Influence of amorphous alkaline lignin on the crystallization behavior and thermal properties of bacterial polyester

Bacterial polyester poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and alkaline lignin composites were prepared via melt processing method, and the influence of amorphous lignin on the crystallization behavior and thermal properties of PHBV were investigated. It was found that dual melting peaks appeared in DSC curves of PHBV/lignin composites, while only one single peak existed in PHBV. The non‐isothermal crystallization process analyzed by Jeziorny method suggested that lignin changed the nucleation mode of composites and hindered the crystallization rate of PHBV. Data calculated from the results of WAXD demonstrated that lignin did not change the basic crystal structure of PHBV, but decreased the average size of the lamellar stacks. POM results confirmed that the effect of lignin on the crystallization behavior of PHBV carried out in two opposite way, namely the enhanced effect of nucleation and the hindered effect of growth. Besides, the thermal stability of composites was also decreased significantly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41325.     

木质素在超临界甲醇和乙醇溶剂中液化过程分析

通过研究木质素分别在超临界甲醇和乙醇溶剂中的液化过程，分析反应温度（260～340℃）及反应时间（0～120min）对木质素在两种溶剂中的转化率、生物油收率及其组分差异的影响。实验表明，木质素在超临界乙醇中的转化率及产物收率均高于甲醇。当反应温度340℃，反应时间60min，木质素在超临界乙醇中的转化率和生物油收率比在甲醇中分别提高了16.23%和11.54%，残渣收率降低了16.23%。通过GC-MS和FTIR对生物油和残渣分析，发现生物油组分中芳香族化合物相对含量较高，在甲醇和乙醇溶剂中分别达到66.13%和58.84%；随着反应时间的延长，甲醇溶剂中残渣的醚键官能团逐渐增强，而在乙醇溶剂中则先增强后减弱。分析认为在木质素降解过程中，超临界乙醇和甲醇均可产生氢自由基作为供氢体，攻击木质素及其大分子片段中的官能团，同时使液化产物中的活性片段减活，减弱重聚合反应，从而更利于芳烃产物的生成。而甲醇在液化过程中容易与木质素断键产生的苯酚中间体发生脱氢缩合反应，通过醚键聚合产生长链芳香族化合物，形成残渣，降低生物油收率。     

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．     

微波作用下苄苯醚催化转移氢解反应动力学

引言木质素是由含氧苯丙烷单元构成的一种复杂三维网状聚合物,是构成植物骨架的主要成分之一。在自然界中,木质素的储量仅次于纤维素,估计每年全世界由植物生长可产生1500亿吨木质素[1]。     

木质素用量对乳液共沉天然橡胶性能的影响

采用共沉方法制备天然橡胶/木质素复合材料,研究了复合材料和炭黑胶料的性能以及木质素用量对天然橡胶性能的影响。结果表明,加有木质素的胶料,随着木质素用量的增加,复合材料的门尼粘度逐渐上升,炭黑胶料的最低转矩(ML)增大,最高转矩(MH)下降,正硫化时间(tc90)延长,焦烧时间(ts1)缩短,炭黑分散性变差,胶料的加工安全性、耐磨性及耐老化性变差,硫化胶的定伸应力降低。当木质素用量在20份以内时,硫化胶的拉伸强度和撕裂强度提高。     

玉米秸秆木质素的超临界提取及结构表征

采用超临界CO2/乙醇-水三元体系反应提取玉米秸秆中的木质素,并采用沉淀法对提取液中的木质素进行回收,得到木质素产品.利用气相色谱-质谱联用、红外光谱、紫外光谱分析了提取液成分及提取木质素产品的结构特性.采用热重分析方法对提取木质素的热稳定性进行了研究.结果表明:本试验方法提取的玉米秸秆木质素具有木质素的典型结构.提取木质素主要在180 ～500℃温度范围内分解失重.原木质素在超临界提取反应过程中发生了相当程度的降解,醚键发生了较大程度的断裂,木质素-水化合物复合体发生了不完全降解,提取木质素中含有一定量的碳水化合物.     

Thermogravimetry‐FTIR Analysis of Pyrolysis of Pyrolytic Lignin Extracted from Bio‐Oil

Pyrolytic lignin is attributed to the instability of bio‐oil but is a potential chemical material. To improve the stability and increase the economic viability of bio‐oil, high‐ and low‐molecular‐mass pyrolytic lignin (HMM and LMM) were obtained using solvent extraction. The microstructure of pyrolytic lignin was examined by Fourier transform infrared spectrometry (FTIR). The dissimilar absorption intensities indicated the different content of corresponding functional groups in HMM and LMM. The pyrolysis behavior of HMM and LMM was studied by thermogravimetry coupled with FTIR. Obviously pyrolytic lignin undergoes three weight loss stages.     

Effect of bacterial inoculum ratio in mixed culture for decolourization and detoxification of pulp paper mill effluent

BACKGROUND: Effluent released from industry is a mixture of various pollutants. For the degradation of complex pollutants, mixed bacterial cultures can be more effective than a single culture. This study investigated the balance of bacterial populations in a mixed culture for maximum reduction of pollutants. RESULTS: This study deals with the degradation and detoxification of pulp paper mill effluent (PPME) by three bacterial strains, i.e. Serratia marcescens, Serratia liquefaciens and Bacillus cereus in different ratios, and found that two ratios, 4:1:1 and 1:4:1, were effective for the degradation of PPME. These ratios reduced the various pollution parameters. Enzyme bioassay revealed that more enzyme was produced during degradation for the ratio 4:1:1. High performance liquid chromatography (HPLC) analysis showed that the ratio 4:1:1 degraded 95% of lignin and related compounds, and chlorophenols up to 98%, whereas ratio 1:4:1 reduced lignin by 84% and chlorophenols by 58% after 7 days incubation. Degradation products were confirmed by gas chromatography–mass spectrometry (GC‐MS) analysis. A seed germination bioassay on Phaseolous mungo L. revealed that toxicity was reduced by the ratio 4:1:1. CONCLUSION: Due to variable potential of different bacteria show variation in their growth pattern at any contaminated site. This study shows that an appropriate ratio of mixed cultures is required for maximum degradation and detoxification of PPME. Copyright © 2012 Society of Chemical Industry     

Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry