Xu F, Sun J X, Liu C F, Sun R C
College of Forestry, North-Western Science and Technology University of Agriculture and Forestry, Yangling 712100, China.
Carbohydr Res. 2006 Feb 6;341(2):253-61. doi: 10.1016/j.carres.2005.10.019. Epub 2005 Nov 28.
Two-stage treatments of sugarcane bagasse with mild alkali and acidic 1,4-dioxane were performed. Pretreatment with 1M NaOH aqueous solution at 20, 25, 30, 35, and 40 degrees C for 18 h released 55.5%, 57.3%, 59.1%, 60.9%, and 62.1% of the original hemicelluloses, respectively. Post-treatment of the corresponding alkali-treated residue with 1,4-dioxane-2M HCl (9:1, v/v) at 87 degrees C for 2h, respectively, degraded 11.6%, 11.9%, 11.4%, 10.9%, and 10.6% of hemicelluloses (% dry starting material). It was found that the five alkali-soluble hemicellulosic preparations contained a much higher amounts of xylose (78.0-82.2%) and slightly higher uronic acids (4.8-5.8%), mainly 4-O-methyl-alpha-d-glucopyranosyluronic acid, but were lower in arabinose (9.3-11.7%) and glucose (2.2-4.1%) than those of the corresponding five acidic dioxane-degraded hemicellulosic fractions in which xylose (44.9-46.8%), arabinose (35.9-38.1%), and glucose (13.0-13.7%) were the major sugar constituents. The studies revealed that the five alkali-soluble hemicellulosic preparations were more linear and acidic, and had a large molecular weight (35,200-37,430 g mol(-1)) than those of the hemicellulosic fractions (12,080-13,320 g mol(-1)) degraded during the acidic dioxane post-treatment. This demonstrated that the post-treatment with acidic dioxane under the condition used resulted in substantial degradation of the hemicellulosic polymers. The 10 hemicellulosic samples were further characterized by FT-IR and 1H and 13C NMR spectroscopy, GPC and thermal analysis, and the results are reported.
对甘蔗渣进行了用温和碱和酸性1,4 - 二氧六环的两步处理。在20、25、30、35和40摄氏度下用1M氢氧化钠水溶液预处理18小时，分别释放出原始半纤维素的55.5%、57.3%、59.1%、60.9%和62.1%。相应的碱处理残渣分别用1,4 - 二氧六环 - 2M盐酸（9:1，v/v）在87摄氏度下后处理2小时，降解了11.6%、11.9%、11.4%、10.9%和10.6%的半纤维素（相对于起始原料干重百分比）。发现这五种碱溶性半纤维素制剂含有更高含量的木糖（78.0 - 82.2%）和略高含量的糖醛酸（4.8 - 5.8%），主要是4 - O - 甲基 - α - D - 吡喃葡萄糖醛酸，但阿拉伯糖（9.3 - 11.7%）和葡萄糖（2.2 - 4.1%）的含量低于相应的五种酸性二氧六环降解的半纤维素级分，其中木糖（44.9 - 46.8%）、阿拉伯糖（35.9 - 38.1%）和葡萄糖（13.0 - 13.7%）是主要的糖成分。研究表明，这五种碱溶性半纤维素制剂比酸性二氧六环后处理过程中降解的半纤维素级分（12,080 - 13,320 g mol(-¹)）更线性、酸性更强且分子量更大（35,200 - 37,430 g mol(-¹)）。这表明在所使用的条件下用酸性二氧六环后处理导致半纤维素聚合物大量降解。对这10个半纤维素样品进一步用傅里叶变换红外光谱、¹H和¹³C核磁共振光谱、凝胶渗透色谱和热分析进行了表征，并报告了结果。
