Studies Of Ionic Liquids In Microwave-assisted Extraction Of Active Ingredients Of Chinese Herbal Drugs And Adsorption Removal

Ionic liquids are promising green solvents, with their unique high solubility, polar, non-volatile, non-oxidized, water and air stability on the characteristics of widespread attention in the chemical synthesis. They have been applied in many fields, such as electrochemistry, extraction, preparation of materials and can replaced volatile chemical solvents in many areas. Therefore, we envisioned that 1-butyl-3-methylimmidazolium chloride ([BMIM]Cl), one of the best ionic liquids in dissolving the cellulose, could be utilized as an solvent to dissolve the cellulose of Chinese herbal drug to increase the extraction efficiency.(1) In this paper, microwave-assisted extraction (MAE) using ionic liquid solution followed by gas chromatography (GC) with a flame ionization detection (FID) was developed for quantitative analysis of menthol in herba menthae samples. The experimental conditions were exactly investigated and the optimal experimental parameters were as follows: concentration of [BMIM]Cl (2.0 mol/L), soak time (60 min), extraction power (440 W), microwave time (10min) and solid-liquid ratio (1:15). Furthermore, the comparison of the proposed ILMAE approach with the conventional method was also studied to demonstrate the method feasibility. It is worth mentioning that the proposed approach could dramatically improve both the extraction efficiency of the menthol and the total extraction time.(2) Microwave-assisted extraction (MAE) using ionic liquid solution followed by HPLC with UV-vis was developed for quantitative analysis of paeonol in cortex moutan samples. The experimental conditions were exactly investigated and the optimal experimental parameters were as follows: concentration of [BMIM]Cl (1.0 mol/L), extraction power (33%), microwave time (6min) and solid-liquid ratio (1:20). The proposed method was applied to quantitative analysis of menthol in cortex moutan samples. In contrast with the conventional method, the ILMAE approach showed more effective, which could significantly improve both the extraction efficiency and the total extraction time.(3) Under static condition, ionic liquid [BMIM]Cl was treated by activated carbon ACG or ACP. Hence, experiments were examined carefully to study the adsorption effects of activated carbon for ionic liquid under different conditions, which included pH value, activated carbon dosage, oscillation time, temperature and concentration of ionic liquid. The results showed that the best conditions was as follows: the dosage of activated carbon (2.5 g/L), the pH value (6), the oscillation time (1 h), the temperature (40℃). Under the optimized reaction conditions, the best treatment effect of ionic liquid [BMIM]Cl was obtained, and the adsorption quantity of ACP reached 15.7 mg/g, while the adsorption quantity of ACG was 22.5 mg/g. Compared with these two kinds of activated carbon, the adsorption effect of ACG was better than that of ACP, which was equal to the results of XPS.