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Cited by 1,557Biofuel production and bioconversionIonic liquids properties and applicationsCatalysis for Biomass Conversion

The DOI matches its Crossref record; 212 of the 214 references it cites were found in a registry or an index; none of the 154 sources its claims cite is checked for support yet.

Deconstruction of lignocellulosic biomass with ionic liquids

Open access
Brandt, Agnieszka, Gräsvik, John, Hallett, Jason P., Welton, Tom·2013·Green Chemistry
DOI 10.1039/c2gc36364j
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Abstract

This paper reviews the application of ionic liquids to the deconstruction and fractionation of lignocellulosic biomass, in a process step that is commonly called pretreatment. It is divided into four parts: the first gives background information on lignocellulosic biomass and ionic liquids; the second focuses on the solubility of lignocellulosic biomass (and the individual biopolymers within it) in ionic liquids; the third emphasises the deconstruction effects brought about by the use of ionic liquids as a solvent; the fourth part deals with practical considerations regarding the design of ionic liquid based deconstruction processes.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This review surveys ionic liquids for deconstruction and fractionation of lignocellulosic biomass, covering biomass composition, biopolymer solubility, deconstruction effects, and process design. It distinguishes Dissolution and Ionosolv approaches and highlights ionic liquid cost, stability, recycling, water sensitivity, and downstream inhibition as key challenges.

Key findings

  • Cellulose solubility in ionic liquids depends strongly on anion hydrogen-bond basicity; high Kamlet-Taft β (>0.8) is apparent, with [C₂C₁im][MeCO₂] dissolving up to 15 wt% Avicel cellulose at 110 °C, while long alkyl/glycol chains or protic cations reduce solubility.
  • Lignin solubility varies widely, from virtually insoluble to 30 wt%; e.g. [C₂C₁im][MeCO₂] dissolves 30 wt% Kraft lignin at 90 °C, [C₁C₁im][MeSO₄] and [C₄C₁im][MeSO₄] dissolve 26 wt% at 50 °C, and [C₄C₁im][PF₆] dissolves 0–1 wt%.
  • [C₂C₁im][MeCO₂] treatment removes 17–65% lignin and 0–83% hemicellulose depending on feedstock and conditions; softwood is generally less delignified. Saccharification yields after ionic liquid pretreatment vary, e.g. Miscanthus with [C₄C₁im][MeSO₃] gave 98% glucose, [C₄C₁im][HSO₄] 91%, and [C₂C₁im][MeCO₂] 73%; maple with [C₄C₁im][MeCO₂] gave 74% glucose.
  • Process challenges include ionic liquid thermal stability: T₀.₀₁/₁₀h for [C₄C₁im][MeCO₂] was measured as 102 °C, implying a maximum process temperature of ca. 90 °C, yet many biomass treatments run above this. Residual ionic liquid inhibits enzymes and yeast; adding 10% v/v ionic liquid decreased cellulase activity by 70–85%, and as little as 0.25% residual [C₂C₁im][MeCO₂] completely inhibited yeast growth and biofuel production.

Methods

  • Review article divided into four parts: background on lignocellulosic biomass and ionic liquids; solubility of lignocellulosic biomass and individual biopolymers in ionic liquids; deconstruction effects of ionic liquids as solvents; and practical considerations for ionic liquid based deconstruction processes.
  • Synthesizes literature and tabulates ionic liquid properties, cellulose/lignin/lignocellulose solubility, delignification and hemicellulose removal, saccharification yields, lignin recovery, and ionic liquid stability/recycling.
  • No new primary experimental data are presented except the authors report an unpublished T₀.₀₁/₁₀h measurement for [C₄C₁im][MeCO₂] as 102 °C.

Limitations

  • The paper does not state a formal limitations section; as a review, it notes that data variability and inconsistent protocols complicate quantitative comparison, e.g. cellulose solubility measurements were performed under different temperature, dissolution time, cellulose degree of polymerisation, moisture content, and ionic liquid purity.
  • Evident from the text: many cited studies are preliminary, especially ionic liquid recycling studies (often only 1–10 reuses), and the review identifies unresolved scale-up issues including ionic liquid cost, drying/reconcentration energy, water sensitivity, ionic liquid degradation, downstream inhibition, and the absence of commercialised ionic liquid deconstruction processes.
  • Evident from the text: the review relies on literature with limited feedstock and ionic liquid coverage; for example, lignin solubility studies are essentially all with imidazolium ionic liquids, and experimental validation of the relative importance of the imidazolium cation for lignin solubilisation is still missing.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1039/c2gc36364j

Cites

212 of 212 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 154 cited sources checked · 0 supported · 0 flagged

Show all 125 claims

  • It may state two separate claims as one. 67
  • Probably not a substantial claim. 54
  • The quote only partly states this claim. 1
103 of 103

  • The paper relies on this without support.

    Lignocellulose is a composite material with cellulose, hemicellulose and lignin making up ca.90% of dry matter.

    “It is a composite material, with three biopolymers, cellulose, hemicellulose and lignin, making up ca.90% of the dry matter.”

  • The paper relies on this without support.

    Lignocellulose contains up to 60-70 wt% sugars/carbohydrates but is not utilised for food production.

    “It contains up to 60-70 wt% sugars/carbohydrates but is not utilised for food production.”

  • The paper relies on this without support.

    Hemicellulose and lignin are covalently cross-linked in lignocellulose.

    “Hemicellulose and lignin are not only entangled, but also covalently cross-linked.”

  • The paper relies on this without support.

    High hydrogen bond basicity is associated with reduced ionic liquid stability.

    “as it has been shown that high hydrogen bond basicity is associated with reduced ionic liquid stability.”

  • The paper relies on this without support.

    Water is essential for stabilising the organic hydroxide salt, which would decompose upon drying.

    “as the water is essential for stabilising the organic hydroxide salt, which would decompose upon drying.”

  • The paper relies on this without support.

    The hemicellulose component in lignocellulosic biomass is 25-30% and large enough to be of significant economic value.

    “The hemicellulose component in lignocellulosic biomass (25-30%) is large enough to be of significant economic value.”

  • The paper relies on this without support.

    Currently most important fermentative organisms (e.g. yeast) are not yet able to utilise all hemicellulose sugars.

    “Although currently most important fermentative organisms (e.g.yeast) are not yet able to utilise all hemicellulose sugars, this is likely to change in the near future by introduction of genetically engineered strains, 161 therefore high recovery of hemicellulose sugars is also desirable.”

  • The paper relies on this without support.

    Raw biomass typically contains about 50% water and even thoroughly air-dried biomass typically contains around 5-10 wt% residual moisture.

    “Raw biomass is wet, typically containing 50% water and even thoroughly airdried biomass typically contains around 5-10 wt% residual moisture.”

  • The paper relies on this without support.

    Ionic liquids are the most expensive solvents currently under investigation for lignocellulose deconstruction.

    “Ionic liquids are the most expensive solvents that are currently under investigation for lignocellulose deconstruction.”

  • The paper relies on this without support.

    Acetate is a metabolic inhibitor of most yeast systems.

    “Acetate is a proven metabolic inhibitor of most yeast systems.”

  • The paper relies on this without support.

    The majority of biomass deconstruction experiments using [C2C1im][MeCO2] and [C4C1im][MeCO2] have been performed at temperatures greatly in excess of 90 °C.

    “It is important to note that the majority of biomass deconstruction experiments using these ionic liquids have been performed at temperatures greatly in excess of this limit.”

  • The paper relies on this without support.

    The 3,5-dinitrosalicylic acid (DNS) assay is not specific for glucose nor for monomers.

    “Studies using 3,5-dinitrosalicylic acid (DNS) were not considered for this table, as this assay is not specific for glucose nor for monomers”
12 of 12

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Reported lignin-removal range omits a table value

    Minor

    The text says lignin removal with [C 2 C 1 im][MeCO 2 ] reached at most 65%, but Table 5 reports 69% for switchgrass.

  • Miscanthus precipitate yield conflicts with Table 8

    Minor

    The text reports a precipitate yield over 60% of the original lignin content for [C 4 C 1 im][HSO 4 ] treatment of Miscanthus, whereas Table 8 lists 47% for that ionic liquid and feedstock.

2 of 2

Citations

Cites

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Show all 214 references

2 of the 214 references couldn’t be matched to a known paper.

Research works printed but not linked: 7

  1. Meng, 2012, e-Polymers, 028, 1
  2. King, 2011, Angew. Chem., Int. Ed., 50, 6301, 10.1002/anie.201100274 · DOI
  3. Gericke, 2011, Macromol. Mater. Eng., 296, 483, 10.1002/mame.201000330 · DOI
  4. Padmanabhan, 2011, Fluid Phase Equilib., 309, 89, 10.1016/j.fluid.2011.06.034 · DOI
  5. Padmanabhan, 2011, Fluid Phase Equilib., 309, 89, 10.1016/j.fluid.2011.06.034 · DOI
  6. McDonough, 1993, Tappi J., 186
  7. Mäki-Arvela, 2012, Int. J. Chem. Eng., 674761

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Metadata

Authors
Brandt, A., Gräsvik, J., Hallett, J. P., & Welton, T.
Affiliations
  • Umeå University (SE)
  • Imperial College London (GB)
Corresponding author
Welton, Tom
ORCID
Venue
Green Chemistry
Publisher
Royal Society of Chemistry (RSC)
Published
2013
Volume
15
Issue
3
Pages
550
ISSN
  • 1463-9262 (ISSN-L)
  • 1463-9270
DOI
10.1039/c2gc36364j
OpenAlex
W2166219224
Semantic Scholar
3bb1c838477a538886acfa02e851d8079e8c1051
Cited by
1,557
References
214
Citations by year
2026: 61 · 2025: 92 · 2024: 81 · 2023: 101 · 2022: 115 · 2021: 159 · 2020: 154 · 2019: 141 · 2018: 130 · 2017: 164 · 2016: 130 · 2015: 113 · 2014: 85 · 2013: 30
FWCI
41.71
Type
journal article
Language
en
Open access
Locations
Green Chemistry (publishedVersion)
Funders
Engineering and Physical Sciences Research Council (EP/K014676/1)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Biofuel production and bioconversion
  • Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Ionic liquids properties and applications
  • Physical Sciences › Chemical Engineering › Catalysis › Catalysis for Biomass Conversion
Keywords
ionic liquids, lignocellulosic biomass, biomass pretreatment, biomass deconstruction, biomass fractionation, process design

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