Thermodynamics of solvent extraction of perrhenate with tertiary isooctyl amine

In the solvent extraction system, the equilibrium molalities of ReO4− were measured at ionic strength from 0.2 to 2.0 mol kg−1 in the aqueous phase containing NH4Cl as supporting electrolyte at temperatures from 278.15 K to 303.15 K. The standard extraction constants K0 at various temperatures were obtained by methods of Debye–Hückel extrapolation and Pitzer polynomial approximation. Thermodynamic properties for the extraction process were calculated.