(599b) Impact of Hemicellulose Pre-Extraction for Bioconversion On Birch Kraft Pulp Properties
The carbohydrate portion of lignocellulosic feedstocks are ideally suited to conversion via biochemical transformations because of their crucial role in cellular metabolism. The combination of hemicelluloses extraction with pulping processes could be one way to generate a sugar feedstock amenable to biochemical transformation to fuels and chemical intermediates. White liquor, green liquor, and water HC extractions of birch wood were performed under conditions compatible with the Kraft process, at different times, temperatures and alkali charges. The effective alkali charge was in extractions between 0%-7% and temperature between 130°C-160°C for 20-90 minutes. The xylan yields from different HC extractions were measured and the chips from select HC extractions were cooked, and the refined pulps were made into hand sheets. Several metrics for hand sheet quality were compared with a reference pulp made from the same wood chips. It is possible using white liquor to extract xylan from birch wood chips prior Kraft cooking without decreasing the pulp yield and paper strength properties, and at the same time achieve an impregnation of the wood chips. It is not possible in that extraction to attain extracted and hydrolyzed liquor containing a fermentable concentration of xylose, 2.63 g/L in this study. Increased extracted wood material, increased final acetic acid concentration and decreased final xylan concentration together with increased effective alkali charge at the same extraction temperature and time in white liquor extractions performed support that xylan degradation increases. Using white liquor or green liquor under the conditions investigated degrades xylan resulting in significant losses of xylose that could have been used as substrate in fermentation processes.