Study On Extraction And Decolorization Of Flavonoids From Sea Buckthorn Leaves

Sea buckthorn（Hippophae rhamnoides L.,Elaeagnaceae）is a thorny nitrogen fixing deciduous shrub.As a dioecious plant,it has strong adaptability to the ecological environment,and has good drought and wind resistance.It is widely used in soil and water conservation and desert greening.Sea buckthorn leaves contain a lot of flavonoids,which are natural active substances with multiple physiological functions and have high development and application value.Xinjiang is rich in sea buckthorn resources,but the sea buckthorn leaves rich in flavonoids are often treated as waste,resulting in a serious waste of resources.In addition,during the extraction process,the chromatography column was polluted by the presence of a large amount of pigment in the sea buckthorn leaf,thus reducing its use efficiency Based on this background,in order to improve the comprehensive utilization of sea buckthorn resources in Xinjiang,this topic uses local sea buckthorn leaves as raw materials to study the extraction and decolorization of sea buckthorn leaves,aiming to provide reliable data for the industrial production of sea buckthorn leaves in Xinjiang.The main research results as follows.（1）The analysis of flavonoids extraction kinetic model is very important for industrial application.In this work,a second-order kinetic model was used to fit the conventional extraction kinetics of total flavonoids from sea buckthorn leaves under the conditions of different particle size,liquid to material ratio,extraction temperature and ethanol concentration.The optimum conditions were obtained:the particle size was 40-60 mesh,the ratio of liquid to material was 60:1（m L/g）,the concentration of ethanol was 75%,the extraction temperature was 65℃,and the highest flavonoid content was 8.77 mg/g in 100 minutes.Taking the extraction temperature as the operating parameter,the comparison with the first order dynamic model shows that the second order dynamic model has smaller average relative percentage deviation and higher linear correlation coefficient,so the second order dynamic model is superior to the first order dynamic model.（2）The effects of five extraction parameters,such as high shear speed,extraction time,extraction temperature,liquid-solid ratio and ethanol concentration,were studied by single factor experiment.Response surface methodology（RSM）was used to optimize the conditions（ethanol concentration,extraction time,liquid-solid ratio and extraction temperature）that significantly affected the content of flavonoids.The optimum conditions were as follows:ethanol concentration 63%,extraction temperature75℃,liquid-solid ratio 66:1（m L/g）,extraction time 7.5 min.Under these conditions,the highest flavonoid content was 47.82±0.52 mg/g.Secondly,the kinetics and thermodynamics of the extraction process were studied on this basis.The results showed that the extraction process of high shear homogenization extraction（HSHE）was in line with the second-order kinetic equation.The thermodynamic data showed that the extraction process was spontaneous,endothermic and entropy increased,and HSHE could effectively reduce the apparent activation energy.Finally,compared with conventional solvent extraction（CSE）and ultrasonic assisted extraction（UAE）,HSHE was the best.（3）Decolorization of Sea buckthorn Leaf Extract（SBLE）by magnetic multi walled carbon nanotubes:Three kinds of multi walled carbon nanotubes（MWCNTs）with different content of MnFe₂O₄were synthesized.The results showed that the comprehensive performance of MWCNTs was the best when the amount of MnFe₂O₄was 50%.Then the decolorization process of 1-1MWCNT was further optimized.The optimal decolorization conditions were obtained as follows:decolorization temperature 60℃,decolorization time 30 min,and the amount of MnFe₂O₄@MWCNT 1.0%.Under these conditions,Kc value is 1.49±0.47,Dr is（53.05±0.84）%,and Rr is（64.50±0.31）%.On this basis,the adsorption kinetics and thermodynamic performance of MnFe₂O₄@MWCNT on SBLE pigment were studied,and the adsorption mechanism of MnFe₂O₄@MWCNT on SBLE pigment was analyzed.The results showed that the adsorption of MnFe₂O₄@MWCNT on SBLE pigment conformed to Langmuir model,and the adsorption of MnFe₂O₄@MWCNT on SBLE pigment conformed to pseudo second order kinetic model.