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绿液的主要成分是Na2CO3和Na2S,可在硫酸盐浆厂碱回收系统中循环产生。将新疆棉秆在不同温度、硫化度和用碱量下经绿液预处理后,在不同酶用量下进行酶水解,并测定酶水解液中总糖得率以评价预处理效果。结果表明,原料预处理得率随用碱量的增加而下降。适当地提高蒸煮温度和用碱量,可以增加木质素脱除量,有利于后续酶水解的进行,但过于剧烈的预处理条件将导致碳水化合物的过度降解,因而降低酶水解糖的转化率。另外,由于新疆棉秆细小,棉秆皮占全秆比例较大,原料总糖含量较低,导致最终酶水解总糖得率偏低。在温度120?C,用碱量16%,硫化度32%条件下绿液预处理,酶水解糖转化率达到最大值,当酶水解酶用量为20 FPU/g(对浆料)时,葡聚糖、木聚糖和总糖的转化率分别为74.0%、61.3%和68.5%。
The main components of green liquor is Na2CO3 and Na2S, which can be recycled in the alkali recovery system of the sulfuric acid pulp mill. Xinjiang cotton stalks were pretreated with green liquor under different temperature, degree of sulfuration and alkali dosage. Enzyme hydrolysis was carried out under different enzyme dosage, and the total sugar yield of enzyme hydrolyzate was determined to evaluate the pretreatment effect. The results showed that the pretreatment yield of raw materials decreased with the increase of alkali dosage. Appropriate to raise the cooking temperature and the amount of alkali, can increase the amount of lignin removal is conducive to the subsequent enzymatic hydrolysis, but too drastic pretreatment conditions will lead to excessive degradation of carbohydrates, thus reducing the enzymatic hydrolysis of sugar conversion rate. In addition, due to the small size of cotton stalks in Xinjiang, cotton stalks accounted for a larger proportion of total stalks, raw materials, lower total sugar content, resulting in the final enzyme hydrolysis of low total sugar yield. At the temperature of 120? C, the green liquor was pretreated with 16% of alkali and 32% of the degree of sulfuration. The conversion rate of enzymatic hydrolyzed sugar reached the maximum. When the amount of enzyme hydrolase was 20 FPU / g The conversion rates of polysaccharides, xylan and total sugar were 74.0%, 61.3% and 68.5%, respectively.