Article

Applied Biochemistry and Biotechnology

, Volume 169, Issue 4, pp 1069-1087

Two-Stage Acidic–Alkaline Hydrothermal Pretreatment of Lignocellulose for the High Recovery of Cellulose and Hemicellulose Sugars

  • Bin GuoAffiliated withDept. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign
  • , Yuanhui ZhangAffiliated withDept. of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Agricultural and Engineering Science Building
  • , Guo YuAffiliated withDept. of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Agricultural and Engineering Science Building
  • , Won-Heong LeeAffiliated withDept. of Food Science and Human Nutrition, Institute for Genomic Biology, University of Illinois at Urbana-Champaign
  • , Yong-Su JinAffiliated withDept. of Food Science and Human Nutrition, Institute for Genomic Biology, University of Illinois at Urbana-Champaign
  • , Eberhard MorgenrothAffiliated withDept. of Civil and Environmental Engineering, University of Illinois at Urbana-ChampaignETH Zurich, Institute of Environmental EngineeringEawag Swiss Federal Institute of Aquatic Science and Technology Email author 

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Abstract

The focus of this work was to develop a combined acid and alkaline hydrothermal pretreatment of lignocellulose that ensures high recovery of both hexose and pentose. Dilute sulfuric acid and lime pretreatments were employed sequentially. Process performance was optimized in terms of catalyst concentration, retention time, and temperature using response surface methodology. Medium operational conditions in the acid stage and harsh conditions in the alkaline stage were desirable with optimal performance at 0.73 wt% H2SO4, 150 °C, 6.1 min in the first stage, and 0.024 g lime/g biomass, 202 °C, 30 min in the second stage. In comparison to single-stage pretreatments with high recovery of either glucose or xylose, two-stage process showed great promises with >80 % glucose and >70 % xylose recovery. In addition, the method greatly improved ethanol fermentation with yields up to 0.145 g/g Miscanthus, due to significantly reduced formation of inhibitory by-products such as weak acids, furans, and phenols. Supplementing biomimetic acids would further increase glucose yield by up to 15 % and xylose yield by 25 %.

Keywords

Two-stage acidic–alkaline pretreatment Miscanthus Combined acid hydrolysis Response surface methodology Lignocellulose