有机/无机杂化复合木材的制备与性能

将硅溶胶/聚丙烯酸酯,有机/无机杂化液浸注于I-69杨木材中,制成有机/无机杂化木材。FT-IR红外光谱、扫描电子显微镜分析了复合木材的微观结构和组成,结果表明,经有机/无机杂化改性后的复合木材,既保持了木材本来的性质,又具有机/无机复合物的某些特性,其力学强度和尺寸稳定性较素材显著提高。     

Studies on Poplar Parthenogenesis Induced by Laser

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Production of phenol compounds by alkaline treatment of technical hydrolysis lignin and wood biomass

Aqueous alkaline depolymerization of technical hydrolysis lignin (THL) was carried out with a 5% NaOH solution at a temperature of 180°C for 6 hours, the ratio between the biomass and depolymerizing agent being 1:8. The poplar wood sawdust was treated under the same conditions for 2 hours, where anthraquinone was added as a catalyst (0.5 wt %). The poplar wood bark was treated for 4 hours, without anthraquinone. Compounds contained in the aqueous phase were extracted three times by means of toluene for a ratio between the organic and aqueous phases equal to 1:5, 1:5 and 1:5. The compounds 2-methoxyphenol, 2,6-dimethoxyphenol, 4-hydroxy-3-methoxybenzaldehyde, 1-(4-hydroxy-3-methoxyphenyl)ethanone, 4-hydroxy-3,5-dimethoxybenzaldehyde, etc., were identified through GC-MS analysis in obtained extracts. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 144–146, March–April, 2008.     

Variation of S/G ratio and lignin content in a Populus family influences the release of xylose by dilute acid hydrolysis

Wood samples from second generation Populus cross were shown to have different lignin contents and S/G ratios (S: syringyl-like lignin structures; G: guaiacyl-like lignin structures). The lignin contents varied from 22.7% to 25.8% and the S/G ratio from 1.8 to 2.3. Selected samples spanning these ranges were hydrolyzed with dilute (1%) sulfuric acid to release fermentable sugars. The conditions were chosen for partial hydrolysis of the hemicellulosic fraction to maximize the expression of variation among samples. The results indicated that both lignin contents and S/G ratio significantly affected the yield of xylose. For example, the xylose yield of the 25.8% lignin and 2.3 S/G (hihg lignin, high S/G) sample produced 30% of the theoretical yield, whereas the xylose yield of the 22.7% lignin and 1.8 S/G (low lignin, low S/G) was 55% of the theoretical value. These results indicate that lignin content and composition among genetic variants within a single species can influence the hydrolyzability of the biomass.     

Acid-Catalyzed Liquefaction of Biomasses from Poplar Clones for Short Rotation Coppice Cultivations

Liquefaction of biomass delivers a liquid bio-oil with relevant chemical and energetic applications. In this study we coupled it with short rotation coppice (SRC) intensively managed poplar cultivations aimed at biomass production while safeguarding environmental principles of soil quality and biodiversity. We carried out acid-catalyzed liquefaction, at 160 °C and atmospheric pressure, with eight poplar clones from SRC cultivations. The bio-oil yields were high, ranging between 70.7 and 81.5%. Average gains of bio-oil, by comparison of raw biomasses, in elementary carbon and hydrogen and high heating, were 25.6, 67, and 74%, respectively. Loss of oxygen and O/C ratios averaged 38 and 51%, respectively. Amounts of elementary carbon, oxygen, and hydrogen in bio-oil were 65, 26, and 8.7%, and HHV averaged 30.5 MJkg⁻¹. Correlation analysis showed the interrelation between elementary carbon with HHV in bio-oil or with oxygen loss. Overall, from 55 correlations, 21 significant and high correlations among a set of 11 variables were found. Among the most relevant ones, the percentage of elementary carbon presented five significant correlations with the percentage of O (−0.980), percentage of C gain (0.902), percentage of O loss (0.973), HHV gain (0.917), and O/C loss (0.943). The amount of carbon is directly correlated with the amount of oxygen, conversely, the decrease in oxygen content increases the elementary carbon and hydrogen concentration, which leads to an improvement in HHV. HHV gain showed a strong positive dependence on the percentage of C (0.917) and percentage of C gain (0.943), while the elementary oxygen (−0.885) and its percentage of O loss (0.978) adversely affect the HHV gain. Consequently, the O/C loss (0.970) increases the HHV positively. van Krevelen’s analysis indicated that bio-oils are chemically compatible with liquid fossil fuels. FTIR-ATR evidenced the presence of derivatives of depolymerization of lignin and cellulose in raw biomasses in bio-oil. TGA/DTG confirmed the bio-oil burning aptitude by the high average 53% mass loss of volatiles associated with lowered peaking decomposition temperatures by 100 °C than raw biomasses. Overall, this research shows the potential of bio-oil from liquefaction of SRC biomasses for the contribution of renewable energy and chemical deliverables, and thereby, to a greener global economy.     

高效液相色谱-线性离子阱-静电场轨道阱高分辨质谱测定杨树胶的指标性成分水杨苷

建立了液相色谱-线性离子阱-静电场轨道阱高分辨质谱(LC-LTQ-Orbitrap)快速测定蜂胶中杨树胶指标性成分水杨苷含量的方法,并根据精确的母离子和子离子质荷比进行定性和确证,以判断蜂胶中是否掺杂杨树胶。样品经无水乙醇提取,Waters xselect HSS T3色谱柱(3.0 mm×100 mm,3.5μm)分离,以乙腈-0.1%乙酸溶液为流动相,正离子扫描模式进行高分辨质谱检测,外标法定量。结果表明,该方法的线性范围为0.5~25.0μg/m L,相关系数(r)大于0.99。在25.0,150.0,300.0 mg/kg 3个加标水平下的平均回收率为81.6%~91.0%,相对标准偏差为9.0%~11.6%。     

Application of fentonś reaction to steam explosion prehydrolysates from poplar biomass

The application of Fenton’s reaction to enhance the fermentability of prehydrolysates obtained from steam explosion pretreatment of poplar biomass was studied. Reaction conditions of temperature and H₂O₂ and Fe(II) concentrations were studied. The fermentability of prehydrolysate treated by Fenton’s reaction was tested by using different inoculum sizes of thermotolerant strain Kluyveromyces marxianus CECT 10875. The highest percentages of toxic compound degradation (ranging from 71 to 93% removal) were obtained at the highest H₂O₂ concentration tested (50 mM). However, a negative effect on fermentability was observed at this H₂O₂ concentration at the lower inoculum loading. An increase in inoculum size to 0.6 g/L resulted in an enhanced ethanol fermentation yield of 95% relative to control.     

Facile fabrication of steam-exploded poplar loaded with non-metal-doped Ni-Fe nanoparticles: Catalytic activities in 4-nitrophenol reduction and electrocatalytic reaction

A simple and effective method for preparing a non-metallic ion-doped nickel-supported catalyst is reported. Using economical and recyclable fibre raw materials as carriers, nickel-supported catalysts were prepared by adsorption and reduction at room temperature. The nanoparticles dispersed and anchored on a rational support, efficiently inhibiting their aggregation and thus enhancing the catalytic activity. For the model catalytic hydrogenation of 4-nitrophenol by NaBH₄, the N-B-NiP/steam-exploded poplar (SEP) and N-B-Ni₅Fe₅P/SEP catalysts exhibited much better catalytic performances than the other recently reported catalysts in terms of the catalytic activity (the reaction was completed within 10 min for both aforementioned catalysts), reaction rate constant (0.19 and 0.344 min^?1, respectively) and the activity factor K (19 and 34.4 min^?1·g^?1, respectively). The catalysts showed activities for electrocatalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) under ambient conditions. In general, the reported preparation method of nickel-supported catalysts is convenient, economical and environment-friendly, and is agreement with many green chemistry and sustainable development principles; further, it employs widely available starting materials.     

基于时域核磁共振技术的木材吸湿过程研究

木材吸湿会对其力学性能和尺寸稳定性产生影响,深入了解木材吸湿过程中水分状态的变化有重要意义.利用时域核磁共振(TD-NMR)技术,以美国黄杨木和红橡木作为研究对象,对木材吸湿过程中水分状态和弛豫特性进行研究.结果显示:吸湿过程的前4h,两种木材试件结合水峰面积迅速增大,自由水峰面积无明显增长,说明在吸湿初期,增加的水分主要以结合水为主;在达到吸湿平衡后,红橡木试件内自由水峰面积约为黄杨木试件内自由水峰面积的2倍,这是由于与黄杨木相比,红橡木管孔孔径较大,因此在吸湿过程中,红橡木的自由水吸湿速度较快,吸湿量大于黄杨木.     

利用TD-NMR技术研究杨木高温干燥过程水分分布

木材中水分状态变化和迁移对木材的物理性质有重要影响.通过时域核磁共振技术(TD-NMR)可以从分子层面解读木材与水分的关系,可以为木材干燥、木制品加工提供理论依据和实践参考.该研究以北京杨为研究对象,通过对高温干燥过程中木材内部水分变化的自由感应衰减(FID)曲线和横向弛豫时间(T_2)进行测定与分析,探究木材干燥过程中水分状态变化及迁移过程.研究结果表明,FID和T_2信号量与木材含水率高度线性相关,由此可以计算木材在干燥过程中任意时刻的含水率.通过对干燥过程中水分T_2分布的分析表明:心材试件在干燥过程中,长弛豫时间自由水(c状态水分)的拟合面积出现了先减小后增大然后再减小的趋势,而边材试件中则不存在这种现象.在北京杨心材试件中含量最多的是弛豫时间为10 ms数量级的水分,而在边材试件中各状态水分含量差异较小,含量最多的是弛豫时间为100 ms数量级的水分.在高温干燥过程中,边材试件内各状态水分百分含量减少的速度快于心材,各试件中自由水的蒸发速度明显快于结合水.