University of Oulu

Suopajärvi, T., Ricci, P., Karvonen, V., Ottolina, G., & Liimatainen, H. (2020). Acidic and alkaline deep eutectic solvents in delignification and nanofibrillation of corn stalk, wheat straw, and rapeseed stem residues. Industrial Crops and Products, 145, 111956.

Acidic and alkaline deep eutectic solvents in delignification and nanofibrillation of corn stalk, wheat straw, and rapeseed stem residues

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Author: Suopajärvi, Terhi1; Ricci, Pierfrancesco2; Karvonen, Ville1;
Organizations: 1Fiber and Particle Engineering Research Unit, University of Oulu, P.O. Box 4300, FI-90014, Oulu, Finland
2Institute of Chemistry of Molecular Recognition National Research Council, Via Mario Bianco 9, 20131, Milano, Italy
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.3 MB)
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Language: English
Published: Elsevier, 2020
Publish Date: 2020-04-03


In this work, six different deep eutectic solvent (DES) treatments—five acidic (natural organic acid–choline chloride) and one alkaline (K₂CO₃–glycerol)—were used and compared in delignification and nanofibrillation of agricultural by-products from wheat straw, corn stalk, and rapeseed stem. The DES treatments were performed at 100 °C for 8 h, at 100 °C for 16 h, and at 80 °C for 24 h. The yield of cellulose and lignin fractions was obtained gravimetrically, and a more detailed composition of fractions was obtained for the 16 h treatment. All the samples were further nanofibrillated, and the properties of nanocelluloses and their nanopapers were measured. Acidic lactic acid–choline chloride and alkaline K₂CO₃–glycerol DESs resulted in the highest delignification yields (11.8–5.7 wt-%), nanocellulose viscosity (1360–555 Pa s), and crystallinity index (54–38 %), but the strength properties of nanopapers from alkaline DES treatment (170–132 MPa) were better compared to acidic DESs (132–24 MPa). A plausible explanation for this difference may be that the alkaline DES also dissolved waxes and proteins, which can mitigate the adhesion and network formation between the nanofibers. It was also observed that the separated lignin fractions from acidic and alkaline DES treatments had different characteristics as determined by FTIR.

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Series: Industrial crops and products
ISSN: 0926-6690
ISSN-E: 1872-633X
ISSN-L: 0926-6690
Volume: 145
Article number: 111956
DOI: 10.1016/j.indcrop.2019.111956
Type of Publication: A1 Journal article – refereed
Field of Science: 215 Chemical engineering
221 Nanotechnology
Funding: The authors acknowledge the financial support of the ERANet-LAC and Academy of Finland, project: Towards a novel and sustainable biorefinery concept based on green technologies for main commercial grain crop residues (BIOCODE) (No. 311974).
Academy of Finland Grant Number: 311974
Detailed Information: 311974 (Academy of Finland Funding decision)
Copyright information: © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (