A comparative study of effect of polyol-based and acid-based deep eutectic solvents pretreatment of rice straw under autoclave conditions on cellulose enrichment and digestibility

Longinus Ifeanyi Igbojionu; Jinesh Cherukkattu Manayil; Alfred Fernandez-Castane

doi:10.1007/s13399-025-06896-9

A comparative study of effect of polyol-based and acid-based deep eutectic solvents pretreatment of rice straw under autoclave conditions on cellulose enrichment and digestibility

Longinus Ifeanyi Igbojionu
, Jinesh Cherukkattu Manayil
, Alfred Fernandez-Castane^*

^*Corresponding author for this work

Aston University

Research output: Contribution to journal › Article › peer-review

9 Citations (SciVal)

7 Downloads (Pure)

Abstract

Deep eutectic solvents (DESs) are attractive for lignocellulosic biomass deconstruction because of their easy synthesis, reusability, inexpensive nature, and eco-friendliness. Pretreatment of rice straw was carried out using three types of DES: choline chloride:glycerol (ChCl:Gly), choline chloride:ethylene glycol (ChCl:EG), and choline chloride:formic acid (ChCl:FA) at 120 °C, 1.5 bars in an autoclave for 1 h. Enzymatic digestibility of pretreated samples was assessed at 10% solids loading and 9.0 filter paper units g−1 cellulose of enzyme loading. A delignification efficiency of 51.6% was obtained with ChCl:FA compared to 30.4% and 36.1% obtained with ChCl:Gly and ChCl:EG respectively. The cellulose content of 58.4% was obtained from ChCl:FA pretreated samples compared to cellulose contents of < 48% from ChCl:Gly and ChCl:EG pretreated samples; cellulose content of pretreated and untreated samples correlated with their crystallinity indexes. The lowest hemicellulose content of 9.5% was obtained from the ChCl:FA pretreated sample, while ChCl:Gly and ChCl:EG were like the untreated (around 22%). As indicated by spectroscopic, microscopic, and thermogravimetric analysis, DES pretreatment caused alterations in chemical composition, structure, and surface morphology. ChCl:FA pretreated sample (Ac-PT4) was significantly hydrolysed, resulting in a glucose yield of 79.7% and a concentration of 45.56 gLl−1 after 72 h of hydrolysis. The glucose yield obtained from ChCl:Gly and ChCl:EG pretreated samples ranged from 32 to 36%, while the glucose concentrations ranged from 14 to 16 gL−1. Pretreatment using ChCl:FA effectively delignified rice straw and led to a threefold increase in enzymatic digestibility compared to untreated; hence, pretreatment using ChCl:FA could support a biorefinery concept.

Original language	English
Pages (from-to)	31107-31120
Number of pages	14
Journal	Biomass Conversion and Biorefinery
Volume	15
Issue number	24
Early online date	6 Sept 2025
DOIs	https://doi.org/10.1007/s13399-025-06896-9
Publication status	E-pub ahead of print - 6 Sept 2025

Bibliographical note

Copyright © The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

Funding

This study was financially supported by UK Research and Innovation — Horizon Europe guarantee funding (RC Grant reference: EP/Y010299/1).

Funders	Funder number
UK Research and Innovation	EP/Y010299/1
UK Research and Innovation

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy
SDG 13 Climate Action

Keywords

Cellulose enrichment
Crystallinity index
Deep eutectic solvents
Delignification
Enzymatic digestibility
Rice straw

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10.1007/s13399-025-06896-9Licence: CC BY 4.0

A comparative study of effect of polyol-based and acid-based deep eutectic solvents pretreatment of rice straw under autoclave conditions on cellulose enrichment and digestibility
Copyright © The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.
Final published version, 2.9 MBLicence: CC BY 4.0

Cite this

Igbojionu, L. I., Manayil, J. C., & Fernandez-Castane, A. (2025). A comparative study of effect of polyol-based and acid-based deep eutectic solvents pretreatment of rice straw under autoclave conditions on cellulose enrichment and digestibility. Biomass Conversion and Biorefinery, 15(24), 31107-31120. Advance online publication. https://doi.org/10.1007/s13399-025-06896-9

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A comparative study of effect of polyol-based and acid-based deep eutectic solvents pretreatment of rice straw under autoclave conditions on cellulose enrichment and digestibility. / Igbojionu, Longinus Ifeanyi; Manayil, Jinesh Cherukkattu ; Fernandez-Castane, Alfred.
In: Biomass Conversion and Biorefinery, Vol. 15, No. 24, 06.09.2025, p. 31107-31120.

Research output: Contribution to journal › Article › peer-review

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AU - Igbojionu, Longinus Ifeanyi

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AU - Fernandez-Castane, Alfred

N1 - Copyright © The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

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N2 - Deep eutectic solvents (DESs) are attractive for lignocellulosic biomass deconstruction because of their easy synthesis, reusability, inexpensive nature, and eco-friendliness. Pretreatment of rice straw was carried out using three types of DES: choline chloride:glycerol (ChCl:Gly), choline chloride:ethylene glycol (ChCl:EG), and choline chloride:formic acid (ChCl:FA) at 120 °C, 1.5 bars in an autoclave for 1 h. Enzymatic digestibility of pretreated samples was assessed at 10% solids loading and 9.0 filter paper units g−1 cellulose of enzyme loading. A delignification efficiency of 51.6% was obtained with ChCl:FA compared to 30.4% and 36.1% obtained with ChCl:Gly and ChCl:EG respectively. The cellulose content of 58.4% was obtained from ChCl:FA pretreated samples compared to cellulose contents of < 48% from ChCl:Gly and ChCl:EG pretreated samples; cellulose content of pretreated and untreated samples correlated with their crystallinity indexes. The lowest hemicellulose content of 9.5% was obtained from the ChCl:FA pretreated sample, while ChCl:Gly and ChCl:EG were like the untreated (around 22%). As indicated by spectroscopic, microscopic, and thermogravimetric analysis, DES pretreatment caused alterations in chemical composition, structure, and surface morphology. ChCl:FA pretreated sample (Ac-PT4) was significantly hydrolysed, resulting in a glucose yield of 79.7% and a concentration of 45.56 gLl−1 after 72 h of hydrolysis. The glucose yield obtained from ChCl:Gly and ChCl:EG pretreated samples ranged from 32 to 36%, while the glucose concentrations ranged from 14 to 16 gL−1. Pretreatment using ChCl:FA effectively delignified rice straw and led to a threefold increase in enzymatic digestibility compared to untreated; hence, pretreatment using ChCl:FA could support a biorefinery concept.

AB - Deep eutectic solvents (DESs) are attractive for lignocellulosic biomass deconstruction because of their easy synthesis, reusability, inexpensive nature, and eco-friendliness. Pretreatment of rice straw was carried out using three types of DES: choline chloride:glycerol (ChCl:Gly), choline chloride:ethylene glycol (ChCl:EG), and choline chloride:formic acid (ChCl:FA) at 120 °C, 1.5 bars in an autoclave for 1 h. Enzymatic digestibility of pretreated samples was assessed at 10% solids loading and 9.0 filter paper units g−1 cellulose of enzyme loading. A delignification efficiency of 51.6% was obtained with ChCl:FA compared to 30.4% and 36.1% obtained with ChCl:Gly and ChCl:EG respectively. The cellulose content of 58.4% was obtained from ChCl:FA pretreated samples compared to cellulose contents of < 48% from ChCl:Gly and ChCl:EG pretreated samples; cellulose content of pretreated and untreated samples correlated with their crystallinity indexes. The lowest hemicellulose content of 9.5% was obtained from the ChCl:FA pretreated sample, while ChCl:Gly and ChCl:EG were like the untreated (around 22%). As indicated by spectroscopic, microscopic, and thermogravimetric analysis, DES pretreatment caused alterations in chemical composition, structure, and surface morphology. ChCl:FA pretreated sample (Ac-PT4) was significantly hydrolysed, resulting in a glucose yield of 79.7% and a concentration of 45.56 gLl−1 after 72 h of hydrolysis. The glucose yield obtained from ChCl:Gly and ChCl:EG pretreated samples ranged from 32 to 36%, while the glucose concentrations ranged from 14 to 16 gL−1. Pretreatment using ChCl:FA effectively delignified rice straw and led to a threefold increase in enzymatic digestibility compared to untreated; hence, pretreatment using ChCl:FA could support a biorefinery concept.

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JF - Biomass Conversion and Biorefinery

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ER -

A comparative study of effect of polyol-based and acid-based deep eutectic solvents pretreatment of rice straw under autoclave conditions on cellulose enrichment and digestibility

Abstract

Bibliographical note

Funding

UN SDGs

Keywords

Access to Document

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