Journal
CELLULOSE
Volume 28, Issue 7, Pages 4385-4396Publisher
SPRINGER
DOI: 10.1007/s10570-021-03779-w
Keywords
Cellulose; Dissolution; Hydrolysis; Reactivity; TEMPO-oxidation
Funding
- Aalto University
- Business Finland
- Walter Ahlstrom foundation
- FinnCERES Materials Bioeconomy Ecosystem
Ask authors/readers for more resources
The study found that hydrolysis under medium consistency (10%) conditions can increase the solubility of cellulose, while hydrolysis under high consistency (50%) conditions only increases solubility to a certain extent, with prolonged treatment causing fiber aggregation and poor dissolution. Additionally, viscosity needs to decrease to a certain level for fiber dissolution to occur.
This paper discusses the effect of hydrolytic pretreatments on pulp dissolution in the aqueous NaOH-ZnO solvent system. Eight samples were studied. They consisted of a never-dried softwood kraft pulp that was hydrolyzed under seven different conditions as well as the pulp without hydrolysis as a reference. The dissolution of the pulps was evaluated both at the macro level as well as at the molecular level based on their reactivity with 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxo-piperidium (4-AcNH-TEMPO+). The fiber properties (i.e. the extent of fibrillation, amount of fines and fiber width, coarseness, and length) as well as the chemical composition (hemicellulose and cellulose contents) and the viscosity of the pulps was investigated. The results show that hydrolysis at medium consistency (10%) was successful in increasing the solubility of cellulose. Hydrolysis at high consistency (50%), on the other hand, increased the solubility only to some extent. With extended treatment time the fibers formed aggregates and their dissolution became poor. This phenomenon could be overcome by mechanically refining the fibers after the hydrolysis. Moreover, comparison of the viscosity of the pulp over the degree of oxidation revealed that the viscosity needed to decrease below ca. 400 ml/g in order for the outer layers of the fibers to dissolve. Finally, when pulps with similar viscosities where compared against each other, the ones with the higher glucomannan contents formed gels over time. This was true also for the pulp with the lowest viscosity and the highest solubility of the studied samples.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available