毛竹半纤维素提取及制备木糖研究

发布时间：2018-02-16 01:29

  本文关键词： 毛竹 半纤维素提取 结构分析 半纤维素利用 制备木糖　出处：《浙江农林大学》2016年硕士论文　论文类型：学位论文

【摘要】：本论文以毛竹为原料,首先采用热水抽提,60%乙醇沉淀,得到水提粗半纤维素。通过高效液相色谱技术(HPLC)研究发现,其化学组成以葡萄糖为主,含有一定量的木糖和少量阿拉伯糖,且通过傅里叶变换红外光谱技术(FT-IR)和核磁共振氢谱技术(1HNMR)的分析可知,水提粗半纤维素是一种含有葡聚糖和木聚糖等多糖的混合多糖。用DEAE-Cellulose-52柱层析纯化,依次加入蒸馏水、梯度NaCl(0.1 M、0.3 M、0.5 M)和梯度NaOH(0.1 M、0.3 M、0.5 M)溶液对竹子水提粗半纤维素进行洗脱,得到5种半纤维素多糖组分,蒸馏水洗脱多糖再进一步经Sephadex G-100柱层析纯化,可得到两种分离完全的半纤维素多糖。采用1%、3%、5%、10%和15%的NaOH溶液提取热水抽提过的毛竹残渣,再依次用15%、30%和60%的乙醇分级沉淀,得到15个半纤维素级分,采用HPLC、FT-IR和1HNMR技术,对得到的半纤维素进行研究。结果显示,半纤维素化学组成主要以木糖为主,还含有葡萄糖和少量阿拉伯糖。毛竹碱提半纤维素主要是以β-苷键连接木糖构成主链,α-L-呋喃阿拉伯糖作为支链连接在主链木糖的C-3位上,并含有少量4-O-甲基-D-葡萄糖醛酸作为支链的木聚糖。以毛竹竹屑为原料,制备木糖。首先采用氨爆法预处理毛竹,氨爆后半纤维素保留了82.62%,得出氨爆预处理方法还是比较好的,可以作为一种保存半纤维素的预处理方法,但相同碱浓度提毛竹原料和氨爆后毛竹的半纤维素,氨爆后碱提半纤维素得率仅提高2.43%,从经济角度和设备安全方面考虑,直接用原料进行碱提半纤维素更好。在单因素的基础上进行正交试验得出碱提半纤维素的最优条件是:温度55℃,NaOH质量分数8%,固液比1:10,时间4h。NaOH质量分数是主要影响因素,其次为时间和温度,固液比影响最小。进一步对半纤维素酸解制备木糖进行了正交试验,得出半纤维素酸解的最佳条件为:温度130℃,硫酸浓度0.25M,固液比2:100,时间1.5h,硫酸浓度是影响半纤维素酸解的主要因素,其次为时间和温度,固液比影响最小。将酸解液进一步加工得纯度较高的木糖晶体,得率达79.60%。
[Abstract]:In this paper, crude hemicellulose was obtained by extracting 60% ethanol from bamboo by hot water extraction. The chemical composition of crude hemicellulose was found to be mainly glucose by high performance liquid chromatography (HPLC). It contains a certain amount of xylose and a small amount of arabinose, and is analyzed by Fourier transform infrared spectroscopy (FTIR) and 1H NMR. Crude hemicellulose extracted by water is a mixed polysaccharide containing polysaccharides such as dextran and xylan. Purified by DEAE-Cellulose-52 column, distilled water was added successively, gradient NaCl(0.1 M0. 3 M0. 3 M0. 5 M) and gradient NaOH(0.1 M0. 3 M0. 3 M0. 5 M) solution were used to elucidate the crude hemicellulose extracted from bamboo water. Five kinds of hemicellulose polysaccharides were obtained, which were eluted by distilled water and further purified by Sephadex G-100 column chromatography. Two completely separated hemicellulose polysaccharides were obtained. 10% and 15% NaOH solutions were used to extract bamboo residue extracted by hot water. Fifteen hemicellulose fractions were obtained by fractionation of 15% and 60%% ethanol respectively. The hemicellulose components were studied by HPLC- FT-IR and 1H NMR techniques. The results showed that the chemical composition of hemicellulose was mainly xylose. It also contains glucose and a small amount of arabinose. The main chain of hemicellulose is composed of 尾 -glucoside bonds, and 伪 -L- furan arabinose is attached to the C-3 position of the main chain xylose as a branching chain. A small amount of 4-O- methyl-Dglucuronic acid was used as a branched xylan. Xylose was prepared from bamboo chips. Firstly, the pretreatment of bamboo by ammonia explosion was carried out. The hemicellulose retained 82.62% after ammonia explosion, and it was concluded that the method of ammonia-explosion pretreatment was better. It can be used as a pretreatment method to preserve hemicellulose. However, the yield of hemicellulose extracted from bamboo with the same alkali concentration and the hemicellulose of bamboo after ammonia explosion can only be increased by 2.43%, which is considered in terms of economic and equipment safety. It is better to directly use raw materials to extract hemicellulose by alkali. The optimum conditions for alkali extraction of hemicellulose are obtained by orthogonal experiment on the basis of single factor: temperature 55 鈩，

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