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Title: Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining

Mechanical refining is a low-capital and well-established technology used in pulp and paper industry to improve fiber bonding for product strength. Refining can also be applied in a biorefinery context to overcome the recalcitrance of pretreated biomass by opening up the biomass structure and modifying substrate properties (e.g., morphology, particle size, porosity, crystallinity), which increases enzyme accessibility to substrate and improves carbohydrate conversion. Although several characterization methods have been used to identify the changes in substrate properties, there is no systematic approach to evaluate the extent of fiber cell wall disruption and what physical properties can explain the improvement in enzymatic digestibility when pretreated lignocellulosic biomass is mechanically refined. This is because the fiber cell wall is complex across multiple scales, including the molecular scale, nano- and meso-scale (microfibril), and microscale (tissue level). A combination of advanced characterization tools is used in this study to better understand the effect of mechanical refining on the meso-scale microfibril assembly and the relationship between those meso-scale modifications and enzymatic hydrolysis. Enzymatic conversion of autohydrolysis sugarcane bagasse was improved from 69.6 to 77.2% (11% relative increase) after applying mechanical refining and an increase in enzymatic digestibility is observed with an increase in refining intensity.more » Based on a combination of advanced characterizations employed in this study, it was found that the refining action caused fiber size reduction, internal delamination, and increase in pores and swellability. A higher level of delamination and higher increase in porosity, analyzed by TEM and DSC, were clearly demonstrated, which explain the faster digestibility rate during the first 72 h of enzymatic hydrolysis for disc-refined samples when compared to the PFI-refined samples. Additionally, an increased inter-fibrillar distance between cellulose microfibrils at the nano-meso-scale was also revealed by SFG analysis, while no evidence was found for a change in crystalline structure by XRD and solid-state NMR analysis.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [2] ;  [1] ;  [1] ; ORCiD logo [1]
  1. North Carolina State Univ., Raleigh, NC (United States)
  2. Pennsylvania State Univ., University Park, PA (United States)
  3. Brazilian Bioethanol Science and Technology Lab. (CTBE), Campinas, SP (Brazil)
  4. National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-2700-72807
Journal ID: ISSN 1754-6834
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 11; Journal Issue: 1; Journal ID: ISSN 1754-6834
Publisher:
BioMed Central
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; sugarcane bagasse; autohydrolysis pretreatment; mechanical refining; enzymatic hydrolysis; fiber morphology; fiber internal delamination; cellulose crystallinity; fiber porosity
OSTI Identifier:
1482793

de Assis, Tiago, Huang, Shixin, Driemeier, Carlos Eduardo, Donohoe, Bryon S., Kim, Chaehoon, Kim, Seong H., Gonzalez, Ronalds, Jameel, Hasan, and Park, Sunkyu. Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining. United States: N. p., Web. doi:10.1186/s13068-018-1289-3.
de Assis, Tiago, Huang, Shixin, Driemeier, Carlos Eduardo, Donohoe, Bryon S., Kim, Chaehoon, Kim, Seong H., Gonzalez, Ronalds, Jameel, Hasan, & Park, Sunkyu. Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining. United States. doi:10.1186/s13068-018-1289-3.
de Assis, Tiago, Huang, Shixin, Driemeier, Carlos Eduardo, Donohoe, Bryon S., Kim, Chaehoon, Kim, Seong H., Gonzalez, Ronalds, Jameel, Hasan, and Park, Sunkyu. 2018. "Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining". United States. doi:10.1186/s13068-018-1289-3. https://www.osti.gov/servlets/purl/1482793.
@article{osti_1482793,
title = {Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining},
author = {de Assis, Tiago and Huang, Shixin and Driemeier, Carlos Eduardo and Donohoe, Bryon S. and Kim, Chaehoon and Kim, Seong H. and Gonzalez, Ronalds and Jameel, Hasan and Park, Sunkyu},
abstractNote = {Mechanical refining is a low-capital and well-established technology used in pulp and paper industry to improve fiber bonding for product strength. Refining can also be applied in a biorefinery context to overcome the recalcitrance of pretreated biomass by opening up the biomass structure and modifying substrate properties (e.g., morphology, particle size, porosity, crystallinity), which increases enzyme accessibility to substrate and improves carbohydrate conversion. Although several characterization methods have been used to identify the changes in substrate properties, there is no systematic approach to evaluate the extent of fiber cell wall disruption and what physical properties can explain the improvement in enzymatic digestibility when pretreated lignocellulosic biomass is mechanically refined. This is because the fiber cell wall is complex across multiple scales, including the molecular scale, nano- and meso-scale (microfibril), and microscale (tissue level). A combination of advanced characterization tools is used in this study to better understand the effect of mechanical refining on the meso-scale microfibril assembly and the relationship between those meso-scale modifications and enzymatic hydrolysis. Enzymatic conversion of autohydrolysis sugarcane bagasse was improved from 69.6 to 77.2% (11% relative increase) after applying mechanical refining and an increase in enzymatic digestibility is observed with an increase in refining intensity. Based on a combination of advanced characterizations employed in this study, it was found that the refining action caused fiber size reduction, internal delamination, and increase in pores and swellability. A higher level of delamination and higher increase in porosity, analyzed by TEM and DSC, were clearly demonstrated, which explain the faster digestibility rate during the first 72 h of enzymatic hydrolysis for disc-refined samples when compared to the PFI-refined samples. Additionally, an increased inter-fibrillar distance between cellulose microfibrils at the nano-meso-scale was also revealed by SFG analysis, while no evidence was found for a change in crystalline structure by XRD and solid-state NMR analysis.},
doi = {10.1186/s13068-018-1289-3},
journal = {Biotechnology for Biofuels},
number = 1,
volume = 11,
place = {United States},
year = {2018},
month = {10}
}

Works referenced in this record:

Pretreatment technologies for an efficient bioethanol production process based on enzymatic hydrolysis: A review
journal, July 2010

Synthetic multi-component enzyme mixtures for deconstruction of lignocellulosic biomass
journal, December 2010