共查询到20条相似文献,搜索用时 62 毫秒
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利用凝胶柱色谱技术, 研究者们通过两步或多步淋洗的方法实现了不同导电属性或电子结构单壁碳纳米管(SWCNTs)的分离, 并提出其分离机制主要是由不同导电属性和电子结构的SWCNTs 与凝胶填料之间作用力的差异所导致的. 基于凝胶柱色谱分离技术, 本文重点考察了超声时间对单壁碳纳米管单分散以及金属型/半导体型SWCNTs 分离的影响. 在一定的低超声功率下, 适当增加超声时间有利于SWCNTs 在十二烷基硫酸钠(SDS)溶液中的单分散. 紫外-可见-近红外(UV-Vis-NIR)吸收光谱、拉曼(Raman)光谱和荧光(PL)光谱表征结果表明, 2 h的超声条件是获得高纯度的金属型以及不同直径分布的半导体型SWCNTs 的最优条件. 我们认为不同超声时间对SWCNTs 分离的影响主要是改变了SWCNTs 的单分散性和长度, 调制了不同SWCNTs 与凝胶之间作用力的差异, 从而导致了不同SWCNTs分离结果. 相似文献
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金属Pt是良好的催化加氢、脱氢催化剂, 利用单壁碳纳米管(SWNTs)自身的还原性, 将K2PtCl6溶液中的Pt直接还原并负载在SWNTs表面上, 制备了具有良好催化性能的SWNTs/Pt负载型催化剂. 通过TEM, XPS和TG对材料进行了表征, 研究了K2PtCl6浓度及溶剂对Pt负载量、粒径的影响, 并测试了SWNTs/Pt的催化性能. 实验结果表明, SWNTs负载的Pt颗粒小, 分散均匀, 负载量高, 与SWNTs结合紧密, 催化性能好, 是催化加氢和脱氢反应的良好催化剂. 相似文献
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利用C1s、O1s、N1s近边X射线吸收精细结构(Near Edge X-Ray Absorption Fine Structure,NEXAFS)光谱对聚合物修饰的碳纳米管进行了分析,研究了氧化及偶联聚合物对碳纳米管结构的影响。氧化碳纳米管及十八胺修饰的、聚合物/十八胺双修饰的碳纳米管的NEXAFS光谱均出现了碳/氧K边π*(C=O)和σ*(C-O)共振峰;而十八胺修饰的、聚合物/十八胺双修饰的碳纳米管则出现了氮K边π*(N-C=O)和σ*(N1s)共振峰。分析表明,NEXAFS光谱可有效表征聚合物修饰的碳纳米管。 相似文献
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变径毛细管柱GC/FTIR联用技术的研究 总被引:1,自引:0,他引:1
本文介绍了使用新型变径毛细管柱的气相色谱/傅里叶变换红外光谱联用技术(GC/FTIR)。以正构烷烃的混合物为样品,研究了载气速流、色谱进样量及柱后死体积对联用效果的影响。分别在变径毛细管柱GC/FTIR和普通毛细管柱GC/FTIR联用系统上分析了烷烃芳烃混合物和合成汽油样品,并利用软件系统提供的程序和红外标准谱库对所得光谱进行了检索。实验结果表明,变径毛细管柱GC/FTIR系统具有色谱进样量大,可鉴定组分多,分离能力强和检测灵敏度高等显著优点。 相似文献
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I. O. O. Korhonen 《Chromatographia》1983,17(2):70-74
Summary Simultaneous determination of aliphatic C2–C20 carboxylic acids and their methyl esters was carried out using SE-30 and OV-351 quartz capillary columns with temperature programming. Complete resolution of all 36 components was achieved. On SE-30 the methyl ester and the corresponding free acid are eluted in turn, whereas on OV-351 acetic acid eluted after methyl octanoate, after which the Cn methyl ester and Cn-6 carboxylic acid (n>9) are eluted one after the other. A non-polar SE-30 column is better for long-chain acids giving sharp peaks without tailing, the analysis time of the mixture being less than 16 minutes. The weight response correction factors for compounds under optimum operating conditions are given. 相似文献
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The analytical potential of the use of surfactant-coated single-walled carbon nanotubes (SC-SWNTs) as pseudostationary phase in CE is described. The pseudostationary phase shows an efficient alternative in enhancing electrochromatographic resolution of compounds which are capable of interacting with a nanotube surface, such as aromatic compounds. In general, the resolution is enhanced by increasing nanotube concentration in the buffer but the maximum amount of SWNTs that can be added to background electrolyte was found limited by compatibility with the UV/visible detection. As an alternative, a low-extension partial filling was used, consisting of the introduction into the capillary of concentrated SC-SWNT, just before the sample, with a plug length similar to the sample one. This has been showed as a reliable procedure in increasing resolution and sensitivity by sweeping phenomena. Finally, the potential of SC-SWNTs to perform chiral separations is discussed. 相似文献
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P. Torline G. du Plessis N. Schnautz J. C. Thompson 《Journal of separation science》1979,2(10):613-616
A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible. 相似文献
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I. O. O. Korhonen 《Chromatographia》1982,15(8):505-508
Summary The gas chromatography of all chlorinated methyl acetates, methyl propanoates and methyl mono- and dichlorobutanoates has been studied on Carbowax 20M and SE-30 glass capillary columns under various running conditions. The order of elution on a non-polar column was largely determined by the boiling point of esters, whereas on a polar column it was much influenced by the structure of compounds. Complete separation of the combined mixture of all 27 compounds could not be achieved, however, methyl 3,3-dichlorobutanoate was the only ester overlapped on both columns in spite of the various column temperatures used. The best separation of the mixture was on Carbowax 20M with a temperature program from 50°C at 8°C/min, isothermal running conditions leading either to poor separation of volatile components or long analysis time and broad peaks of higher chlorinated esters. The relative retention times for compounds at the various column temperatures are given and the retention order on a polar and on a non-polar column discussed. 相似文献
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Mustafa I. Selim Joseph R. Strubinger 《Fresenius' Journal of Analytical Chemistry》1988,330(3):246-249
Summary The mass spectrometric tracer pulse (MSTP) chromatography method was used to measure the amount of supercritical n-pentane dissolved or adsorbed into SE-54 and SE-30 capillary columns. Partition data were measured above the critical point of n-pentane at temperatures from 200 ° to 300 °C and pressures between 35.04 and 54.42 atm. The data obtained provide evidence for mobile fluid solubility or adsorption into the stationary phase under the conditions of supercritical fluid chromatography (SFC). At 220 °C, solubility and/or adsorption of supercritical n-pentane decreases by increasing the pressure and reaches a minimum at approximately 45.00 atm. The effect of mobile-fluid pressure on its solubility or adsorption becomes limited at temperatures over 260 °C. This study demonstrates the unique experimental capabilities of the MSTPC method for quantitative measurement of the physico-chemical interaction of the complex multicomponent system encountered in SFC which is not possible by any other technique. An innovative instrumental design for modification of GC/MS systems for SFC, GC/MS operation is also described.
Verteilung von superkritischem n-Pentan in den stationären Phasen SE-54 und SE-30 bei der Capillar-Chromatographie mit superkritischen fluiden Phasen相似文献
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Karajanagi SS Yang H Asuri P Sellitto E Dordick JS Kane RS 《Langmuir : the ACS journal of surfaces and colloids》2006,22(4):1392-1395
We report a simple method that uses proteins to solubilize single-walled carbon nanotubes (SWNTs) in water. Characterization by a variety of complementary techniques including UV-Vis spectroscopy, Raman spectroscopy, and atomic force microscopy confirmed the dispersion at the individual nanotube level. A variety of proteins differing in size and structure were used to generate individual nanotube solutions by this noncovalent functionalization procedure. Protein-mediated solubilization of nanotubes in water may be important for biomedical applications. This method of solubilization may also find use in approaches for controlling the assembly of nanostructures, and the wide variety of functional groups present on the adsorbed proteins may be used as orthogonal reactive handles for the functionalization of carbon nanotubes. 相似文献
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Discrete dispersion of single-walled carbon nanotubes 总被引:1,自引:0,他引:1
Single-walled carbon nanotubes (SWNTs) have been effectively wetted and dispersed in saturated sodium hydroxide (NaOH) alcohol-water solutions with little surface damage or shortening of the tubes; the treated material was dissolvable as individual tubes in many common organic solvents. 相似文献