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1.
Summary Wood samples that had been ball-milled and extracted with dioxane under various conditions were observed in the scanning electron microscope. Ball milling causes not only a reduction in size of the cells and cell walls but also an internal disruption of the particles. The intensity of milling has a larger influence on the particle size than a prolongation of the milling time. A direct relation was established between particle size and the previously determined yield of purified milled wood lignin.Submitted by Erwin-Riesch-Stiftung zur Förderung der wissenschaftlichen Forschung. 相似文献
2.
Feng Xu Jian-Xing Jiang Run-Cang Sun Jiang-Ning Tang Jin-Xia Sun Yin-Quan Su 《Wood Science and Technology》2008,42(3):211-226
Sequential extractions of the mild ball-milled Eucommia ulmoides Oliv with 80% neutral dioxane, 75% dioxane containing 0.025 M HCl, 75% dioxane containing 0.1 M NaOH, 60% ethanol containing
0.5 M NaOH, 5% KOH, 5% NaOH, and 8% KOH at 75°C for 3 h released 91.3% of the original lignin. The results showed that the
procedure for extracting lignin from the mild ball-milled wood with mild alkaline organic solvent was more efficient than
the traditional method of neutral and mild acidic dioxane extractions. The structure of the seven lignin fractions were analysed
using wet chemical analysis, such as alkaline nitrobenzene oxidation, FT-IR, and solution-state 1H, 13C, and 31P NMR techniques. It is clear that the sequential mild acidic and alkaline organic solvent extractions of the mild ball-milled
E. ulmoides Oliv offered significant yield improvements over the traditional signal acidolysis procedure for isolating lignin from wood,
and the alkaline organic solvent extraction led to more lignin release than that of the mild acidolysis. This new procedure
proposed in this study could be used for the lignin structural analysis, whereby wood is mild ball-milled and successively
extracted with both mild acidic and alkaline organic solvents as well as aqueous alkalis to produce lignin fractions with
high yield and purity and representing the total lignin in wood. 相似文献
3.
Summary The lignin in birch wood has been subjected to analysis by oxidative degradation after milling of wood samples in a Wiley
mill and in a rotatory ball mill. For comparison milled wood lignin from birch has also been analysed. It was found that the
type of milling affects both the total yield of degradation acids and their relative frequency of occurrence. These findings
are interpreted as being due to a cleavage of aryl ether linkages during the milling procedure.
The oxidative degradation analysis gave rise to a total of 30 different acids which were tentatively identified on the basis
of their mass spectral fragmentation patterns. Among the acids some were found having either a phenoxyacetic acid or a phenoxypropionic
acid structure. The possible origin of these is discussed.
A grant to one of us (R.A.N.) from Jacob Wallenbergs Forskningsstiftelse is gratefully acknowledged. Thanks are due to Kristina
Gustafsson for skilful experimental assistance 相似文献
4.
超临界流体在林产工业中的应用 总被引：15，自引：0，他引：15
本文简述了超临界流体的特征和应用,着重叙述了超临界流体在林产工业中的应用,包括木材中低分子物质的超临界流体抽提、木材超临界流体脱木素和制浆、木材超临界流体热解和水解、黑液中木素的超临界流体抽提和造纸废水的超临界水氧化等。 相似文献
5.
Summary In an X-ray diffraction investigation, the recrystallization behavior of ball-milled Chinese southern pine wood was found to differ from that of cellulose. The crystallinity of lignocellulose milled for a very long time and recrystallized by wetting in water did not decrease with increasing milling time as was the case with milled cellulose. In addition, it appeared that the presence of lignin tended to restrict the amorphous cellulose produced by milling from recrystallizing into Cellulose II, whereas it had no influence on the recrystallization into Cellulose I. These results were discussed in the context of the mechanism of the conversion of Cellulose I to Cellulose II. 相似文献
6.
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. 相似文献
7.
8.
Pseudo-lignin induced by high-severity dilute acid treatment of lignocellulose has been widely studied because of its detrimental effect on enzymatic hydrolysis. However, cooling-induced pseudo-lignin (CIPL) formed during the cooling process after treatment has always been ignored and never been characterized systematically. To investigate the formation and chemistry of CIPL, liquid hot water treatments of poplar wood were conducted. Samples of treated wood and hydrolysate were taken out from digester at various temperatures during the cooling process for characterization. SEM images evidenced a progressive deposition of CIPL on the surface of the treated wood during cooling process with a yield of 19.6 mg/g treated wood. However, the treated wood which was collected isothermally at reaction temperature showed no pseudo-lignin. Variation of organic compounds in hydrolysate from lignocellulose degradation during cooling process revealed that depolymerized lignin and furfural accounted for 80.4 and 10.6 % of CIPL, respectively, while soluble saccharides from carbohydrate hydrolysis were independent from CIPL formation. These findings stress the importance of isothermal separation of treated wood and hydrolysate. Otherwise, CIPL should hinder enzymatic hydrolysis for biofuels production or delignification for cellulosic fiber production. 相似文献
9.
J. -Y. Chen Yuichi Shimizu Mitsuo Takai Jusuke Hayashi 《Wood Science and Technology》1995,29(4):295-306
Summary A new lignin isolation method has been developed. Wood and pulp were subjected to ball milling, swelled in an organic solvent, and then treated with a cellulase. The enzyme digestion time could be shortened to 1 day with this method. The lignin obtained has been named Swelled Enzyme Lignin (SEL). Swelling and enzyme digestion conditions and their effects on lignins were investigated. The SEL's from wood could be directly washed with water, while those from pulp had to be washed with aqueous acetic acid because they were water soluble. The purification of crude SEL's was accomplished by extracting them with dioxane-water, and then precipitating and washing with ethyl ether. Lignin yields were 24–67% based on the total amount of lignin present. The characteristics of the SEL's were further investigated by gel-permeation chromatography (GPC), infrared and 13C nuclear magnetic resonance (NMR) spectroscopy.Symbols SUKP
Softwood Unbleached Kraft Pulp
- BUKP
Birch Unbleached Kraft Pulp
- TD
Todomatsu (Abies sachalinensis) wood
- MWL
Milled Wood Lignin
- MWLS (BK, TD)
Milled Wood Lignin of SUKP (BUKP, TD)
- SEL-C
Swelled Enzyme Lignin (crude)
- SELS-C
SEL-C of SUKP, other materials named in the same way
- SELS-90
SEL-C of SUKP and extracted with 90% dioxane-water
- SELS-96
SEL-C of SUKP and extracted with 96% dioxane-water, other materials named in the same way 相似文献
10.
采用蒸汽爆破技术处理尾叶桉木材，研究蒸汽爆破对其主化学成分的影响，以及爆破材料用纤维素酶水解的工艺，确定了水解糖化条件：温度50qC，pH值4．8，酶用量25FPIU／g底物，底物浓度2％。结果表明，蒸汽爆破过程溶解出一定量的半纤维素和木质素，而纤维素基本不受损失，有利于提高酶解率；爆破前用硫酸预处理，木质素脱除率和木聚糖分解率在同样的爆破压力下比未用硫酸预处理的高。在最优的水解条件下，硫酸预处理，2．2MPa爆破的尾叶按木材多糖水解率达到82．43％，比未用硫酸预处理的提高36．86％。 相似文献
11.
Summary The behaviour of lignin-polysaccharide complex of spruce wood in soda pulping was studied by the characterization of lignin-saccharide fractions isolated from a series of soda pulps. The dioxane pulp lignins contain 8–14% of carbohydrates in which glucose was the predominant component. Its content increased with increasing degree of delignification indicating the formation of secondary lignin-carbohydrate linkage. Both glycosidic and ether type of bond between residual lignin and cellulose in pulp was proved by methylation analysis of the pulp dioxane lignin.The work was supported by the Slovak Academy of Sciences grant number 2/999389/92. 相似文献
12.
To elucidate the formation mechanism of acidsoluble lignin (ASL) formed in the Klason lignin determination, beech wood meals were treated with sulfuric acid (SA) under various conditions, and the ASL solution was extracted with CHC13. The results indicated the following: (1) wood components yielding ASL are dissolved in 72% SA during the initial stage; (2) the quantity of ASL is highest during the initial stage, then decreases with prolonged time of 72% SA treatment and finally reaches a constant value; (3) soluble lignin prepared by 72% SA treatment and subsequent standing in 3% SA again yield insoluble Klason lignin and ASL after boiling in 3% SA; and (4) about half the amount of ASL is dissolved in CHC13. The foregoing suggest that wood components yielding ASL are dissolved in 72% SA at the beginning and finally change to ASL after being subjected to depolymerization, hydrolysis, and other reactions. ASL may thus be composed of low-molecular-weight degradation products and hydrophilic derivatives of lignin. 相似文献
13.
Kazuchika Yamauchi Natthanon Phaiboonsilpa Haruo Kawamoto Shiro Saka 《Journal of Wood Science》2013,59(2):149-154
Japanese beech (Fagus crenata) wood was treated by two-step semi-flow hot-compressed water (the first stage: 230 °C/10 MPa/15 min, the second stage: 270 °C/10 MPa/15 min), and produced lignin-derived products in the hot-compressed water-soluble portions at the first and second stages, and the final residue of the second stage was characterized with alkaline nitrobenzene oxidation method and gel permeation chromatographic analysis. As a result, the lignin-derived products at the first stage, where hemicellulose was also decomposed, consisted of lignin-based monomers and dimers and oligomers/polymers in the water-soluble portion. A large part of the oligomers/polymers was, however, recovered as the precipitate during 12 h setting after hot-compressed water treatment. By the analysis of nitrobenzene oxidation products, there were relatively higher contents of ether-type lignin in the precipitate at the first stage than in original beech wood. Since the ether linkages of lignin are more preferentially cleaved by this hot-compressed water, lignin-based polymeric fractions were flowed out from the porous cell walls from which hemicellulose was removed. On the other hand, at the second stage condensed-type lignin remained in the precipitate and residue. Based on these results, decomposition behavior of lignin in Japanese beech wood as treated by the two-step semi-flow hot-compressed water was discussed regarding the topochemistry of lignin structure. 相似文献
14.
15.
本文讨论了木质纤维自身胶合的问题，湿法纤维板是实现自身胶粘的典型例子，提出利用木质纤维原料生成实现自身胶合，以及木质纤维原料表面活化是实现良好先决条件，对木质纤维原料自身胶粘的研究寄予厚望。 相似文献
16.
对汽爆麦草和麦草进行乙醇萃取木质素实验比较 ,其脱木质素分别为80 .2 2 %和 64.11%。进而分析了乙醇萃取脱木质素率、萃取渣的酶解率和抄纸性能。对乙醇萃取的汽爆麦草和萃取木质素进行了红外光谱、1HNMR电子能谱分析 ,并初步探讨了乙醇萃取木质素的作用机制 相似文献
17.
Condensation of lignin during heating of wood 总被引：3，自引：0，他引：3
Summary The structural change of lignin during heating of wood was investigated quantitatively by a method combining nucleus exchange and nitrobenzene oxidation. Lignin modification during heating was mainly a diphenylmethane type condensation. About 40 and 75% of noncondensed units in protolignins were converted to diphenylmethane type units by heating of dry and wet wood meals up to 220 °C, respectively. On the other hand, during heating of modified lignin (dioxane lignin) various types of modifications in addition to diphenylmethane type condensation occurred. Lignin modification via the diphenylmethane type condensation was proposed as a new route for its utilization. 相似文献
18.
Non-isothermal autohydrolysis treatments of Eucalyptus globulus wood were carried out in batch reactors in order to assess the kinetics of hemicellulose degradation, as well as the effects
caused on cellulose and lignin. Experiments were carried out at a liquor to wood ratio of 8 g/g, and two heating profiles
were explored. The maximum temperature considered was 224 °C, and the longest reaction time was 0.94 h. The experimental variables
considered were solid residue yield, solid residue composition and composition of liquors. Up to 90.4% of the initial xylan
was removed in treatments, which also caused some delignification (up to 13.8% of the initial lignin was removed), whereas
cellulose was almost quantitatively retained in solid phase. The conversion of xylan into xylooligomers, with further hydrolysis
to xylose and decomposition of this sugar into furfural was assessed by means of a kinetic model based on sequential, first
order reactions involving kinetic coefficients with Arrhenius-type dependence on temperature.
Received 23 November 1999 相似文献
19.
Xin Lu Kazuchika Yamauchi Natthanon Phaiboonsilpa Shiro Saka 《Journal of Wood Science》2009,55(5):367-375
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. 相似文献
20.
杨木预水解过程中化学组分的降解行为及P因子调控作用 总被引：1，自引：0，他引：1
预水解具有环境友好性,符合生物炼制的理念。前期关于预水解的研究多集中于半纤维素的降解、分离和利用,而有关预水解过程中木质素降解的系统研究鲜有报道。以杨木为原料,在130~210℃条件下保温30~120 min进行预水解,结合P因子研究得率、葡聚糖、木聚糖、酸不溶木质素和酸溶木质素的降解率,揭示P因子对木质素降解行为的调控作用,探讨各化学组分在预水解过程中的相互作用。研究表明,预水解过程中木质素发生了一定程度的碎片化。随温度升高和时间延长,酸不溶木质素降解率均逐渐升高;当温度为190和210℃时,随时间延长,酸溶木质素降解率先升高后降低。试验证明,P因子对杨木木质素的降解具有调控作用。随着P因子增加,酸不溶木质素降解率呈指数上升,且分为快速降解(P因子<1500)和缓慢降解(P因子>1500)两个阶段;酸溶木质素降解率先上升后下降,在P因子为1926时达到最大值45.9%。此外,预水解过程中碳水化合物和木质素的降解具有相互作用关系。碳水化合物的降解为木质素的溶出打开了物理通道,同时木质素的重新吸附阻碍了其进一步降解。 相似文献