对制浆废液脱磺以提取木质素

以亚硫酸盐法制浆废液为原料,经脱磺处理后木质素的提取率显著提高,并通过(53)正交实验深入探讨经脱磺处理的黑液中硫酸用量、沉淀时间、沉淀温度等反应条件对木质素提取纯化的影响,得到高纯木质素提取纯化最佳条件为:黑液与15%硫酸体积比为1∶2,沉淀温度90℃,沉淀时间1.5 h。红外光谱、凝胶色谱、差热和流变特性分析结果表明,脱磺处理的木质素具有纯度高、分子量大、热稳定性和塑化性好等特点。     

Synthesis and characterisation of polyurethanes derived from waste black liquor lignin

Waste black liquor lignin, obtained from bagasse from the small-scale paper industry, can be utilized for the synthesis of polyurethanes (PUs). Several polyurethane samples were prepared from laboratory black liquor (LBL) by reacting varying amounts of lignin ranging from 5 to 70% (w/v) in poly(ethylene glycol) (PEG) (having molecular weights of 200, 600, 1000, 1500 and 4000) with tolylene 2,4-diisocyanate (TDI). The effects of lignin concentration and molecular weight of PEG on mechanical and thermal properties of PUs obtained were investigated. The polyurethanes synthesised were characterized for different properties such as shear strength, adhesion and thermal stability. The shear strength of PU joints with aluminum was found to decrease with increase in both lignin concentration and molecular weight of PEG. Maximum shear strength, i.e. 3.6 N/mm², was shown by 50% (w/v) lignin in PEG of molecular weight 200.     

蔗渣碱法造纸黑液回收木质素的结构及其燃烧特性

以酸析法从蔗渣碱法造纸黑液中回收蔗渣木质素（BL）,通过红外光谱（FTIR）,核磁共振氢谱（¹H NMR）和凝胶渗透色谱（GPC）对其进行了表征。结果表明,BL主要由愈创木基丙烷单元（G）和紫丁香基丙烷单元（S）通过C-O、C-C键合方式连接而成,其分子量分布较宽,分子之间存在较大差异。通过热重分析法（TG）研究了BL的燃烧特性,结果表明BL的燃烧主要发生在300~500℃的阶段,在此过程中BL分子中的C-C键发生断裂形成挥发分和焦炭,并迅速燃烧,失重率超过80%。通过扫描电子显微镜（SEM）和X射线荧光光谱（XRF）研究了BL在300、600、900和1100℃燃烧灰渣（BLR）的微观形貌和元素组成,结果表明BL呈结实、饱满的颗粒状,而BLR则表现为多孔的疏松堆积体或规则的片状结晶颗粒。随着燃烧温度的升高,BLR中的Na和K质量分数逐渐减少,而其他元素质量分数变化不大。     

Fractionation and concentration of kraft black liquor lignin with ultrafiltration

Kraft black liquor lignin is a biofuel that is separated from the cellulose during kraft pulping. Improved technology and energy integration in paper mills have led to an energy surplus at many mills. It is therefore of great interest to extract the lignin from the pulp mill and sell it as fuel to replace fossil fuel in other furnaces. The fractionation of kraft black liquor with a total dry matter content of about 15 wt% has been studied using ultrafiltration. The flux for three polymeric membranes with different cut-offs was investigated as well as their retention of lignin and other process specific substances. The retention of lignin for the three membranes with cut-offs of 4,8 and 20 kDa was 80%, 67% and 45%, respectively. The retention of sulphur and sodium was zero for all three membranes. The purity of the final lignin fuel is of importances as the ash content preferably should be as low as possible. The flux and retention during concentration and diafiltration of the black liquor were therefore studied. The dialfiltration operation was conducted in batch and semicontinuous mode. The lignin purity was 36% in the original kraft black liquor and 78% after semi-continuous dialfiltration.     

Process performance in lignin separation from softwood black liquor by membrane filtration

Black liquor is a side-stream in the production of kraft pulp. The extraction of lignin and hemicelluloses from black liquor would reduce the load on the recovery boiler and give valuable by-products. Lignin was separated from black liquor by membrane filtration, using one ceramic and three polymeric nanofiltration membranes, with molecular weight cut-offs in the range of 200 Da to 1 kDa. Ultrafiltration was tested as a form of pretreatment prior to nanofiltration to separate hemicelluloses from lignin. The use of ultrafiltration prior to nanofiltration increased the flux drastically in the nanofiltration step with three of the membranes. The ceramic membrane exhibited a higher flux and lower lignin retention than the polymeric membranes. The two membranes with a molecular weight cut-off of 1 kDa were found to have the best performance in parametric studies, and were therefore used in concentration studies. The results were used for a preliminary economic evaluation of the process. These calculations showed that the most cost-effective alternative for the extraction of lignin was with the polymeric 1 kDa membrane without pretreatment, and that the production cost for a lignin solution with a concentration of 230 g L⁻¹ would be 46 € per ton of lignin.     

快速消解分光光度法测定造纸黑液酸析絮凝木质素

介绍了通过快速消解分光光度法测定造纸黑液分离酸析絮凝木质素后滤液化学需氧量(COD)值计算木质素含量的方法.建立了COD值对吸光度的工作曲线.分别考察了pH、温度、絮凝剂用量对COD值的影响,得到了最佳工艺条件,分析了呈现的规律和原因.     

The pyrolysis of extracted solids from oxidized kraft black liquor after lignin precipitation

A laboratory investigation of the possibilities for the reduction of odor from Kraft mill stack gases by lignin precipitation from oxidized Kraft black liquor and subsequent pyrolysis of the filtrate solids has been carried out. Samples of oxidized black liquor were acidified with sulphuric acid and the lignin precipitate extracted. The extraction scheme indicates that > 90% w/w of the sodium in the original black liquor samples can be retained in the filtrate after lignin removal at final pH 2.0. The evaporated filtrate solids containing the bulk of the black liquor inorganic chemicals were pyrolyzed and the evolved hydrogen sulphide, methyl mercaptan and dimethyl sulphide monitored by gas-chromatography. Gas-chromatograph traces displaying the increase and decrease of methyl mercaptant evolution levels on pyrolysis of the filtrate solids to increasing temperatures are shown. A thermogravimetric technique was used to investigate the decomposition rates of the extracted samples and these rates correlated with the levels of sulphur gases evolved on pyrolysis. Heats of combustion were determined by bomb calorimetry. Sulphur losses from the filtrate solids and the Kraft black liquor total solids are compared. The results show a significant decrease in the evolution of organo sulphur gases from samples of ligninextracted black liquor solids in comparison with original total solids samples, an increase in the level of hydrogen sulphide evolution however, presents a problem.     

Novel silicon-contained lignin-based carbon fibers derived from bamboo pulping black liquor with improved electrochemical performance for supercapacitors

Carbon fibers (CFs) are a promising candidate as electrode materials for flexible supercapacitors given its light weight and moderate cost. In this study, the lignin used was partially separated from kraft bamboo pulping black liquor and the higher molecular weight fraction, unavoidably contains a small amount of silicon compounds, so named silicon-contained lignin. Novel CFs were prepared using commercial polyacrylonitrile (PAN) and the lignin by electrospinning and further carbonization. Even in the presence of silicon compounds, the fibrous morphology of precursor fibers was significantly good, and the CFs with uniform fiber diameter and high specific surface area up to 182 m²/g were obtained with an increase in silicon-contained lignin. The CFs fabricated from silicon-contained lignin and commercial PAN had higher specific capacitance (22.20 mF/cm² at 10 mA/cm²) and superb cycling stability (94.21%) than that from silicon-free lignin or pure PAN separately.     

Preparation and performance evaluation of a lignin-based solid acid from acid hydrolysis lignin

A new lignin-based solid acid was prepared by sulfonation of sulfuric acid lignin (a typical acid hydrolysis lignin). The solid acid has been characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), mercury injection apparatus, and elemental analysis. Structural analyses suggest that the material with high thermal and hydrothermal stability is composed of amorphous phenylpropane-based polymers with sulfonic acid groups. Catalytic tests in esterification of acetic acid with ethanol and hydration of 2, 3-dimethyl-2-butene show that the lignin-based solid acid exhibits high catalytic activities in acid-catalyzed reactions, which can be used as a replacement for the conventional solid acid catalysts. This may be attributed to good accessibility of reactants to sulfonic acid groups in the material structure.     

紫外-可见光谱法测定黑液中木素含量

通过对3,5-二硝基水杨酸(DNS)及草浆黑液木素溶液紫外-可见特定波长区域光谱图的研究,建立了一种快速、简便、准确的草浆黑液中木素含量测定方法。研究结果表明,草浆黑液木素在520nm处DNS溶液吸光度值与木素溶解量二者具有较高的线性关系。该方法在测量时可以排除草浆黑液中还原糖及亚硫酸钠的干扰。不但能测定碱法草浆黑液中木素含量,还可以测定碱性亚硫酸盐法草浆黑液中木素含量。采用该方法测定草浆黑液中木素相对含量是准确可靠的。     

草浆造纸黑液用于人造板胶粘剂的研究

用造纸黑液、酸析后的木质素为原料制取了不同固含量的木质素酚醛树脂，采用热压机在1．2MPa压力、热压时间5min、温度140℃进行固化成型，分别测试了直接采用黑液和采用酸析后的木质素制成胶粘剂的剪切强度，并分析了苯酚取代量与剪切强度的关系。     

从造纸黑液中提取木质素制备工业水处理剂M-03

以造纸黑液为原料,用絮凝—酸析联用技术从中提取木质素,对木质素磺化改性处理后,加入有机磷、锌盐和苯并三唑等与其复配,制备工业水处理药剂M-03。探讨了主原料配比、药剂用量、反应温度、反应时间等对药剂处理性能的影响,得出最佳复配条件:m(改性木质素)∶m(有机磷)∶m(氯化锌)∶m(苯并三唑)∶m(水)∶m(乙醇)=10 3∶0∶15∶2 4∶0∶3、反应时间2 h、反应温度(70±2)℃。并用静态实验法评价了M-03药剂的缓蚀阻垢性能,结果表明,该药剂缓蚀阻垢性能优良。     

一种可降解共聚酯的合成及表征

采用对苯二甲酸、1,4-丁二醇和脂肪酸为原料,以直接酯化法缩聚合成了生物可降解的高分子质量脂肪-芳香族共聚酯,并分析表征了此共聚酯的结构、分子质量、力学性能、流变性能及降解性能等。     

Recovery and characterization of lignin from alkaline straw pulping black liquor: As feedstock for bio‐oil research

Conversion of lignin derived from lignocellulosic biomass to bio‐oil has the promising potential to significantly reduce petroleum dependence. For that purpose, it is necessary to search for a low‐cost lignin source. In this study, lignin sample was separated from straw pulping black liquor by HCl‐precipitation, followed by extraction with a mixture of dioxane and water. The content of lignin in the total black liquor solid reached up to 34.8%, determined by UV spectroscopy, and the yield could account for 74.4% of the total lignin composition. The structure of lignin was investigated by various spectroscopic techniques such as FTIR, ¹H‐NMR, XRD, and XPS. The structural analysis revealed that recovered lignin preserved basic lignin structure, but had relatively lower amount of β‐O‐4 linkages. The molecular weights were studied through THF‐eluted GPC showing that separated lignin had the low M_n, which was favorable for the full degradation process during conversion of lignin to bio‐oil. Therefore, a feasible solution for effective utilization of lignin in straw pulping black liquor as feedstock for bio‐oil was proposed in the study. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42057.     

Coliquefaction of coal and black liquor

Black liquor from the Kraft pulping process to produce cellulose pulp contains lignin and sodium hydroxide, which are known to enhance the dissolution of coal. But no work has so far been done on the depolymerization of coals using black liquor as an additive. The addition of black liquor enhanced the coal conversion yield about 38.6% in this experiment. But the extent of the enhancement was lower than expected values from separate NaOH/coal and lignin/coal experiments.     

利用草浆黑液制备两性木质素絮凝剂

用硫酸沉淀回收造纸黑液中的木质素,经与Na2SO3磺化和季铵盐接枝聚合,合成出两性木素基絮凝剂.研究表明:用制备出的两性絮凝剂处理蒙脱土悬浮液和印染废水,可有效降低浊度和色度,当絮凝剂质量浓度分别为25mg/L和300 mg/L时,除浊率和脱色率均＞85%.     

An improved Hummers method for eco-friendly synthesis of graphene oxide

An improved Hummers method without using NaNO₃ can produce graphene oxide nearly the same to that prepared by conventional Hummers method. This modification does not decrease the yield of product, eliminating the evolution of NO₂/N₂O₄ toxic gasses and simplifying the disposal of waste water because of the inexistence of Na⁺ and NO₃⁻ ions. For the first time, we also developed a prototype method of post-treating the waste water collected from the systems of synthesizing and purifying graphene oxide. The content of Mn²⁺ ions in the purified waste water was measured to be lower than the guideline value for drinking water.     

木质素基环氧树脂的合成与应用

木质素是一种储量丰富的多酚类天然高分子材料,以木质素为原料合成的木质素基环氧树脂具有原料可再生、成本低、可降解等特点。本文从木质素直接环氧化以及通过酚化、酯化、丙氧基化等改性后再环氧化这2方面综述了木质素基环氧树脂的合成与应用,并对其未来的发展进行了展望。     

从胱氨酸母液中提取L-精氨酸工艺概述

介绍了特殊沉淀法、电渗析法和离子交换法从胱氨酸母液中提取L-精氨酸的过程,并讨论了NaCl、NH4Cl对离子交换法提取L-精氨酸的影响。     

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...