山杨和速生杨硫酸盐浆多相水解动力学的研究

研究了木质素含量为０．２３％的山杨漂白浆和１．０５％的速生杨未漂浆稀酸低温多相水解降解反应动力学特性。结果表明，该过程与棉浆、桦木和针叶材浆具有相类似的特点，即纤维素多相水解降解过程分为两个明显阶段（快速降解和缓慢降解），而最终降至极限聚合度（山杨漂白浆为１８０；速生杨未漂浆为２０６）。两个阶段的纤维素水解降解动力学以其不同反应速度为特征，根据试验数据计算出反应速度常数：山杨漂白浆为Ｋ＝２．５×１０￣（－４）／ｍｉｎ；速生杨未漂浆为Ｋ＝１．６×１０￣（－４）／ｍｉｎ，前者明显地高于后者。随着水解时间的增加，水解残渣得率下降，最终结果达到８３％～８４％。测定了各水解试样的木质素含量，结果表明，水解前期（１０～４０ｍｉｎ）木质素变化较大，山杨漂白浆下降４８％，速生杨未漂浆下降３８％；水解后期，木质素含量变化不大。木质素的存在对于多相（固－液）水解降解反应起着阻碍作用并降低其反应速度常数。木质素含量越高水解液渗透至纤维素大分子链之β－Ｄ－葡糖键的速度越慢。     

山杨和速生物硫酸盐浆多相水解动力学的研究

研究了木质素含量为０．２３％的山杨漂白浆和１．０５％的速生杨末漂浆稀酸低温多相水解降解反应动力学特性。结果表明，该过程与棉浆、桦木和针叶材浆具有相类似的特点，即纤维素多相水解降解过程分为两个明显阶段（快速降解和缓解降解），而最终降到极限聚合度（山杨漂白浆为１８０；速生杨未漂浆为２０６）。两个阶段的纤维素水解降解动力学以其不同反应速度为特征。根据试验数据计算出反应速度常数：山杨漂白浆为Ｋ＝２．５×１     

阔叶材(山杨和速生杨)漂白浆和未漂浆水解降解及其产物性质的研究(英文)

本文研究了木素含量为0.2—1.2％的山杨和速生杨漂白浆和未漂浆的水解降解过程。研究结果表明,该过程与先前已研究过的其它种类的木浆具有相类似的特点,即水解过程存在两个明显的阶段(快速降解阶段和缓慢降解阶段),最终纤维素降解至“极限”聚合度。由不同原料用不同方法制成的不同种类的浆,其水解速度以递减的顺序排列为:山杨浆(漂白浆和未漂浆)→白桦浆→速生杨浆(漂白浆和未漂浆)→针叶材硫酸盐浆→针叶材亚硫酸盐浆(3.7×10~(-4)/分,1.7×10~(-4)/分→1.6×10~(-4)/分→1.3×10~(-4)/分,0.9×10~(-4)/分→1.2×10~(-4)/分,0.8×10~(-4)/分) 水解后纤维索达到“极限”聚合度,后者大小取决于原料种类。山杨硫酸未漂浆分别为206和135;氧碱法山杨浆为160;速生杨硫酸盐未漂浆和漂白浆分别为250和240。水解后试样呈白色粉末状,得率82～85％。试样以其吸水能力为显著特征。未经超声波分散作用的试样,其吸水值比原浆低(从未漂浆90～115％和漂白浆75～95％降至70～80％)。反之,于水中经超声波分散作用后,试样的吸水值急剧增大(山杨微晶纤维素为160％,速生杨微晶纤维素为260％),接近于桦木浆和棉浆微晶纤维素的水平。对原浆纤维和微晶纤维颗粒形状和大小进行了显微观测。测得的数量分布微分曲线表明,在酸水解     

酸催化的蒸汽爆破预处理强度对麦草酶水解影响的研究

以蒸汽爆破法对0.5 %的稀硫酸浸渍的麦草进行预处理,研究了不同处理强度对麦草浆得率、半纤维素回收率、纤维素回收率、纤维素酶水解得率产生的影响.实验结果表明,在蒸汽爆破预处理过程中,麦草纤维组分发生分离.随着处理强度的提高,粗浆得率降低,细浆得率上升,纤维素的降解程度和半纤维素的去除程度提高,酶水解得率相应提高.在处理强度为4.14的预处理条件下,半纤维素的水解程度最大,而细浆得率和纤维素的酶解得率最高,分别为62.0 %和73.4 %;最佳的处理强度为3.55,此条件下,汽爆麦草原料细浆中的葡萄糖得率和滤出液中总糖的得率最高,分别为20.0 %和13.0%.     

棉杆制漂白化学浆和人造丝浆的研究

研究了棉杆烧碱蒽醌法制化学浆和预水解烧碱蒽醌法制人造丝浆的适宜蒸煮条件，用Ｄ／Ｃ ＥＤ，Ｄ／Ｃ ＥＨＤ，Ｄ／Ｃ ＥＤＥＤ流程进行了漂白试验。试验表明，用适宜的蒸煮条件，Ｄ／Ｃ ＥＤＥＤ漂白流程可得到白度８７、聚合度１３９９和α－纤维素８５％的化学浆和白度８９、聚合度８３０、α－纤维素含量达９４％的人造丝浆。     

桉木氨水浸渍预处理响应面优化提高酶解效率

采用氨水中温浸渍（SAA）方法对桉木进行预处理,以期提高其后续酶水解效率。以响应面法主要预处理条件进行优化,以期筛选出SAA预处理的最优工艺条件。结果表明：最佳预处理工艺为氨用量80％、时间11h、温度90℃,在此条件下预处理物料的后续酶解转化率可达31．7％。对预处理物料的分析表明：在SAA预处理过程中,可在不损失纤维素的前提下脱除木素51％,而且主要是紫丁香基型和愈疮木基型木素降解溶出,半纤维素主要是木聚糖也有部分降解溶出。木素及半纤维素的降解、纤维素结晶度的降低都有利于后续的酶水解。     

人工林米老排木材化学成分及其在树干高度上的变异

采用我国木材化学成分分析国家标准,对人工林米老排木材化学成分进行了测定和研究分析.结果表明:人工林米老排木材冷水抽提物含量和热水抽提物含量分别为2.67%和3.12%,1%NaOH抽提物含量为17.08%,纤维素含量为47.49%,综纤维素含量为80.42%,木素含量为28.80%,pH值为5.44;木材冷水抽提物和综纤维素含量在树干的不同高度上略有差异,但方差分析检验,差异不显著,热水抽提物、1%NaOH抽提物、纤维素和木素含量在树干的不同高度上差异显著,达到1%显著性水平;由树基往上,热水抽提物含量略呈两端高、中间低的趋势,冷水抽提物、1%NaOH抽提物和木素的含量逐渐降低,综纤维素含量和木材pH值逐渐升高;纤维素含量在树干上的分布规律为中间高、两端低,而且从树干中部往上的降低幅度较大.     

葡萄牙：利用香蕉树干生产纸浆和纸

萄葡牙Braga大学科技人员研究利用香蕉树干（假树干、非主干）作为制浆和造纸纤维资源的可行性。香蕉树干的化学组成：综纤维素含量60％，木素含量12％，有利于用作造纸原料。测试了香蕉树干纤维形态，化学浆的物理机械性质以及用化学浆与两种不同木浆（桉木和松木）混和制得纸页的强度性质：香蕉树干纤维平均长度较长，长度分布范围宽为0．20～4．19毫米，     

机械辅助酶水解法制备竹基纤维素微粒的研究

研究采用机械匀浆法对竹纤维进行预处理,然后用半纤维素酶和纤维素酶对其进行酶水解,通过红外光谱、扫描电镜、X射线衍射以及热重分析等手段,考察酶的种类与用量对产物性状的影响。结果表明,用半纤维素酶进行水解时,竹纤维发生横向断裂,产物结晶度有所上升,热稳定性略有下降。用半纤维素酶和纤维素酶共同水解后,得到了粒径在10～15μm的纤维素球状微粒,产物结晶度明显下降,并出现纤维素I型结晶向II型结晶的转化,同时产物热稳定性降低。     

乙酸预处理对木质纤维素结构及性能的影响

对木质纤维素进行乙酸预处理及三段磨浆,分析了不同试样的化学组分,并进行了结构表征。结果显示,经乙酸预处理及三段磨浆后,相思木木片表面出现大量坍塌、裂纹及孔洞,纤维间的结合也变得更为疏松,木片超微结构受到不同程度的破坏。试样中半纤维素含量显著降低,纤维素及木质素所占比例相对增加,纤维素的结晶度指数有所降低。核磁共振波谱(P31NMR)分析结果表明,经预处理及磨浆后,试样中木素的脂肪族羟基含量降低,酚羟基含量增加,酚型/非酚型木素值增加,S/G(紫丁香基/愈创木基型木素)值增加,且随着预处理温度的升高,酚型/非酚型值下降,S/G值增加。热重-红外(TG-IR)分析结果表明,经预处理及磨浆后,DTG曲线在280℃左右少一个肩峰,半纤维素的降解产物木聚糖的特征吸收峰大幅降低,纤维素降解产物的特征吸收峰强度略微增强,木质素热解产物的特征吸收峰强度略有下降。为探讨预处理及磨浆对木质纤维素孔结构的影响,采用低温氮气吸附法(BET)对试样进行分析,结果显示,试样的比表面积增大,大孔所占比例减小,介孔所占比例增加。     

Effect of the presence of lignin on the structure and reactivity to hydrolysis of lignincarbohydrate complexes of poplar wood obtained by sulfate pulping

Summary Lignincarbohydrate complexes (LCC) of poplar wood obtained by sulfate pulping and containing lignin in amounts of 0.9–8.3% have been studied by X-ray diffractometry. Heterogeneous hydrolysis methods have been used to determine their reactivity. The content of the crystalline fraction in LCC depends on the lignin removal and increases with the decrease of the lignin content. The degree of crystallinity of cellulose in sawdust and in LCC is fairly high and changes slightly with the lignin removal. The presence of lignin plays a blocking role in the heterogeneous hydrolysis and decreases the rate constant. It is suggested that lignin is bonded to cellulose on the outer surfaces of the crystalline part of the cellulose fibril. Some possible variants of these bonds are discussed.     

Investigation on enzymic hydrolysis of lignified cellulosic materials

Investigations on enzymic hydrolysis of cotton cellulose and spruce groundwood pulp with the multicomponent enzyme Onozuka SS have shown that lignin causes an almost total inhibition of the enzyme action. Breaking of lignified covers of cell walls and fibrillar bundles by grinding increases the accessibility toward the enzyme very effectively. Depolymerization of lignin is less important for improving the accessibility. The compact fibrillar structure of both cotton and wood cellulose also have an inhibitory effect on the penetration of the enzyme into the fiber. Beating loosens the compactness of the fibrillar structure and increases the accessibility. Only about 10% of the cellulose, probably highly crystalline, requires more drastic treatment e.g. ball-milling. Last units of polysaccharides linked to lignin in the lignin carbohydrate complex are resistant toward enzyme hydrolysis and require chemical cleavage. Total enzymic solubilization of lignified polysaccharides can therefore be attained only after a combined mechanical and chemical pretreatment.     

蒸煮处理对竹纤维化学组成的影响及机理

采用热机械-蒸煮方法制备慈竹纤维,并运用FTIR、x-射线衍射分析技术对蒸煮处理前后慈竹纤维的化学组成、结晶结构进行了研究,此外,还研究了处理前后慈竹化学成分的变化,结果表明:不同蒸煮工艺处理后竹纤维的纤维素较未处理竹材有所上升,而木质素含量有所下降,其中,第2组蒸煮工艺所得纤维素含量提高了19.27%,木质素含量下降了38.85%,运用x-射线衍射测得的纤维素结晶度均有所上升。     

木质纤维原料制备纤维素酶的反应历程

阐述了木质纤维原料纤维素酶制备过程中诸影响因素如纤维素、滤纸酶活性、还原糖、蛋白质、ＰＨ、菌丝体、结晶度等的变化规律。较低的ＰＨ值有利于纤维素酶Ｃｌ酶和Ｃｘ酶的诱导，纤维素酶酶活较高，产酶过程中大部可及性好的无定形我及部分结构较疏松结晶区纤维素被降解利用，而约有２０％高结晶度结晶区纤维素很难被利用；木质素的存在对纤维素酶生产有一定的影响，但影响效果并不大     

Two-step hydrolysis of Japanese cedar as treated by semi-flow hot-compressed water

Two-step hydrolysis of Japanese cedar (Cryptomeria japonica) was studied as treated by semi-flow hot-compressed water at 230°C/10 MPa for 15 min and 280°C/10 MPa for 30 min as the first and second stages, respectively. At the first stage, hemicelluloses and para-crystalline cellulose, whose crystalline structure is somewhat disordered, were found to be selectively hydrolyzed, as well as lignin decomposition, whereas crystalline cellulose occurred at the second stage. In all, 87.76% of Japanese cedar could be liquefied by hot-compressed water and was primarily recovered as various hydrolyzed products, dehydrated, fragmented, and isomerized compounds as well as organic acids in the water-soluble portion. The remainder, 12.24%, could not be hydrolyzed and remained as the water-insoluble residue composed entirely of lignin. Based on the distribution of various products from hemicelluloses in Japanese cedar, their decomposition pathways were proposed as independent.     

蒸汽爆破和有机溶剂预处理对杨木底物酶水解性质的影响

选取三倍体毛白杨为原料,通过分析最优条件下有机溶剂法和蒸汽爆破法预处理后纤维素得率、结晶度指数、木质素含量及酶水解的结果,比较两种预处理工艺对底物性质的影响。结果表明:蒸汽爆破法能脱出部分木质素,而有机溶剂法能使大部分木质素脱除,木质素质量分数比未处理的降低63.34%。与原料相比,经过预处理后,结晶度指数都有所提高,蒸汽爆破预处理后达1.962,有机溶剂法预处理后达1.712。有机溶剂法预处理的样品葡萄糖转化率为81.36%,蒸汽爆破预处理的样品的葡萄糖转化率可达91.29%。     

Enzymatic hydrolysis of wood with alkaline treatment

Pulverized samples of wood, cedar and eucalyptus were treated with 5 N NaOH solutions at 25–150 °C. Hemicellulose and lignin content in the samples decreased with increasing treatment temperatures, while the recovery of glucose was maintained at nearly 90 %. X-ray diffraction analysis showed that the content of the original cellulose I structure in the samples decreased with increasing temperature, and most of the cellulose in the sample treated at 150 °C was converted to cellulose II by mercerization. Enzymatic hydrolysis of the alkaline-treated samples was carried out at 37 °C using solutions comprising a mixture of cellulase and β-glucosidase. The samples treated at higher temperatures showed better enzymatic degradability. Treatment with an alkaline solution of lower concentration (1 N NaOH) at 150 °C was also used. Despite significant quantities of hemicellulose and lignin being removed, mercerization was not induced. The enzymatic degradability was much lower than that of the sample treated with a 5 N NaOH solution at 150 °C. Thus, treatment with concentrated alkaline solution at high temperature led to not only the removal of hemicellulose and lignin, but also to modification of the cellulose structure, which resulted in high efficiency of enzymatic saccharification of the wood samples.     

通过RNAi技术抑制杨树c3h基因表达提高糖转化效率

利用克隆得到的毛白杨c3h1基因构建其RNAi抑制表达载体,通过根癌农杆菌介导的叶盘法转化银腺杨无性系84 K,Realtime PCR检测表明其转基因株系323、325和322中c3h1基因表达量较野生型植株分别下调89.04%、82.22%和68.38%;茎横切片组化染色和显微结构观察表明转基因植株木质部发育和木质素沉积方式发生了改变;木质素、纤维素含量测定及苯酚—硫酸法总糖含量与HPLC法可溶性总糖和单糖含量检测结果表明:转基因植株木质素含量平均降低23.00%,最高可达39.71%;酸前处理效率最高提高了41.39%;未经酸处理直接酶解的糖化效率是对照植株的2.34～2.72倍,322株系和323株系比对照植株经酸前处理后再酶解的糖化效率高出81.18%和375.53%。     

Two-step hydrolysis of Japanese beech as treated by semi-flow hot-compressed water

A two-step hydrolysis of Japanese beech (Fagus crenata) was conducted by semi-flow treatment with hot-compressed water. The first treatment stage was conducted at 230°C/10 MPa for 15 min and the second at 270°C/10 MPa for 15 min. Hemicellulose and lignin were found to be hydrolyzed in the first stage, while crystalline cellulose was hydrolyzed in the second stage. The treatment solubilized 95.6% of the Japanese beech wood flour into water with 4.4% remaining as water-insoluble residue, which was composed mainly of lignin. Hydrolysis products from the first stage were xylose and xylo-oligosaccharides, glucuronic acid and acetic acid from O-acetyl-4-O-methylglucuronoxylan, and hydrolyzed monomeric guaiacyl and syringyl units and their dimeric condensed-type units from lignin. Products from the second hydrolysis stage were glucose and cello-oligosaccharides from cellulose. The dehydrated products levoglucosan, 5-hydroxymethylfurfural (5-HMF), and furfural, as well as fragmented products glycolaldehyde, methylglyoxal, and erythrose, were recovered in the first stage from hemicellulose, and to a greater extent in the second stage from cellulose. Furthermore, organic acids such as glycolic, formic, acetic, and lactic acids were recovered in both stages. Based on these lines of evidence, decomposition pathways of O-acetyl-4-O-methylglucuronoxylan and cellulose are independently proposed.     

香蕉假茎纤维成分的分析

以香牙蕉（Musa cavendisihii,Me）的假茎纤维为原料,对它的水分、灰分、水溶物、脂肪和蜡质、果胶、木质素、半纤维素、含胶率和纤维素成分进行了分析。结果表明：纤维素是构成香蕉假茎纤维的主要成分,占总量的55．591％;胶质总含量41．948％,其中脂蜡质含量1．438,果胶含量6．975％,木质素含量8．742％,半纤维素含量17．378％。与其它植物纤维相比,虽然香蕉假茎纤维含纤维素量中等,含木质素较高,但仍然有开发价值。