阔叶木碱法造纸黑液提取物成分的研究

应用裂解-气相色谱-质谱、红外色谱、凝胶色谱、元素分析仪研究了阔叶木碱法造纸黑液提取物的成分.结果表明:黑液中含有木质素、有机酸等物质.其中,阔叶木木质素属愈创木-紫丁香(GS)型木质素,木质素分子中存在少量的α-β碳碳双键,紫丁香基结构单元的质量分数高于愈创木基结构单元,二者质量分数比为2.27;木质素的结构经验式为...     

碱法造纸废液的化学利用

木材中除含纤维素外还含有20%左右的木质素。木质素并非一种固定有机化合物,而是一些相似化合物的聚合物,其分子结构目前尚无法准确测定,从化学角度讲,木质素是由邻甲氧苯基丙烷的单体形成。碱法制浆过程中,在NaOH 作用下使木质素中的酚醚键及木质素与碳水化合物之间的键断裂开,生成可电离游离酚羟基的较小的分子,溶于稀碱溶液中,形成污染严重的黑液。木质素以碱木素形式存在,一般以下式表示:碱木素分子中含有甲氧基、酚基和脂肪族羟     

木质素絮凝剂的研究进展

根据不同的制浆方法,文章介绍了3种从造纸黑液中提取木质素的方法:从硫酸盐法草浆黑液中提取木质素、从碱法草浆黑液中提前木质素、从亚硫酸盐法纸浆黑液中提取木质素。木质素作为阴离子型高分子絮凝剂,对酿造废液和合成染料废水的处理效果良好。文章还介绍了几种改性木质素的应用。     

模拟烟道气处理碱法纸浆黑液回收木质素的研究

本文根据用纯CO_2处理碱法纸浆黑液回收木质素的规律,研究用烟道气代替纯CO_2的可能性。试验采用模拟烟道气处理碱法蔗渣纸浆黑液,研究了“烟道气”中CO_2含量和通气量与木质素回收率的关系。试验结果表明,模拟烟道气代替纯CO_2处理黑液,其木质素回收率大约下降了10％。     

定量~(13)C-NMR谱表征蔗渣碱木素结构

从蔗渣纸浆黑液中制出纯蔗渣碱木素，然后测定其定量13C-NMR谱．图谱分析表明，蔗渣碱木素主要由紫丁香基，愈创木基和对羟苯基三种丙烷结构单元组成，其中未绩合的紫丁香基、愈创木基和对羟羊基含量比为2.2：1．0：1．4．蔗渣碱术素结构单元间主要以β-O－4烷基芳基醚键连接，也有一定量的非环状α-醚键存在．蔗渣碱木素中，相当部分对香豆酸类结构并非通过酯键而是通过醚键或碳双键连接于芳核上．     

碱法制浆造纸黑液的资源化利用

从我国造纸工业的污染现状及环境保护的角度出发,提出碱法制浆黑液资源化利用的观点。对木质素的结构和性质及其磺化改性的工艺及机理做了相应介绍,对改性产物木素磺酸盐的应用领域研究成果做了综述,最后总结了制浆黑液综合治理资源化利用的意义。     

稻麦草碱法纸浆黑液酸化处理的研究

一、前言将稻麦草碱法[NaOH或Ca(OH)_2]制浆废水—纸浆黑液进行酸化处理,可以回收溶解在黑液中的木质素。木质素是一种天然的芳香族高分子化合物,亦是一种表面活性物质,很有回收价值。近年来,世界各国对黑液中溶解的木质素展开了广泛的工业研究。从发展来看,木质素的用途将会越来越广泛和变得宝贵。我国众多的中、小型造纸厂多采用稻麦草碱法制浆。到目前为止,稻麦草纸浆     

木质素磨削液的研制与应用

利用碱法草浆黑液经磺化、复配研制成的木质素磨削液,经测试性能良好。可代替易变质发臭、使用期短的乳化液。木质素磨削液的研制成功.为碱法草浆蒸煮黑液的工业利用提供了新途径。     

水溶性和碱溶性蔗渣木质素的分离与表征

以蔗渣为原料,经脱蜡后依次用H₂O、1% NaOH和3% NaOH进行抽提,分别得到水溶性木质素L1和碱溶性木质素L2、L3,并对其理化性质和结构特征进行分析。通过硝基苯氧化法、高效液相色谱检测来确定蔗渣木质素的组分,通过凝胶渗透色谱检测蔗渣木质素的分子质量,利用紫外分光光度计和二维核磁共振推导出蔗渣木质素的结构单元和连接方式。结果表明,L1、L2和L3的得率（以绝干原料计）分别为0.4%、5.7%和3.7%,占蔗渣木质素总量的54.1%,而且水溶性木质素分子质量大于碱溶性木质素。L2和L3主要来自于蔗渣次生壁,富含紫丁香基单元和大量的非缩合醚结构。蔗渣木质素的结构单元间的主要连接方式是β-O-4'醚键,还有β-β'、β-5'和β-1'等碳碳结构。蔗渣木质素是由紫丁香基、愈创木基和少量对羟苯基结构单元组成的GSH型木质素,此外,还含有对香豆酸和阿魏酸,通过酯键与木质素相连。     

相分离条件下楠竹碱木素改性产物的集聚态研究

楠竹经三种条件碱法蒸煮,所得黑液经酸化沉淀干燥,用60％（wt）硫酸、相分离法处理,精制有机相得到三种碱木质素酚,将三种碱木质素酚分别与由竹粉经相分离法直接提取的木质素酚通过红外光谱（FT-IR）、凝胶色谱（GPC）、原子力显微镜（AFM）、动态光散射（DLS）进行结构和分子集聚态的分析与比较.结果表明,在缓和的碱法蒸煮条件下,黑液中的木素还具备一定的酚化改性潜力,所得碱木素酚结构和官能团与竹粉木质素酚未见较大差异,但在分子集聚态上其分散性明显不同于竹粉木质素酚,表现为尺度小,分布密集等特点.     

Delignification of Pinus taeda wood chips treated with Ceriporiopsis subvermispora for preparing high‐yield kraft pulps

Pinus taeda wood chips were treated with the white‐rot fungus Ceriporiopsis subvermispora in 20‐dm³ bioreactors for periods varying from 15 to 90 days. Decayed samples, non‐inoculated controls and extractive‐free wood samples were submitted to kraft pulping using 25% of sulfidity and different active alkali concentrations in the cooking liquor. Cooking reactions were carried out isothermally at 170 °C. Residual lignin contents of pulps prepared from biotreated wood chips were lower than those observed in pulps from the undecayed control. Delignification kinetic studies showed that the initial delignification phase was accelerated and shortened by the fungal pretreatment. At a cooking time fixed before the end of the bulk delignification phase, the fungal pretreatment provided pulps with significantly lower kappa numbers or pulps with a fixed kappa number were obtained by reducing the amount of active alkali added to the liquor. Pulps of kappa 80 were obtained both from the undecayed control cooked with 20.8% of active alkali and from the 15‐day‐biotreated sample cooked with only 15% of active alkali. The biopulping benefits were neither proportional to the extent of the biodelignification nor to the biological removal of some specific wood component. DFRC‐determination (derivatization followed by reductive cleavage) of the amount of aryl–ether linkages in residual lignins of biotreated samples indicated an extensive depolymerization during the initial stages of biodegradation, which suggested that bio‐depolymerized lignin was easily released during the first stages of cooking, resulting in a faster and shorter initial delignification phase. © 2002 Society of Chemical Industry     

Modified Kraft Pulping of Bagasse: Infrared Spectroscopy of Lignin

Abstract

The infrared spectroscopy of precipitated lignin from waste black liquors of bagasse pulping with kraft sulfite pulping process was investigated. Also the effect of anthraquinon and methanol addition in the soda, kraft and kraft-sulfite pulping liquor on the infrared specra of the precipitated lignin was studied. The presence of methanol in the pulping liquor causes an increase in the degradation as well as increase in the carboxylic group in the precipitated lignin. Also, the phenolic hydroxyl group in case of kraft lignin is higher than soda lignin. Presence of sulfite in the kraft-sulfite pulping liquor produces lignin hydroxyl groups.     

Purification process for recovering hydroxy acids from soda black liquor

Black liquor, a side product of chemical pulping, contains hydroxy acids that have many potential applications, e.g., as polymer precursors. Currently there are no feasible separation processes available for recovery of hydroxy acids from such solutions. Neutralization is usually though to be a necessary pre-treatment, but it adds into chemical consumption and may impede the integration of the recovery process to a pulp mill. In this work, an experimental investigation of a new process concept for the recovery and purification of hydroxy acids from soda black liquor without neutralization is presented. The process consists of ultrafiltration, size-exclusion chromatography, ion-exchange, adsorption, and evaporation. Mixtures of hydroxy acids in high purity were produced from black liquor of soda pulping using the process. A reduction of 99% in lignin content of the organic acid fraction was achieved. In the chromatographic separation step, the recovery of sodium hydroxide was almost 100%. The average purities of hydroxy acids isolated from softwood and hardwood black liquors were 81% and 63% on mass basis, respectively.     

Structural Characterization of Pine Kraft Lignin: BioChoice Lignin vs Indulin AT

BioChoice lignin (BCL) is a newly commercialized pine kraft lignin from Plymouth Mill of Domtar, which is precipitated from black liquor of bleachable-grade pulp. Indulin AT is a pine kraft lignin commercialized by Meadwestvaco for the past 60 years, which is precipitated from black liquor of linerboard-grade pulp. Thus, the two technical lignins are produced under quite different conditions in terms of alkali charge and pulping time/temperature. While the chemical structure of Indulin AT is well documented, that of BCL is totally unknown. In this study, chemical structures of BCL and Indulin AT are characterized using modern analytical techniques and compared with those of pine milled wood lignin (MWL) in order to elucidate the structural changes that occur during kraft pulping and the structural differences, if any, between BCL and Indulin AT. Both BCL and Indulin AT are structurally very different from the native lignin (MWL) in wood, indicating drastic structural modification during the kraft pulping process. Surprisingly, BCL and Indulin AT are structurally very similar, in spite of the fact that they are produced under different process conditions. However, there are subtle structural differences between BCL and Indulin AT. BCL has higher phenolic hydroxyl, catechol, enol ether, and stilbene contents, but lower methoxyl and β-O-4 contents. These differences are explained by the different pulping conditions under which the two technical lignins are produced.     

Electrochemical Treatment of Black Liquor from Straw Pulping

Abstract

The conventional black liquor regeneration process is not always suitable for pulping plants of nonwood fibers due to the unfavorable ratio of organic to inorganic solids. This paper presents an alternative treatment based on an electrolysis process of the soda black liquor from straw pulping. This alternative method minimizes the environmental impact by recovering the caustic at the same time that the liquor is acidified, which favors the later separation of the lignin.     

Laser-Induced Fluoresence of Lignins with Excitation from 457 to 621 Nanometers

Laser-induced fluorescence has been used to examine changes in lignin and black liquor during the course of kraft pulping. When excited with a laser at 457 and 488 nm, lignin samples isolated during the course of pulping, purified, and redissolved in alkali exhibited increasing fluorescent emission intensity. This may be explained by changes in lignin structure during pulping. At higher excitation wavelengths, differences between samples diminished. Black liquors showed decreasing fluorescent intensity with increasing pulping. We attribute this behavior to the increase in optical density of the liquors as cooking time proceeds. The optical density increases with cooking time proceeds. The optical density increases with cooking time because greater amounts of lignin and other materials dissolve from the wood and enter the black liquor.     

The Characteristics and Reactivity of Acid-Labile Aryl Ether Units in Wood Lignin

Wood lignin contains significant amounts of acid-labile aryl ether units, which play a significant role in lignin modification or delignification processes. We have evaluated the rate and reaction kinetics on the acid-catalyzed cleavages of aryl ether structures for wood lignin in situ based on the formation of phenolic hydroxyl groups. The content of acid-labile aryl ether units was quite uniform for a variety of softwood wood lignins (～4% per C₉ unit) and it varied appreciably among hardwood species, ranging from 4% for aspen to 9% for beech wood lignin. These variations, however, appear to be related to the content of syringyl units in wood lignin. The reactivity of these reactive aryl ether structures was noticeably higher for the spruce than for the aspen wood lignin. This difference in reactivity, based on the behavior of lignin model compound reactions, can be attributed to the influence of syringyl moieties in aspen wood lignin. It appears that most of the acid-labile aryl ether units in hardwood were associated with the syringy moiety being present as a benzyl unit, which is much less reactive than the corresponding guaiacyl moiety.     

Characterization of Lignins from Organosolv Pulping According to the Organocell Process. Part 4. Molecular Weight Determination and Investigation of Fractions Isolated by GPC

Soluble and residual spruce lignins were subjected to permanganate oxidation and thioacidolysis to elucidate changes in lignin's structure during Organocell pulping.

As expected degradation reactions known from soda pulping are dominant especially in stage 2, including extensive enol ether formation. The chemical effect of methanol appears to be restricted to a minor methylation of the α-C-atom which prevents quinone methide formation and thus suppresses subsequent condensation reactions. Other beneficial effects of methanol such as liquor diffusion into the chips and a better lignin solubility obviously contribute to the successful delignification of softwoods in Organocell pulping.