STUDIES ON THE THERMODYNAMICS OF THE SOLVENT-EXTRACTION OF METALS .5.(TL2SO4-C8H18+WATER)(NA2SO4+D(2)EHMTPA+N)

The equilibrium molality of Tl+ in the extraction reaction Tl+(aq) + H 2A2(org) = TlHA2(org) + H+(aq) in {Tl2SO4 + Na2SO4 + D2EHMTPA + n-C8H1 8 + water} (where D2EHMTPA is diethylhexylmonothiophosphoric acid) was measured. The ionic strength of the aqueous phase with Na2SO4 as supp orting electrolyte was varied between 0.1 and 2.0 mol kg-1 and, at con stant initial molality of extractant in the organic phase, the tempera ture was varied in the range 278.15-303.15 K. The standard extraction constants K-degrees at vaious temperatures were deter-mined using the two methods proposed in our previous paper Yang, J.-Z., Liu, X.-Z., K ang, Y.-H. and Song, K.-Y., 1992. Fluid Phase Equilibria, 78: 249-2601 . Thermodynamic quantities for the extraction process were calculated.