The Research Of Glycyrrhizic Acid Production Wastewater By Membrane Treatment And Recovery Of Components

Glycyrrhiza is an important traditional Chinese hebal medicine,and its effective components have a wide range of biological activities.Glycyrrhizic acid is the main active ingredient.The wastewater of glycyrrhizic acid refers to the supernatant which is produced by a acid precipitate treatment in industrial glycyrrhizic acid production.It has been estimated that at least thousands of tons wastewater is produced each year in China,which are reported contains a large number of amino acid,sugar,flavones,glycyrrhizic acid and other substances.Most of the wastewater was discharged into rivers and reservoirs,which causes serious envirounmental pollution and waste.Nowadays,the comprehensive utilization of glycyrrhizic acid production wastewater has been attached great importance both for economical and environmental reasons.Therefore this paper selected glycyrrhizic acid production wastewater as experimental materials,and explored the best technology for various membrane process.Both analytical and preparative high performance liquid chromatography were applied to separation and identified the main chemical compositions in glycyrrhizic acid wastewater.The antioxidation activities and anti-bacterious activities of the main chemical components in wastewater were investigated.The results of this dissertation provide theoretical basis for the comprehensive utilization of glycyrrhizic acid production wastewater.1.The treatment technology of glycyrrhizic acid production wastewater is researched by multi-stage membrane in the paper.In order to implement clean glycyrrhizic acid production process,the optimization of process conditions of the glycyrrhizic acid production wastewater recycling is explored using membrane such as MF,UF,NF and RO.First of all,the main process parameters of the treatment of glycyrrhizic acid production wastewater were studied with single factor experiment.The optimal conditions were:the pressure is 0.20 Mpa at room temperature for 0.45 um MF;the pressure is 0.90 Mpa at room temperature for UF;the pressure is 1.80 Mpa at room temperature for NF.In the regeneration process of the membrane,alkaline washing is better than pure water cleaning.The experimental results show that:regeneration rate of membrane flux by using membrane alkaline cleaning were 96.7%(membrane microfiltration),95.0%(ultrafiltration),96.1%(nanofiltration)and 97.0%(reverse osmosis),respectively.Recovery extract is obtained with spray drying of the concentrate of MF,UF and NF.The waste water COD value is 11.28 mg/L after the RO treatment,which is far below the national discharge standard 50 mg/L,the electrical conductivity is 75.2 us/cm ≤ 2000 us/cm,which meet the national wastewater discharge standard.2.The separation and structural identification of major compounds of the recovery extract is studied in the paper.8 main compounds are separated from the recovery extract by using HPLC,pHPLC and circulating preparation chromatography method.The structures of the 8 main compounds are identified through UV,NMR and other means.8 compounds are:p-hydroxybenic acid,liquiritigenin-7,4’-diglucoside,liquiritigenin-apiosyl(1→2)glucoside,licuraside,isoliquiritin,liquiritigenin,isoliquiritigenin,formononetin.3.The quantitation of major compounds of the recovery extract is analysised in the thesis.The quantitative analysis of the main compounds of recovery extract has carried on using HPLC.The result shows that p-hydroxybenic acid is 8.26 μg/mg,liquiritigenin-7,4’-diglucoside is 101.11 μg/mg,liquiritigenin-apiosyl(1→2)glucoside is 72.89 μg/mg,licuraside is 22.49 μg/mg,isoliquiritin is 3.6 μg/mg,liquiritigenin is 13.26 μg/mg,isoliquiritigenin is 20.52 μg/mg,formononetin is 6.31 μg/mg.4.The activity of the main compounds in the recovery extract is explored in the thesis.The main compounds antioxidant activity and bacteriostasis from recovery extract have been studied.The result shows that with DPPH and ABTS as model compounds in vitro antioxidant,ABTS+ radical scavenging ability of licuraside(ICso is 18 μg/mL)is better than reference substance BHT under the same conditions,and isoliquiritoside,liquiritigenin,isoliquiritigenin and formononetin has good antioxidant activity;with S.aureus(ATCC 25923)and Escherichia coli(ATCC 25922)as model compounds in bacteriostasis research,MIC of licuraside were 31.25 μg/mL and 7.813 μg/mL,respectively,isoliquiritoside,liquiritigenin,isoliquiritigenin and formononetin known as good antibacterial activity.