弹道明胶老化初级阶段的模型

用流变震荡模式研究了10 wt%浓度的弹道明胶在冷却和等温下的老化行为.对明胶从sol-gel点冷却到某个目标温度的过程,通过不同冷却速率的实验,建了一个弹性模量与温度的线性关系.不同温度下明胶的等温老化实验表明,弹性模量-时间曲线具有相似的形状.依据Normand提出的二级反应动力学模型,引入一个表征明胶老化行为的速率常数,构建了一个预测弹道明胶在老化初级阶段的弹性模量演化的模型.该模型中模量-温度关系在初始和无穷大时是直线,其他模量-温度线是近似直线,并交于sol-gel点.老化速率常数和过冷度之间符合Flory-Weaver方程.对弹性模量和老化时间进行归一化处理,可将不同温度下的老化曲线叠加成一条主曲线.     

高效液相色谱法同时测定啤酒中4种老化味物质

建立了同时测定啤酒中5-羟甲基糠醛、糠醛、苯乙醛和反-2-壬烯醛4种主要老化味物质的高效液相色谱方法.确定了最佳梯度洗脱程序和时间变化波长检测程序,实现了30 min内对4种老化味物质的分离和检测;优化了样品前处理条件,使4种老化味物质得到了同时提取和富集.所建立的4种物质工作曲线相关系数良好(r为0.9996～0.9999),线性范围≥103,检出限为0.002～0.003μg/mL(S/N=3),样品加标平均回收率为87.1%～108%,相对标准偏差为2.6%～5.5%.     

高效液相色谱法测定油茶籽壳水热碳化液中的3种糠醛类物质

采用高效液相色谱法同时测定油茶籽壳水热碳化液中的5-羟甲基糠醛、糠醛和5-甲基糠醛的含量。油茶籽壳水热碳化液经Thermo ODS色谱柱分离,以甲醇-水混合液作为流动相进行梯度洗脱,采用二极管阵列检测器,检测波长为285 nm。3种糠醛类物质的质量浓度在一定范围内与其峰面积呈线性关系,5-羟甲基糠醛、糠醛和5-甲基糠醛的检出限(3S/N)分别为0.02,0.005,0.02 mg·L~(-1),测定下限(10S/N)分别为0.04,0.02,0.05 mg·L~(-1)。加标回收率分别在74.9%~101%,94.5%~109%和98.6%~112%之间,测定值的相对标准偏差小于10%。     

以糠醛为原料的成对电合成

研究了Ti/Ru-Ti-Sn,Ni,Ti/PbO_2,Pt和Ti/BDD(钛基掺硼金刚石电极)5种电极的析氧情况及对糠醛电化学氧化成糠酸的催化作用,得出氧化的最佳电极为Ni.以糠醛为原料,Ni电极为阳极,Cu电极为阴极,成对电合成糠醇和糠酸,研究了溶液p H值、电流密度、糠醛浓度、温度及电解时间对反应的影响.结果表明,溶液pH=11,阴极电流密度为2 mA/cm~2,阳极电流密度为1 mA/cm~2,糠醛浓度为0.1 mol/L,温度为25℃时,经过优化,总的电流效率最佳为130%.     

响应面优化分析镧引发提高玉米幼苗素质的初探

提高玉米幼苗素质是玉米安全生产的重要保证之一。本研究以老化和未老化玉米种子为试验材料，采用响应面分析法优化镧(La)引发提高玉米幼苗素质的引发浓度和引发时间的处理组合。结果表明：响应面分析发现未老化种子的根长和苗长指标具有最佳组合，根长最佳组合为引发浓度0.33 g·L^-1，引发时间10.85 h，预测值为20.01 cm，苗长最佳组合为引发浓度0.34 g·L^-1，引发时间12.89 h，预测值为10.97 cm；老化种子根干重La引发浓度和引发时间最佳组合为引发浓度1.6 g·L^-1，引发时间14.85 h，预测值为0.64 g。其他指标未发现最佳组合。此方法为La引发提高玉米幼苗素质，筛选最佳组合提供参考。     

利用余补误差函数模拟土壤中铜老化微孔扩散过程模型的构建

土壤中铜的老化是指土壤中外源铜的生物有效性或毒性、同位素可交换性及化学有效性随时间降低的过程. 此前Ma等提出了两个半机理模型, 并分别预测了铜在土壤中的短期和长期老化作用. 本文在探讨土壤中铜的老化规律及影响因素的基础上, 通过对Ma等的两个半机理模型进行整合与修正, 结合Crank对扩散过程的描述, 发现利用余补误差函数可以模拟土壤中铜老化的微孔扩散过程的短期(扩散作用与时间的平方根线性相关)和长期行为(扩散作用与时间的自然对数线性相关), 解决了土壤中铜短期和长期老化模型之间缺少连续性的问题. 本模型考虑了土壤pH及老化时间对老化作用的影响, 这两个因素均与老化作用呈正相关, 相较于Ma等此前提出的半机理模型, 本模型可获得更为准确的预测结果.     

界面法合成聚糠醛纳米球

采用界面自组装聚合的方法, 成功地制备出聚糠醛纳米球, 利用TEM, FT-IR, XRD, GPC及TG-DTA等技术对其形貌、结构等进行了表征, 并考查了单体浓度、催化剂用量以及乳化剂的存在与否对聚糠醛形貌等的影响. 结果表明, 由该方法合成的聚糠醛为不规则的结晶结构, 当乳化剂浓度在临界胶束浓度cmc附近、单体浓度在3～5 mol•L^－1、催化剂的用量在10 mol•L^－1左右时, 能够得到成球性好、粒径分布范围窄、平均尺寸在100 nm左右的聚糠醛纳米球结构材料. 利用该法在上述优化条件下合成的聚糠醛的M_w＝2451, M_w/M_n＝1.14, 且分子量分布窄. 聚糠醛分子链的柔韧性较强, 具有很好的加工性能. 该法具有合成条件温和、易于控制、纯化简单等众多优点, 而且省去了使用模板/消除模板的过程, 能够一步合成出大量聚糠醛纳米球.     

固定床催化及气相中和法转化木糖制备糠醛

采用固定床催化及气相中和的方法优化了糠醛的洁净生产工艺.在固定床催化阶段主要考察了催化剂硫酸的浓度、原料木糖溶液的浓度及添加助催化剂对糠醛收率的影响;气相中和阶段主要考察了不同金属阳离子及阴离子对糠醛收率及糠醛液酸度的影响.实验结果表明,当固定床催化条件选定为2 mol/L硫酸,木糖溶液质量分数为10%,助催化剂Na Cl添加量80 g时,糠醛收率最高可达到74. 12%;在气相中和阶段,阴离子对提高糠醛收率的影响顺序为SO_4~(2-)Cl-CO_3~(2-)OH~-,而不同金属阳离子的影响不大.经过气相中和制备的糠醛液的酸度均符合国家标准GB/T1926.1-2009.     

二维相关红外光谱法及标准线性固态模型对天然橡胶热氧老化机理的研究

对天然橡胶复合材料进行了不同时间下的热氧加速老化实验并分析其老化机理.采用红外测试研究天然橡胶在热氧老化过程中可能的基团变化规律,同时对不同老化时间下的红外结果进行二维相关分析,发现老化产物的生成速率依次为酯过氧化物醚;核磁交联密度测试表明总交联密度(XLD)与网链分子量(Mc)及横向弛豫时间(T2)有很好的对应关系,XLD随着老化时间的增加而增加,即天然橡胶热氧老化过程中交联反应占主导地位;示差扫描量热(DSC)测试发现,随着老化时间的增加,玻璃化转变温度(Tg)升高,玻璃化转变区变宽,表明交联反应占主导地位,与核磁交联密度测试结果一致.通过对天然橡胶进行压缩应力松弛实验,采用修正的标准线性固态模型(SLS模型)进行拟合分析,发现在短时热氧老化过程中,老化以氧化和交联反应为主,与核磁交联密度及DSC实验结果一致.     

反相高效液相色谱法测定白酒中糠醛

<正>糠醛又称呋喃甲醛或麸醛,广泛存在于蒸馏酒中。它主要是由戊聚糖分解或酵母发酵所产生,具有一定的毒性。传统的酿造工艺生产的白酒普遍含有一定量的糠醛,糠醛是构成白酒风味的重要成分,含量在300 mg·L~(-1)以下时,能赋予白酒特殊的香味。研究表明酒中糠醛的含量与香型有一定的关系     

The research for low-temperature rheological properties and structural characteristics of high-viscosity modified asphalt

High-viscosity modified (HVM) asphalt was prepared by the addition of styrene–butadiene–styrene, furfural exact oil (FEO, plasticizer), sulphur (crosslinker). The low-temperature rheological properties of HVM asphalt were investigated by using bending beam rheometer, and different analysis ways including Fourier transform infrared (FTIR) analysis, thermal analysis, ¹hydrogen nuclear magnetic resonance (¹NMR) analysis, elemental analysis, optical microscopy were used to investigate the structural characteristics of modified asphalts and FEO. Rheological tests demonstrated the effect of each modifier on low-temperature rheological performances of asphalt and displayed the structural characteristics of each binder to some extent. FTIR analysis indicated the effect of ageing and modifier on the distribution of functional groups of modified asphalt before and after ageing. Morphology observation showed the distribution of polymer in asphalt with different modifications or ageing. The thermal analysis showed the effect of each modifier on thermal behaviour of asphalt before and after ageing and confirmed the result of FTIR analysis and morphology observation further. Besides, the constituents of base asphalt and plasticizer were also investigated and compared further by adopting elemental analysis, and ¹HNMR and FTIR tests.     

Degradation of Furfural by UV/O3 Technology

Furfural in aqueous solution was treated by UV/O3 method.The results show that the removal rate of furfural is severely enhanced and the synergism phenomenon appears when ultraviolet and ozone are present together.The influences of experimental parameters such as pH,the intensity of light and the negative-positive ions on furfural degradation were investigated.The results indicate that furfural(300 mg/L) is almost completely degraded after 3 h under the optimum conditions.The intermediate in the furfural de...     

Effect of Furfural on <Emphasis Type="Italic">Saccharomyces carlsbergensis</Emphasis> Growth,Physiology and Ethanol Production

This work described the effect of furfural, a product resulting from the lignocellulosic material pretreatment, on Saccharomyces carlsbergensis growth and ethanol production. Flow cytometry was used to evaluate the yeast membrane potential, membrane integrity, reactive oxygen species production and lipid content. Above 0.3 g/L of furfural, a progressive decrease in the maximal specific growth rate was observed, reaching 53% of the value obtained in the absence of toxic when the cells were grown in the presence of 4 g/L of furfural. In general, the yeast biomass concentration and yield were less affected by the furfural presence than the specific growth rate, and a maximum reduction of 25% was observed for the assay at 4 g/L. The ethanol production was even less affected by the furfural presence than the yeast growth. At 4 g/L of furfural, the maximum ethanol concentration was reduced by only 10% relatively to the maximum ethanol concentration observed in the absence of toxic. At 5 g/L of furfural, the yeast cells were barely able to keep metabolic functions and produced a final ethanol concentration of 0.87 g/L although growth was undetectable. S. carlsbergensis membrane potential was affected by the furfural presence, concomitantly with the ethanol production. However, at 4 g/L, most of the yeast cells (90%) displayed the cytoplasmic membrane depolarized. The proportion of cells with increasing reactive oxygen species (ROS) production levels increased for the experiments at 0–4 g/L. For the experiment at 4.5 g/L of furfural, ROS production was observed for only 11% of the yeast cells. The yeast lipid content was also severely affected by the furfural presence. Both polar and neutral lipids decreased in the presence of furfural, and this reduction was more notorious during the stationary phase.     

廉价离子液体体系中玉米芯生成糠醛优化

采用廉价绿色离子液体[TEA][HSO4]作为溶剂,利用微波加热法辅助玉米芯水解并脱水制备糠醛.通过响应面法优化糠醛生成反应条件,有效转换玉米芯中的木糖,并得到82.2％糠醛收率.利用2-丁醇作为萃取剂对糠醛进行回收.重复4次萃取实验,从[TEA][HSO4]中回收99.7％糠醛.在2次[TEA][HSO4]的回收实验...     

Rapid determination of furfural in biomass hydrolysate by full evaporation headspace gas chromatography

This paper reports a full evaporation (FE) headspace gas chromatographic (HS-GC) method for rapid determination of furfural in the biomass hydrolysate. The data show that a near-complete mass transfer of furfural in the sample from biomass hydrolysate to the vapor phase (headspace) was achieved within 3 min at 105°C when a very small (<40 μL) sample was added to a 20 mL headspace sample vial. The acid-catalyzed furfural decomposition under these conditions was negligible. The furfural in the vapor phase was then determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD<0.5%) and accuracy (recovery=100.2±1.7%) for furfural quantification in carbohydrate hydrolysate samples. The method requires no sample pretreatment, so it is simple, rapid and accurate, and suitable for applications in lignocellulosic biomass conversion to fuel ethanol or other high value-added products.     

Degradation of furfural (2- furaldehyde) to methane and carbon dioxide by an anaerobic consortium

Furfural, a byproduct formed during the thermal/chemical pre-treatment of hemicellulosic biomass, was degraded to methane and carbon dioxide under anaerobic conditions. The consortium of anaerobic microbes responsible for the degradation was enriched using small continuously stirred tank reactor (CSTR) systems with daily batch feeding of biomass pretreatment liquor and continuous addition of furfural. Although the continuous infusion of furfural was initially inhibitory to the anaerobic CSTR system, adaptation of the consortium occurred rapidly with high rates of furfural addition. Addition rates of 7.35 mg furfural/700-mL reactor/d resulted in biogas productions of 375%, of that produced in control CSTR systems, fed the biomass pretreatment liquor only. The anaerobic CSTR system fed high levels of furfural was stable, with a sludge pH of 7.1 and methane gas composition of 69%, compared to the control CSTR, which had a pH of 7.2 and 77% methane. CSTR systems in which furfural was continuously added resulted in 80% of the theoretically expected biogas. Intermediates in the anaerobic biodegradation of furfural were determined by spike additions in serum-bottle assays using the enriched consortium from the CSTR systems. Furfural was converted to several intermediates, including furfuryl alcohol, furoic acid, and acetic acid, before final conversion to methane and carbon dioxide.     

Hydrogenation of furfural with alkali-metal amalgams

The possibility of reducing furfural to furyl alcohol with potassium and sodium amalgams under the conditions of neutralizing the alkali formed with carbon dioxide has been investigated. The reduction of furfural can be directed to the predominant formation of furyl alcohol by regulating the rate of feed of furfural into the reaction vessel.     

Hydrogenation of furfural with alkali-metal amalgams

The possibility of reducing furfural to furyl alcohol with potassium and sodium amalgams under the conditions of neutralizing the alkali formed with carbon dioxide has been investigated. The reduction of furfural can be directed to the predominant formation of furyl alcohol by regulating the rate of feed of furfural into the reaction vessel.     

介孔Ni/MgO催化剂催化水蒸气重整生物质油制氢

采用水热法制备了介孔MgO作为催化剂的载体,并制备了介孔Ni/MgO催化剂。利用N_2吸附-脱附、XRD、H_2-TPR等对样品进行表征,并考察了介孔Ni/MgO催化水蒸气重整糠醛、生物质油模型物和两种商用生物质油制氢的活性。结果表明,在介孔Ni/MgO催化剂催化水蒸气重整糠醛制氢反应中,随着反应温度的提高,水蒸气重整糠醛中糠醛的转化率、氢气的产率和氢气的选择性,都呈现递增的趋势。在反应温度提高到600℃时,糠醛的转化率和氢气的产率分别达到94.9%和83.2%。Ni/MgO催化水蒸气重整二组分模拟生物质油,糠醛/乙酸、糠醛/羟基丙酮制氢的反应中,氢气的产率分别达到87.3%和86.8%,均高于水蒸气重整糠醛反应中氢气的产率。由此表明,乙酸或羟基丙酮的存在,提高了模拟生物质油中主要有机物组分糠醛的转化率,并相应地提高了氢气的产率。在水蒸气重整商用生物质油制氢反应中,随着反应物水碳比(S/C(molar ratio)=5、10、15、20、25)的提高,主要有机物的转化率、氢气的产率和选择性呈现出增加的趋势。在水碳比为20时,两种生物质油的主要有机物组分(糠醛、乙酸和羟基丙酮)的转化率均可达90%以上,氢气的产率也达到81.0%以上。由此可知,Ni催化剂对于水蒸气重整商用生物质油也具有较高的催化活性。     

糠醛渣热解特性的研究

以糠醛渣为研究对象,应用热重分析法,以高纯氮气为载气对其进行了详细的热重分析试验。结果表明糠醛渣热解随温度升高经历五个不同阶段,表现了糠醛渣热解的复杂性。通过对5 ℃/min、20 ℃/min、50 ℃/min和80 ℃/min的升温速率及不同粒径下的失重曲线进行的对比表明,随着升温速率和粒径的增大,糠醛渣热解的初始温度增大,热解向高温侧移动。最后根据实验数据建立了热解动力学模型,并对数学模型进行了求解,得到了糠醛渣热解反应的动力学参数,表明糠醛渣热解属三级反应。