Study On Extraction And Purification Of Rutin From Quercus Leaves By Deep Eutectic Solvent

Quercus dentate Thumb is mainly distributed in Northern mountainous area of China,and has been applied in medical treatment,food packaging materials,disposable tableware and other fields.Quercus leaves contain many kinds of active substances,such as chlorogenic acid,flavonoids and so on.These active substances are widely used in anti-oxidation,antibacterial,anti-inflammatory and other medical fields.In addition to the conventional solvents such as water,ethanol,methanol,deep eutectic solvents(DES)have gradually emerged as a substitute for conventional extraction solvents.At present,there is no research on the extraction of Flavonoids from Quercus leaves by deep eutectic solvent.In this paper,the extraction of flavonoids(Rutin)from Quercus leaves by DES and its separation and purification process were studied,in order to provide theoretical reference for the further development of Quercus leaves resources.The main research contents and results are as follows:(1)The extraction experiment of flavonoids(Rutin)from Quercus leaves was carried out with DES.The effects of different DES systems,DES composition ratio,water content,extraction time,liquid-solid ratio,extraction temperature on the extraction of Rutin were discussed.Firstly,the optimum DES system was determined as choline chloride-acetic acid.Secondly,through single factor experiment,the optimum extraction conditions were determined as follows:the molar ratio of choline chloride and acetic acid was 1:3,the water content was 30%,the extraction temperature was 60℃,the liquid-solid ratio was 40:1 m L/g,and the reaction time was 90 min.(2)According to the principle of response surface methodology,the extraction conditions of Rutin were optimized.The optimization experiment was designed with the extraction amount of Rutin as response value,reaction temperature,liquid-solid ratio and reaction time as variables.The regression polynomial model of Rutin Extraction in DES system was:Y=55.34+2.66*A+3.73*B-0.017*C-0.13*AB+0.098A C-0.053BC-2.84A~2-3.45B~2-0.94C~2.The correlation coefficient R~2 of the model was0.9800,which indicated that the model could be used to analyze the extraction process of Rutin from DES.The optimum conditions were as follows:extraction temperature61℃,liquid-solid ratio 51 m L/g,extraction time 85 min,Rutin yield was 58.79 mg/g.(3)A kinetic model of Rutin extraction from Quercus leaves by DES was established.The results showed that Fick’s First Law could well be described the extraction process of Rutin from DES system.When the extraction temperature was313 K,328 K and 343 K,and the extraction time was 60 min,the extraction could be regarded as reaching equilibrium.The concentrations of Rutin in DES extraction solution were 3.71,3.90 and 4.12 mg/m L,respectively.The relationship diagram and regression equation between Rutin concentration and extraction time were obtained,which provided theoretical support for Rutin Extraction from Quercus leaves by DES system.The experimental activation energy Ea was 4048.65 J/mol.(4)The adsorption and separation of Rutin in crude extract by macroporous resin were studied.HPD-600 macroporous resin was selected from four different macroporous resins to adsorb Rutin in crude extract.The thermodynamics and kinetics of rutin adsorption on macroporous resin were studied.Langmuir model and quasi second order kinetic model was suitable for describing the adsorption process of Rutin on macroporous resin.It was found that the equilibrium adsorption capacity decreased with the increase of temperature,that was to say,high temperature was not conducive to the adsorption of Rutin by macroporous resin.In the dynamic adsorption experiment,the best experimental conditions were obtained as follows:the concentration of injection solution was 2 mg/m L,the flow rate was 1.5 m L/min,the injection volume was 20 m L,the adsorption capacity was 35.40 mg,the adsorption rate was 88.50%;the concentration of ethanol was 60%(V/V),the flow rate was 2 m L/min,the injection volume was 40 m L,the analytical amount was 27.83 mg,the analytical rate was 78.61%and the recovery was 69.57%.