| Abstract:Bagasse contains rich hemicelluloses. Most of hemicelluloses were dissolved in black liquor during pulping. In order to improve the application value of this part of hemicelluloses, hemicelluloses were extracted by sodium hydroxide solution at room temperature prior to alkaline pulping. When the alkali concentration of 40～200 g/L, liquor to bagasse ratio of 8∶1 and extraction time of 1 h were applied, the extraction yield of hemicelluloses first increased with increasing alkali concentration. At the alkali concentration of 100 g/L, the hemicelluloses extraction yield reached its maximum value and then declined slowly with increasing alkali concentration. During extraction, the consumption of alkali increased with increasing extraction yield of hemicelluloses. If keeping the total alkali dosage constant, when the alkali concentration of 40～60 g/L was used, the pulping yield decreased a little, the content of hemicelluloses in pulp also decreased a little compared with traditional pulping. However, with the alkali concentration of 80～100 g/L, the pulping yield decreased sharply, it was found the content of hemicelluloses in pulp was very low. The delignification efficiency was improved after extraction with alkali concentration of 60 g/L, but decreased as the alkali concentration of 80～100 g/L because of the insufficiency of alkali dosage. In order to guarantee the quality of the bagasse pulp, it was recommended to extract hemicelluloses from bagasse prior to cooking with alkali concentration of 40～60 g/L. |
