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Enhanced pre-treatment of cellulose pulp prior to dissolution into NaOH/ZnO

Grönqvist, S., Kamppuri, T., Maloney, T., Vehviläinen, M., Liitiä, T., Suurnäkki, A.
Cellulose 2015 v.22 no.6 pp. 3981-3990
cellulose, cellulosic fibers, endo-1,4-beta-glucanase, enzymatic hydrolysis, manufacturing, molecular weight, pretreatment, pulp, sodium hydroxide, solvents, textile fibers, viscosity, zinc oxide
As a result of the constantly growing demand for textile fibres interest in utilising cellulose pulps for manufacturing regenerated cellulose fibres is growing. One promising water-based process for the manufacture of regenerated cellulosic products is the Biocelsol process based on an NaOH/ZnO solvent system. The drawback of the Biocelsol process is the need for pre-treatment of the pulp, i.e. long mechanical pre-treatment (up to 5 h) followed by a 2–3-h enzymatic hydrolysis utilising a rather high amount of cellulolytic enzymes. In this work more efficient conditions to carry out the pre-treatment of cellulose pulp prior to dissolution into NaOH/ZnO are presented. Based on the results, cellulase treatment, when carried out in an extruder, can be used to effectively open up and fibrillate the fibres without completely destroying the fibre structure. The molar mass of the pulp treated enzymatically in an extruder was 14 % lower as compared to the state-of-the-art-treated cellulose. As a consequence, the alkaline solutions prepared from the pulp treated enzymatically in an extruder had clearly lower dope viscosities regarding the cellulose content than the solutions prepared from the state-of-the-art-treated pulp. This enabled increasing the cellulose content in the dope up to 7 % (w/w) without increasing the dope viscosity.