Comparative material balances around pretreatment technologies for the conversion of switchgrass to soluble sugars

Rebecca J. Garlock, Venkatesh Balan, Bruce E. Dale, V. Ramesh Pallapolu, Y. Y. Lee, Youngmi Kim, Nathan S. Mosier, Michael R. Ladisch, Mark T. Holtzapple, Matthew Falls, Rocio Sierra-Ramirez, Jian Shi, Mirvat A. Ebrik, Tim Redmond, Bin Yang, Charles E. Wyman, Bryon S. Donohoe, Todd B. Vinzant, Richard T. Elander, Bonnie HamesSteve Thomas, Ryan E. Warner

Research output: Contribution to journalArticlepeer-review

113 Scopus citations


For this project, six chemical pretreatments were compared for the Consortium for Applied Fundamentals and Innovation (CAFI): ammonia fiber expansion (AFEX), dilute sulfuric acid (DA), lime, liquid hot water (LHW), soaking in aqueous ammonia (SAA), and sulfur dioxide (SO 2). For each pretreatment, a material balance was analyzed around the pretreatment, optional post-washing step, and enzymatic hydrolysis of Dacotah switchgrass. All pretreatments+enzymatic hydrolysis solubilized over two-thirds of the available glucan and xylan. Lime, post-washed LHW, and SO 2 achieved >83% total glucose yields. Lime, post-washed AFEX, and DA achieved >83% total xylose yields. Alkaline pretreatments, except AFEX, solubilized the most lignin and a portion of the xylan as xylo-oligomers. As pretreatment pH decreased, total solubilized xylan and released monomeric xylose increased. Low temperature-long time or high temperature-short time pretreatments are necessary for high glucose release from late-harvest Dacotah switchgrass but high temperatures may cause xylose degradation.

Original languageEnglish
Pages (from-to)11063-11071
Number of pages9
JournalBioresource Technology
Issue number24
StatePublished - Dec 2011

Bibliographical note

Funding Information:
This research was funded under the Office of the Biomass Program of the United States Department of Energy (Contract: DE-FG36-07GO17102). We would like to acknowledge the many undergraduate and graduate students, post doctoral candidates, and technicians at their respective institutions for their vital role in obtaining and compiling this information.


  • Cellulosic ethanol
  • Enzymatic hydrolysis
  • Material balance
  • Pretreatment
  • Switchgrass

ASJC Scopus subject areas

  • Bioengineering
  • Environmental Engineering
  • Renewable Energy, Sustainability and the Environment
  • Waste Management and Disposal


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