硫酸盐木素及其应用

1前言木素（又称木质素）是木板材料的主要成分之一，是一种储量丰富却没有对其充分利用的宝贵资源。木素属天然高分子化合物，具有超分子特性和高比表面积，并且还含有较多的表面活性基团，如酚羟基、苄式羟基、羰基、羧基、乙烯基等。由于这些活性基团的存在，使木素容易进行多种化学改性反应，如磺化、硫氢化、硝化、卤化、甲酸化、氰乙基化、酚化以及接技共聚等。硫酸盐水素是由硫酸盐法制浆废液中提取出来的。目前的制浆工艺所产生的废液（亦称黑液）都采用蒸发、燃烧、苛化等过程用以回收热能和烧碱，然而这一工艺只能回收占黑液于固…     

硫化钠预处理制浆残余木质素的化学结构特性

用化学和波谱分析研究了硫化钠预处理硫酸盐制浆中残余木质素的化学结构特性。结果表明 ,硫化钠处理能促进硫与木片中木质素的结合 ,而甲氧基的含量有所下降。与对照硫酸盐制浆相比 ,预处理条件下木质素的缩合程度较低 ,经过蒸煮后残余木质素的缩合程度有较大的提高。     

红麻硫酸盐法蒸煮中溶出木素的分子量分布及变化

采用凝胶色谱法（GPC）对红麻皮和秆芯硫酸盐法蒸煮过程中溶出木素的分子量及其分布的变化进行了研究。结果表明，随着蒸煮的进行，红麻皮和秆芯溶出木素的平均分子量逐渐增大，多分散性和特性粘数也相应增大。此外，在同一蒸煮条件下，红麻秆芯溶出木素的平均分子量高于红麻皮，这也说明了红麻秆芯比红麻皮更难脱木素。研究还发现，红麻原料木素以及溶出木素的分子量分布曲线都呈单峰现象。     

硫酸盐蒸煮过程中溶出木质素特性的变化

用化学和波谱分析研究了常规硫酸盐制浆过程中溶出木质素化学结构特性的变化。结果表明 ,溶出木质素的缩聚程度较高 ,其共轭双键的增加主要发生在蒸煮前期。蒸煮过程中木质素的降解溶出伴随着甲氧基的脱除反应 ,木质素溶出之后基本不存在脱甲氧基反应。随着蒸煮反应的进行 ,溶出木质素的醇羟基不断减少 ,而酚羟基则不断增加     

硫酸盐法提取竹子木素的工艺研究

采用传统的硫酸盐法制浆工艺,对竹子进行木素提取和造纸实验.优化的蒸煮工艺条件为:温度170℃,升温90 min,保温30 min;用碱量17.5%(以NaOH计),硫化度20%,粗浆得率47.65%,废液木素浓度49.43%,木素提取率78.10%,并用电镜、能谱对提取液和纤维进行分析,Na、S含量高,对碱的回收是减少污染的重要问题,提出采用不含Na和S元素的制浆法可减轻对环境的污染,使后处理简化.     

枫香树材硫酸盐制浆工艺技术研究

通过对枫香树材硫酸盐蒸煮的用碱量、硫化度、温度和保温时间四因素三水平方差分析工艺技术研究发现,在所选的四因素三水平内,用碱量对浆料得率和卡伯值的影响最大,硫化度对浆料得率和卡伯值的影响最小。枫香树材硫酸盐蒸煮较为适宜的工艺条件为:用碱量17%(Na2O计),硫化度20%,温度165℃,保温时间60 min,液比1∶6。另外,在枫香树材硫酸盐蒸煮过程中添加AQ,对提高蒸煮脱木素选择性具有明显的效果。     

硫酸盐制浆废水的厌氧生物处理

本文是对用厌氧生物法处理酸盐制浆废水的一次尝试。实验证明,只要控制好合适的微生物生长环境。即使是在高浓、难以暴气处理的硫酸盐制浆废水中厌氧菌也能很好地生长,消化分解一部分有机物。发酵过程中,温度应控制在40℃以上,最佳pH值为7.0或略高于7.0,而滞留时间可视废水处理的工艺要求而定。厌氧发酵处理硫酸盐制浆废水可作为一种治理环境的手段,如果要从产甲烷的角度考虑,就必须排除硫对甲烷菌的干扰,或者优选出单纯的抗硫菌,本文采用酸化法除硫产生了一定的效果。     

磺甲基化硫酸盐木素的表面活性研究

本文探索采用硫酸盐木素制备混凝土减水剂的可能性,研究了分子量和碘化度对磺甲基硫酸盐木素表面活性的影响。其结果表明,将硫酸盐木素磺甲基化能够制得一种优良的混凝土减水剂。     

Investigation of oil palm based Kraft and auto-catalyzed organosolv lignin susceptibility as a green wood adhesives

The aim of this study is to highlight the application and potentiality of oil palm based lignins in the synthesis of green phenolic resins. The delignification processes were conducted using Kraft and auto-catalyzed ethanol–water pulping processes. The extracted lignins were characterized using elemental analysis, Fourier transform-infrared, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, molecular weight distribution (M_n, M_w and polydispersity), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The obtained FTIR results revealed that the Kraft lignin contained substantial amounts of guaiacyl units with smaller amounts of syringyl units. The molecular weight of Kraft lignin was 1564 g mol⁻¹ which is higher than organosolv lignin at 1231 g mol⁻¹. The activated free ring position (2.99%) of Kraft lignin was comparatively higher than that of organosolv lignin (2.06%) which was measured using Mannich reactivity analysis. Thermal analysis of Kraft lignin showed higher thermal stability compared to organosolv lignin. The structural and thermal characteristics implied that Kraft lignin had higher potential for the production of green phenolic resins when compared with organosolv lignin.     

Effect of Kraft Cooking Conditions on the Chemical Composition of the Surface and Bulk of Spruce Fibers

By varying cooking temperature, alkali charge, ionic strength, and cooking time in Kraft pulping of spruce chips, pulps ranging between kappa numbers 20–80 were obtained. The unbleached Kraft pulp fibers were subjected to mechanical peeling in order to separate the surface material from the bulk of the fibers and the carbohydrate composition and lignin content of the two fractions were analyzed. As expected, the lignin and xylan contents were higher on the fiber surface than in the fiber wall. The percentage of xylan on the fiber surface was fairly constant, independent of different pulping conditions or degree of delignification. The lignin proportion on the fiber surface gradually decreased with decreasing kappa number. At a given kappa number, pulping at a higher temperature resulted in less lignin on the fiber surface, probably because of the higher solubility of lignin at higher temperature. Cooking at lower alkali charge also resulted in lower lignin content on the fiber surface at a given kappa number. In this case, there was more time available for degradation of the surface lignin since the lower alkali charge resulted in longer cooking time needed to reach a certain kappa number.     

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.     

Reactions of Conventional Kraft and Superbatch Pulp Residual Lignins with Peroxyformic Acid

Abstract

The residual lignins KRL and SRL, isolated from a conventional kraft pulp and a SuperBatch pulp respectively, were reacted with peroxyformic acid (PFA). The reagent consumptions were determined and the products fractionated according to their solubility. Both lignins consumed a roughly equal amount of PFA, which was nearly 50% higher than that consumed by kraft lignin. The undissolved fractions of PFA-treated residual lignins (yield >80%) contained less aromatic units, phenolic hydroxyl and methoxyl groups, and considerably more carboxyl groups (including those of formate esters) than the untreated lignins. The extent of these modifications was approximately equal for KRL and SRL, which together with the similar PFA consumptions and product yields of KRL and SRL indicates that the two residual lignins showed no essential difference in reactivity toward PFA. The effect of fiber wall morphology on delignification efficiency during PFA delignification is suggested to be small because of the cleavage of lignin-carbohydrate linkages occurring under acid conditions. The part of KRL remaining insoluble after PFA-treatment had a 40% higher molar mass than KRL while in the case of SRL there was hardly any such difference in molar mass. The lignins solubilized during the PFA treatments represented the most highly degraded part of the lignins, having very low molar masses and being richer in carboxyl groups and lower in aromatic units, phenolic hydroxyl, and methoxyl groups than the undissolved lignins.     

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.     

Preparation of functionalized Kraft lignin beads

Kraft lignin from black liquor wastes have been converted into epichlorohydrin‐crosslinked beads by inverse suspension polymerization. A careful control of the different parameters allowed the preparation of spherical beads with a relatively narrow diameter size distribution. The obtained beads, without permanent porosity, swell well in hydroalcoholic media. Grafting of the sulfonylhydrazine moiety using a two‐step route was further performed to apply them to carbonyl compounds scavenging. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kraft lignin degradation products for tanning and dyeing of leather

Kraft lignin degradation by a biomimetic system was investigated, using hemin as a catalyst and hydrogen peroxide as an oxidising agent, which mimics the catalytic mechanism of lignin peroxidase (LiP) to produce phenolic compounds. The degradation products were identified using spectroscopy and gas chromatography–mass spectrometry (GC–MS): 2‐methoxyphenol, 4‐hydroxybenzaldehyde, vanillin and vanillic acid were produced and their formaldehyde polymerisation products used for tanning hide powders. The denaturation (shrinkage) temperature of hide powder was raised to 80 °C through hydrogen‐bonding interactions between the polymers and the collagenic hide powder. For dyeing of hide powder, the lignin degradation products were reacted with laccase (a polyphenol oxidase): 2‐methoxyphenol gave the darkest colour. These products have potential to be used as raw materials for tanning and dyeing of animal skins. Therefore, value can be added to this industrial byproduct and reduce its environmental impact. Copyright © 2004 Society of Chemical Industry     

Sulfonation of Phenolated Kraft Lignin to Produce Water Soluble Products

Kraft lignin is water insoluble and has limited end-use applications. To produce water soluble lignin-based products, the modification of softwood kraft lignin through phenolation followed by sulfonation of sulfuric acid or sodium sulfite treatment were investigated in this work. Fourier transform infrared (FTIR) spectrophotometer, nuclear magnetic resonance (NMR), and thermo-gravimetric analysis were also considered for characterizing the lignin-based products. The results showed that phenolation pretreatment was effective to generate sulfonated lignin (SAP-lignin) by sulfuric acid treatment with a high charge density (3.12 meq/g) and solubility, which is due to the addition of sulfonation sites on the phenolic ring. However, sodium sulfite treatment of phenolated lignin generated sulfonated lignin (SSP-lignin) with the charge density of 1.20 meq/g due to hindered sulfonation by occupation of reactive α-position. SAP-lignin was soluble across the tested pH range of 1–13, but SSP became insoluble at a pH lower than 3. Thermogravimetric analysis revealed that phenolation pretreatment reduced the thermal resistance of modified lignin when compared to kraft lignin, while SAP-lignin exhibited the highest thermal resistance due to condensation under sulfuric acid treatment. SAP- and SSP-lignin were successfully used as a coagulant for dye removal from simulated solutions as they could remove 72.1 and 90.4% of ethyl violet from a simulated dye solution, respectively.