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Title: Effects of organosolv and ammonia pretreatments on lignin properties and its inhibition for enzymatic hydrolysis

Lignin offers structural support and protection for plant cell walls; but, it also contributes to biomass recalcitrance and the costs of biofuel production via the biological pathway. Organosolv and ammonia pretreatments have been developed to reduce biomass recalcitrance and improve sugar release performance during enzymatic hydrolysis. It is believed that lignin properties are related to its inhibition on enzymatic hydrolysis; therefore, understanding the characteristics of lignin is a key for effective biomass conversion to biofuels. In this study, an organosolv pretreatment using 60% ethanol with 1.25% H 2SO 4 significantly deconstructed poplar lignin and reduced its molecular weights due to the cleavage of lignin inter-unit linkages. The organosolv pretreatment increased the contents of phenolic OH units and the lignin residue showed a high cellulase maximum adsorption capacity. Ammonia pretreatment with 5% ammonium hydroxide was not as effective as organosolv pretreatment on lignin deconstruction. Organosolv lignin residue had lower lignin S/G ratio than the untreated one. Furthermore, when compared to the organosolv lignin residue and untreated lignin, ammonia lignin residue had a higher cellulase adsorption affinity. In addition, the effects of lignin on cellulose hydrolysis was investigated and the results suggested that the presence of lignin with cellulose substrates reduced cellulosemore » hydrolysis, and its inhibitory effect was primarily determined by the lignin properties after each pretreatment. The organosolv pretreatment resulted in a slightly lower cellulase binding strength (249.7 mL g -1) on poplar lignin than that on untreated samples (261.1 mL g -1), while ammonia lignin residue showed a higher cellulase binding strength (402.8 mL g -1) and had more significant inhibition effect on cellulose hydrolysis. Our results demonstrated that the binding strength significantly affected the lignin-derived inhibition on enzymatic hydrolysis of cellulose in the cellulose-lignin mixtures.« less
Authors:
 [1] ;  [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center and Biosciences Division and UT-ORNL Joint Inst. for Biological Science
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering and Center for Renewable Carbon
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center and Biosciences Division
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center and Biosciences Division and UT-ORNL Joint Inst. for Biological Science; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering and Center for Renewable Carbon
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Green Chemistry
Additional Journal Information:
Journal Volume: 19; Journal Issue: 8; Journal ID: ISSN 1463-9262
Publisher:
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Joint Institute for Biological Sciences (JIBS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1352795