Study On Extraction, Flocculation And Hydrolyzation Of Dioscin

Dioscorea zingiberens is also known as yellon ginger, which belongs to perennial dioscorea. It contains 5%-10% dioscin of the mass fraction. Diosgenin can be obtained by hydrolysis of dioscin under acidic conditions, which are the raw material and intermedium for synthesis the steroidal hormones. However,90% starch of the total raw material and part of the cellulose are also hydrolysised when dioscin is hydrolysised. On the one hand, this kind of usual hydrolysis leads to an addition of the dosage of acid; on the other hand, it leads the COD(chemical oxygen demand)and BOD(biochemical oxygen demand) values to increase in the wastewater. At the same time, it enhances the difficulty of the treatment of turmeric wastewater. Hence, it is significant to study on dioscin extraction and cleaning production of diosgenin.In this paper, the influence factors of dioscin extraction were researched employing the ultrasound-assisted extraction and surfactant solubilization technology; Meanwhile, the effect of different flocculants on enrichment ratio of dioscin are studied. The hydrolysis conditions of dioscin were researched via the hydrothermal method, which provided technical indicators for cleaning production of diosgenin. The main conclusions of the experiment are as follows:1. Results showed that lauryl sodium sulfate is the optimal surfactant and critical micelle concentration (cmc) is 3 cmc mol/L. The optimal conditions of dioscin extraction can be recommended as: soaking time,12 h; solid-liquid ratio,1:10; time for treatment of ultrasonic wave at frequency 25.98 kHz,30 min; and the extraction is to be operated for three times.2. Best flocculation conditions are as follows:Dosage of chitosan is 40% of the extraction liquid volume; system pH value,7; flocculation temperature,45?; flocculation time,5 h. When poly aluminum combines with chitosan, poly aluminum to chitosan ratio, 1:2; enrichment ratio is as high as 93.56%; Zeta potential,7.23 mV. When diatomite combines with chitosan, diatomite to chitosan ratio, 1:2; enrichment ratio is as high as 96.36%; zeta potential,10.8 mV.When adopted chitosan, poly aluminum and diatomite as three kinds of flocculants, the mixture ratio,1:1:1; enrichment rate is as high as 82.07%; Zeta potential,18.7 mV. The cost is lowest when chitosan, poly aluminum and diatomite are used as flocculants to compound, chitosan compounds with diatomite the cost comes second. While poly aluminum compounds with chitosan or single chitosan is used, the cost is the highest. Thus, the chitosan compounds with diatomite were deemed as an ideal composite flocculants under considering comprehensively the condition of the flocculation effect and the cost.3. The optimal conditions of dioscin hydrolysis can be recommended as:hydrolysis temperature,120?; solid to liquid ratio, 1:3 g/mL; time for hydrolysis of hydrothermal reaction at the temperature 120?,5h; extraction time,4 h. It can be found that the hydrothermal method will not damage to the character of diosgenin products, but also can decrease the concentration of hydrolysis acid, when samples were compared with standard samples via infrared chromatography.