Effects of Spacer Chain Length and Additives on Solution Properties of Cationic Gemini Surfactant

The critical micelle concentration (CMC) has been determined for the gemini surfactant trimethylene-1,3-bis(dodecyldimethyl ammonium bromide)12-s-12,2Br^?1 by means of electricity conductivity measurements. For the same number of carbon atoms in the hydrophobic chain per hydrophilic head group, geminis have CMC values well below those of conventional single-chain cationic surfactants. The CMC of 12-3-12 reduces with the addition of n-alcohol except ethanol and with the increase of n-alcohol chain length as well as increase of concentration of n-butanol and sodium chloride. Steady-state fluorescence quenching technology has been employed to study the aggregation number of micelle, which increases with increase in the length of n-alcohol. The Kraft temperature measurements also indicate that the stability of solid surfactant hydrate decreases along with the improvement of concentration of n-butanol and sodium chloride.     

碳酸钾催化的铁基氧载体煤催化化学链燃烧

研究了K₂CO₃催化剂及惰性担体对铁基氧载体煤化学链燃烧的影响.实验结果表明,K₂CO₃的添加可明显促进铁基氧载体与煤之间的反应速率,其原因可归结为从氧载体上迁移到煤颗粒上的K₂CO₃对煤-CO₂气化步骤的催化作用(该步骤为整个还原过程的速率控制步骤);由于K₂CO₃本身的促熔效果及加入K₂CO₃后导致的剧烈氧化还原反应,可以发现,K₂CO₃会增大铁基氧载体的烧结;不同惰性担体对铁基氧载体与煤的反应性影响不大,这是由于惰性担体对还原速控步没有影响;K₂CO₃在多循环化学链燃烧过程中依然可以保持一定的催化活性,另外由于催化剂的流失与失活,使得氧载体的反应活性有所下降.     

铜基载氧体与可燃固体废弃物化学链燃烧特性研究

采用机械混合法制备了铜基载氧体,利用两段式管式炉反应平台和磁悬浮热重分析仪分别研究了铜基载氧体与石墨、可燃固体废弃物典型组分及可燃固体废弃物热解气模型物CH₄的化学链燃烧特性。结果表明,机械混合法制备的Cu80Si950载氧体强度高,具有良好的转化率和循环稳定性,是实现可燃固体废弃物化学链燃烧的一种比较理想的载氧体。利用扫描电镜(SEM)、X射线衍射仪(XRD)和颗粒强度测定仪对各个反应阶段载氧体进行分析。结果表明,Cu80Si950载氧体参与反应后表面结构发生巨大改变,机械强度骤降。多次循环之后载氧体结构趋于规则均匀化,形成类似球棒形状的大孔隙率结构,强度保持不变,使得载氧体在长时间使用过程中反应性能得以维持。     

两相流中煤粉的燃烧机理及动力学特征

利用微型流化床动力学分析仪研究了两相流条件下无烟煤粉的燃烧反应机理和动力学特征,并与热重法所得结果进行比较分析。结果表明,当温度大于850℃时,煤粉燃烧机理发生了变化,燃烧气态产物的生成比例也随之改变;当气速大于0.10 m/s时,气体扩散限制基本被消除,煤粉燃烧反应速率主要受界面化学反应控制;煤粉燃烧反应速率随着氧气分压的增大呈幂函数形式增长,且氧气分压对煤粉静置燃烧的影响更加显著。煤氧两相流燃烧的表观活化能与静置燃烧相比降低了49 kJ/mol,相同温度条件下两相流燃烧的界面化学反应阻力也明显小于热重法测试结果。     

Fe2O3/Al2O3氧载体用于甲烷化学链燃烧：负载量与制备方法的影响

以不同方法制备了系列Fe₂O₃/Al₂O₃氧载体,采用XRD、H₂-TPR、CH₄-TPR、O₂-TPD和BET等分析技术对氧载体进行了表征。研究了不同Fe₂O₃负载量氧载体的甲烷化学链燃烧性能,考察了不同制备方法对Fe₂O₃/Al₂O₃氧载体结构、反应性和产物选择性的影响。结果表明,Fe₂O₃负载量对氧载体活性及产物中CO₂选择性的影响较大,负载量较低时氧载体活性较低且引起甲烷部分氧化产物CO含量增加。制备方法亦对氧载体与甲烷的反应活性有所影响,整体上共沉淀法制备的质量分数60％Fe₂O₃/Al₂O₃氧载体具有较高的氧化活性和化学链循环稳定性。其在反应温度850℃、反应时间15 min、30次循环后甲烷转化率及产物中CO₂选择性均未见明显降低。     

Naphthalene and benzene levels in microenvironments associated with potential exposure: new and old apartments with moth repellents,and cabins of passenger cars

A lesser degree of information is available with respect to microenvironments associated with potential exposure to naphthalene, in comparison with other volatile organic compounds. The current study investigated the levels of benzene as well as naphthalene, both in the indoor and outdoor air of apartments and in the cabins of passenger cars. Two groups of 20 apartment buildings (20 new and 20 old) were chosen on the basis of the selection criteria (apartment location and size). In addition, 10 actual commuters were recruited for this study. The equal number of drivers was recruited for the study for comparison of two types of fuels for vehicles (five drivers of gasoline-fuelled and five drivers of diesel-fuelled passenger cars). Indoor naphthalene concentrations were similar between old and new apartments, while the benzene concentrations in new apartments were significantly higher than those of old apartments. The naphthalene concentrations in bedrooms, where wardrobes with moth repellent (MRs) were placed, were significantly higher than those for living rooms where no MRs were present. In turn, these indoor concentrations were significantly higher than outdoor levels. It is noteworthy that the mean and median values of naphthalene measured in the bedrooms exceeded the USEPA RfC (inhalation reference concentration) of 3?µg?m^?3, and the living room values were close to the RfC, while the residential benzene levels exceeded the European benzene limit of 5?µg?m^?3. In contrast, the maximum outdoor levels were well below that of the RfC. The use of passenger cars appeared to be a significant daily activity for both naphthalene and benzene exposure. The naphthalene-to-benzene ratios varied with the type of microenvironments. Both the indoor naphthalene and benzene concentrations in the present study were much higher than those of other studies.     

多种类表面活性剂临界胶束浓度定量构效关系

表面活性剂的临界胶束浓度(CMC)是个非常重要的物质特性参数, CMC在研究表面活性剂的工业应用和生物利用方面发挥着关键作用. 本工作提出了一个新的拓扑指数—扩展距离矩阵, 建立了一个稳定的构效关系模型, 并对175种表面活性剂的临界胶束浓度进行了计算预测. 结果表明, 基于新的拓扑指数建立的构效关系模型计算临界胶束浓度能给出稳定可靠的预测结果, 其预测结果相关性系数R²(training set)=0.9295, 相对标准偏差ARD(training set)=8.20%, R²(testing set)=0.9257, ARD(testing set)=6.76%. 与文献中模型预测结果的对比表明, 本工作在稳定性和可靠性上均有显著改善.     

大型砂尘风洞中砂尘浓度测量与控制方法的研究

砂尘浓度指标严重影响砂尘风洞试验效果;在大型砂尘风洞中准确的测量及有效的控制砂尘浓度是砂尘风洞设备研制中的两个关键问题;针对动态试验工况环境中浓度传感器标定的问题,分析了浓度测量时标定参数与风速和浓度的关系,使用模型树算法建立了三者之间的关系模型,以此模型来预测各种动态情况下的标定参数;针对复杂环境下浓度动态控制问题,采用专家PID算法,提出了多回路控制系统结构和专家规则;工程实践表明该测量和控制方法满足了动态试验环境的需求,取得了良好效果;模型树算法和专家PID系统能有效的解决动态工况下砂尘浓度的测量与控制问题。     

R3中一类Kirchhoff型方程变号解的存在性及集中性

本文研究了一类Kirchhoff型方程。利用极大极小原理及惩罚函数方法,证明了上述方程变号解的存在性及集中性,我们的结果推广了文献[4]的结果。     

生物燃料电池处理生活污水同步产电特性研究

以某生活污水处理厂缺氧池活性污泥为接种体,以葡萄糖为模拟生活废水,构建双室型微生物燃料电池。利用微生物燃料电池(MFC,Microbial fuel cell)实现生活废水降解与同步产电。研究基质降解动力学及温度对MFC电极过程动力学的影响,明确微生物电化学活性、阳极传荷阻抗、阳极电势、电池产能之间的关系,考察库伦效率及COD去除率。研究结果表明,电池功率输出与基质浓度关系遵循莫顿动力学方程:P=Pmaxc/(ks+c),其中,半饱和常数ks为138.5 mg/L,最大功率密度Pmax为320.2 mW/m2。葡萄糖浓度较小时,反应遵循一级动力学规律:-dcA/dt=kcA,k=0.262 h-1。操作温度从20℃提高到35℃,生物膜电化学活性不断提高,传荷阻抗从361.2Ω减小到36.2Ω,阳极电极电势不断降低,同时,峰值功率密度从80.6 mW/m2提高到183.3 mW/m2。45℃时,产电菌活性降低,峰值功率密度减小到36.8 mW/m2。葡萄糖浓度为1 500 mg/L,温度为35℃时,MFC电化学性能最佳,稳定运行6 h后库伦效率为44.6%,COD去除率为49.2%。