Fermentability of water-soluble portion to ethanol obtained by supercritical water treatment of lignocellulosics

The water-soluble (WS) portion obtained by supercritical water treatment of lignocellulosics was studied for its fermentability to ethanol. A fermentation test of the WS portion showed it was not fermented to ethanol. Therefore, a wood characoal treatment was applied to the WS portion to remove furan and phenolic compounds, which are thought to be the inhibitors to sugar fermentability. It was found that treatment with wood charcoal can be effective at removing these inhibitors and improving the fermentability of the WS portion without reducing the levels of fermentable sugars.     

Structure and thermal properties of bamboo viscose,Tencel and conventional viscose fiber

Comparative investigations of new regenerated cellulosic fibers, bamboo viscose fiber and Tencel, together with conventional viscose fibers have been carried out to explain the similarity and difference in their molecular and fine structure. The analyses jointly using SEM, XRD and IR reveal that all the three fibers belong to cellulose II. Tencel consists of longer molecules and has a greater degree of crystallinity, while bamboo viscose fiber has a lower degree of crystallinty. TG-DTG-DSC study shows three fibers resemble in thermal behavior with a two-step decomposition mode. The first step is associated to water desorption, suggesting that bamboo viscose fiber holds better water retention and release ability, the second a depolymerization and decomposition of regenerated cellulose, indicating that Tencel is more thermally stable in this process than bamboo and conventional viscose fiber.     

Charcoal open tubular traps for the analysis of air and headspace samples

5 cm × 0.3 mm i.d. glass capillary tubes coated with fine charcoal particles are used for the analysis of organic compounds, particularly tri- and tetrachloroethylene, benzene, and toluene, in air and headspace samples. Due to their small size, these traps are easy to use with capillary GC. As, e.g. 20 ml of gas can be sucked through this trap in 20 s, it is a simple technique providing high sensitivity; compared to headspace with split injection, sensitivity is increased by a factor exceeding 100. The column effluent is split into FID and ECD in such a way that small as well as large amounts of the chlorinated compounds can be detected.     

Kinetic Study of Erbium Ion Adsorption on Activated Charcoal from Aqueous Solutions

The kinetics of the adsorption of erbium ions on activated charcoal from aqueous solutions has been studied in the temperature range of 10 to 40∘C. It was observed that the diffusion of erbium ions in to the pores of activated charcoal controls the kinetics of the adsorption process, and the values of intra-particle diffusion rate constant, k_d (g/g ⋅ min^1/2) were evaluated as 0.7 × 10⁻³ to 1.6 × 10⁻³ in the temperature range studied. Various thermodynamic parameters Δ H, Δ G and Δ S were also computed from values of the equilibrium constant K_C. The results showed that the adsorption of erbium ions on activated charcoal is an endothermic process.     

竹浆纤维素转化制低碳多元醇反应中有机氮对金属催化剂稳定性影响的研究

采用等体积浸渍法制备了一系列多孔竹炭负载的有机氮掺杂的镍钨催化剂,并将其应用于催化竹浆纤维氢解制C_2,3多元醇反应。有机氮源与催化剂前驱体中Ni²⁺络合,高温煅烧时载体表面碳、氮和金属离子相互作用后生成一定量的C₃N₄、氮化物和合金物相。通过XRD、XPS和TEM等表征手段分析了催化剂Ni-W/MBC表面物理化学性质与催化活性间的关系。结果表明,除了金属镍、氧化钨物相外,表面还含有Ni-W合金（NiWO₄为主）;金属粒子表面包围了一层石墨化C₃N₄物相。XPS分析表明,有机氮源高温分解反应后形成了C₃N₄物相。在反应条件下,15% Ni-20% W/MBC@M-0.25催化剂得到乙二醇收率为55.8%,而未添加有机氮源的催化剂15% Ni-20% W/MBC获得的乙二醇收率仅为36.9%。催化剂稳定性实验结果表明,Ni-W合金和C₃N₄物相的形成显著增强了Ni-W/MB催化剂的稳定性,延长了催化剂寿命。     

基于X射线CT技术快速检测不同含水率状态下的毛竹密度

密度是竹材材性的重要指标之一,与竹材诸多物理力学性质紧密相关,且测定结果因含水率状态不同而不同。基于X射线计算机断层扫描(X-CT)技术,比较了不同竹龄毛竹全干、气干、饱水状态下CT值的差异程度,除4年生和10年生毛竹CT值差异较大以外,其余竹龄CT值差异较小;分别在全干、气干、饱水状态下对所测定的CT值与相应状态下毛竹的密度进行拟合建模,同时还对不同含水率梯度状态下的CT值与密度进行拟合建模,进而系统分析了不同竹龄毛竹在单一含水率状态下和不同含水率梯度状态下CT值与密度之间的关系;对不同竹龄毛竹全干状态下相对竹青径向位置的CT值进行了拟合,依据CT值与密度之间的关系,解释说明了毛竹径向密度因竹龄不同所产生差异的原因。试验结果表明,毛竹全干、气干、饱水密度与相应的CT值之间均存在线性关系,且拟合斜率相近;在所选含水率梯度状态下毛竹密度与CT值之间存在线性关系,且密度与CT值关系受水分影响较小,回归方程为：D=0.001H+1.003 2,R2=0.968 3(D为密度,H为CT值),验证模型决定系数R2=0.974 3;不同竹龄毛竹全干状态下竹青、竹黄处密度差异较小,而在竹肉处差异较大。这些结果为实现快速检测毛竹在不同含水率状态下的密度提供了技术支持和数据参考,同时X射线计算机断层扫描(X-CT)技术也为深入研究竹材材性和构造提供了一种切实可行的新途径。     

大熊猫主食竹开花后叶片光谱特性的变化

以佛坪自然保护区为研究区域,选取不同开花状态的大熊猫主食竹种巴山木竹、秦岭箭竹和龙头竹进行高光谱遥感测定,用原始光谱分析法和红边参数法分析开花对大熊猫主食竹光谱特征的影响。结果表明：(1)开花改变了各种竹子叶片反射光谱,龙头竹三种状态之间的光谱差异最大,其次为秦岭箭竹;(2)开花后,巴山木竹红边位置未发生明显移动,而秦岭箭竹和龙头竹则发生“蓝移”。研究发现原始光谱特征和红边位置在不同开花状态下都发生了变化,可以为大熊猫主食竹开花的遥感预测提供一定的实验基础及理论依据。     

利用二维相关红外光谱研究竹原纤维的热微扰作用

采用红外光谱法和二维相关光谱分析技术,对竹原纤维的热微扰作用进行了研究。通过竹材和服用竹原纤维的红外光谱图的比较,可以看出,和竹材相比,服用竹原纤维木质素和半纤维素含量明显 降低。从不同温度（50～120 ℃）服用竹原纤维的动态红外光谱图得出,在这个缓慢升温的过程中,温度只是一种微扰,并没有发生剧烈的氧化作用。最后,借助于二维相关光谱分析,研究了服用竹原纤 维和竹材在温度微扰作用下,红外光谱中各基团的相关变化情况。二者的二维相关红外光谱分析结果表明,服用竹原纤维和竹材都在1 655 cm-1处出现最强自相关峰,说明其对应的化学基 团对于温度变化十分敏感。二者的区别在于,在800～1 300 cm-1波段,竹原纤维只有几个较弱的自相关峰和交叉峰,而竹材在这一波段出现一个较强的5×5峰组,说明服用竹原纤维和竹材 的化学成分具有显著的差别,其对热微扰的敏感性大大降低。初步的研究结果表明,二维相关红外分析可以作为分析服用竹原纤维热微扰过程中结构动态变化的一种新方法,也为竹原纤维氧化机理的研究 提供了一种新手段。     

竹炭-泡沫塑料复合材料对甲醛吸附性能的研究

考察了竹炭-泡沫塑料复合材料(ZP)对甲醛蒸汽的吸附量,研究了ZP中竹炭含量和吸附时间对甲醛吸附量的影响。结果表明:吸附时间2 h时,ZP-2(含竹炭5%)对甲醛的吸附量为7.157 mg.g-1,ZP-6(含竹炭25%)的吸附量增至11.913 mg.g-1;吸附时间为48 h时,ZP-2的吸附量为15.321 mg.g-1,ZP-6的吸附量增至28.668 mg.g-1。运用扫描电子显微镜(SEM)观察了竹炭与泡沫塑料的结合形态,初步解释了ZP对甲醛吸附性能变化的微观影响因素。采用SPSS软件以吸附时间、竹炭含量为变量对甲醛吸附量进行回归分析,得出回归方程为:Y=3.94×Ln(X1)+30.56×(X2)+1.7,相关系数R2=0.95。表明随着吸附时间(X1),竹炭含量(X2)的增加,ZP对甲醛的吸附量(Y)逐渐增大,ZP能够有效地吸附甲醛。     

固相萃取-高效液相色谱-串联质谱联用测定竹笋中残留的7种杀虫剂农药

建立了高效液相色谱-串联质谱(HPLC-MS/MS)同时测定竹笋中丁烯氟虫腈、毒死蜱、氯虫苯甲酰胺、氟虫腈、吡虫啉、茚虫威和辛硫磷7种农药残留的分析方法。样品用乙腈提取后,经PSA固相萃取小柱净化,采用Atlantis T3色谱柱分离,以0.1%甲酸水溶液(含5 mmol/L乙酸铵)和乙腈为流动相,梯度洗脱分离,在电喷雾离子源正、负离子模式下采用质谱多反应监测(MRM)模式检测。结果表明,7种农药在10～100 μg/L范围内具有良好的线性关系(相关系数r为0.9900～0.9994); 4、8、32 μg/kg添加水平下的平均回收率为76.0%～102.6%;相对标准偏差为3.2%～11.0%;7种农药的检出限为0.02～0.5 μg/kg,定量限为0.08～1.5 μg/kg。该方法准确度、灵敏度高,简单、快速,可满足竹笋中7种杀虫剂残留同时检测的要求。