Liquid-liquid Equilibrium For Extraction Separation Of Benzene And Cyclohexane Using Furfural/(Furfural And Potassium Thiocyanate)

At present,there is a groundbreaking subject which we should extract the aromatic hydrocarbons from the mixture of aliphatic hydrocarbons.In this project,the lowest azeotropic mixture system is a very typical which is formed by benzene and cyclohexane.And the boiling point of benzene is very close to the cyclohexane.Liquid-Liquid Equilibrium for extraction separation of benzene and cyclohexane is an effective solvent extraction method.And there are some remarkable advantages for solvent extraction method such as continuous operation,larger processing capacity and good separation effect.However,the choice of extraction solvent is the decisive factor of the separation performance for solvent extraction method.In this paper,the properties of extraction solvent are studied and analyzed.The main contents of this paper is that:The compound solvent is preparated which is formed potassium thiocyanate and furfural.It is the extraction solvent to separate benzene and cyclohexane.The conductivity and density of compound solvent is measured at 25?and 30?,and the infinite dilution molar conductivity is calculated.The correction factor of the components is measured.The time when the system reaches the liquid-liquid equilibrium is measured.Equilibrium data of the ternary system benzene+cyclohexane+furfural and the quaternary system cyclohexane+benzene+dimethyl sulfoxide+potassium thiocyanate are measured at different temperatures.The selectivity coefficient of the solvent and distribution coefficient of the solute are calculated,and it is compared with some extractant.It is concluded that:As the mass fraction of potassium thiocyanate in the co-solvent becomes large,the conductivity becomes larger,the molar conductivity becomes smaller;the selectivity coefficient becomes larger.The selectivity coefficient is certain affiliated with the operating temperature.As the temperature increasing,the selectivity coefficient of the solvent will be reduced.At 25?,the infinite dilution molar conductivity is 208 S·cm2·mol-1.At 30?,the infinite dilution molar conductivity is 183 S·cm2·mol-1.At 25?,the selectivity coefficient of the ternary solvent system is 2.58-5.59.At 30?,the selectivity coefficient of the ternary solvent system is 2.42?5.94.At 35?,the selectivity coefficient of the ternary solvent system is 2.53?5.45.At 40?,the selectivity coefficient of the ternary solvent system is 2.81?4.33.At 25 ?,the selectivity coefficient of the quaternary solvent is 2.59?24.38.At 30?,the selectivity coefficient of the quaternary solvent is 2.35?19.08.In order to analyze liquid-liquid equilibrium data intuitively,triangle phase diagrams of the ternary system and the quaternary system are plotted at different temperatures.The experimental data of the ternary system are correlated by Othmer-Tobias equation and Hand equation.And the experimental data of the ternary system and the quaternary system are correlated by the NRTL equation,the system can be correlated and predicted well by these equations.