Interaction Mechanism Of Several Spearation Process With Imidazolium-based Ionic Liquids

Liquid/liquid extraction and extractive distillation are very important separation technology，and usedin the chemical industry widely. Traditional liquid/liquid extraction always employs volatile organicsolvents as extractant, which is toxic and flammable. To improve the safety and environmental friendliness,suitable alternatives are needed urgently. The use of room temperature ionic liquids (RTILs) special indistillation of azeotropic or close-boiling mixtures, obvious advantages over classical entrainers orinorganic salts can be achieved, such as noncorrosive and recycling ease. RTILs can be used as idealsubstitutes because of their stability, nonvolatility and adjustable miscibility and polarity. However, thereare very few researches on the interaction mechanism of ionic liquids as extraction and entrainer. Thusfurther progress and application of ILs on the liquid/liquid extraction and extractive distillation has beenrestricted.In this research, a systematic study on the extraction of benzene derivative and separation ofazeotropic mixtures of methanol and acetone using ILs have been carried out. The used experimentaltechnique includes NMR, ATR-IR spectroscopies and Density Functional Theory (DFT) calculations. As apart of the project supported by the National Natural Science Foundation of China (No.21173069) and byDoctoral Program Foundation of Institutions of Higher Education of China (No.20104104120002), themajor content of the present work is as follow:1. The properties of the mixed systems of [Bmim][PF6] and the benzene derivatives have beenmeasured with the1H NMR,13C NMR and ATR-IR spectroscopies. The interactions between theimidazolium cations and the benzene derivatives have been discussed, and the potential stericconfigurations have been put forward. The structure of the mixed systems of [Bmim][PF6] and the benzenederivatives are calculated through the DFT. The strength of the interaction between the imidazolium cationsand the benzene derivatives have been analyzed by Atoms-in-molecules (AIM) and electron densitydifference.2. The Raman (3500-100cm-1), mid and far-infrared (4000-100cm-1) spectra of1-ethyl-3-methy-limidazolium dicyanamide ([Emim][DCA]) are measured experimentally. The structure and theoretical vibrational spectra of [Emim][DCA] are calculated through the DFT，and the low energy conformer isobtained and discussed. Combined with the experimental frequencies, detailed assignment of thevibrational frequencies of [Emim][DCA] are given. The changing of electron density and interactionbetween the cation and anion of [Emim][DCA] are illustrated through AIM and electron density differenceanalysis.3. The microscopic information for the binary systems of [Emim][DCA] and methanol/acetone havebeen measured with the1H NMR,13C NMR and ATR-IR spectroscopies. The interactions between[Emim][DCA] and the two solvent have been discussed, and the potential steric configurations have beenput forward. The effect of [Emim][DCA] on the separation of methanol/acetone azeotropic mixtures havebeen indicated through analysis the stable structures calculated through the DFT by AIM and electrondensity difference.