Studies Of Microwave-assisted Extraction Of Flavonoids In Radix Puerariae Using Ionic Liquids Solution And Purification Process

In recent years, green chemistry is getting more and moreattentions because of people’s environmental awareness. Ionic liquid,which is widely applied in electrochemistry, chemical synthesis andseparation process, is received significant attention as a potential greensolvent. Therefore, the active ingredients in Chinese herbal medicine areleached in this thesis by the solvent of the ionic liquid, and then theionic liquid will be recycled. The work is mainly divided into thefollowing three parts:（1）The ionic liquid solution of bromide1-butyl-3–methylimidazolium ([bmim]Br) is used as solvent, and the puerariageneral flavone is extracted by microwave-assisted. The processconditions are optimized by the single experiments and response surfaceexperiments, the results are as follow: solid-liquid ratio is1:20,extraction time is9min, extraction temperature is76℃, the power ofmicowave is500W, ionic liquid concentration is1.1mol/L. Theextraction rate of the pueraria general flavone is98.17%under theseconditions. Then in comparison with the typical ethanolmicrowave-assisted extraction, this new method is proved moreefficient.（2）As a kind of solvent, the ionic liquid has good abilities ofabsorption and heat conversion for microwave, so the The extractionrate of the pueraria general flavone is improved and the ionic liquid isquite suitable for the extraction solvent of MAE. However, theproblems follow as: the separation of the solvent and the target, and therecovery of the ionic liquid. In the coming part, the pueraria generalflavone left in the ionic liquid is extracted by the resin, so the solventand the target will separate, and the impurities are taken out at the sametime. Static adsorption and desorption for pueraria flavone by four kind of extraction resins (AB-8、S-8、HPD100、polyamide) is researched, andthe best one is S-8. As a carrier, the dynamic adsorption characteristicsof S-8macroporous resin are studied, the optimized adsorptionconditions are: at normal temperature, with flow rate of3BV/h,concentration of3.4mg/mL, the extracting solution is placed in thecolumns to make the resin adsorption saturation. Then the resin iswashed by deionized water until it’s colourless to take out of theimpurities, and the resin is desorbed by ethanol with concentration of70%and flow rate of9BV. At last, puerarin in the samples before andafter the S-8macroporous resin purification is compared by the HPLC,and the results show that: after the adsorption with macroporous resin,the puerarin is8.93%more than before, and separation of target andsolvent is completed.（3）At the end of this thesis, the recovery of the [bmim]Br isresearched, and under the optimized extraction and purificationconditions, the recovery ratio of the ionic liquid is78.9%, purity is87.6%. Then this recycled ionic liquid is used to extract pueraria generalflavone under the certain conditions. The extraction rate is98.02%andquite stable.