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在稀酸等化学预处理过程中,木质素会降解生成酚类等产物进入后续糖化阶段,研究表明这些木质素降解产物会抑制木质纤维降解酶的水解效率,然而其抑制机制尚不清楚。笔者选择了3种典型的木质素降解产物:香草醛、4-羟基苯甲醛和丁香醛,考察了它们对商品纤维素酶和木聚糖酶,以及单一关键纤维素酶组分和β-木糖苷酶水解的影响,并探讨其抑制规律。实验结果表明,这3种木质素降解产物对纤维素酶和木聚糖酶的水解均有抑制,其抑制能力随降解产物浓度的增加而增强。当3种木质素降解产物的质量浓度为10 mg/m L时,纤维素酶水解微晶纤维素48 h的葡萄糖得率由71.17%分别减少到33.80%、29.52%和32.03%,说明这3种木质素降解产物对纤维素酶的抑制作用差异不明显。3种木质素降解产物对β-葡萄糖苷酶水解纤维二糖的效率没有影响,但是会强烈抑制外切葡聚糖酶CBH I的酶活。当木质素降解产物的质量浓度为2 mg/m L时,与未添加木质素降解产物的酶活相比,CBH I酶活分别降低至79.64%、86.76%和71.89%,抑制强弱顺序为:丁香醛香草醛4-羟基苯甲醛。此外,3种木质素降解产物对木聚糖酶和β-木糖苷酶的抑制强弱顺序均为:4-羟基苯甲醛香草醛丁香醛,当3种木质素降解产物的质量浓度为10 mg/m L时,木聚糖酶水解木聚糖48 h的木糖得率由57.28%分别减少到12.26%、20.16%和30.43%。抑制动力学试验表明,4-羟基苯甲醛对CBH I的抑制属于竞争性抑制,对β-木糖苷酶的抑制属于非竞争性抑制。 相似文献
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麦草催化热化学液化产物的组成分析 总被引：10，自引：0，他引：10
麦草和纤维素、木质素等原料分别在乙二醇反应介质中，以浓硫酸/苯酚为催化剂进行液化反应。分析了液化产物组成，探讨了液化过程中各成分的液化情况。实验表明：麦草中要木质素组分在酸性条件下酚化降解，生成一系列单体、二聚体和多聚体，纤维素则最终降解生成乙二醇缩-2-羰基戊酸乙酯。元素分析显示，麦草、碱木质素液化残渣主要成分为灰分，且灰分中主要成分为SiO2。残渣中碳的含量比原料有显著增加，显示原料在反应条件下发生炭化。测定了产物的相对分子质量分布，发现随着反应的进行，降解和缩合同时发生，从而导致相对分子质量分布变宽。 相似文献
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《林业工程学报》2017,(4)
采用一步合成法制备氯化胆碱/丙三醇(ChCl/Glycerol)低共熔溶剂(deep-eutectic solvent,DES),研究该低共熔溶剂在不同条件下催化活化木质素磺酸钠的最佳工艺,并探讨了处理前后木质素磺酸钠的结构与性能,及其用于环氧树脂乳化剂的可行性。结果表明:在不加搅拌的条件下,木质素磺酸钠与DES的质量比为1∶12,处理温度为90℃,处理时间为5 h时,体系的反应效率最高,所得木质素磺酸钠的综合性能最好。木质素磺酸钠经DES催化活化处理后酚羟基总含量得到增加,苯环等大分子有所降解,表面张力和泡沫性能也得到了提高和改善。经ChCl/Glycerol DES处理后的木质素磺酸钠与OP-10乳化剂作为复合乳化剂,以环氧树脂E-44为油相,采用相反转法,可制得较为稳定的环氧树脂乳液。 相似文献
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直接使用超声波处理木质素磺酸钠(LS)水溶液,探索了超声波作用时间、功率以及体系的pH值对超声波作用效果的影响,并通过UV、FT-IR、1H NMR和TGA来考察超声波对木质素磺酸钠物化性能的影响。结果显示:超声波作用15、45、60和120 min,木质素磺酸钠的酚羟基质量分数由0.65%分别提高到0.71%、0.74%、0.81%和0.87%。10 g的LS在100 mL水中经超声波处理,超声波功率从100 W增强到300 W时,酚羟基的质量分数从0.69%提高到0.92%。超声波体系的pH值对超声波结果具有最明显的影响,当用H2SO4调节体系的pH值为0时,超声波处理得到最高质量分数的酚羟基,高达1.58%。UV、FT-IR和1H NMR综合结果显示,超声波对木质素磺酸钠分子的整体结构影响不大,但也会造成局部结构如苯环的部分破裂和磺酸基团的破坏。TGA结果显示超声波对木质素磺酸钠热稳定性能的影响比较复杂,原因是超声波使降解和交联作用同时发生。300 W,20 kHz超声波处理LS水溶液60 min时,超声波的降解效应使超声波木质素磺酸钠(ULS)在200~600℃温度区间的热稳定性低于LS;当超声波150 W40 kHz,pH值为0(浓硫酸调节),超声波处理60 min时处理所得的ULS,交联效应使其在680℃以上高温区的耐热性能比LS有所提高。 相似文献
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木质素电氧化的影响因素研究 总被引：3，自引：0，他引：3
木质素是天然高分子聚合物，具有一定的化学反应惰性。本文率先研究草类木质素在膜助电解时的电化学氧化作用。其结果表明：膜助电解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打开；同时木质素的氧化作用与施加的电压、阳极的电极材料等因素有关。通过对木质素氧化产物结构的进一步研究，可为木质素的电化学改性提供了新的方法。 相似文献
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采取了先提木质素再将木质素磺化的方案进行造纸黑液的磺化,由分段正交试验(先羟甲基化再磺化)确定最佳磺化工艺,制备出磺化木质素.利用红外光谱表征产物,并测定了产物的磺化度、净浆流动度和重均分子质量(Mw).最佳磺化工艺:酸析木质素4 g,水40 g,甲醛溶液5 g,pH值11,75℃下反应2h,再调pH值为7,加亚硫酸钠2 g于140℃下反应4h,所得磺化木质素的净浆流动度为232 mm.红外分析表明磺化木质素中引入了较多的磺酸基;磺化木质素的磺化度为0.821 mmol/g,Mw为22.97 ku,均优于市售木质素磺酸钠,从而导致水灰比值0.35时其净浆流动度亦优于同掺量下的木钠. 相似文献
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在Ru/C和甲酸(甲酸盐)的共同作用下,275~350℃的亚临界水中,进行碱木质素的水热解聚反应。通过GC-MS定性分析和GC-FID定量分析,探究了供氢试剂及用量、反应温度、木质素分子级分对木质素水热解聚的影响。结果表明:在甲酸和Ru/C条件下,木质素解聚液相产物得率最高,组成较简单,具有较好催化降解效果;在甲酸添加量为0.8 mol/L,反应30 min时,木质素解聚液相产物最多,其中含量最高的单酚类物质为4-甲基愈创木酚,在主要单酚类物质中占32.77%,木质素水热解聚液相产物得率随温度升高而先增后减,并在325℃时取得峰值;L1、L2和L3是碱木质素的3个不同的分子级分,L1级分对木质素解聚液相产物得率贡献最大,达61.80%,且产物中单酚类物质总得率最高,为112.71 mg/g。其中,愈创木酚与4-甲基愈创木酚所占比例最高,可分别为35.38和35.52 mg/g;对木质素进行分级分离处理后再进行水热转化反应,有利于液相产物和单酚类物质得率的进一步提高。 相似文献
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在氧化镁载体上浸渍醋酸钙后烧结制备了CaO/MgO复合固体碱催化剂,所制固体碱催化剂的表面碱度与催化剂制备条件有关:当CaO/MgO比值为0.08、在700℃下煅烧时间24 h时制得的催化剂表面碱度可达到30.2 mmol/g.以该固体碱催化剂催化木质素中醚键断裂反应,测试结果表明木质素降解产物重均相对分子质量(Mw)可从3000降低至800以下,羟值由200 mg/g增加至480 mg/g左右.FT-IR表征结果表明降解产物中醚键含量明显减少,羟基含量增多. 相似文献
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The chemical conversion of phenolized sulfuric acid lignin (P-SAL), prepared from sulfuric acid lignin (SAL) by phenolation
with sulfuric acid catalyst, to novel cationic surfactant was investigated. To elucidate the chemical reactivity of the P-SAL
to a Mannich reaction, 1-guaiacyl-1-p-hydroxyphenylethane (I) as a simple phenolized sulfuric acid lignin model compound was reacted with dimethylamine and formaldehyde. Quantitative
analysis of the products by gas-liquid chromatography suggested that the p-hydroxyphenyl nucleus was more reactive than the guaiacyl nucleus. The Mannich reaction of SAL with dimethylamine did not
yield a soluble cationic surfactant, but P-SAL produced water-soluble cationic surfactant in a quantitative yield. The Mannich
reaction products (MP-SAL) of P-SAL had 1,3-dimethylaminomethyl groups/C9-C6. The results of the surface tension measurements showed that the decrease in surface tension of MP-SAL was much larger than
that of lignosulfonate as a commercial surfactant from lignin. 相似文献
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The chemical conversion of phenolized sulfuric acid lignin (P-SAL), prepared from sulfuric acid lignin (SAL) by phenolation
with sulfuric acid catalyst, to novel cationic surfactant was investigated. To elucidate the chemical reactivity of the P-SAL
to a Mannich reaction, 1-guaiacyl-1-p-hydroxyphenylethane (I) as a simple phenolized sulfuric acid lignin model compound was reacted with dimethylamine and formaldehyde. Quantitative
analysis of the products by gas-liquid chromatography suggested that the p-hydroxyphenyl nucleus was more reactive than the guaiacyl nucleus. The Mannich reaction of SAL with dimethylamine did not
yield a soluble cationic surfactant, but P-SAL produced water-soluble cationic surfactant in a quantitative yield. The Mannich
reaction products (MP-SAL) of P-SAL had 1,3-dimethylaminomethyl groups/C9-C6. The results of the surface tension measurements showed that the decrease in surface tension of MP-SAL was much larger than
that of lignosulfonate as a commercial surfactant from lignin.
Received: February 13, 2002 / Accepted: June 12, 2002
Acknowledgments The authors thank Nippon Paper Industries Co. and Lion Corp. for providing the commercial products and Dr. K. Aoi (Graduate
School of Bioagricultural Sciences, Nagoya University, Japan) for advising us on the measurement of surface tension. This
research was conducted with the support of a Grant-in-Aid for Scientific Research (11460079) from the Ministry of Education,
Culture, Sports, Science and Technology of Japan.
Part of this report was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002
Correspondence to:Y. Matsushita 相似文献
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木质素磺酸盐的接枝改性及应用研究进展 总被引：3，自引：0，他引：3
综述了木质素磺酸盐的各种接枝改性方法，讨论了木质素磺酸盐接枝产物在土壤调节、水增稠、石油钻井、胶粘剂等方面的应用，并对我国木质素磺酸盐接枝改性及应用的前景进行了展望。 相似文献
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Weimiao Lu Qian Li Yan Zhang Hongwei Yu Shigeo Hirose Hyoe Hatakeyama Yuji Matsumoto Zhenfu Jin 《Journal of Wood Science》2018,64(3):287-293
Lignin containing substantial aromatic rings and high content of carbon has been employed as carbonizing agent to investigate the flame retardancy in the lignin/ammonium polyphosphate (APP) intumescent flame retardant (IFR) system. In addition, owing to the abundant phenolic and aliphatic hydroxyl groups, lignosulfonate, which is considered as a renewable aromatic macropolyols, substituted part of diethylene glycol (DEG) and copolymerized with isocyanate to produce lignosulfonate-based rigid polyurethane (LRPU) foams. Thermal stability was characterized by thermogravimetric analysis (TGA), and flame retardancy was investigated by limiting oxygen index (LOI) and cone calorimetry testing (CCT). Lignosulfonate increases thermal stability of LRPU foams and LRPU containing 15 wt% of lignosulfonate based on DEG (L15RPU) give rise to the best thermal stability. When 15% of lignosulfonate incorporated in the LRPU, reduced the heat release rate (HRR) and total heat release (THR) value 21 kW/m2 and 13 MJ/m2, respectively, and postponed 96 s time-to-peak carbon monoxide production than that of pure DEG rigid polyurethane (RPU) foam, the LOI values increased progressively with lignosulfonate content increasing. These results showed that lignosulfonate polyol may substitute polyol to produce lignosulfonate-based RPU foam and the presence of lignosulfonate could improve the flame retardancy. The mass loss gradually decreases with increasing APP addition, and the highest char yield was obtained from LRPU5 foam which at the lignosulfonate-to-APP ratio is 1:5. At the lignosulfonate-to-APP ratio of 1:5, the LOI value increased over 30%, and the HRR value reduced and the time-to-peak HRR postponed significantly. In addition, LRPU5 foams give rise to the lowest effect heat combustion (EHC) value, less smoke, and carbon monoxide (CO) production. Lignosulfonate acts as carbonizing agent in the lignosulfonate/APP IFR system, and the best fire retardancy is obtained at 1:5 of lignosulfonate-to–APP ratio. 相似文献
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以木质素磺酸钠(LS-Na)、丙烯酸(AA)、丙烯酰胺(AM)为原料,高岭土(Kaolin)为无机添加剂,过硫酸钾(KPS)为引发剂,N,N’-亚甲基双丙烯酰胺(NMBA)为交联剂,通过溶液聚合制备高岭土/木质素磺酸钠-g-AA-AM复合高吸水树脂(LPAAM)。选用正交试验设计方法,以蒸馏水和0.9%NaCl溶液中的平衡吸液倍率为评价参数得到了较优配方:m(AM):m(AA)=1:1,m(KPS)=1.0%,m(NMBA)=0.1%,pH=3。将上述配方制备的LPAAM以不同浓度NaOH于90℃皂化2h,得到皂化后的LPAAM,该树脂在蒸馏水和0.9%NaCl溶液中的平衡吸液倍率分别为1003及89g·g-1。 相似文献
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Summary A commercial lignosulfonate preparation consumed a small amount of chlorosulfamic acid. The reaction was probably due to the presence of sulfite in the preparation and to some reactive lignin groups. About one tenth of these reactive groups seem to be stilbene groups. The structures of the other groups are unknown. Simple phenols did not react or reacted only slowly with chlorosulfamic acid. 相似文献
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