Cellulose and Paper Department, National Research Center, Dokki, Cairo, Egypt.
Bioresour Technol. 2010 Jun;101(12):4446-55. doi: 10.1016/j.biortech.2010.01.047. Epub 2010 Feb 24.
Rice hulls (RH) and bean hulls (BH) were subjected to prehydrolysis treatments, to define the optimum conditions for producing a high percentage of hydrolyzed hemicellulose with a small or moderate degradation of the cellulosic portion. The hydrolysis experiments were performed using hydrochloric and sulfuric acids in concentrations ranging from (0.5 to 5)% (w/w) at 120 degrees C for 90 min and 10% consistency. The effects of different temperatures (80 to 120 degrees C) and time (30 to 120 min) on acid hydrolysis of lignocellulosic materials were recorded. It was found that, the optimum condition to hydrolyze the lignocellulosic materials (RH) and (BH) are 2% (w/w) of mineral acid at 120 degrees C for 90 min and 10% consistency. The cellulose crystallinity index in the different types of lignocellulosic materials with and without acid treatment, were increased from 0.32 to 0.46 in case of RH and from 0.43 to 0.61 in case of BH. Due to the lignin depolymerization during the pretreatment process, the relative absorbency of the methoxyl group and the aromatic rings bands were lowered for the pretreated than the untreated lignocellulosic materials. Also, the band at 1730 cm(-1) which is attributed to carbonyl groups of uronic acids was lowered due the hemicellulose hydrolysis.
稻壳 (RH) 和豆壳 (BH) 经过预水解处理，以确定生产高比例水解半纤维素并适度降解纤维素部分的最佳条件。水解实验在 120°C 下使用浓度为 0.5 至 5%（w/w）的盐酸和硫酸进行 90 分钟和 10%浓度。记录了不同温度（80 至 120°C）和时间（30 至 120 分钟）对木质纤维素材料酸水解的影响。结果发现，水解木质纤维素材料 (RH) 和 (BH) 的最佳条件是 2%（w/w）的矿物酸在 120°C 下反应 90 分钟，浓度为 10%。在酸处理前后，不同类型木质纤维素材料的纤维素结晶度指数从 0.32 增加到 0.46（对于 RH），从 0.43 增加到 0.61（对于 BH）。由于预处理过程中木质素解聚，与未处理的木质纤维素材料相比，预处理后的木质纤维素材料的甲氧基和芳环带的相对吸光度降低。此外，由于半纤维素水解，归因于糖醛酸羰基的 1730 cm(-1) 带降低。
