Determinação dos coeficientes de atividade em diluição infinita de álcoois em água na presença de sais de sódio por microextração em fase sólida associada a cromatografia a gás (HS-SPME-GC/FID)

Abstract

In general, separation and purification processes account for most of the operational and design costs of industrial facilities. Therefore, the knowledge of physical and transport properties as well as equilibrium properties are fundamental for the design of such process. However, the limited availability of experimental data, particularly due to the complex composition and structure of certain products, experimental data availability rarely meets industries real demands. In this work, solid phase microextraction (SPME), combined with gas chromatography, was used to evaluate the influence of different concentrations of inorganic salts on the infinite dilution activity coefficients of alcohol/water/salt systems at temperatures of 25, 45 and 60 °C. The technique used is fast, inexpensive and easy to implement, which, coupled with the specific equations of the methodology, allowed us to determine the activity coefficient in infinite dilution, evaluating the influence of salt concentration and solution temperature. The alcohols studied were ethanol, propanol and butanol. And the salts studied were, respectively, Sodium Nitrate (NaNO3), Sodium Carbonate (Na2CO3) and Sodium Sulphate (Na2SO4), in concentrations of 0.528, 1.368 and 2.121 mol/kg of water. Among the salts studied, Na2SO4 and Na2CO3 had a better influence on the separation of the studied alcohols at the infinite dilution. The obtained results indicate that the technique used can be considered an alternative method to the determination of infinite dilution activity coefficients.