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

Equilibria of aqueous solutions of ZnSO4 + H2SO4 with bis(2-ethylhexyl)phos phoric acid in isododecane (pentamethylheptane), a system which is proposed as an EFCE (European Federation of Chemical Engineering) test system for r eactive extraction, and of aqueous solutions of ZnCl2 + HCl with bis(2-ethy lhexyl)phosphoric acid in isododecane were investigated. Equilibrium concen trations and physical properties (density, viscosity, interfacial tension) are given at 298 K. The experimental data could be described well with a mo del that assumes the formation of one organic complex and regards the hydro gen 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 d escribe nonidealities in the organic phase. For quick estimations, shortcut formula for physical properties and the activities are given.