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将半纤维素预抽提与化学制浆工艺相结合,可将溶出的糖类物质转化成燃料及化学品。首先用热水或硫酸盐蒸煮的白液(NaOH、Na2S和Na2CO3)对白桦(Betula pendula)木片的半纤维素进行抽提,抽提工艺条件为:时间20～90min,温度130～160℃,有效碱用量为0～7%。对抽提后的木片进行硫酸盐法蒸煮、打浆及抄片,并与未抽提的试样进行对比。结果表明,硫酸盐法蒸煮前用蒸煮白液对木片进行抽提可将木聚糖溶出,但不会降低浆料得率和成纸强度,同时可将蒸煮用的碱液预浸到木片中,但当抽提液pH值>10时会降低木聚糖浓度。热水抽提工艺溶出的木聚糖浓度最高,所得的水解液中不存在有毒或抑制性的无机物和极少的可溶木素,可用木聚糖酶水解成木糖单体和发酵成丁二酸。然而,热水抽提会对浆料性能产生不利影响,如降低成纸的压缩强度、耐破度、抗张强度及挺度,但伸长率变化较小,撕裂度稍有改善。
The combination of hemicellulose pre-extraction and chemical pulping processes converts dissolved sugars into fuels and chemicals. First, the hemicellulose of Betula pendula wood chips was extracted with hot water or kraft boiled white liquor (NaOH, Na2S and Na2CO3) under the conditions of 20-90 minutes, 130-160 ° C, Effective alkali dosage is 0 ~ 7%. The extracted wood chips were subjected to kraft cooking, beating and sheeting, and compared with the unspiked samples. The results showed that the extraction of wood chips with steamed white liquor prior to kraft cooking can dissolve the xylan without reducing the yield of the pulp and the strength of the finished paper while pre-dipping the cooking alkali into the wood chips , But when the extract pH value> 10 will reduce the concentration of xylan. Hot water extraction process to dissolve the highest concentration of xylan, the resulting hydrolyzate does not exist toxic or inhibitory inorganic and minimal soluble lignin, xylanase can be hydrolyzed into xylose monomer and fermentation into Butanedioic acid. However, hot water extraction can adversely affect the properties of the slurry, such as reducing the compressive strength, burst resistance, tensile strength and stiffness of the paper, but the change in elongation is small and the tear slightly improves.