other · Aaltodoc (Aalto University) · 2021
Endoglucanase-assisted refining of bleached chemical birch pulp
Nuutinen, Inkeri
Cited by 0Abstract and details only
Abstract
Pulp refining is a prerequisite in the production of high-quality papers and boards while it is also one of the most energy consuming steps in the manufacturing process. Enzymatic refining has been identified as a potentially feasible and sustainable method for reducing the refining energy demand while preserving or even improving specific pulp and paper properties. However, enzymatic refining of birch pulp has not been addressed in the literature. The present work addresses this research gap and studies the applicability of endoglucanases for the refining of bleached birch sulfate pulp. The thesis includes a theoretical framework conducted as a literature acquisition and experimental laboratory-scale refining trials with four enzymes conducted as a case study in conditions corresponding to the conditions of the case paper machine. \n \nThe results of this study indicate that endoglucanase-assisted refining of birch pulp caused similar or even enhanced effects compared to corresponding studies conducted with softwoods in the literature. The most suitable treatments were determined to be enzyme IV with 40 g/t of pulp dose for quality improvements at an equal specific refining energy (SRE), enzyme III with 50 g/t of pulp dose for quality improvements at an equal drainage resistance, and enzyme I with 50 g/t of pulp dose for refining energy reductions and quality improvements at an equal tensile index. The most important enzyme-induced changes were the enhanced development of tensile index and internal bond strength, which took place without significantly impairing drainability, water retention value or tear index. These changes were determined to be mostly due to increased external fibrillation and modest fines content formation compared to the reference. A tensile index of 80 Nm/g was reached with 12.0–28.5% lower SRE when enzymes were utilized. At 60 kWh/t, the tensile index, internal bond strength and Gurley air resistance of paper were increased by 2.3–9.0%, 20.0–63.1%, and 30.9–341.2%, respectively, compared to the enzymatically untreated reference. However, since hardwoods require lower SRE compared to softwoods, the achieved absolute refining energy savings were lower in the case of birch compared to corresponding studies conducted with softwoods in the literature. The break-even price for enzyme I (50 g/t of pulp) was calculated to be 0.75€ per ton of pulp when refined to a tensile index of 80 Nm/g. With this price, the increased chemical costs could be fully covered with the savings generated from the reduced refining energy. The improved quality and the potential possibility to run paper machine with a higher velocity are additional benefits that could improve the feasibility. \n \nCurrently, the method is not net positive from the perspective of the case paper machine. The key issue with industrial-scale enzymatic refining was concluded to be the inadequate availability of well-controlled enzymes and their price. However, with the advances in protein engineering and enzyme production technologies, the availability of different enzyme preparations for refining applications is expected to improve and the price to decrease, which may help in the industrial-scale breakthrough of the method. Additionally, the tightening of environmental regulations may increase the interest in enzymatic refining in the future.
Cite this paper
Nuutinen, I. (2021). Endoglucanase-assisted refining of bleached chemical birch pulp. Aaltodoc (Aalto University).
Nuutinen, Inkeri. “Endoglucanase-assisted refining of bleached chemical birch pulp.” Aaltodoc (Aalto University), 2021.
Nuutinen, Inkeri. 2021. “Endoglucanase-assisted refining of bleached chemical birch pulp.” Aaltodoc (Aalto University).
Nuutinen, I. (2021) ‘Endoglucanase-assisted refining of bleached chemical birch pulp’, Aaltodoc (Aalto University).
@misc{nuutinen2021endoglucanase,
title = {{Endoglucanase-assisted refining of bleached chemical birch pulp}},
author = {Nuutinen, Inkeri},
journal = {Aaltodoc (Aalto University)},
year = {2021}
}Made from the index record. Check names, capitalisation and page numbers against the paper. Need another style? AI for Research has over 10,000.