czech Republic

Abstract
From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium Zn²⁺(aq) + SrL²⁺(nb) ↔ ZnL²⁺(nb) + Sr²⁺(aq) taking place in the two-phase water-nitrobenzene system (L = valinomycin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K_ex (Zn²⁺,SrL²⁺) = –0.1. Furthermore, the stability constant of the valinomycin-zinc complex in nitrobenzene saturated water was calculated for a temperature of 25 °C: log β_nb(ΖnL²⁺) = 6.2.

Keywords: Zinc, valinomycin, water-nitrobenzene system, extraction and stability constants.