Diosgenin Production Technology By Ferric Chloride Hydrolysis Of Dioscorea Composita Hemsl.in Biphasic Solution

Dioscorea composita Hemsl.has high diosgenin content,high starch content and high yield,and is an important raw material for diosgenin.Steroid hormone is the second largest class of drugs after antibiotics.Diosgenin is the basic raw material of steroid hormone drug intermediates,and is known as the“mother of hormones”and“medicine gold”.In this paper,the D.composita is prepared to produce diosgenin by using biphasic Fe Cl₃ hydrolysis to solve the problems of traditional production techniques,such as low yield of diosgenin,high acid consumption,serious environmental pollution,etc.Then the wastewater and residue are subjected to anaerobic fermentation treatment,which contributes to establish a technical plan for the clean production of diosgenin and realize the comprehensive utilization of the resources of D.composita.On the basis of the biphasic extraction technology of water/petroleum ether as the reaction solution,the D.composita was hydrolyzed by Fe Cl₃ to produce diosgenin.The concentration of Fe Cl₃ solution was 4.0 g/L,and the volume ratio of water/petroleum ether was 80/100 m L.The reaction was carried out at an extraction temperature of 160°C for 2.0 h,and the highest yield of diosgenin was 1.71%.However,the yield of diosgenin extracted by the biphasic Fe Cl₃ method was much lower than that of the traditional concentrated H₂SO₄ method.Therefore,the biphasic Fe Cl₃ extraction technology needs further study to improve the diosgenin yield.As a widely used extraction solvent for extracting natural products,ethanol is beneficial for extracting total saponins of D.composita.In the ternary biphasic system of ethanol/water/petroleum ether as the reaction solution,the saponins was hydrolyzed by using Fe Cl3 to produce diosgenin.Under the reaction conditions of a temperature of 150°C for 2 h,eventually the diosgenin yield was up to 3.02%with the ethanol/water/petroleum ether volume ratio of 15/16/20（v/v/v）.The diosgenin yield obtained by the new technology of ternary biphasic Fe Cl₃ hydrolysis was 16.60%higher than that of the conventional sulfuric acid method,79.76%higher than the biphasic Fe Cl₃ hydrolysis method without using ethanol,and 2.3 times more than the biphasic sulfuric acid hydrolysis method.Therefore,the ethanol extractant assisted ternary biphasic Fe Cl₃ hydrolysis technology significantly increases the diosgenin yield,shortens the extraction cycle,and greatly reduces the amount of acid consumed.More importantly,the risk of environmental pollution will be minimized greatly without the use of concentrated H₂SO₄.The starch residue and sugar-containing wastewater after extracting diosgenin were used as raw materials to investigate the biomethane potential of anaerobic fermentation.The inoculum activated sludge was mixed with starch residue and wastewater by VS or VS:COD with different proportions.After anaerobic fermentation,the maximum biogas production rate of starch residue and wastewater was 255.4 m L/g VS and 326.9 m L/g COD,respectively.The ammonia nitrogen value was below 1500 mg/L throughout the fermentation cycle and its p H change was within the normal range.In the wastewater fermentation,when the organic loadings VS:COD ratios were 2:1,1:1 and 1:2,the COD removal rates of the fermentation broths were 81.41%,91.11%and 87.46%,respectively.The highest COD removal efficiency was the fermentation group of VS:COD=1:1,which was consistent with the highest biogas production rate.Consequently,the co-production of diosgenin and biomethane by recycling the wastewater and waste residues from D.composita with Fe Cl₃-catalyzed hydrolysis in ternary biphasic solution had been demonstrated to be an effective utilization of D.composita resources and a full-scale comprehensive process for biorefinery.The technical advantages of combined diosgenin extraction and anaerobic fermentation achieve the objective:higher diosgenin yield and higher COD decomposition efficiency of wastewater which greatly reduces the risk of environmental pollution.Therefore,combining the extraction and fermentation processes to produce the diosgenin and biogas surpassed the shortcomings of the individual process,thus achieving the green sustainable development of the diosgenin industry.The established ternary biphasic Fe Cl₃-catalyzed hydrolysis technology was giving an alternative approach and idea to better utilize dioscorea resources and improving the biotransformation efficiency of biomass comprehensively.