Study on pre-extraction of hemicelluloses in kraft pulping from triploid populus toomentosa carr

In this paper, the process of hemicelluloses pre-extraction from triploid poplar toomentosa carr in kraft pulping was investigated, some parameters which may affect the pre-extraction of hemicelluloses were optimized, such as alkali charge of precooking (base on NaOH, the same as the following), the temperature and time. Then the total sugar content in hemicelluloses was analyzed. The characteristic of hemicelluloses was studied by FT-IR. The results showed that the extraction of hemicelluloses benefited from the increasing alkali charge and the maximum temperature properly at same liquid-to-solid ratio for the same pre-extraction time. When the time varied from 90 min to 120 min, the dissolved content of hemicelluloses had no significant change. However, if the time was prolonged further, the dissolved content would be decreased obviously. Finally, the optimized conditions for hemicelluloses pre-extraction were obtained and as follows: charge of NaOH 8%, liquid-to-solid ratio 1:4, the maximum temperature 120 degrees C, the time 150 min. On this condition, 8.4% of hemicelluloses was obtained (base on bond dry).