Solubility of Enzyme-Treated Cellulose in Aqueous Alkaline Solvent
Yliannala, Henriikka (2016)
2016
Materiaalitekniikan koulutusohjelma
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2016-06-08
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201605264147
https://urn.fi/URN:NBN:fi:tty-201605264147
Tiivistelmä
Purpose of this thesis was to study the dissolution of enzyme-treated cellulose in aqueous alkaline solution. The first objective was to study the effect of zinc oxide on the solubility of the cellulose to aqueous NaOH solution. The second objective was to investigate the effect of cellulose and NaOH concentration on the solubility of cellulose with constant AGU:NaOH molar ratio. The third objective was to study the solubility of the cellulose at constant concentration by changing the NaOH:ZnO molar ratio and raising the concentration of NaOH.
In these experiments two different enzyme-treated cellulose samples were used. In the first two experiments the used pulp was mechanically shredded and enzyme-treated at TUT. For the third experiment the enzyme treated pulp was provided by VTT. The solubility was determined by freeze-thaw method, in which the samples were frozen at the desired temperature for at least 18 hours. The first two experiments were frozen at 40 °C, and the third at -15 °C. In addition, the solubility was analyzed at 20 °C (for the first two tests) and 15 °C (third experiment). After thawing the solubility of the samples were determined.
The effect of ZnO on solubility was clear. Adding ZnO increased the solubility of cellulose to aqueous NaOH. When the AGU:NaOH ratio was kept constant, the best solubility was obtained with the cellulose concentration between 5-6 wt%. In addition, cellulose was soluble at higher temperature when the cellulose concentration was slightly lower (4 wt%) and NaOH concentration was between 1.3-2.4 mol. However the effect of ZnO was not clearly seen and additional studies are needed to study this further. For example this can be achieved by increasing the concentration of the cellulose and the test temperature.
In these experiments two different enzyme-treated cellulose samples were used. In the first two experiments the used pulp was mechanically shredded and enzyme-treated at TUT. For the third experiment the enzyme treated pulp was provided by VTT. The solubility was determined by freeze-thaw method, in which the samples were frozen at the desired temperature for at least 18 hours. The first two experiments were frozen at 40 °C, and the third at -15 °C. In addition, the solubility was analyzed at 20 °C (for the first two tests) and 15 °C (third experiment). After thawing the solubility of the samples were determined.
The effect of ZnO on solubility was clear. Adding ZnO increased the solubility of cellulose to aqueous NaOH. When the AGU:NaOH ratio was kept constant, the best solubility was obtained with the cellulose concentration between 5-6 wt%. In addition, cellulose was soluble at higher temperature when the cellulose concentration was slightly lower (4 wt%) and NaOH concentration was between 1.3-2.4 mol. However the effect of ZnO was not clearly seen and additional studies are needed to study this further. For example this can be achieved by increasing the concentration of the cellulose and the test temperature.