Sugarcane bagasse was pretreated with both the white-rot fungus, Ceriporiopsis subvermispora, and xylanase enzyme for 2 weeks before soda chemithermomechanical (CTMP) and soda chemical (CP) cooking. For fungi-CTMP (BCTMP) and enzyme-fungi-CTMP (EBCTMP), the bagasse, after bio-pretreatment, was cooked with 5% sodium hydroxide, at 130 degrees C for 20 min. For the chemical pulping (CP), after fungi pretreatment (BCP) or after xylanase and fungal pretreatment (EBCP), the bagasse was cooked with 14.5% sodium hydroxide. With the BCTMP, the Klason lignin was reduced, all of the pulp strength properties were increased, and a 28% savings in refining energy consumption was obtained, but the brightness was reduced 5 points compared to the control. With the EBCTMP, the brightness losses were overcome but with a mild reduction in the pulp strength properties compared to the BCTMP. The energy savings were 5% greater than from BCTMP and 33% over the control. The BCP treatment increases somewhat the pulp strength properties, reduces the energy consumption 23%, and reduces the brightness by 9 points compared to the control; however, the kappa no. was 5.5 points higher than the control. EBCP treatment reduces brightness losses and increases the pulp yield 2% compared to the control, but with some reduction in the strength properties compared to BCP.
Arabinoxylans from corn cob and oat spelt were studied in sorption experiments onto bleached and unbleached softwood kraft pulp. The corn cob (CC) xylans were produced by steam extraction (SE-CC) and alkaline extraction (NaOH-CC), while the oat spelt xylan (NaOH-OS) was obtained by alkaline extraction. Both alkaline extracted xylans exhibited a high degree of polymerization (DP) (230-240), whereas the steam extraction induced a significant degradation resulting in DPs around 36. Investigation of the xylan addition mode revealed that adding xylan before beating of pulp is most effective for increasing the beating degree and the strength properties. The tensile and burst indices are improved by xylan addition over the whole range of beating degrees. In contrast to that, the tear strength is increased significantly for unbeaten pulps but declines after beating, compared to the reference. Xylan sorption rates are increased with prolonged beating. Highest sorption rates are observed for the NaOH-OS (12-32%) and lowest for the SE-CC xylan (6.6-14%). In general, the alkaline extracted xylans have a better performance, most likely as a result of their higher molar masses.
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