木质素的电化学氧化

利用离子交换膜的选择透过性和直流电场作用手MAE技术是处理草浆黑液的一种可选方法，其结果表明MAE对黑液中的有机物具有一定的氧化作用，能使木质素中的芳环被氧化而找开。     

氧漂过程中脱木质素与木质素氧化之间定量关系的研究

对氧碱漂白过程中木质素氧化进行定量分析,分析方法是基于氧化前后高锰酸钾消耗量的变化。该方法对溶出残余木质素的氧化结果分析发现其呈明显3个阶段：第一段木质素氧化的当量电荷数约4～5／木质素单元;木质素总氧化电荷数大约为9／木质素单元。这些数据以及甲氧基的脱除（75％）均表明：木质素的氧化不仅发生在酚型木质素单元,同时也发生在非酚型结构单元上。只有第一阶段氧化反应是木质素与氧气直接反应,而在第二、三阶段主要是协同氧化作用,氧化反应过程中产生的活性氧基团扮演了一定角色。通过对低浓度针叶材硫酸盐浆的氧漂研究发现：当卡伯值下降一半（25．4至13．4）时平均每个木质素单元氧化3当量电子,氧漂后的纸浆中仍然有大量未被氧化的残余木质素。定量地证明了在氧漂过程中木质素氧化是脱木质素反应的实质。     

循环冷却水中木质素磺酸盐对细菌繁殖的影响

木质素磺酸盐是来源丰富、价格低廉的造纸制浆废液回收物。改性木质素磺酸盐(GCL2)具有较好的缓蚀阻垢性能。通过平皿计数法研究了不同类型木质素磺酸盐及其组分对循环冷却水中细菌繁殖速度的影响。结果表明，木浆木质素磺酸钙(简称木钙，CL)和草浆木质素磺酸镁(简称木镁，ML)对细菌繁殖具有明显的助长作用；木钙中的糖分是其对细菌助长作用的主要原因；GCL2对冷却水中细菌繁殖具有一定抑制作用；木钙经过氧化氢氧化后对细菌的繁殖具有明显的抑制作用。     

木质素分子在储能器件中的应用研究进展

木质素是一种绿色环保、低成本的不规则酚类聚合物,其结构中富含羟基和甲氧基等官能团,并且可以从造纸工业的副产品以及农林废弃物中大量获取,因此在各行各业中具有巨大的应用潜力。在储能领域,大量的研究报道了木质素作为可再生碳源制备用于储能装置的电极材料。近年来,越来越多的研究关注了木质素结构中丰富的官能团结构,并充分利用官能团性质将其应用于储能设备,如：利用羟基的亲水性将木质素应用于液流电池的膜结构中提高膜的质子传导率,利用酚-醌结构的可逆变化增加超级电容器的赝电容,利用与苯环共轭的发色基团对太阳能电池光电化学界面进行调控与敏化,利用木质素结构高电荷密度的含氧官能团改善锂离子电池存储的不稳定性,利用木质素分子中丰富的碳和杂原子官能团制备电极从而提高燃料电池的电化学性能。基于木质素分子的官能团结构和性能特点,概述木质素分子对超级电容器、锂离子电池、燃料电池、太阳能电池、液流电池等主流储能器件电化学性能的提升作用和代表性应用,认为最大化保留木质素分子的官能团并将其应用于电化学器件,可以实现木质素分子的多功能化应用,充分发挥木质素基团的特点以提高储能设备的电化学性能。最后,总结归纳了木质素分子应用于...     

非木本木质素磺酸镁的缓蚀性能及其氧化反应研究

非木本木质素磺酸镁(ML)来源于造纸厂非木本原料亚硫酸盐制浆废液，属于来源丰富、无毒的可再生生物质资源。作者研究了ML在循环冷却水中对碳钢的缓蚀性能，用失重法测定其对20^#碳钢的缓蚀率可达22％，缓蚀率随运行浓度升高而减小。通过氧化反应制备了改性木质素磺酸镁(MML)缓蚀剂，失重法测定其对20^#碳钢的缓蚀率可达75％，并且随运行浓度的升高而增大；通过测定粘度和红外光谱分析发现，氧化反应后ML分子被部分降解；通过电化学极化发现MML和ML都是阴极型缓蚀剂。     

漆酶催化活性中心结构及其特性研究进展

漆酶是一种多酚氧化酶，参与木质素的降解或聚合，具有氧化木质素的能力，但不同来源的漆酶其氧化降解木质素的能力相差很大。漆酶的结构决定了漆酶的特性，因而也就决定了漆酶氧化降解木质素的能力。本文综述了近10年来漆酶分子催化活性中心的结构与功能及其特性的研究进展。     

电化学催化木质素解聚的研究进展

综述了近年来木质素解聚的电化学技术的研究进展,包括木质素解聚的微观电化学表达、催化剂类型以及电化学反应器的电极材料、电极作用原理等;分析了电化学技术协同离子液体催化体系、生物酶催化体系以及与光催化技术耦合后对木质素解聚的前沿研究;总结了电极材料、电流密度等条件对电化学催化效率的影响,并展望了电化学技术实现应用所面临的挑...     

木聚糖超滤脱盐废水的电化学降解研究

用RuO2-Ti网作为阳极，Ti网为阴极对木聚糖超滤脱盐废水进行电氧化反应。结果表明：采用电化学法处理木聚糖超滤脱盐废水，使废水的色度、CODcr和BOD5由原来的1400倍、5160mg／L和l820mg／L降为50倍、150mg／L和100mg／L，达到国家排放标准。同时通过紫外光谱图探讨了电化学氧化作用的机理。     

仿酶催化脱木质素研究进展

综述了目前金属配合物仿酶催化脱木质素的研究现状及发展趋势，着重评价了卟啉类和非卟啉类金属配合物作为木质素氧化降解的仿酶催化剂的效果，对金属配合物仿酶催化脱木质素技术的应用前景进行了展望。金属卟啉配合物由于在相对温和的条件下具有较高的催化活性而受到瞩目。氯代铁卟啉由于氯原子对卟啉骨架环的保护作用而十分稳定，表现出高活性及可循环性。卟啉中心金属离子的种类也对脱木质素的催化活性产生影响。由于金属卟啉配合物的成本较高，因而给实际应用带来一定困难。非卟啉金属配合物如金属酞菁、Gif体系、希夫碱等，由于具有较高的催化活性和选择性以及易于合成等特点正倍受关注。     

对氯苯甲醛商机亮丽

对氯苯甲醛外观为无色片状结晶，其生产方法有多种，大多是以对氯甲苯为原料的合成路线，在该路线中主要有氯化水解法和氧化法两种，其中氯化水解法选择性好，总收率可达８０％左右，易于实现工业化生产。氧化法中的电化学氧化法生产成本低、产品纯度高、无三废污染、经济效益好。此外，以对硝基甲苯为原料的合成方法，该法工艺操作简便、产品质量好、原料来源广，具有较好的工业开发前景。 随着国内精细化工应用领域的不断开发，对氯苯甲醛已成为农药、医药、染料及有机合成的重要中间体。对氯苯甲醛与醋酥反应，再电解还原得对氯苯丙酸，…     

Analysis of progress of oxidation reaction during oxygen-alkali treatment of lignin I: method and its application to lignin oxidation

A new method is applied to evaluate the progress of the oxidation reaction of lignin during oxygen-alkali treatment. This method employs the difference in permanganate consumption of the sample before and after the oxygen-alkali treatment as an indication for the lignin oxidation. When kraft lignin and residual lignin isolated from unbleached softwood kraft pulp were subjected to oxygen-alkali treatment up to 6000min, the progress of the oxidation expressed by this method was separated into clearly distinguished three phases. During the first and second phases, the progress of oxidation was well correlated to the loss of methoxyl group and to the decrease in the yield of nitrobenzene oxidation products. The addition of Mn⁺ to the oxygen-alkali treatment depressed oxidation during the second phase partly and that during the third phase almost completely. Calculations based on the change in the permanganate consumption revealed that the oxidation during the first phase corresponded to 4.2 electrons abstracted from one lignin structural unit on average. The oxidation process by oxygen-alkali treatment was hypothetically attributed to the direct reaction between molecular oxygen and the phenolic unit of lignin, which mainly took place during the first phase, and to the autooxidation-type oxidation during the second and third phases.Part of this paper was presented at the 9th ISWPC, Montreal, June 1997; and at the 42nd Lignin Symposium, Sapporo, October 1997     

Application of the amount of oxygen consumption to the investigation of the oxidation mechanism of lignin during oxygen-alkali treatment

The dioxygen consumption by kraft lignin and several lignin model compounds during oxygen-alkali treatments were directly analyzed using a dioxygen fl owmeter. The average dioxygen consumption by 200 g of kraft lignin was about 3 moles. Because this value was as much as those obtained for monomeric phenolic lignin model compounds, guaiacol and vanillyl alcohol, it was postulated that not only phenolic but also nonphenolic moieties in kraft lignin are extensively oxidized. The dioxygen consumption by 0.5 moles (one equivalent of aromatic units) of a dimeric lignin model compound, guaiacylglycerol-β-guaiacyl ether (GG), was also similar to that for 1 mole of guaiacol and vanillyl alcohol, regardless of the type of the aromatic moiety, which supports the above postulation. The most plausible mechanism for the oxidation of nonphenolic moieties is the oxidation of side chains of residual β-O-4 substructures by active oxygen species. By this mechanism, nonphenolic moieties in kraft lignin and GG are converted into corresponding phenolic moieties, and the oxidation by dioxygen progresses. Part of this article was presented at the 13th International Symposium on Wood, Fiber, and Pulping Chemistry (13th ISWFPC), Auckland, New Zealand, May 2005     

木质纤维生物质的电化学催化研究进展

电催化是一种可以将电能转化为化学能的清洁、高效转化技术.在生物质精炼的各种策略中,电催化主要通过电子从电极表面转移到反应底物,在阳极和阴极分别发生氧化和还原反应,将生物质衍生物转化为高附加值的产品.总结了几种代表性的木质纤维生物质衍生物,如糠醛、5-羟甲基糠醛(HMF)、木质素及其衍生物等,通过电催化反应转化为高附加值...     

Attempts to understand the nature of phenolic and etherified components of wood lignin

Summary Periodate oxidation, because of its high selectivity in degrading phenolic nuclei, has been combined with nitrobenzene oxidation and phenyl nucleus exchange techniques to investigate the nature of wood lignin in situ. For both softwood and hardwood, the phenolic and etherified components of wood lignin have been shown to differ significantly in chemical composition, and the etherified lignin structure appears to be substantially more condensed.Financial support from the Empire State Paper Research Associate (ESPRA) and by the NRICGP of USDA (No. 93-37103-9318) is greatly appreciated     

Analysis of chemical changes in Picea abies wood decayed by different Streptomyces strains showing evidence for biopulping procedures

The present study is focused on analysing the suitability of different Streptomyces strains for biomechanical pulping purposes using spruce wood (Picea abies) as substrate. After 2 weeks of incubation, no apparent variations in lignin Klason content of treated woods were detected compared with the control. However, the increase in acid-soluble lignin fraction pointed out chemical alterations in lignin moiety. Through Py-GC/MS analysis enrichment in cellulose and lignin molecule modifications were detected in treated woods. The increase in the relative abundance of the most G-type phenol units with a higher oxidation degree suggests that some oxidation occurred in the lignin C3-alkyl chain. In addition, the decrease in the phenylmethane + phenylethane/phenylpropane (phC1 + ph C2/ph C3) ratio would indicate the ability of Streptomyces strains to breakdown the C3-alkyl chain linkages once carbons had been oxidized. From this study it could be concluded that the assayed strains are able to produce a delignification of spruce wood which may improve mechanical pulping processes.     

Characterization of lignin-derived products from Japanese beech wood as treated by two-step semi-flow hot-compressed water

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.     

Analysis of progress of oxidation reaction during oxygen-alkali treatment of lignin 2: significance of oxidation reaction of lignin during oxygen delignification

The progress of lignin oxidation during oxygenalkali bleaching of pulp was evaluated by the method based on the difference between permanganate consumption of original pulp and that of the mixture of pulp and effluent after oxygen-alkali bleaching. By low-consistency oxygen bleaching of softwood kraft pulp, the permanganate consumption decreased very little. When the kappa number of the pulp was halved (from 25.4 to 13.4), the decrease in permanganate consumption of 1 g pulp was only 1.22ml of 0.02mol/l potassium permanganate. This value was smaller than that obtained for the oxygen-alkali treatment of a corresponding amount of isolated residual lignin, 6.40ml. This was not due to the slow oxidation of lignin in pulp but to the formation of permanganate-consuming substances from carbohydrates. Those newly formed substances cannot be oxidized by oxygen-alkali treatment. Taking these facts into account, lignin originally present in pulp was found to be oxidized well. Reduction of carbonyl groups in carbohydrates prevented the formation of such substances.Part of this paper was presented at the 10th ISWPC, Yokohama, June 1999; and at the 43rd Lignin Symposium, Fuchu, October 1998     

Evaluation of the extent of the oxidation reaction during chlorine bleaching of pulp

A modified method was developed to evaluate how much chlorine is consumed by the oxidation reaction during the chlorine bleaching process. This evaluation is, in principle, based on the sum of chloride produced during the chlorination stage (C-stage) and produced during alkali treatment of both the C-stage effluent and the chlorinated pulp. Results obtained by this method proved that about 50%–75% of chlorine was consumed by the oxidation reaction during chlorine bleaching, depending on the reaction condition of chlorination. Even under a reaction condition that is not favorable to an oxidation reaction (low pH), approximately three electrons were abstracted from one lignin structural unit by chlorine bleaching. This result provides additional evidence for our recent observation that lignin is extensively oxidized during chlorine bleaching even when pure chlorine without any chlorine dioxide substitution was used.Part of this paper was presented at the 40th Lignin Symposium. Tsukuba, Japan, October 12, 1995