Preparation Of Porous Carbon Materials And Continuous Extraction And Purification Of Active Components In Licorice

In this paper,glycyrrhizic acid,licorice polysaccharides and total flavonoids in licorice were extracted continuously,and their purification processes were investigate d respectively;then,the licorice slag was used as raw material to prepare porous carbon electrode material,and its electrochemical performance was explored.So as to achieve the purpose of comprehensive utilization of licorice and increase its economic v alue.1.The optimal extraction and purification process conditions of glycyrrhizic acid from licorice were optimized through single factor and orthogonal experiments.Extraction process conditions:heat reflux extraction system,0.1%ammonia solution as a solvent,solid-liquid ratio 1:10,extraction temperature 85℃,time 3 h,and extraction twice,the highest yield of glycyrrhizic acid was 9.05%.Purification process conditions:acid precipitation process,concentration multiple 6,p H 1.5,sedimentation time 12 h.The content of crude glycyrrhizic acid was 54.18%,and the yield was 4.08%.2.The crude glycyrrhizic acid was used as the raw material to product the glycyrrhizic acid monopotassium salt,and the optimal process conditions for the reconstitution of the glycyrrhizic acid crude and the preparation of the glycyrrhizinate monopotassium salt were screened through single factor and orthogonal experiments.The reconstitution process conditions were:solid-liquid ratio 1:10,extraction time 3h,temperature 50℃,and extraction twice,the reconstitution rate of crude glycyrrhizic acid can reach 92.3%.The preparation process conditions of glycyrrhizinate monopotassium salt:p H 7.5,glacial acetic acid 1 times,95%ethanol 20 times,sedimentation time 12h,the highest yield of glycyrrhizic acid monopotassium salt was59.50%,and the content was 72.32%.3.Experimental studies had shown that when extracting glycyrrhizic acid,licorice polysaccharides was extracted together with glycyrrhizic acid.Therefore,the filtrate obtained in the purification process of glycyrrhizic acid in the first experiment was used as the raw material,and the optimal process conditions for the separation and purification of licorice polysaccharides were screened by single factor and orthogonal experiments.Extraction process conditions:adjust the p H of the glycyrrhizic acid filtrate to neutral,the extract was concentrated 10 times,80%ethanol,alcohol precipitation time 16 h,the yield of licorice polysaccharide was 4.11%,and the content was 31.10%.Purification process conditions:the process was the combination of trichloroacetic acid and Sevage,solid-liquid ratio 1:5,7%trichloroacetic acid,stirring time 0.5 h,filtering and alcohol precipitation,the obtained licorice polysaccharide was white,the content was 38.50%,and the yield was 89.00%.In the Sevage method,the amount of chloroform-n-butanol solution was 0.2 times of the original solution,shaking time 30 minutes,deproteinizing 4 times,filtering,alcohol precipitation and drying to obtain an average content of licorice polysaccharide of 46.90%,and a yield of 84.10%.4.Using licorice residue after extracting glycyrrhizic acid and licorice polysaccharides as raw materials,the optimal extraction and purification process conditions of total flavonoids in licorice residue were screened through single factor and orthogonal experiments.Extraction process conditions:heat reflux extraction system,solid-liquid ratio 1:8,extraction temperature 80℃,time 3 h,and extraction twice,the yield of total flavonoids in licorice was stable at 1.30%.Purification process conditions:ethyl acetate-water ultrasonic extraction purification process,solid-liquid ratio 1:10,extraction time 1 h,extraction three times,then,the total flavonoid content and yield were 42.20% and 70.4%,respectively.In addition,the flavonoids in the waste liquid were recovered,and the final total flavonoid content and yield were about 42.28%and 1.30%.5.A pilot test was carried out on the extraction and purification process of three active substances,each group used 6.4 kg licorice as the raw material,and the following results were obtained under the optimal process parameters:the crude glycyrrhizic acid yield and content were 4.16%and 53.20%,the glycyrrhizic acid monopotassium salt yield and content were 2.40%and 73.40%,the yield and content of licorice polysaccharides were stable at about 3.20%and 46.00%,the yield and content of licorice total flavonoids were about 1.28% and 43.60%.6.Porous carbon was prepared from licorice residue after extracting active molecules as electrode material.The process conditions were screened and the electrochemical properties of the material were characterized.The optimum conditions were:Pre-carbonization at 400℃for 2 h,KOH with a mass ratio of 1:1 was used as the activator and carbonized at 800℃for 2 h.Under this condition,the specific capacitance of the material is 322 F/g at 0.5 A/g,from 0.5A/g to 10 A/g,the capacitance retention rate was 73%,and after 5000 cycles of charging and discharging at 1 A/g,the cycle performance of porous carbon can still be maintained at 93%and the specific surface area reached 2103 m~2/g.