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991.
992.
993.
A method is developed to effectively functionalize carbon nanotubes (CNTs) by intermittent microwave heating (IMH)-assisted HF/H2O2 solution treatment. CNTs functionalized by IMH-assisted HF/H2O2 solution treatment (CNTs-HF/H2O2) are characterized by high oxygen-containing groups and high graphitization degree, as compared with CNTs treated by HF (CNTs-HF) or by IMH-assisted H2O2 solution treatment without prior HF treatment (CNTs-H2O2). Pt supported on CNTs-HF/H2O2 (Pt/CNTs-HF/H2O2) has an average particle size of 2.8 nm, smaller than 2.9 nm for Pt supported on CNTs-HF, 3.3 nm for Pt supported on CNTs-H2O2 and 4.0 nm for Pt supported on pristine CNTs. Pt/CNTs-HF/H2O2 electrocatalysts display a high electrochemical surface area, high Pt utilization efficiency, a superior electrocatalytic and mass activity for the O2 reduction reaction (ORR) with respect to other catalyst samples in the present study. The results demonstrate the efficiency and effectiveness of the IMH-assisted HF/H2O2 solution methods for the functionalization of CNTs, and the method could be easily scaled-up to treat CNTs in large quantities. 相似文献
994.
3-氯-2-羟丙基三乙基氯化铵的微波合成及性能 总被引:2,自引:1,他引:1
以环氧氯丙烷、三乙胺盐酸盐为原料,采用微波辐照合成3-氯-2-羟丙基三乙基氯化铵(CTA)。利用乙酸乙酯和乙醇混合溶液反复结晶提纯后,采用薄层色谱与化学滴定方法定性、定量分析产物纯度达到99%以上,使用红外吸收光谱、核磁共振对目标产物的结构进行分析鉴定;研究了微波功率、反应温度、反应时间和摩尔比对CTA合成产率的影响,从而得出CTA的最佳微波合成条件为:微波功率300 W, 反应温度50℃,反应时间为20 min,三乙胺盐酸盐和环氧氯丙烷的摩尔比为1.15∶1,比传统加热工艺反应时间缩短340 min,产率提高了16.58%;测定了CTA的表面张力、克拉夫点、临界胶束浓度和熔点等物理化学性能。 相似文献
995.
Beri Rengaraju Prasannakumar Iyyaswami Regupathi Thanapalan Murugesan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(1):83-91
BACKGROUND Removal of phenol from industrial waste waters involves basic techniques namely extraction, biodegradation, photocatalytic degradation, etc. Among the available processes, the oxidation of phenols using H2O2 is a suitable alternative because of low cost and high oxidizing power. The application of an oxidation process for the decomposition of stable organic compounds in waste water leads to the total degradation of the compounds rather than transferring from one form to another. Since oxidation using Fenton's reagent is more dependent on pH, in this present work it was proposed to use H2O2 coupled with microwave irradiation. The effects of initial phenol concentration, microwave power and the irradiation time on the amount of decomposition were studied. RESULTS: In the present work experiments were conducted to estimate the percentage degradation of phenol for different initial concentrations of phenol (100, 200, 300, 400 and 500 mg L?1), microwave power input (180, 360, 540, 720 and 900 W) for different irradiation times. The kinetics of the degradation process were examined through experimental data and the decomposition rate follows first‐order kinetics. Response surface methodology (RSM) was employed to optimize the design parameters for the present process. The interaction effect between the variables and the effect of interaction on to the responses (percentage decomposition of phenol) of the process was analysed and discussed in detail. The optimum values for the design parameters of the process were evaluated (initial phenol concentration 300 mg L?1, microwave power output 668 W, and microwave irradiation time 60 s, giving phenol degradation 82.39%) through RSM by differential approximation, and were confirmed by experiment. CONCLUSION: The decomposition of phenol was carried out using H2O2 coupled with microwave irradiation for different initial phenol concentrations, microwave power input and irradiation times. The phenol degradation process follows first‐order kinetics. Optimization of the process was carried out through RSM by forming a design matrix using CCD. The optimized conditions were validated using experiments. The information is of value for the scale up of the oxidation process for the removal of phenol from wastewater. Copyright © 2008 Society of Chemical Industry 相似文献
996.
Xiao‐Fang Shen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(12):1811-1817
BACKGROUND: One‐dimensional (1D) nanostructures such as wires, tubes and belts have attracted much attention in recent years because of their fascinating properties and promising applications, and various methods have been developed to prepare 1D nanostructures. Microwave and ultrasound, two methodologies for rapid synthesis, have both been applied to fabricate nanostructures. This paper reports on combining microwave and ultrasound irradiation as a new strategy for rapid synthesis of nanowires. Using Pb(OH)Br as a study case, nanowires were rapidly synthesized under the combined irradiation. The use of the ionic liquid 1‐butyl‐3‐methylimidazolium bromide as a structure‐directing agent and microwave absorbent significantly simplified the preparation procedure. RESULTS: Combined microwave–ultrasound irradiation at (50 W–50 W) greatly reduced the reaction time (10 min) and significantly increased the product yield (45.0%) in comparison with conventional heating (24 h reaction time, 23.0% yield). Combined microwave–ultrasound irradiation at (50 W–50 W) also changed the resultant wires from 20–30 µm diameter and 2–3 mm long to 80–800 nm and 50–100 µm, respectively. Further increase in power of the combined irradiation (250 W–50 W) led to a dramatic reduction in the reaction time (80 s) with a slightly increased yield of 48.2%. CONCLUSIONS: The obvious advantages of combined microwave–ultrasound irradiation are marked improvement of the product yield, significant enhancement of reaction rate and increased aspect ratio of the 1D structure. Copyright © 2009 Society of Chemical Industry 相似文献
997.
采用自行设计制造的萃取装置进行了乙醇水溶液常压微波辅助浸取枳椇总黄酮的单因素实验研究,获得的最适宜工艺条件为:微波功率700 W、辐射(时间)至溶液沸腾,辐射1次;乙醇的质量分数50%;固液比1:10;预泡时间1 h和颗粒尺寸60目,在此条件下,总黄酮提取率高达为80%左右。 相似文献
998.
以马铃薯片微波干燥单位时间降水率和收缩率为试验指标,进行了3因素(脉冲频率、电场强度和微波功率密度)2次回归正交试验。试验结果使用SPSS统计软件进行回归分析,得到各指标回归方程;并采用MATLAB软件编程对指标进行综合优化,得出最优工艺组合(41.67Hz,2.0kV/cm,1.0W/g)。将其中2因素固定在最优水平上,逐个分析另1因素对各指标的影响,结果表明马铃薯片微波干燥单位时间降水率随电场强度的增大先增大后减小,随微波功率密度的增大而增大;马铃薯片微波干燥收缩率随脉冲频率和微波功率密度的增加先减小后增大。在最优工艺组合下,马铃薯片微波干燥单位时间降水率为0.881%/min,收缩率为0.545mm/mm。 相似文献
999.
首先介绍了在线煤质分析的现状及其紧迫性,然后分析了国内外常用的几种在线测量煤中含碳量的方法,最后提出微波测量技术可以用于在线测量煤粉中的含碳量.通过电磁场与电磁波理论,论证了采用微波技术测量煤粉中含碳量的原理. 相似文献
1000.
基于DDS的信号模拟器设计 总被引:5,自引:2,他引:3
通过对DDS的信号模拟器设计的研究,不仅设计出能够实现普通射频合成信号源的功能,正如能够在幅度、频率等方面对所需生成的信号加以控制,也能够实现定频、扫频以及跳频等输出方式上的选择。同时,该系统增加了叠加噪声和灵敏度设置,以便能够更好地实现对各种条件下雷达回波信号的模拟。 相似文献