Study On Liquid-liquid Equilibrium Of Multicomponent Containing Dibutyl Ether

Dibutyl ether(DBE) is an oxygenated hydrocarbon, which is often used as an important solvent and an excellent extracting agent since it has many advantages such as: low toxicity, insoluble in water, good stability, safe operation, etc. Liquid-liquid equilibrium(LLE) data play a critical role in the process of separating of chemical materials. LLE data can also provide important information for the designing of industrial solvent extraction equipment. A good knowledge of the liquid phase equilibrium at different temperatures is necessary to better understand the thermodynamic behavior of multicomponent, since different temperatures have an effect upon the two liquid-phase regions. The precise LLE data has been the subject of much interest in recent years. In this work, LLE data for the(water + DBE),(water + ethanol + DBE) and(water + 2-propanol + DBE) systems were measured by gas chromatography at T =(293.15, 298.15, 303.15, and 308.15) K and the atmospheric pressure. Furthermore, the temperature influence on liquid-phase regions was analyzed. The ability of DBE to remove alcohol from aqueous solutions was observed by separation factors for ethanol and 2-propanol.In order to improve the air pollution problem caused by automobile exhaust, more and more research was studying on the development of new gasoline additive in recent years. The gasoline additive were used to improve the fuel quality, reduce fuel consumption and improve emissions, so as to achieve the purpose of energy saving and emission reduction. DBE is considered as a potential new blending agent in gasoline due to its very low water solubility and high octane number. The LLE data for quaternary system [water + 2-propanol + 2,2,4-trimethylpentane(TMP) + DBE] at T = 298.15 K and atmospheric pressure were also measured in this work. The distribution coefficients of various substances for quaternary system were calculated to investigate the influence on each component in the organic and aqueous phases when DBE was added to gasoline system.The reliability of the experimental values was verified by using the Othmer-Tobias and Hand equations. The average values of regression coefficient(R2) for Othmer-Tobias and Hand equation were 0.9942 and 0.9948 for(water + ethanol + DBE) system; for(water + 2-propanol + DBE) system were 0.9624 and 0.9771, respectively; for the measured quaternary system were 0.9315 and 0.9826. The values of R2 for each case are close to unity which illustrate that the accuracy and reliability of the experimental tie-line data measured in this paper are very high. The measured LLE data were correlated by using the modified and extended UNIQUAC models. For the two measured ternary systems, the average rmsd values of correlated results were 1.22 mol% and 1.48 mol% for the modified and extended UNIQUAC models, respectively; for the quaternary system, the rmsd values were 1.31 mol% and 2.38 mol%. The correlated results by the modified and extended UNIQUAC models were in agreement with the experimental LLE data.