Extraction equilibria of zinc with bis(2-ethylhexyl)phosphoric acid

Equilibria of aqueous solutions of ZnSO4 + H2SO4 with bis(2-ethylhexyl)phosphoric acid in isododecane (pentamethylheptane), a system which is proposed as an EFCE (European Federation of Chemical Engineering) test system for reactive extraction, and of aqueous solutions of ZnCl2 + HCl with bis(2-ethylhexyl)phosphoric acid in isododecane were investigated. Equilibrium concentrations and physical properties (density, viscosity, interfacial tension) are given at 298 K. The experimental data could be described well with a model that assumes the formation of one organic complex and regards the hydrogen sulfate equilibrium in the aqueous phase. The Pitzer equation was used for the aqueous phase, and the theory of Hildebrand and Scott was used to describe nonidealities in the organic phase. For quick estimations, shortcut formula for physical properties and the activities are given.