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In this work, chemical pulp was used to prepare hazy transparent films, and the effects of hemicellulose content on carboxyl group formation during TEMPO-(2,2,6,6-tetramethylpiperidine-1-oxyl) mediated oxidation, and the properties of the film prepared from the chemical pulp were evaluated. The hemicellulose content exhibited a negligible effect on carboxyl content formation, while prior alkaline extraction significantly enhanced the selective oxidation indicating a substantial increase of carboxyl group. The prior alkaline extraction and TEMPO-mediated oxidation initiated severe hemicellulose removal and fiber swelling, and therefore promoted the subsequent ultrasonic fibrillation. The optical transmittance of the film prepared from the chemical pulp was near-constant at ~ 89%, while the haze increased slightly from 85 to 94%, when the hemicellulose content was increased from 6.7 to 19.2%. Conversely, the presence of hemicellulose significantly impaired the film surface properties, possibly due to the large size of the cellulose fibers. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we studied the effects of pretreatment with glucanase (G), xylanase (X), and their combinations [G/X mixtures or sequential addition (G-X and X-G)] on the efficiency of ionic liquid/water (IL/w)—promoted extraction of hemicelluloses from paper-grade pulp. Mild G pretreatment effectively increased the efficiency and selectivity of hemicellulose removal, whereas severe G pretreatment resulted in high glucose loss and low selectivity. Under optimized conditions, G and X pretreatments achieved similar removal efficiencies, especially in IL/w systems with high water content (25 and 20%), whereas the former was inferior to the latter at low water content (15%). Simultaneous G/X treatment achieved more efficient and selective hemicellulose removal than sequential G-X and X-G treatments, with the former sequence outperforming the latter. Finally, sequential extraction with IL/w-20 and IL/w-15 allowed extremely effective hemicellulose removal, decreasing the xylose content of pulp to 1.5%.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Herein, an ionic liquid/water (IL/w) system was developed to separate hemicelluloses from the chemical pulp with enhanced efficiency by employing xylanase. In the traditional IL/w process, when the water content was in the range 20-15%, the extraction of hemicelluloses was 71–80%. However, the highly efficient hemicelluloses removal was always accompanied with an increased cellulose loss. In this regard, xylanase (X) pretreatment was introduced to facilitate the IL/w process for improving the separation selectivity/efficiency of the hemicelluloses. In the case of the IL/w-20 (water content is 20%) procedure, X 30 (30 mg/g xylanase) pretreatment could increase hemicelluloses removal from 71 to 78%, while the separation selectivity increased from 11.0 to 43.8. Additionally, X pretreatment also reduced IL usage/charge to achieve the same degree of hemicelluloses removal. [ABSTRACT FROM AUTHOR]