One-Pot Degradation And Ethanol Production Of Dioscorea Zingiberensis C.H.Wright

Dioscorea zingiberensis C.H.Wright(DZW)residues was produced after extracted diosgenin from the medicinal plant DZW.It contains high level of starch and cellulose and low lignin,so it great potential to convert into biomass ethanol.In this study,the “one-pot” method of pretreatment and hydrolysis was applied on DZW residues degradation and ethanol conversion to utilize it.Three reagents including sulfuric acid,citric acid and sodium hydroxide were used to pretreat DZW residues.And sulfuric acid showed the best hydrolysis effect due to its degradation of starch.The total enzymatic hydrolysis efficiency and cellulose conversion rate after sulfuric acid pretreatment were 72.73% and 81.93%,respectively.The “one-pot” was then applied on DZW residues,in which the pretreatment and enzymatic hydrolysis were carried out in one pot without washing step.The highest total fermentable sugar concentration and yield were 62.157 g/L and 0.743 g/g respectively,and the cellulose conversion rate was 62.55%.The conditions of sulfuric acid pretreatment were optimized by single factor experiment and orthogonal experiment.The optimized conditions were pretreating DZW residues with 2% sulfuric acid concentration at 121 ?C for 80 min.Under these conditions,the DZW residues treated with “one-pot” method could obtained the highest total fermentable sugar concentration and yield of 67.724 g/L and 0.813 g/g respectively,while the cellulose conversion rate was 72.22%.The pretreating temperature demonstrated the maximal impact on total fermentable sugar yield,while the pretreating time demonstrated the minimal impact.The DZW residues was directly subjected to in-situ simultaneous saccharification and ethanol fermentation after the pretreatment and enzyme hydrolysis using “one-pot” method.The highest ethanol concentration and yield were 35.728 g/L and 357.28 g/kg respectively in the group without adding nitrogen source.It was 23.35 times that of the untreated DZW residues and was also significantly higher than that of group with adding nitrogen source.In this study,the "one-pot" method was applied to DZW conversion for the first time.This was an economical way to solve the environmental pollution of DZW and make full use of it.