| Imidazolium-based ionic liquid is a designable and green solvent with a low vapor pressure,strong solubility and environmental friendly.In our thesis,the Ionic liquid was combined with microwave-assisted extraction method to extract lignan from S.chinens S.fruit,isofraxidin from A.senticosus root,hydroxytyrosol from S.oblata stem.Single factor method was used to optimize the extraction process,and the dispersion state of ionic liquids in water and the hydrolysis mechanism of active material derivatives are discussed.Besides,the extraction effects of different extraction methods were compared and the SEM and FTIR of the residue after ionic liquid microwave-assisted treatment were used to explain decreasing"biomass recalcitrance effect".The research in the thesis were included:(1)Ionic liquid microwave-assisted was used to extract lignans and their ester derivatives from S.chinensis fruit,and hydrolyze lignans derivatives to free-state lignans,which achieve significant increment of free-state lignin.The dispersion state of the ionic liquid in water were detected by infrared and Raman,water can dilute ionic liquid solution,so that the dispersion state of the ionic liquid in the solution is controllable,and the ionic liquid with high water content won’t form cluster,which is beneficial to the extraction process.The optimal extraction conditions were:600 W microwave power;12 min microwave time;0.2 g[C4mim]Ac catalyst,the extraction rate of total lignans was 3.0 mg/g.Compared with different extraction methods,ionic liquid microwave-assisted method has the best extraction effect,the highest extraction rate and spend the shortest time.(2)The extraction process of isofraxidin from A.senticosus root by ionic liquid microwave-assisted method was established.By measuring the acidity of different ionic liquids and its hydrolysis effect on isofraxidin,[C4mim]HSO4 has the strongest acidity and the best hydrolysis effect.The dispersion state of[C4mim]HSO4 in water was detected by infrared and Raman,low concentration ionic liquid in water is ion-pair structure,and has low viscosity and high permeability,which is beneficial to the extraction process.The optimal conditions were:adding 2.0 g[C4mim]HSO4 and heating at 400 W microwave power for 20 min,the extraction rate of isofraxidin was 57 μg/g.By comparing the extraction efficiency of different extraction methods,the ionic liquid microwave-assisted method is a simple and efficient method for extracting A.senticosus isofraxidin.(3)In this experiment,the ionic liquid microwave-assisted was used to extract hydroxytyrosol from S.oblata stem,which realize one step to extract hydroxytyrosol and hydrolyze oleuropein into hydroxytyrosol.The anion and cation composition of ionic liquid and its concentration,microwave power and time were screened by single factor method.The optimal conditions were as follows:0.3 g[C4mim]Ac was added and heated at 800 W microwave power for 4 min.The ionic liquid microwave-assisted method is compared with the ionic liquid heating reflux method and the ethanol solution microwave-assisted method,ionic liquid microwave-assisted method not only saves the extraction time,but also has the best extraction effect.(4)S.chinensis fruit,Asenticosus root and S.oblata stem residue were analyzed by SEM and FTIR.SEM showed that the plant cells residue extracted by ionic liquid microwave-assisted method was obviously atrophy and broken,and the surface was rough and damaged.FTIR further proves that ionic liquid microwave assisted-method can effectively dissolve cell wall lignocellulose,destroy cell wall structure,decrease "biomass recalcitrance effect",and achieve efficient extraction of active substances. |
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