Switch grass was developed as a pioneer energy crop in USA with great industrial prospect. It contains about 60% sugars and 18% lignin. The purpose of this research is to find pretreatment process to fractionate cellu...Switch grass was developed as a pioneer energy crop in USA with great industrial prospect. It contains about 60% sugars and 18% lignin. The purpose of this research is to find pretreatment process to fractionate cellulose, hemicellulose and lignin from switch grass to obtain much more useful chemicals and enhance the residue solid to be hydrolyzed by enzymes. The six different pretreatment methods were studied, such as hot water pretreatment （HWP） alone, dilute acid pretreatment （DAP）, ammonia pretreatment （AP）, lime pretreatment （LP）, organosolv water / ehanol pretreatment （OWEP）, and organosolv water / acetone pretreatment （OWAP）. It was the best method combining DAP with OWEP because the hemicellulose sugars were recovered in the first residual liquid while a varied amount of cellulose was retained in the residual solid and the lignin fraction was obtained by simply adjusting the pH from the second liquid. The result shows the optimal two-stage process consisted of the first stage DAP at 428 K for 7 min with 0.8% sulfuric acid, resulting in 79.82% glucose recovery yield and 98.74% xylose removal and the second stage OWEP at 468K for 20 min in 45% （v / v） ethanol with 0.4% NaOH, resulting in 62% total glucose yield 99% xylose and 80% lignin removal. After enzymatic hydrolysis, the glucose yield was up to 92.6%, compared with 16% yield from untreated switch grass. Scanning electron microscopy （SEM） highlighted the differences in switch grass structure from the various pretreatment methods during biomass fractionation.展开更多
In this study,modified clean fractionation process was optimized for prairie cordgrass,with usage of alternative organic constituent-ethyl acetate.Other constituents of the solvent mixture included ethanol and water.C...In this study,modified clean fractionation process was optimized for prairie cordgrass,with usage of alternative organic constituent-ethyl acetate.Other constituents of the solvent mixture included ethanol and water.Clean fractionation solvent was used in different proportions of the constituents.Process efficiency was determined by lignin recovery,solvent composition,as well as time and temperature applied to each sequential process.Glucose yield during enzymatic hydrolysis and overall pretreatment were calculated.Optimal conditions(125℃,37 min,with the solvent composition of ester:ethanol:water=32.5:22.5:45)yielded a 20%lignin recovery,38%glucose yield during enzymatic hydrolysis and 26%xylose recovery in aqueous fraction.展开更多
基金Acknowledgments This research was supported by Hubei Provincal Department of Education （No. CXY2009B2008）, Angel Yeast Co.Ltd （SDH200800230）, the Science Foundation of Yichang City （No. A2007103-1）, the Alan G. MacDiarmid Institute of Renewable Energy, Yichang, China and the USDA Western Regional Research Center （WRRC）. The authors thank WRRC Center Director James N. Seiber, Artur, Klamczynski and Charles Lee for the thoughtful discussions and technical insights, and Miss Tina William for the SEM imagines.
文摘Switch grass was developed as a pioneer energy crop in USA with great industrial prospect. It contains about 60% sugars and 18% lignin. The purpose of this research is to find pretreatment process to fractionate cellulose, hemicellulose and lignin from switch grass to obtain much more useful chemicals and enhance the residue solid to be hydrolyzed by enzymes. The six different pretreatment methods were studied, such as hot water pretreatment （HWP） alone, dilute acid pretreatment （DAP）, ammonia pretreatment （AP）, lime pretreatment （LP）, organosolv water / ehanol pretreatment （OWEP）, and organosolv water / acetone pretreatment （OWAP）. It was the best method combining DAP with OWEP because the hemicellulose sugars were recovered in the first residual liquid while a varied amount of cellulose was retained in the residual solid and the lignin fraction was obtained by simply adjusting the pH from the second liquid. The result shows the optimal two-stage process consisted of the first stage DAP at 428 K for 7 min with 0.8% sulfuric acid, resulting in 79.82% glucose recovery yield and 98.74% xylose removal and the second stage OWEP at 468K for 20 min in 45% （v / v） ethanol with 0.4% NaOH, resulting in 62% total glucose yield 99% xylose and 80% lignin removal. After enzymatic hydrolysis, the glucose yield was up to 92.6%, compared with 16% yield from untreated switch grass. Scanning electron microscopy （SEM） highlighted the differences in switch grass structure from the various pretreatment methods during biomass fractionation.
基金This work was supported by funding from the South Dakota Center for Bioprocessing Research and Development,Sun Grant Initiative and SDSU Agricultural Experiment Station.
文摘In this study,modified clean fractionation process was optimized for prairie cordgrass,with usage of alternative organic constituent-ethyl acetate.Other constituents of the solvent mixture included ethanol and water.Clean fractionation solvent was used in different proportions of the constituents.Process efficiency was determined by lignin recovery,solvent composition,as well as time and temperature applied to each sequential process.Glucose yield during enzymatic hydrolysis and overall pretreatment were calculated.Optimal conditions(125℃,37 min,with the solvent composition of ester:ethanol:water=32.5:22.5:45)yielded a 20%lignin recovery,38%glucose yield during enzymatic hydrolysis and 26%xylose recovery in aqueous fraction.
