Thermodynamics Properties Of Solutes In Ionic Liquids And Application Of [PDMIM][SCN] As The Gas Chromatography Stationary Phase

Ionic liquids（ILs）are expected to replace traditional volatile organic solvents in many industrial processes due to their unique properties such as almost non-volatility,good thermal stability,strong solubility and designability.Infinite dilution activity coefficient（γ_i^∞）is an important chemical thermodynamic parameter that could reflect the selectivity and solubility of solvents,thereby providing a theoretical basis for ionic liquids as solvents to separate various difficult separation systems and other applications.In addition,the unique properties of ionic liquids could match well with those of the stationary phase of gas chromatographic columns,thus it is of great theoretical and practical significance to apply ionic liquids in the field of chromatographic analysis.In this work,two kinds of ILs,1-decyl-3-methylimidazole bistrifluoromethanesulfonimide（[DMIM][Tf₂N]）and 1-propyl-2,3-dimethylimidazole thiocyanate（[PDMIM][SCN]）,were prepared.The structures of the two ILs were characterized and the physicochemical properties were measured.The gas chromatography method（GC）was used to determine infinite dilution activity coefficients,infinite dilution partial molar amount and other relevant thermodynamic parameters of 32 organic solutes（namely,N-hexane,ethanol and benzene）in the two ionic liquids at a temperature range of 313.15 K at 363.15 K under atmospheric pressure.According to the Hildebrand-Scatchard（RST）theory and the Flory"Combinatorial"equation,the Hildeband solubility parameter of ionic liquidsδ₃was estimated based onγ_i^∞,the infinite dilution selectivity of the two ionic liquids for different mixed solutes（including alcohols/alkanes,alcohols/aromatics,etc.）was calculated.The results showed that the two ionic liquids have great performance in separating solutes mixtures containing straight-chain alkanes.In this thesis,the preparation of capillary-column chromatography with ionic liquid as the stationary phase was also explored.The effects of the pretreatment of stationary phase solution,the pretreatment method of capillary column,the coating method of chromatographic column and the aging of chromatographic column were studied.Capillary columns with[PDMIM][SCN]as the stationary phase were successfully prepared.The separation ability and efficiency of the chromatographic column for 5different kinds of mixtures were evaluated and the limit temperature of chromatographic column was inspected with temperature programmed method.The experimental results show that the capillary column with ionic liquid[PDMIM][SCN]as the stationary phase is a qualified polar capillary column,and can withstand higher operating temperature,and has a good application prospect.