摘要
在不同条件下对桉木片进行碱预处理和高温水预水解,研究了其对木片残渣及提取液的影响.在高温水预水解后,木片中的聚戊糖含量随温度的升高或时间的延长而降低,这是预处理后木片失重的主要原因.凝胶渗透色谱(GPC)分析结果显示,碱预处理后木片及提取液中半纤维素的数均分子量降低,且温度越高降低越明显.与碱预处理相比,高温水预水解后木片中半纤维素的分子量大幅度降低,但多分散性仍与原料木片相近.采用酶解-温和酸水解的方法制备木素(EMAL),水预水解后木片与原料木片相比,木素的平均分子量增加,而多分散系数略有降低.木素的31P-NMR定量分析结果表明,经高温水预水解后,总酚羟基含量几乎增加一倍,S/G有所增加,但脂肪族羟基与羧基含量则大大降低.
Hot water and alkaline pretreatment was done on eucalyptus chips under different conditions .The impact on prehydrolysate and wood residue is investigated .For autohydrolysis ,higher decrease of pentosan content in wood is shown with elevated temperature and extended reaction time ,which mainly contribute for the weight loss during pretreatment .Based on the GPC(Gel Permeation Chromatography) results ,the numberaverage molecular weight of hemicelluloses in alkaline extraction liquor and wood residues decreases ,which is greater for higher temperature .Compared with alkaline pretreatment ,hemicelluloses in autohydrolyzed chips has much lower molecular weight ,with similar dispersity to that in original wood .In the case of EMAL (Enzymatic/Acidolysis Lignin) lignin ,after autohydrolysis ,the average molecular weight is increased while the polydispersity shows a little decrease compared to that from original wood .Based on the quantitative 31 PNMR analysis ,after autohydrolysis ,the total phenolic hydroxyl groups almost doubled with higher S/G ratio ,but the amount of aliphatic hydroxyl and carboxyl groups shows great decrease .
出处
《陕西科技大学学报(自然科学版)》
2014年第6期5-9,共5页
Journal of Shaanxi University of Science & Technology
基金
教育部高等学校博士学科点专项基金项目(20126125120002)
陕西省教育厅专项科研计划项目(12JK0593)
陕西科技大学博士科研启动基金项目(BJ11-18)
陕西科技大学学术团队计划项目(2013XSD24)
关键词
桉木
预处理
固形物
提取液
eucalyptus
pretreatment
wood residue
extraction liquor