SO2-Ethanol-Water (SEW) Pulping: I. Lignin Determination in Pulps and Liquors

Abstract

Quantitative determination of lignin in SO₂-ethanol-water (SEW) pulps and spent liquors is described. The methods developed for conventional sulfite pulping are successfully applied to the SEW process. Linear correlations between Klason/total lignin content and kappa number are found over a wide pulp yield range for spruce, beech, and wheat straw. Lignin content of the spruce spent SEW liquors is determined using either hydrogen peroxide to remove SO₂ and dilution by 3% sulfuric acid or simply by dilution with 0.1M sodium hydroxide. The recommended wavelength is 280 nm. The experimentally found values for the extinction coefficient of dissolved lignin in 3% sulfuric acid and in 0.1M NaOH are 19 and 23 L/(g·cm), respectively. The interference of furanic compounds is eliminated by reduction with sodium borohydride.     

有机溶剂型木质素提取方法探索

本文采用有机溶剂法对汽爆稻壳中木质素的提取工艺进行了探索，通过正交分析提出了合适的提取方法以及最优的工艺条件，并对木质素产品的理化指标及结构特点进行了表征。结果表明，有机溶剂型木质索（organosolv lignin）与传统木质素产品相比具有灰分、残糖含量低，分子量大小和分布适中以及活性基团丰富等优点，在高分子材料的合成和改性领域有广阔的应用前景。     

麦草氧碱木素合成聚氨酯及其性能的研究

利用麦草氧碱木素取代部分聚乙二醇合成了木素 聚醚型聚氨酯 ,对其热性能、机械性能进行了初步研究。结果表明 ,麦草氧碱木素可取代部分聚乙二醇与二苯甲基二异氰酸酯合成木素 聚醚型聚氨酯 ,异氰酸基指数和木素含量对合成的木素 聚醚型聚氨酯性能有着重要影响     

制浆造纸厂实行生物炼制的可行性

生物炼制是解决石化资源紧缺的新途径,而制浆造纸厂是生物炼制技术最容易实现产业化的平台。文章综述了制浆造纸厂中半纤维素、木质素、松节油、妥尔油等废弃生物质进行生物炼制的可行性及存在的问题,并对发展前景作了展望。     

Separation of Alcohols from Solution by Lignin Gels

Abstract

Partition relationships of radioisotope labeled ethanol and 1-butanol between aqueous solutions and a hydrated commercial Kraft softwood lignin gel are presented. These initial evaluations indicate that lignin hydrogels preferentially concentrate 1-butanol and, to a lesser extent, ethanol. The process implications and potential use of lignin as an inexpensive extractant are discussed.     

溶剂型木质素在高分子合成和改性中的应用

溶剂型木质素(Organosolv lignin)与传统木质素盐类相比具有反应活性基团含量高、容易提纯以及不含任何含硫杂质等优势,论文着重介绍了溶剂型木质素的制备、结构特点以及近几年来在高分子合成和改性领域的研究进展,并对其发展方向作了总结。     

Fiberboards Based on Sugarcane Bagasse Lignin and Fibers

Summary: Fiberboards were prepared using phenolic type resins (phenol‐formaldehyde) and sugarcane bagasse fibers. Lignin extracted through an organosolv process from sugarcane bagasse was used as substitute of phenol in phenolic resins from 40 (lignin‐phenol‐formaldehyde) to 100 wt.‐% (lignin‐formaldehyde) substitution. Some of the fibers were chemically modified by oxidation with chlorine dioxide and treatment with furfuryl alcohol (FA), leading to fibers coated with polyfurfuryl alcohol. Thermal analysis (DSC and TGA) of the prepolymers allowed setting up an efficient curing to prepare fiberboards. Impact strength and water absorption were measured showing the importance of the curing pressure to obtain good performance. When chemically modified fibers were used to prepare board samples, enhanced durability against white root fungi is observed, and to a less degree against brown root fungi. Sugarcane bagasse fiberboards were prepared from prepolymers where lignin substituted phenol up to 100%. This replaces these materials in advantageous position, relating to those prepared from phenol‐formaldehyde resins, due to their high content of renewable raw materials. The results obtained are promising for the utilization of sugarcane bagasse as raw materials for preparing fiberboards to be used in tropical areas.

Stabilization of sugarcane bagasse fiberboards made with unmodified and modified (ClO₂ + furfuryl alcohol) fibers and phenolic resin after 8 weeks exposure against fungi.     

Structural Variation of Bamboo Lignin before and after Ethanol Organosolv Pretreatment

In order to make better use of lignocellulosic biomass for the production of renewable fuels and chemicals, it is necessary to disrupt its recalcitrant structure through pretreatment. Specifically, organosolv pretreatment is a feasible method. The main advantage of this method compared to other lignocellulosic pretreatment technologies is the extraction of high-quality lignin for the production of value-added products. In this study, bamboo was treated in a batch reactor with 70% ethanol at 180 °C for 2 h. Lignin fractions were isolated from the hydrolysate by centrifugation and then precipitated as ethanol organosolv lignin. Two types of milled wood lignins (MWLs) were isolated from the raw bamboo and the organosolv pretreated residue separately. After the pretreatment, a decrease of lignin (preferentially guaiacyl unit), hemicelluloses and less ordered cellulose was detected in the bamboo material. It was confirmed that the bamboo MWL is of HGS type (p-hydroxyphenyl (H), vanillin (G), syringaldehyde (S)) associated with a considerable amount of p-coumarate and ferulic esters of lignin. The ethanol organosolv treatment was shown to remove significant amounts of lignin and hemicelluloses without strongly affecting lignin primary structure and its lignin functional groups.     

Beyond Yield Optimization: The Impact of Organosolv Process Parameters on Lignin Structure

When optimizing the process parameters of the acidic ethanolic organosolv process, the aim is usually to maximize the delignification and/or lignin purity. However, process parameters such as temperature, time, ethanol and catalyst concentration, respectively, can also be used to vary the structural properties of the obtained organosolv lignin, including the molecular weight and the ratio of aliphatic versus phenolic hydroxyl groups, among others. This review particularly focuses on these influencing factors and establishes a trend analysis between the variation of the process parameters and the effect on lignin structure. Especially when larger data sets are available, as for process temperature and time, correlations between the distribution of depolymerization and condensation reactions are found, which allow direct conclusions on the proportion of lignin's structural features, independent of the diversity of the biomass used. The newfound insights gained from this review can be used to tailor organosolv lignins isolated for a specific application.     

麦草木素在臭氧处理中的作用行为

采用FTIR和1H-NMR研究了麦草木素在臭氧处理中的作用机理。结果表明,在麦草木素臭氧处理中,苯环开裂,愈创木基较易降解,对羟苯基发生降解,酚羟基增加,甲氧基减少,酯键断裂,发色基团、助色基团减少。     

两种木质素对纤维素酶水解的影响机制

为探究木质素对纤维素酶水解效率的影响,将苦竹中提取的乙醇木质素（EOL-B）和磨木木质素（MWL-B）作为模型物添加到微晶纤维素中进行酶吸附和水解。结果表明：添加8 g/L MWL-B使得反应72 h的葡萄糖得率从51.34%降低到46.06%;添加8 g/L EOL-B使得反应72 h葡萄糖得率从51.34%增加到61.06%。与MWL-B相比,EOL-B与纤维素酶蛋白之间亲和力和结合力较低,故纤维素酶在EOL-B上的非特异吸附更少。FT-IR和¹³C NMR分析表明：经乙醇处理后,木质素分子中C-C凝缩单元减少,β-O-4'键断裂,导致木质素分子的亲水性增加,阻断了与纤维素酶蛋白疏水性氨基酸的结合,对纤维素酶蛋白吸附量减少,从而使得纤维底物周围的酶蛋白浓度增加,水解率提高。     

Fractionation of Lignocellulosic Materials for the Biorefinery: Separation and Characterization of Lignin from Calamagrostis angustifolia Kom

Dewaxed Calamagrostis angustifolia Kom was pretreated with hot water at 60 and 90°C for 3 h, and then the residue obtained was successively treated with 70% ethanol, and 70% ethanol containing 0.2%, 1.0%, 2.0%, 4.0%, and 8.0% NaOH at 80°C for 3 h. The dissolved components were subjected to further separation to get eight lignin fractions, which were characterized by gel permeation chromatography, Fourier transform infrared, and sugar analysis. All the lignin fractions had small weight-average molecular weights between 810 and 2580 g/mol. Two typical lignins, L₃ (prepared with 70% ethanol) and L₅ (prepared with 70% ethanol containing 1.0% NaOH), were further analyzed using ¹H, ¹³C NMR and HSQC spectroscopy. Signals from guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H) units observed in aromatic/olefinic region of HSQC spectra indicated that the lignin from Calamagrostis angustifolia Kom could be classified as “GSH” lignin. In aliphatic-oxygenated region, β-O-4′ together with small amounts of β-5′, β-β′, and p-hydroxycinnamyl alcohol end group were the main interunit linkages observed. Aqueous ethanol, which could avoid the cleavage of ether bonds in lignin at neutral condition, was more effective than water on lignin extraction.     

木质素的提纯及其在脲醛树脂胶粘剂中的应用

采用连续浸提和半纤维素酶处理方法,从工业碱木质素（M1）中脱去糖类物质后得到纯度不等的木质素样品M2和M3,同时进行木质素脲醛树脂的制备。结果表明,木质素经过抽提和酶处理后得到木质素M3其纯度为97％,当其添加量为甲醛和尿素总量的35％时,合成的胶粘剂的粘结性能优良,具有资源环保意义。     

微波辐射常压麦草中木质素快速提取方法研究

采用微波辐射技术,建立了从麦草中提取木质素的工艺.使用微波法分离木质素和纤维素是微波应用的一种新途径.考察了固液比例、微波辐射功率、辐射时间、碱浓度等对木质素提取效果的影响.结果表明,最佳提取工艺条件为:2 g样品在微波辐射功率为550 W,辐射时间为75 min,固液比为1:12.5,碱浓度为16%时,木质素提取液的吸光度达到1.25,并且验证性试验的结果很稳定.     

Techno-Economic Assessment of a Microalgae Biorefinery

A preliminary techno-economic assessment of a microalgae biorefinery plant is reported, with pulsed electric field treatment (PEF) hydrothermal liquefaction as core technology. The results indicate that standalone production of microalgae biofuel would lead to an annual loss of 2.615 M€. PEF treatment could improve this scenario by bringing the microalgae biofuel to a competitive level (0.78 € kg⁻¹). Assuming that microalgae biofuel would be sold at the price of crude oil (0.44 € kg⁻¹), the minimum price of the amino-acid based product should be 7.56 € L⁻¹ for positive capital returns.     

Biogenic Catalysis by Adding Compost when Using Wheat Straw in a Biorefinery Concept

The high content of lignocellulose limits the biodegradability of wheat straw for bioenergy production. To counteract this fact, a thermobiological pretreatment was applied to improve the utilization of lignocellulose biomasses for a biorefinery concept. The use of compost assured the growth of cellulose-degrading anaerobic microorganisms under thermophilic conditions. Results revealed a lignocellulose material degradation in all samples. Moreover, the combination of a thermobiological pretreatment under thermophilic conditions created a synergistic effect that accelerated the biomethanization of wheat straw due to the sugar compounds released during the biogenic catalysis.     

化学生物法联合纯化木质素及其对脲醛树脂胶粘剂性能的改进

采用连续浸提和半纤维素酶处理方法联合,从工业碱木质素(M 1)中脱去糖类物质后得到纯度不等的木质素样品M 2和M 3,同时进行木质素脲醛树脂的制备.结果表明,木质素经过抽提和酶处理后得到木质素M 3,其木质素纯度为97%,当其添加量为甲醛和尿素总量的35%时,合成的胶粘剂的粘结性能优良,具有资源环保意义.     

玉米秸秆木质素的去甲基化/羟乙基化复合改性研究

利用亚硫酸钠和乙二醛对玉米秸秆木质素进行去甲基化/羟乙基化复合改性,以提高木质素的羟基含量和反应活性。通过FT-IR、TG、DSC以及乙酰化滴定等技术研究了木质素复合改性效果。结果表明:经过去甲基化/羟乙基化复合改性后的玉米秸秆木质素具有优异的活性,其总羟基质量分数较原料木质素提升了88.33%,酚羟基提升了14.70%,反应活性得到明显增强。FT-IR表征发现:复合改性从多方面提升了木质素的羟基含量,对羟基含量的增加有着较为显著的效果。热重和DSC表征发现:复合改性木质素(G-DL)相较于原料木质素降解得更加彻底,其放热峰出现在77℃,放热量达459.82 J/g,反应活性较去甲基化木质素(DL)和原料木质素更高。     

Lignin for Bioeconomy: The Present and Future Role of Technical Lignin

Lignin, the term commonly used in literature, represents a group of heterogeneous aromatic compounds of plant origin. Protolignin or lignin in the cell wall is entirely different from the commercially available technical lignin due to changes during the delignification process. In this paper, we assess the status of lignin valorization in terms of commercial products. We start with existing knowledge of the lignin/protolignin structure in its native form and move to the technical lignin from various sources. Special attention is given to the patents and lignin-based commercial products. We observed that the technical lignin-based commercial products utilize coarse properties of the technical lignin in marketed formulations. Additionally, the general principles of polymers chemistry and self-assembly are difficult to apply in lignin-based nanotechnology, and lignin-centric investigations must be carried out. The alternate upcoming approach is to develop lignin-centric or lignin first bio-refineries for high-value applications; however, that brings its own technological challenges. The assessment of the gap between lab-scale applications and lignin-based commercial products delineates the challenges lignin nanoparticles-based technologies must meet to be a commercially viable alternative.