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51.
显微激光拉曼光谱技术可以实现纤维素与木素在木材细胞壁中原位状态分布规律的观察研究。首先采用透射电子显微镜(TEM)研究了结香细胞壁的超微结构。进而采用显微激光拉曼光谱技术对细胞壁各层中纤维素与木素分布特点进行了原位分析测定,拉曼图像及光谱分析结果表明,纤维素与木素在细胞壁各形态区分布不均一,纤维素的分布情况与木素相反。 相似文献
52.
毛竹化学成分光谱分析的快速建模方法研究 总被引:1,自引:0,他引:1
研究了毛竹综纤维素和木质素含量近红外光谱定量分析方法的建立。选用不同竹龄、纵向和横向部位的54个竹材粉末样品,用湿化学方法测定其综纤维素和木质素含量。在综纤维素和木质素含量的分布范围内,从低值、中间值和高值中挑选11个代表性样品,11个样品按预定比例混合得到21个混合样品,混合样品的综纤维素和木质素含量计算得到,再挑选22个目标成分含量不同的样品组成54个样品的校正集。用偏最小二乘法分别建立样品综纤维素含量、木质素含量和近红外漫发射光谱之间的相关模型。结果表明,综纤维素含量的预测模型的相关系数(Rp)为0.92,标准偏差(SEP)为1.04%;木质素含量的预测模型的Rp为0.93,SEP为0.91%,与常规方法建立的模型预测精度相似。说明利用样品混合的方式可快速增加校正集样品的数量、改善校正集样品的分布状况,继而建立稳定可靠的近红外定量分析模型。 相似文献
53.
He-Ne激光选育高木质素降解率的白腐真菌Lx 总被引:6,自引:1,他引:5
用He-Ne激光对一株木质素降解活性较高的白腐真菌L1进行选育.将该菌的菌丝体和原生质体多次照射诱变,结果得出:在波长632.5nm,用功率为6mW和7mW照射该菌的菌丝体,选育出的菌株L6和L7木质素降解率可达38.1%和39.88%,比出发菌株L1提高了33%和39%.用功率9mW的He-Ne激光辐照原生质体,照射20min时,原生质体致死率已达100%.在照射时间为10min时,选育出一株木质素降解率达43.03%的菌株Lx,比出发菌株L1提高了50%.同工酶分析显示该菌株发生了稳定的遗传突变. 相似文献
54.
Lignin is a major byproduct in the biomass-to-ethanol process. The lignin produced from acid treatment of biomass has characteristics
suitable for further conversion to organic chemicals. It is free of contaminants and has a relatively low molecular weight.
In this study, catalytic oxidative conversion of the acid-soluble lignin precipitated from acid hydrolysates of hardwood was
investigated. The process is based on aqueous alkaline oxidation of lignin with dissolved O2 in the presence of Fe3+ and Cu2+ catalysts at moderate reaction temperatures (160–180°C). Aromatic aldehydes, ketones, and organic acids are found to be the
primary products identifiable on extraction with ether. The combined weight yield of the total ether extractable products
is about 20–25% of the initial lignin. The yield of the aldehydes (vanillin + syringaldehyde) is in the vicinity of 15% with
an additional 3 to 4% of aromatic ketones. The yields of aldehydes plus ketones observed in this work far exceeded those obtainable
from the conventional alkaline air oxidation of spent sulfite liquors. This article also provides comprehensive batch reaction
data on conversion and product distribution. 相似文献
55.
《Arabian Journal of Chemistry》2020,13(12):9019-9033
Adsorption performance and stability of the carboxyl groups modified straws and their extracts of cellulose, lignin, and hemicellulose for Pb2+ were investigated, and the optimum pH range for Pb2+ adsorption was determined by considering both the stability and capacity of the modified biosorbents for the first time. Results showed that adsorption capacity and stability of the straws and extracts were both improved significantly after modification. Adsorption capacities of the modified straws and extracts followed the order: modified hemicellulose > modified lignin, modified straw > modified cellulose, while stability of them followed the reverse order. In the optimum pH range from 4.0 to 5.0, modified rape and cotton straw showed better stability than the modified maize straw, and total organic carbon (TOC) values determined from the two modified straws and extracts were lower than 5.0 mg L−1 even after adsorption for 30 days, which reached the drinking water standard in China. 相似文献
56.
The feasibility of using DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy combined with a multivariate
analysis method (a PLS (projection to latent structures), regression) for predicting the distribution of the main organic
constituents (cellulose, glucomannan, xylan, lignin, and extractives) within the Scots pine (Pinus sylvestris) stemwood was examined. PLS calibrations were carried out to establish a mathematical correlation between the data sets of
conventional (“wet-chemistry-based”) wood analysis and the DRIFT spectra of the corresponding wood samples. Based on this
approach, different surface maps on variations in the content of the main organic constituents within the stemwood matrix
were shown. 相似文献
57.
木质素改性高分子材料研究进展 总被引:16,自引:0,他引:16
木质素改性高分子材料的基础研究和应用开发极为活跃.在材料中引入木质素,不仅可提高材料的性能,还能降低成本,产生可观的经济效益.本文综述了木质素改性高分子材料的最新研究成果,并由此归纳出木质素结构与材料性能之间的关系,提出了基于控制木质素多级结构的材料设计和性能优化的思路. 相似文献
58.
59.
Guaiacol, pyrocatechol and resorcinol, were isolated and quantified as the major products from catalytic pyrolysis of lignin of various origin. The novel procedure utilises formic acid as the hydrogen source in combination with a palladium catalyst and Nafion® SAC-13 as a solid acid catalyst with water as reaction medium. The reaction is conducted at moderate pyrolysis temperature and short reaction time. Several palladium based catalysts and different types of lignin were investigated. The lignins and the model compounds demonstrated various chemical behaviour, under identical reaction conditions; various phenols were formed from the lignins, while the model compounds were hydrodeoxygenated, demethylated and demethoxylated. 相似文献
60.