Preparation And Characterization Of Supported Ionic Liquids Composed Of Quinoline Cation And Their Widening Application In Concentration And Separation Of Phenolic Compounds

Supported ionic liquids (SILs) were solid carrier of non-volatile ionic liquids (ILs) adsorbed on the solid surface. They have been successfully used in separation work due to its characteristic cations and anions. There are many advantages over ILs, such as an easier separation of the products, the lower residue of ILs and improved environmental performance. SILs have been aroused great interest in the chemical world due to its improved designability and selectivities. In this work, six kinds of SILs composed of the imidazolium cation and quinoline cation were separately synthetized, and their adsorbing and separating phenolic compounds were studied. Besides, SILs were applied in separation and purification of active components from natural products.Chapter 1 In this section, the synthetic method and immobilization procedures of ILs were reviewed, the advantage and application of SILs in various fields were induced. And the significance and objective of the research were also elucidated.Chapter 2 Six kinds of silica SILs (SiO2·Im+·-Cl-, SiO2·Im+·BF4-, SiO2·Im+·PF6-, SiO2·Qu+·Cl-, SiO2·Qu+·BF4 and SiO2·Qu+·PF6-) were synthesized by combination of imidazole, quinoline cations and chloride, tetrafluoroborate, hexafluorophosphate anions. And they were characterized by IR, ICP, thermogravimetric analysis and elemental analysis. No articals were reported the synthesis of quinoline SILs.Chapter 3 Using the six kinds of SILs synthesized above as adsorbents, the effects of different solvents, adsorption time, sample concentrations, solid-liquid ratio, and pH values on the adsorption properties of SILs for phenolic compounds were investigated in this paper. The results indicated that the adsorption equilibrium for tested compounds was a totally aqueous solution, achieved within 30 min, the adsorption efficiencies of these three compounds were found to improve with the increase of solid-liquid ratio, and decrease with the increase of their concentrations. Moreover, the pH value should between 1.0 and 3.0 at least. Adsorption efficiency of SiO2·Qu+·Cl- was found to be the optimum sorbent. The saturated adsorption capacity of SiO2·Qu+·Cl- for ferulic acid, caffeic acid and salicylic acid was 62.3 mg·g-1,45.6 mg·g-1,75.4 mg·g-1 respectively. Adsorption efficiency of SiO2·Qu+·Cl- could reach more than 90% at the sample flow rate of 1.5 mL·min-1. Using 70% ethanol as eluent, the saturated desorption efficiencies of ferulic acid, caffeic acid and salicylic acid were 97.2%,90.3% and 96.5% respectively. The elution order of the three tested compound was salicylic acid, ferulic acid and caffeic acid. By comparison, SiO2·Qu+·Cl- had relatively higher adsorption ratio and desorption ratio, compared with silica gel and the three resins. Therefore, SiO·Qu+·Cl- had strong adsorption and separation capacity for three tested compound, which was hopeful to be applied in separation and purification of naturally occurring phenolic compounds. The residues of SILs in optimum elute components are low and the SILs was recycled three times without obvious loss in the concentration separation capacity.Chapter 4 The concentration and separation of SILs SiO2·Im+·Cl- for shikimic acid from Chinese star anise (Illicium verum Hook, f.) were studied. Static and dynamic adsorption-desorption methods were adopted. The adsorption equilibrium and kinetics for shikimic acid were obtained. The equilibrium at different temperature (303 K,313 K and 323 K) could be described with both Frundlich and Langmuir isotherm equations, and determination of shikimic acid in Illicium verum Hook.f. by HPLC. The results indicated that the optimum sorbents is SiO2·Im+·Cl-, SILs were suitable for adsorbing and purifying shikimic acid from Illicium verum Hook.f. Both Freundlich and Langmuir equations fitted the experimental data quite well, while Freundlich equation might fit better. Using this method to enrichment shikimic acid, the recovery of shikimic acid was 80.34%. This method is simple and feasible with good efficiency of enrichment, which could also meet the industrial requirements. Therefore, it was worth further research that SILs was applied in separation and purification of active components from natural products.