Studies On Construction Of Ternary Phase Diagram Of1-Butyl-3-Methylimidazolium Tetrachloroferrate, Alcohols And Water And Its Application On Separation

Volatile organic solvents（VOCs） has been widely used in traditionalseparation process, which has created great harm to the environment andhuman. Ionic liquids（ILs） are more and more used in separation process asnew “green solvents” based on the guidelines of green chemistry.The liquid-liquid equilibrium（LLE） datas of1-butyl-3-methylimidazolium tetrachloroferrate （[Bmim]FeCl₄）+ethanol/n-butanol+watersystems were determined in this paper.This work provided basic researchdata and scientific evidence for the practical separation process of alcoholsand water systems.The [Bmim]FeCl₄was synthesized by the reaction of1-butyl-3-methylimidazolium coloride （[Bmim]Cl） and FeCl₃6H₂O with a molar ratio of1:2at room temperature.Samples of [Bmim]FeCl₄were characterized by FTIR、NIR and UV-Vis spectrometer. The moisture content was also determined.[Bmim]FeCl₄is hydrophobic, which is benefit to the separation of alcoholsand water systems.The LLE data of [Bmim]FeCl₄+ethanol/n-butanol+waterat T=273.2K,298.2K and313.2K were obtained in this research.The ternaryphase diagrams were also constructed.The selectivity （S） and distributioncoefficient （β） values, calculated based on the LLE data, indicated that the [Bmim]FeCl₄is a feasible solvent for the separation of ethanol/n-butanol+water systems as replacement of conventional VOCs. Theselectivity and distribution coefficient values of ethanol+water system are inthe order of273.2K>298.2K>313.2K and the values of n-butanol+watersystem are in the order of313.2K>298.2K>273.2K. Therefore, thetemperature decreasing is favorable to the separation of ethanol+watersystem. On the contrary, the temperature increasing is beneficial to theseparation of n-butanol+water system. The LLE datas determinated in thispaper were correlated using the NRTL model with a value of thenon-randomness parameter α=0.2.The root mean square deviation （rmsd）values of the two systems are all very small. The rmsd values ofethanol+water system and n-butanol+water system are less than0.04and0.02respectively. It indicates that the calculated values are in a goodaccordance with those of experiment values and the parameters obtained areall credible.In this paper，the mechanism of alcohols extraction process with[Bmim]FeCl₄was also explored using the FTIR and NIR technique.It wasdeduced that the imidazolium C₂-H formed C₂-H O interactions withalcohols molecules and complex also formed. Therefore, the extractionincludes both physical and chemical process.