Equilíbrio líquido-líquido e estudos das forças motrizes de partição de íons em novos sistemas aquosos bifásicos baseados em líquidos iônicos

Abstract

The present work had its objectives centered on obtaining and characterizing the phase behavior of new ATPSs based on the ionic liquid [Bmim]BF 4 and the inorganic salts CuSO 4 or Li 2 SO 4 . In the ATPSs formed by [Bmim]BF 4 + CuSO 4 + H 2 O, phase diagrams were obtained at temperatures of 283.15, 298.15, and 313.15K.As for the mixtures of [Bmim]BF 4 + Li 2 SO 4 + H 2 O the phase behavior was studied at temperatures of 283.15, 298.15, 308.15, and 318.15K. In both ATPSs the effect of temperature, composition, cation and ion exchange on the formation of these systems were evaluated. It was experimentally found that the temperature had a remarkable effect on the position of the phase diagrams for the two types of mixtures. In general, the decrease in temperature promotes phase segregation, indicating the exothermic character of the formation of these ATPSs. In the future, changes in density in the systems formed by CuSO 4 led to the occurrence of phase inversion in some blend compositions at 283.15 and 298.15K. A scale was established to evaluate the ability of different cations of sulfate salts to induce the formation of mixtures involving [Bmim]BF 4 . Thermodynamic parameters of hydration were used in conjunction with experimental data of saturation solubility to make several adjustments that seem to show that the entropy of hydration is the driving force for the separation process. Transfer's thermodynamic parameters of the components (cations, anions, and water)between the phases were also calculated from the experimental data and indicated that the transfer of material from the lower phase to the upper part is not spontaneous and tends to be less spontaneous with the increase in TLL. It was observed experimentally that there was no significant exchange of ionic pairs in the phase separation process involved in these mixtures studied. In addition, the equilibrium data and the binodal curves were fitted to an empirical nonlinear expression (Merchuk equation) and the effect of salting-out was explored using a Setschenow equation.