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题名:
汽爆玉米秸秆制备羧甲基纤维素及其组分分离
作者: 杨叶
学位类别: 硕士
答辩日期: 2009-05-25
授予单位: 中国科学院过程工程研究所
授予地点: 过程工程研究所
导师: 陈洪章
关键词: 羧甲基化 ; 秸秆 ; 组分分离 ; 羧甲基纤维素 ; 酶解速率 ; 蒸汽爆破
其他题名: Preparation of Carboxymethyl Cellulose from Steam Exploded Maize Straw and Its Fractionation
学位专业: 生物化工
中文摘要: 预处理是实现秸秆高值化利用的关键。本论文对整株秸秆进行羧甲基化处理,实现秸秆组分分离,得到高附加值的羧甲基化产品,并研究了羧甲基化秸秆的酶解机理,为实现秸秆资源的高值化利用探索了新途径。 玉米秸秆在蒸汽爆破处理后反应性能增强,再结合羧甲基化反应对玉米秸秆进行了组合预处理,通过羧甲基化产物的性质不同使组分得以分离,并制备得到了高附加值的羧甲基纤维素(Carboxymethyl Cellulose,CMC)。实验确定了整株秸秆的最优羧甲基化反应条件为:颗粒度大小80目,液固比(mL/g)18:1,氢氧化钠:氯乙酸钠的摩尔比为4:3,H2O/底物(V/m,mL/g)为1:2,75℃反应2小时。进一步对羧甲基化产物进行溶剂分离,结果表明,从碱溶物中可分离得到DS(Degree of Substitution,DS)达0.91的CMC,质量分数为总质量的40.70%,从碱不溶物中可用醇抽提分离得到22.63%(wt.%)的木质素组分。所制备得到的CMC具有低粘的性质,并利用SEM、FTIR和1H-NMR进行了表征。 对不同纤维素底物、不同纤维素醚类进行了酶解测定,发现木质素与半纤维素对纤维素的物理包裹作用、纤维素自身的化学结构都制约了纤维素的酶解。CMC是最易被酶解的一种纤维素醚,而其酶解速率受聚合度(Degree of Polymerization ,DP)和DS的影响,其中DS占主要作用,且DS在0.7左右的CMC能够获得最高的酶解初速率,Vi可达6.611umol/ml/min,为原秸秆酶解速率的12.26倍。通过SEM与XRD对经组合预处理后的玉米秸秆进行了形貌与结构分析,发现秸秆纤维素结构破裂、结晶度下降是促进其酶解速率提高的重要原因。
英文摘要: Pretreatment is the key to high value conversion of straw resources. In this thesis, the fractionation through the carboxymethylation of whole maize straw was realized and the high value-added carboxymethylated products were obtained. It was a new exploration for the high value conversion of straw resources. Maize straw was activated after steam explosion, combined with the carboxymethylation, the high value-added Carboxymethyl Cellulose (CMC)was separated from other components through solvent extraction according to their different physical chemical properties. The results indicated that the best reaction condition was that the whole straws (grinded into 80 mesh)were carboxymethylated at 75℃ for 2h with the liquid volume / solid weight , molar ration of NaOH/SMCA (Sodium Monochloroacetate, SMCA) and H2O/straw (V/m)were 18:1, 4:3 and 1:2 respectively. In the optimized reaction conditions, the yield of CMC in the products could reach 40.70%(wt.%)while the lignin content was 22.63%(wt.%)of the insoluble residues , the degree of substitution (DS) of CMC obtained reached 0.91, and the CMC was characterized with SEM, FTIR and 1H-NMR. Besides, the enzymatic hydrolysis tests of different cellulosic substrates were also carried out, results showed that both of the packaging effect of lignin and hemi-cellulose, and the chemical structure of cellulose itself had negative effect on its enzymatic hydrolysis. CMC was such kind of cellulose ether which was most easily to be degraded, and CMC with 0.7 DS had the highest enzymatic hydrolysis velocity of 6.611umol/ml/min, 12.26 times of that of the raw maize straw, while the DS and DP (Degree of Polymerization,DP) affected the hydrolysis velocity and DS played a major role. In order to investigate the inner mechanism, the SEM and XRD tests were carried out and results showed that the breakage of cellulose structure and the decrease of degree of crystallinity had important role in enhancing its enzymatic hydrolysis process.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ipe.ac.cn/handle/122111/1297
Appears in Collections:研究所(批量导入)_学位论文

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Recommended Citation:
杨叶. 汽爆玉米秸秆制备羧甲基纤维素及其组分分离[D]. 过程工程研究所. 中国科学院过程工程研究所. 2009.
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