Kraft lignin in phenol formaldehyde resin. Part 1. Partial replacement of phenol by kraft lignin in phenol formaldehyde adhesives for plywood

The objective of this study was to investigate the potential for partially replacing phenol with kraft lignin in the phenol formaldehyde (PF) resin designed for application as an adhesive in the production of plywood. The kraft lignin, considered to be an environmentally friendly alternative to phenol, was precipitated from black liquor recovered from kraft pulping of softwood. Kraft lignin phenol formaldehyde (KLPF) resin was prepared in a one-step preparation with different additions of lignin. Replacing 50 wt% of the phenol with kraft lignin (50KLPF) was, under the conditions used, considered to be optimal with respect to resin viscosity, storage stability, and bonding ability. The resin consists of an integrated kraft lignin-phenol network. The hot-pressing time in the plywood manufacturing had to be increased by approximately 30% at 150°C for the 50KLPF resin compared with that normally used for PF resin, in order to comply with plywood standard demands. The mechanical properties of test samples made from KLPF resins were equal to or better than those of test samples made from PF resin only.     

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.     

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。     

Reversible polycondensation characterized by unequal reactivities of functional groups

Molecular weight distributions and moments for reversible condensation polymerizations with unequal reactivities of functional groups both in the forward and reverse steps, have been obtained. Results are qualitatively similar to those obtained for the corresponding irreversible case, i.e., MWD curves split into two, one for odd-n and one for even values of n for R (= reactivity of monomer with monomer/reactivity of other oligomers) larger than unity. When R is less than one, there is a preponderance of monomer in the reaction mass. However, these effects are considerable reduced due to the reversibility of polymerization. Comparison with Flory's most probable distribution indicates that this function represents the MWDs of the polymer for both irreversible and reversible cases only when the functional groups exhibit equal reactivity. For the unequal reactivity case, such a one-parameter (in terms of functional group conversion) characterization of the MWDs is unlikely.     

麦草碱木素分级和结构特性的研究

用酸沉淀法对山东兖州市造纸厂麦草碱木素按分子量进行沉淀分级．共分为3个级分。探讨了影响分级效果的因素，确定了分级的优化条件。各级分经纯化后分析其结构特性。发现，随着体系PH值的降低，沉淀出的各级分的分子量逐渐降低。碱木素中碳水化合物含量降低，且主要分布于小分子级分中．分级后，碱木素分子量的分布有不同程度的变窄，但各级分的分子量均有相当程度的重叠．硝基苯氧化结果表明，在高分子量级分中，木素的缩会程度较为严重。该方法用于碱木素的简易分级是可行的．     

褐煤中含氧官能团的测定与研究

煤表面的官能团的种类和数目对煤的化学性质有很大的影响,最重要的表面基团是含氧官能团。含氧官能团对煤的性质,尤其是表面性质,如亲水性、疏水性、表面电性、表面作用及表面作用方式等的影响较大,从而也对煤的选别、煤炭改质、煤炭转化及其合理加工利用影响较大。干燥后的煤样与原煤相比,固定碳含量逐步提高,氧含量呈逐步降低的趋势,O/C比逐步降低,煤样的芳碳率和平均缩环数也是随着干燥工艺的不同而呈现出递增的趋势,说明干燥后煤样的芳构化程度加深,基本结构单元的缩合度增加,干燥工艺在一定程度上提高了内蒙古褐煤的煤阶。     

Pyrolysis of kraft lignin in molten ZNCL2-KCL media with tetralin vapor addition

Kraft lignin was pyrolyzed in molten salt media of ZnCl₂-KCl mixture with tetralin vapor added in 0.4 and 4 mol% diluted with N₂ in the temperature range of 400 to 700°C. The gas chromatographic analyses of pyrolysis products revealed that the yield of H₂ was not increased by tetralin vapor addition. This fact implies that the hydrogen radical produced from tetralin is consumed in the formation of phenolic compounds and light liquids but not in the formation of H₂. p-Cresol was the most abundant phenolic compound. The yield of total phenolic compounds with 4 mol% tetralin vapor added was increased by ca. 80% as compared to that in neat pyrolysis of Kraft lignin.     

活性炭表面官能团表征进展

对活性炭表面官能团的种类和各种定性定量分析方法如Boehm滴定法、零电荷点法(pHPZC)、傅里叶变换红外色谱法(FTIR)和X射线光电子能谱(XPS)以及程序升温脱附法(TPD)等进行了综述,并比较了各种方法的优缺点。     

活性官能团对煤/PAN复合材料导电性能的影响

通过原煤及氧化煤中的总酸性基的测定、FTIR分析及煤/PAN电导率变化研究,表明煤在氧化过程中,弱的醚键的水解及羧酸盐向羧酸的转化,增加了煤中的羧基和羟基含量。而羧基和羟基含量的增加有利于提高煤与苯胺的作用,从而提高复合材料的电导率,其值最高可达4.72×10-1S/cm。     

Importance of activated carbon's oxygen surface functional groups on elemental mercury adsorption

The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury (Hg⁰) was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N₂), air oxidation (693 K), and nitric acid (6N HNO₃) treatment of two activated carbons (BPL, WPL) were conducted to vary their surface oxygen functional groups. Adsorption experiments of Hg⁰ by the activated carbons were conducted using a fixed-bed reactor at a temperature of 398 K and under N₂ atmosphere. The pore structures of the samples were characterized by N₂ and carbon dioxide (CO₂) adsorption. Temperature-programmed desorption (TPD) and base-acid titration experiments were conducted to determine the chemical characteristics of the carbon samples. Characterization of the physical and chemical properties of activated carbons in relation to their Hg⁰ adsorption capacity provides important mechanistic information on Hg⁰ adsorption. Results suggest that oxygen surface complexes, possibly lactone and carbonyl groups, are the active sites for Hg⁰ capture. The carbons that have a lower carbon monoxide (CO)/CO₂ ratio and a low phenol group concentration tend to have a higher Hg⁰ adsorption capacity, suggesting that phenol groups may inhibit Hg⁰ adsorption. The high Hg⁰ adsorption capacity of a carbon sample is also found to be associated with a low ratio of the phenol/carbonyl groups. A possible Hg⁰ adsorption mechanism, which is likely to involve an electron transfer process during Hg⁰ adsorption in which the carbon surfaces may act as an electrode for Hg⁰ oxidation, is also discussed.     

核磁共振法在研究木素和碳水化合物结构方面的应用

本文评述了核磁共振法（ＮＭＲ）在木素和碳水化合物结构方面的 应用情况，介绍了以及它们的应用原理和方法．     

COREX系统用煤燃烧过程中含氧官能团的转变研究

COREX是现有熔融还原方法中的主要工艺流程,该系统对煤质量有严格的要求。我们对系统运行中所涉及的主要煤种大同煤和兴隆庄煤燃烧行为进行深入研究。利用同步热分析仪（TG．DSC）研究高温条件下煤的热分解行为;通过电子扫描显微镜（SEM）观察了煤的微观结构,进行了岩相分析;通过傅里叶红外光谱仪（Frm）和湿式化学分析法,定性及定量的研究了煤中含氧官能团,尤其是热解过程中有机含氧官能基团的组分、数量、化学结构和转化机理。全面评价煤炭的质量,为系统稳定运行选用煤种,提高块煤利用率提供了理论基础。     

电导滴定法测定桉木浆中酚羟基和羧基

两相含水有机介质中电导滴定法测定接木浆中酚羟基和羟基的方法是可行的。较好的滴定条件是：滴定介质为丙酮：吡啶：乙醇：水（40：10：1：1,体积比）;样品浓度为2g/L,滴定剂KOH-异丙醇浓度为0．01mol/L。     

离子液体[BMIm]Cl中H_2O_2改性碱木质素的结构及热稳定性

采用等体积质量分数30%的H2O2溶液和离子液体[BMIm]Cl的混合液对提取自造纸黑液的碱木质素氧化改性后,清液加水再生,所得氧化改性碱木质素结构上发生解聚和活化,热稳定性显著降低。FT-IR分析表明,改性后碱木质素发生了部分解聚并仍保留着木质素的主要官能团结构,且邻位二取代酚类结构含量增多;XRD分析表明,改性后杂质盐被脱除,晶体衍射强度减弱,碱木质素解聚使有机结构复杂性增强,其紫丁香基结构经氧化降解产物类似2,6-二羟基苯甲酸结构;由SEM分析可知,碱木质素团聚结构由氧化改性前的杂乱紧簇晶体状转变为改性后较为规则的层状叠加结构,颗粒粒径则大幅减小。而TG/DTG/DTA分析发现氧化改性后的碱木质素热分解温区收窄为533—649 K,最大分解速率加快1倍,969 K时总质量损失率上升约15%。研究表明,经离子液体[BMIm]Cl中H2O2氧化改性后的碱木质素,降低了其在材料合成和热解制备化学品的工艺操作条件,可进一步拓展其在化工产品中的应用。     

Influence of temperature,molecular weight,and molecular weight dispersity on the surface tension of PS,PP, and PE. I. Experimental

In this work, the influence of temperature, molecular weight (M?_n), and molecular weight dispersity (MWD) on the surface tension of polystyrene (PS) was evaluated using the pendant drop method. The influence of temperature on the surface tension of isotatic polypropylene (i‐PP) and of linear low‐density polyethylene (LLDPE) was also studied here. It was shown that surface tension decreases linearly with increasing temperature for all the polymers studied. The temperature coefficient ?dγ/dT (where γ is the surface tension, and T, the temperature) was shown to decrease with increasing molecular weight and to increase with increasing MWD. The surface tension of PS increased when the molecular weight was varied from 3400 to 41,200 g/mol. When the molecular weight of PS was further increased, the surface tension was shown to level off. The surface tension was shown to decrease with increasing molecular weight distribution. Contact angles formed by drops of diiomethane and water on films of PS with different molecular weights were measured at 20°C. The surface energies of those polymers were then evaluated using the values of the different pairs of contact angles obtained here using two different models: the harmonic mean equation and the geometric mean equation. It was shown that the values of the surface energy obtained are slightly less than are the ones extrapolated from surface‐tension measurements in the rubbery state. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1907–1920, 2001     

对用于活性炭表面含氧官能团分析的Boehm滴定法的几点讨论

不同的研究者在采用Boehm滴定法测定活性炭表面含氧官能团的含量时在操作方法上存在差异.本文探讨了Boehm滴定法中CO2的去除,直接滴定与返滴定,振荡时间,溶液的浓度对滴定过程的影响,提出适宜的操作建议.     

木质素胺的制备及其在重金属废水处理中的应用研究

以木质素、甲醛为原料分别与乙二胺、二乙烯三胺、三乙烯四胺通过Mannich反应合成三种木质素胺,考察了吸附时间、温度、pH等吸附条件对废水中铅(Ⅱ)和铬(Ⅵ)吸附效果的影响。实验结果表明:随着温度的升高、pH值的增大、时间的延长,铅(Ⅱ)和铬(Ⅵ)的去除率都增大。铅(Ⅱ)的去除率随着胺基的引入增多而增大,铬(Ⅵ)的去除率没有随着胺基引入增多而增大。     

碱木素分子量及其分布的GPC表征

采用水溶性凝胶渗透色谱测定了碱水素的分子量特征,并对影响分子量分布测定的因素进行了探讨。结果发现,所用流动相的酸度对碱木素在凝胶色谱柱上可能发生的吸附影响比较显著。当流动相的碱性不够时,碱水素会发生吸附,并且大分子量木素优先被吸附,当pH升至12时可消除吸附现象。流动相的离子强度增大亦可以部分消除木京的吸附。     

Changes to the organic functional groups of an inertinite rich medium rank bituminous coal during acid treatment processes

A South African inertinite rich medium rank bituminous coal was subjected to a series of acid treatment steps using concentrations of HF and HNO₃ ranging between 1.5 and 4 M, temperatures between 65 and 80 °C and reaction time between 1.5 and 3 h for each acid. A HF and HCl procedure was used to reduce mineral matter to less than 2.5%. Analyses indicate that oxygen and nitrogen containing species are incorporated in the coal structure during the HF/HNO₃ leaching processes, but not during the HCl/HF/HCl procedure. The HF/HNO₃ methods lead to increased amounts of = N-OH groups formed on the remaining coal structure, whereas the HCl/HF/HCl procedure did not. The -COOH content upon HCl/HF/HCl treatment increased slightly possibly due to protonation of COO⁻ groups by HCl. The results show that the CO₂ reactivity doubled after the HF/HNO₃ procedures and increased by a factor of 2.5 for the HCl/HF/HCl treatment. Surface areas of the treated coal samples increased with the highest increase for the HCl/HF/HCl method. The increased surface areas may cause the increased CO₂ reactivity. The results indicate that the described acid treatment procedures with mixtures containing nitric acid have slight, but measurable, effects on the coal structure.     

Determination of functional groups of coal-derived liquids by n.m.r. and elemental analysis

A new method of structural analysis was applied to a group of hydroliquefied coal samples. The method uses elemental analysis and n.m.r. data to estimate the concentrations of functional groups in the samples. The samples included oil and asphaltene fractions obtained in a series of hydroliquefaction experiments, and a set of nine fractions separated from a coal-derived oil. The structural characterization of these samples demonstrates that estimates of functional group concentrations can be used to provide detailed structural profiles of complex mixtures and to obtain limited information about reaction pathways.