Mechano-chemical, high-consistency activation of kraft pulp in deep eutectic solvent of choline chloride and urea
Vehviläinen, Marianna; Suopajärvi, Terhi; Sirviö, Juho Antti; Spönla, Elisa; Ahokas, Pauliina; Rahikainen, Jenni; Minkkinen, Hannu; Liimatainen, Henrikki (2024-08-16)
Springer
16.08.2024
Vehviläinen, M., Suopajärvi, T., Sirviö, J.A. et al. Mechano-chemical, high-consistency activation of kraft pulp in deep eutectic solvent of choline chloride and urea. Cellulose 31, 8295–8310 (2024). https://doi.org/10.1007/s10570-024-06116-z
https://creativecommons.org/licenses/by/4.0/
© The Author(s) 2024. 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 http://creativecommons.org/licenses/by/4.0/.
https://creativecommons.org/licenses/by/4.0/
© The Author(s) 2024. 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 http://creativecommons.org/licenses/by/4.0/.
https://creativecommons.org/licenses/by/4.0/
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202408265581
https://urn.fi/URN:NBN:fi:oulu-202408265581
Tiivistelmä
Abstract
Deep eutectic solvents (DESs) offer an appealing green medium for the activation of cellulose fibres to promote their swelling, reactivity, hydrolysis, disintegration, and solubility for further processing. Typically, DES treatments are carried out below 5 wt% consistency even though a higher solids content could enhance the fibre activation and reduce the solvent consumption. In this work, a high-consistency (HC) mechano-chemical activation of bleached softwood kraft pulp was elucidated using a simultaneous fibre treatment with DES of choline chloride-urea and a sigma-type kneader or a twin-screw extruder at a solids content of 15–35 wt% and 30 wt%, respectively. Both HC treatments efficiently triggered fibre swelling, which was indicated by an increase in the fibre width, and loosened the cell wall structure which was indicated by an increase in the mesopore volume. Mechano-chemical HC processing generated fibre fines and external fibrillation, while the molecular-level structural alteration or changes in chemical composition were minor; the intrinsic viscosity and the crystallinity of the pulp remained at their initial level and only a small amount of xylan was dissolved. Overall, HC treatment in a twin-screw extruder caused notably more severe morphological changes in the fibres than batch treatment in a sigma-type kneader. Thus, the mechano-chemical HC treatment with DES provides an industrially relevant technology for cellulose modification and opens possibilities to enhance heterogeneous cellulose modification processes in which the highly available surface area of pulp is a key parameter.
Deep eutectic solvents (DESs) offer an appealing green medium for the activation of cellulose fibres to promote their swelling, reactivity, hydrolysis, disintegration, and solubility for further processing. Typically, DES treatments are carried out below 5 wt% consistency even though a higher solids content could enhance the fibre activation and reduce the solvent consumption. In this work, a high-consistency (HC) mechano-chemical activation of bleached softwood kraft pulp was elucidated using a simultaneous fibre treatment with DES of choline chloride-urea and a sigma-type kneader or a twin-screw extruder at a solids content of 15–35 wt% and 30 wt%, respectively. Both HC treatments efficiently triggered fibre swelling, which was indicated by an increase in the fibre width, and loosened the cell wall structure which was indicated by an increase in the mesopore volume. Mechano-chemical HC processing generated fibre fines and external fibrillation, while the molecular-level structural alteration or changes in chemical composition were minor; the intrinsic viscosity and the crystallinity of the pulp remained at their initial level and only a small amount of xylan was dissolved. Overall, HC treatment in a twin-screw extruder caused notably more severe morphological changes in the fibres than batch treatment in a sigma-type kneader. Thus, the mechano-chemical HC treatment with DES provides an industrially relevant technology for cellulose modification and opens possibilities to enhance heterogeneous cellulose modification processes in which the highly available surface area of pulp is a key parameter.
Kokoelmat
- Avoin saatavuus [38840]
Ellei muuten mainita, aineiston lisenssi on https://creativecommons.org/licenses/by/4.0/