Influence of the Sodium Acetate on the Vapor- Liquid Equilibrium of the System Water- Ethanol at Normal Pressure

RESUMO – This work aimed the evaluation of a saline extractive distillation for the ethanol production. Unlike the current method of dehydration of ethanol, which uses a solvent, distillation with the use of salt does not include problems related to toxicity and has lower power consumption, since salt is not volatilized within the distillation column. Many salts had been tested like calcium chloride, calcium nitrate and a mixture of sodium and potassium acetates, although vaporliquid equilibrium data involving them are scarce in the literature. Other works proved that pure potassium acetate and the mixture of acetates can break the azeotrope, but there were not results involving pure sodium acetate. Due to that, in this work, vapor-liquid equilibrium data of the water-ethanol system with pure sodium acetate, at different concentrations, were measured in a Othmer type ebuliometer, at normal pressure. The data were measured at 10, 15 and 20% w/w and at 0.06 mol.L -1 , to better understand the influence of the salt in the equilibrium behavior. Analysis of the vapor and liquid phases were done in a digital densimeter. The sodium acetate enriched vapor phase in ethanol concentration and lower quantities of the salt better influence the equilibrium. Higher quantities of salt did not have good results because the salt did not yet solubilize in the solution. The model well correlated the data measured with lower deviations in temperature (1.49%) and vapor phase concentration (1.95%).