碱浓度和温度对玉米秸秆木聚糖提取率和品质的影响  

Effect of alkali concentration and temperature on extraction yield and quality of xylan from corn stover

作　　者：刘凯旋[1,2] 张傑[2] 李宏强[1] 徐建[1] 

机构地区：[1]中国科学院过程工程研究所生化工程国家重点实验室,北京100190 [2]北京化工大学常州先进材料研究院,北京100029

出　　处：《农业工程学报》2016年第11期302-308,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金(21276259);863计(2012AA022301);中科院外青项目(2013Y2GB0004);国家基金委国际(地区)合作与交流项目计划:国际青年科学家基金(21450110062)

摘　　要：由于提取率和产品品质等方面的原因,作为玉米秸秆主要成分之一的木聚糖还未能得到充分有效的利用。为改善玉米秸秆木聚糖的提取率和品质,对影响木聚糖提取的碱浓度和温度2个关键因素进行了研究。使用组分分析和凝胶渗透色谱等手段对木聚糖得率、纯度和结构进行了研究,同时分离得到纤维素和醇溶木质素。结果表明,Na OH浓度对木聚糖得率和结构的影响比温度显著,较优提取条件为:Na OH浓度为10%(w/v),提取温度90℃,此条件下木聚糖的溶出率和回收率分别为86.37%和76.92%,木聚糖纯度为63.90%。凝胶渗透色谱结果显示,碱浓度的增加使木聚糖的分子量降低,而随温度的升高则呈先升后降的趋势。此外,提取剩余物中纤维素的含量随碱浓度和温度强度的增加而增加。研究证明组合适当的碱浓度和提取温度可以在保证品质的前提下得到较高的木聚糖提取率。Xylo-oligosaccharides derived from xylan have a high application potential in food and pharmaceutical industries. As an agricultural by-product, corn stover with high hemicellulose content is an important raw material for biorefinery. In order to broaden the raw material source of xylo-oligosaccharides, the work was carried out to investigate the effect of alkali extraction conditions on the quality of xylan. NaO H mass concentration and extraction temperature were selected to study their influence on yield, purity and structural characteristics of xylan. The de-waxed corn stover was treated with NaO H solution of 4, 6, 8, 10, 12, 16, 20 and 24wt% at 121 ℃ for 2 h with a constant solid-liquid ratio of 1：10（g/mL）. The extracts were neutralized to the p H value of 5.0 with the concentrated HCl, and then concentrated under vacuum. Xylan was precipitated from the filtrate by adding the ethanol with the volume of 3 times and then freeze-dried. The remained extracts were freeze-dried and the alcohol-soluble lignins were obtained. The components of the xylan, alkali-insoluble residues and alcohol-soluble lignins were determined by the National Renewable Energy Laboratory. The extractability and structural characteristics of xylan were elucidated by gel permeation chromatography（GPC） techniques. The results demonstrated that xylan isolated with different alkali concentrations presented different chemical compositions and structural characteristics. The alkalinity played an important impact on cleaving the chemical linkages between hemicellulose and lignin. The recovery of xylan increased first and then decreased following the increasing alkali concentration with a maximum value at 10%. At the optimum Na OH concentration, the recovery and purity of xylan were 76.20% and 59.35%, respectively. The weight average molecular weight of xylan decreased from 48.62 to 32.02 kD with alkaline concentration increasing. A high alkaline concentration could degrade a considerable amount of hemicellulose. Based on the molecul

关 键 词：温度 秸秆 生物质 玉米秸杆 半纤维素 木聚糖 碱浓度 

分 类 号：TQ35[化学工程]