Estudo do equilíbrio líquido-líquido de sistemas ternários 2-propanol-sal-água: experimental e modelagem

Abstract

The great industrial and economic importance of isopropanol around the world and in the national scenario, strongly affects the production of this alcohol with high purity. However, the azeotropic behavior of this compound in aqueous solution complicates its complete purification. Thus, the study of a sustainable and economically viable new technique becomes extremely important. From this point of view, a liquid-liquid extraction from an aqueous two-phase system (ATPS) appears as a potential method due to its advantages such as low cost, non-toxic and possibility of large-scale application. The separation of the phases of this system is based on the salting-out effect, showing the behavior of the salts against hydrophilic solvents, such as isopropanol. Due to that, this work has as goal the study of the liquid-liquid equilibrium of ternary systems composed of isopropanol-sodium salts-water at 298.15 K and 101.3 kPa, specifically NaNO3, Na2SO4 and NaCH3COO. The binodal curves of the systems were experimentally determined and modeled using empirical models found in the literature. The tie-lines were measured and the reliability of their equilibrium data was tested. The evaluation of the force of the saline effect was studied for each of the systems. The e-NRTL and extended UNIQUAC models were used for a better correlation of the experimental data in order to obtain important parameters for a possible industrial design. Based on the found results, the experimental methodology to obtain the binodal curves and the tie-lines was satisfactory. In addition, sodium sulphate showed the highest salting-out effect, although nitrate and acetate presented better possibilities of use for the initially proposed objective. The e-NRTL and extended UNIQUAC showed lower deviations what indicates the good correlation of the experimental data using these thermodynamic models.