铅电解液中木质素磺酸钙的快速测定

铅电解液中加入木质素磺酸钙(以下简称木钙),能改善析出铅的表面物理性能,但对木钙的测定尚未见报导。为适应生产需要,试验了分光光度法测定铅电解液中木钙的方法。木钙是一种表面活性剂,经硝酸氧化后生成相应的醌式硝基酯有色物质,通过测量其颜色的吸光度可确定木钙的含量。本法可用于大量金属盐类及其他有机物(例如骨胶、稻草)存在下,电解液中木钙含量的测定,测定范围为0.003—25克。实验表明:至少2克的PbSiF_6;5毫克Cu~(2+)、Zn~(2+)、Bi~(3+)、Ag~+、Fe~(3+);2.5毫克As~(3+)、As~(5+)、Sn~(4+)、CO~(2+)、Ni~(2+)、Se~(4+)、     

Co-gasification of petroleum coke and straw char

在热天平中采用等温热重法对石油焦、稻草焦、石油焦/稻草混合物以及石油焦/稻草焦混合物进行了CO2共气化研究,实验温度900～1050℃,添加稻草焦的质量比为0～0.5,考察稻草焦对石油焦的催化气化作用.结果表明,在一定气化温度下,石油焦和稻草焦混合物的共气化碳转化率高于各自气化碳转化率的简单加和,具有一定的协同效应,混合物的气化反应速率随着稻草焦添加比例的增加而升高.石油焦、稻草、稻草焦及其各个混合物的反应活性由大到小的顺序为:稻草半焦＞脱灰稻草半焦＞石油焦/稻草混合物＞石油焦/稻草焦混合物＞石油焦/脱灰稻草混合物＞石油焦/脱灰稻草半焦混合物＞石油焦.     

石油焦与稻草焦共气化研究

在热天平中采用等温热重法对石油焦、稻草焦、石油焦/稻草混合物以及石油焦/稻草焦混合物进行了CO₂共气化研究,实验温度900~1 050 ℃,添加稻草焦的质量比为0~0.5,考察稻草焦对石油焦的催化气化作用。结果表明,在一定气化温度下,石油焦和稻草焦混合物的共气化碳转化率高于各自气化碳转化率的简单加和,具有一定的协同效应,混合物的气化反应速率随着稻草焦添加比例的增加而升高。石油焦、稻草、稻草焦及其各个混合物的反应活性由大到小的顺序为:稻草半焦>脱灰稻草半焦>石油焦/稻草混合物>石油焦/稻草焦混合物>石油焦/脱灰稻草混合物>石油焦/脱灰稻草半焦混合物>石油焦。     

乙酰化稻草/聚己内酯接枝共聚物的合成及表征

以稻草秸秆为原料,经粉碎后进行全植物秸秆的乙酰化改性,再用此乙酰化稻草同ε-己内酯(ε-CL)接枝共聚合成乙酰化稻草/聚己内酯接枝共聚物(ACSW-g-PCL)。研究了反应时间、反应温度、及单体用量对接枝率(G%)的影响。在反应温度140℃,反应时间10h,ε-CL对乙酰化稻草的质量比2:1时获得的接枝率最大为39%。产物的结构和性能通过红外光谱、核磁共振、扫描电镜、X-射线衍射和热分析仪表征,结果表明乙酰化稻草秸秆已成功接枝上聚己内酯(PCL)链段,经接枝ε-CL改性后的ACSW-g-PCL热稳定性有所改善,并具有了一定的热塑性。     

环氧稻草纤维球的傅立叶红外及扫描电镜研究

本文以天然纤维素中的农副产品稻草秸秆作原料,先用高沸醇(1,4-丁二醇)做溶剂,于200℃、0.9MPa下两小时蒸煮(即HBS处理,除去其半纤维素和大部分木质素)后过滤,以提高稻草秸秆中纤维素的含量。SEM结果表明,上述条件下经HBS处理后,稻草秸秆表面发生了明显变化,IR结果表明,其木质素含量明显减少。再用NaOH预处理后与环氧氯丙烷反应,制得了环氧稻草纤维素球,探讨了其制备的优化实验条件。用SEM、IR对其进行表征,证实制得的环氧稻草纤维素球具有圆球的形状和一定的孔隙结构,并含有环氧基官能团。     

黄连素-染料木素有机盐水合物的制备、晶体结构及溶解性

合成了黄连素和染料木素的有机盐水合物[C₂₀H₁₈NO₄]⁺·[C₁₅H₉O₅]^-·2.5H₂O·0.5(C₂H₅OH),并测定了其晶体结构。 解析结果表明,该有机盐水合物属于单斜晶系,P2₁/c空间群。 染料木素7取代位的羟基失去了质子变成了染料木素阴离子。 羟基阴离子与4'取代位上的羟基形成了O—H••••O^-氢键,产生了一维的氢键链状结构。 两个水分子通过氢键作用形成了链状结构,并与染料木素阴离子形成二维的氢键结构。 加热失去水分子后,有机盐水合物变成无定型状态。 在乙醇水溶液中悬浮后,无定型可以转变成结晶的水合物结构。 形成黄连素-染料木素有机盐水合物后,染料木素在水中的溶解度略有增加。     

温度对稻草流化床快速热解液相产物影响的研究

研究了温度对稻草流化床快速热解中热解油产率的影响,利用GC/MS、FT-IR考察了不同热解温度(300℃~600℃)及冷凝温度(22℃、-4.4℃)下,稻草经过热解所获得的热解油组成。结果表明,稻草在400℃热解温度下可获得最高热解油产率43.1%;冷凝温度对热解油的品质有较大影响,降低冷凝温度能够增加热解油中有机物的含量,热解油中的水分含量随之降低,同时热解油的热值也随之得到提高。     

多胺型稻草纤维素球的制备及其对水体中Zn2+的吸附性能

多胺型稻草纤维素球的制备及其对水体中Zn2+的吸附性能;农副产品;稻草;多胺型稻草纤维素球;锌     

氧化黑液木素-Mn2+(Cu2+、Zn2+)螯合物稳定性的研究

随着造纸工业的发展 ,造纸黑液的污染愈来愈受到人们的重视。目前 ,人们已采用多种方法来试图消除或降低黑液的污染。其中一重要方法是 :通过酸析法等从造纸黑液中分离出木素 (亦称木质素 ) [1] 。据估计 ,我国造纸厂每年可提取数百万吨的干木素。因此 ,有效地开拓造纸黑液木素的应用途径 ,不仅可以解决造纸厂的后顾之忧 ,更重要的是可为社会提供大量的物质财富 ,成为当今重要的研究课题。最近 ,我们通过氧化黑液木素与无机盐作用制得木素螯合微肥。试验结果表明 :与无机盐相比 ,木素螯合微肥表现出较强的肥效作用 ,这种作用可能与氧化木素…     

稻草与煤固定床共热解特性的研究

选取稻草为生物质原料,将其与两种不同煤阶的煤(内蒙褐煤和神府烟煤)分别以0∶100、20∶80、40∶60、60∶40、80∶20、100∶0的干基质量比均匀混合.借助固定床反应器,研究了稻草与两种煤的共热解特性,探讨了共热解过程中可能存在的协同作用.结果表明,稻草添加有利于共热解气体产物的生成,且对神府煤作用更明显;稻草含量越高,热解气体产量的实验值与加权平均计算值的偏差也越大,说明稻草与煤共热解过程发生了协同作用.而共热解所得焦产量的实验值与加权平均计算值基本一致.热解焦傅里叶红外光谱分析结果表明,稻草添加对热解焦的官能团未造成显著影响.     

麦草造纸黑液中木质素的提取及结构分析

采用有机溶剂萃取的方法从麦草造纸黑液中提取木质素,并采用红外光谱（FT—IR）、^1H NMR、紫外光谱等方法对其结构进行了表征．试验表明,所提取的木质素具有明显的紫丁香基和愈疮木基苯环结构．同时测定了木质素的元素组成和甲氧基含量,并计算得到经典的C9结构模型,其结构形式为C9H8.89O1.17（OCH3）1.39.     

Nitration of lignin isolated from spruce wood by mechanical grinding

Summary 1. The nitration of spruce lignin obtained by mechanical grinding has been carried out with nitric acid in an anhydrous medium under heterogeneous and homogeneous conditions. Fractionation of the nitrolignin has been carried out and the elementary and functional composition of the fractions has been determined; the mean semi-empirical formulas of the C₉ structures have been calculated for both fractions. It has been shown that, depending on the nitration conditions, from one to two nitro groups enter the C₆-C₃ structural element of nitrolignin and, with an excess of HNO₃, nitrate groups as well.The fall in the content of OCH₃ groups corresponds to the content of phenolic hydroxyl groups in the initial MGL and can be explained by the demethylation of the guaiacyl structures of the lignin on nitration.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 1, pp. 58–65, 1966     

The chemistry and kinetic behavior of Cu-Cr-As/B wood preservatives. II. Fixation of the Cu/Cr system on wood

The kinetic behavior of a Cr⁶⁺/Cu²⁺ system in its reaction with wood has been elucidated. The same reactions with carbohydrates and lignin of wood for Cr^VI alone are still present. Approximately 20% of the copper is fixed to the guaiacyl units of lignin in the form of copper chromate; the remaining copper forms complexes with cellulose and mainly with the guaiacyl units of lignin. The Cr^VI/lignin guaiacyl unit complexes already found for the treatment of wood with CrO₃ are still the main Cr^VI complexes formed. Copper chromate is present as [Cu(H₂O)₂(guaiacol)]CrO₄(guaiacol) complexes, and CuCrO₄ bridges between different guaiacyl units of the lignin network appear to be likely. Substantial interference of the Cu²⁺ ions in the second-zone reactions of Cr^VI with wood occurs. The amount of Cr^VI and Cr^III fixed onto lignin and cellulose compares well with experimental values. Rate constants, energies of activation, and Arrhenius equations of the various reactions have been obtained. The amount of Cu²⁺ interference in the reaction has also been calculated.     

Cleavage by sodium in liquid ammonia of kenaf lignins and the biological activity of the cleavage products

The natural lignin of kenaf stems and fractions of the dioxane lignin of kenaf stems isolated previously were cleaved by sodium in liquid ammonia in order to study their structure. It was established that the kenaf lignins consist of three types of structural units: p-coumaryl, guaiacyl, and syringyl, with a predominance of the guaiacyl types. An antioxidation activity of the monomeric products of the degradation of the kenaf lignins has been found.     

Synthesis of beta-O-4-type artificial lignin polymers and their analysis by NMR spectroscopy

We describe the synthesis and NMR spectroscopic analysis of three artificial lignin polymers containing only the beta-O-4 substructure: syringyl-type homopolymer, p-hydroxyphenyl-type homopolymer and guaiacyl/syringyl-type heteropolymer. Using gel permeation chromatography, the weight-average degree of polymerization (DP(w)) of the three polymers was determined as 19.2, 38.6, and 13.9, respectively. The polymers were prepared based on the synthetic methodology of guaiacyl-type homopolymer, and were fully characterized using (1)H-, (13)C-, and (1)H-(13)C NMR spectroscopy of the acetylated and non-acetylated forms. The spectra of guaiacyl/syringyl-type heteropolymers were in good agreement with those of the beta-O-4 substructure of milled wood lignin obtained from the hardwood of Japanese white birch.     

The chemistry and kinetic behavior of Cu-Cr-As/B wood preservatives. III. Fixation of a Cr/As system on wood

The kinetic behavior of a Cr/As system in its reaction with wood is described, as are its reactions with lignin and carbohydrates of wood for Cr^VI alone. Chromium^III arsenate complexes with the guaiacyl units of lignin, as well as the usual chromic acid/guaiacyl unit complexes already characterized, was formed. The interference of As concentration on the various zones of fixation of chromium are identified. Complexes between guaiacol and chromium arsenates indicate that in this Cr/As system Cr^III can also be linked to the guaiacyl units of lignin when in the form of CrAsO₄·6H₂O contrary to what obtained with systems not containing As. An initial increase in the rate of reduction Cr^VI → Cr^III by the carbohydrates fraction in wood is ascribed to the catalytic effect of the arsenic. The percentages of chromium fixed onto lignin and cellulose of wood compare well with experimental values.     

Molecular variability of lignin fractions isolated from wheat straw

Three lignin fractions were isolated from wheat straw internodes and leaves: alkali lignin (LA), milled lignin (LM) and enzyme lignin (LE). Thioacidolysis and alkaline nitrobenzene oxidation were used for the characterisation of the lignin monomeric composition. Esterified and etherifiedp-coumaric and ferulic acids were characterised by alkali hydrolysis and acidolysis, respectively. Lignin fractions from leaves are more condensed than those from internodes. The syringyl/guaiacyl (S/G) ratio is higher in the case of internode lignins. Among the three lignin fractions, LA is the less condensed whereas LM and LE do not present significant structural differences according to their monomeric composition. Finally, the lignin fractions studied differ in their contents and proportions of associated phenolic acids.     

Elucidation of lignin structure by quantitative 2D NMR

Quick quantitative HSQC (QQ‐HSQC) was applied to quantitative evaluation of different inter‐unit linkages in an array of milled softwood and hardwood and technical lignins by using the guaiacyl C2 and syringyl C2–C6 signals as internal standards. The results were found to be highly reproducible and comparable with earlier literature reports. The advantage of QQ‐HSQC NMR analysis of lignin is contemporary detection and quantification of lignin inter‐unit linkages with a direct, non‐destructive method requiring short acquisition times.     

Structure of Alkali Lignins Fractionated from Ricinus communis and Bagasse. 3. IR Spectra

Abstract

The lignin fractions isolated by one- and multistage soda and sulfate cookings showed almost identical IR spectra, indicating the similarity of the lignin skeletal structure throughout the plant. However, the absorbances reveal some differences. Similarity of the spectra includes: 1) chelation and bonding of the hydroxyl groups. 2) Stretching vibration of C-H bonds in methyl, methoxyl, and methylene groups. 3) Stretching vibration of C≡N. 4) Carbonyl unconjugated β-ketone, conjugated acids, or esters at 1725 cm^?1. There is no change in the intensity of absorption at this band from that at 1515 cm^?1 with the cooking stage. 5) Aromatic skeletal vibration at 1610 and 1515 cm^?1, affected by ring substituents at 1425 cm^?1. 6) The band at 1465 cm^?1 showed a higher intensity for soda and soluble kraft lignins than for insoluble kraft ones. 7) The band at 1370 cm^?1, assigned to phenolic OH bending, is affected by the methoxyl group. 8) The absence of condensed guaiacyl and the presence of syringyl and uncondensed guaiacyl. Assignments for hardwood lignin are shown for soda and soluble kraft lignins of bagasse, while those for softwood lignin are shown for soda, soluble, and insoluble kraft lignins of Ricinus communis and for insoluble kraft lignin of bagasse. A relation exists between the carbohydrate's lignin and the band at 920 cm^?1. Lignins from Ricinus communis are of higher guaiacyl to syringyl ratios than those from bagasse. The presence of C—S vibration and the absence of thiol groups for kraft lignins are indicated.     

Cleavage by sodium in liquid ammonia of kenaf lignins and the biological activity of the cleavage products

The natural lignin of kenaf stems and fractions of the dioxane lignin of kenaf stems isolated previously were cleaved by sodium in liquid ammonia in order to study their structure. It was established that the kenaf lignins consist of three types of structural units: p-coumaryl, guaiacyl, and syringyl, with a predominance of the guaiacyl types. An antioxidation activity of the monomeric products of the degradation of the kenaf lignins has been found.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 738–742, September–October, 1987.