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101.
超临界流体色谱在金属络合物和金属有机化合物中的分析应用 总被引:10,自引:0,他引:10
超临界流体色谱(SFC)在色谱分离过程中能在较低的温度下分析对热不稳定性的化合物,包括金属络合物和金属有机化合物。本文总结了近来文献报道的各种过渡金属、重金属、镧系和锕系以及铅、汞和锡的金属有机化合物的SFC分离,还讨论了SFC检测系统和金属有机化合物的溶解度的测定。 相似文献
102.
103.
Anuj Kumar Yuvraj Singh Negi Veena Choudhary Nishi Kant Bhardwaj 《International Journal of Polymer Analysis and Characterization》2017,22(2):139-151
Cellulose nanocrystal-reinforced poly(vinyl alcohol)/silica glass hybrid scaffolds were fabricated using the freeze-drying method. In this study, we develop molecular-level-based hybrid scaffolds with possible bioactivity behavior by adding silica sol–gel. The results showed a highly porous structure and a significant improvement in mechanical performance (stiffness) of hybrid scaffolds with an increased content of cellulose nanocrystals followed by the addition of silica-based bioactive glass. In vitro cell study with MC3T3-E1 cells on hybrid scaffolds for 1 and 3 days revealed good cell adhesion and growth. Thus, the obtained hybrid scaffold may be a competitive candidate for bone tissue engineering applications. 相似文献
104.
Sameena Ashraf Keith D. Bartle Anthony A. Clifford Robert Moulder 《Journal of separation science》1992,15(8):535-538
Lubricating oil additives have been analyzed by supercritical fluid chromatography on open tubular and packed capillary columns. Carbon dioxide and modified carbon dioxide were used as mobile phases and detection was accomplished by flame ionization and micro UV. Rapid and efficient analysis of the lubricating oil additives was demonstrated. 相似文献
105.
Daixin Tong Keith D. Bartle Anthony A. Clifford Robert E. Robinson 《Journal of separation science》1992,15(8):505-509
A unified approach to sequential gas and supercritical fluid Chromatography using 50 μm i.d. open tubular columns is described. Sample introduction is performed by means of a rotary injection valve. In order that linear velocities can be optimized independently, a second rotary valve in the chromatographic oven is used to direct the flow of column eluate to the flame ionization detector through either fused silica tubing in GC, or a frit restrictor in SFC. Applications of sequential GC-SFC on a 50 μm i.d. open tubular column are demonstrated, and comparisons made between sequential GC-SFC on 50 and 100 μm i.d. columns. 相似文献
106.
Ganesh P. Sanganwar Ram B. Gupta Alexandre Ermoline James V. Scicolone Rajesh N. Dave 《Journal of nanoparticle research》2009,11(2):405-419
Due to the increased use of nanocomposites, mixing at nanoscale has become important. Current mixing techniques can be classified
into: (a) dry mixing (mechanical mixing), (b) wet mixing, and (c) simultaneous production of mixed nanoparticles (when possible).
Dry mixing is in general not effective in achieving desired mixing at nanoscale, whereas wet mixing suffers from different
disadvantages like nanomaterial of interest should be insoluble, has to wet the liquid, and involves additional steps of filtration
and drying. This paper examines the use of pressurized carbon dioxide having high density and low viscosity to replace the
liquids (e.g., n-hexane, toluene). Ultrasound is applied to the suspension of nanopowders in gaseous and supercritical carbon dioxide where
high impact collisions during sonication help mixing and the final mixture is obtained by simple depressurization. The method
is tested for binary mixture of alumina/silica, silica/titania, MWNT (multiwalled carbon nanotubes)/silica, and MWNT/titania.
The effects of sonication intensity and pressure on the degree of mixing are studied. Comparative study is also done with
liquid n-hexane as a mixing media. Quantitative characterization (e.g., mean composition standard deviation, intensity of segregation)
of mixing of alumina/silica and silica/titania is done with energy-dispersive X-ray spectroscopy, and that of MWNT/silica
and MWNT/titania is done using field-emission scanning electron microscopy and day-light illumination spectrophotometry. Results
show that mixing in carbon dioxide at higher ultrasound amplitudes is as good as in liquid n-hexane, and the final mixed product does not contain any residual media as in the case of liquid n-hexane. 相似文献
107.
Romain Valentin Karine Molvinger Françoise Quignard Francesco Di Renzo 《Macromolecular Symposia》2005,222(1):93-102
Nitrogen adsorption at 77 K has been applied to the study of the texture of alginate aerogel microspheres obtained by CO2 supercritical drying of alcogels. The limited volume shrinkage suggests that the aerogels preserve the texture of the hydrogels. Alginate aerogels presents a N2 adsorption at small pressure higher than reference non-porous silica, to be attributed to the polarity of the surface or to a small microporous volume. The aggregated nanobead strings of the guluronic-rich gels accounts for a significant mesoporosity. The N2 adsorption results correspond to electron microscopy observations for features smaller than 50 nm. 相似文献
108.
Rikard Westbom Sarah Josefsson Lennart Mathiasson Erland Björklund 《International journal of environmental analytical chemistry》2013,93(4):259-274
A method for studying PCB desorption behaviour from sediments using supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) is presented. Four sediments were investigated and extracted with supercritical carbon dioxide employing increasingly harsher extraction conditions ranging from 40°C and 12?MPa to 100°C and 36.5?MPa. To ensure quantitative extractions, the remaining SFE residues were also extracted with PLE. Resulting profiles identified at least three different PCB fractions within the four sediments. Furthermore, a distinct fraction was obtained with extraction for 2?h at 40°C and 36.5?MPa. This fraction has previously been found to correlate well with bioavailable fractions. The dependency of this fraction on sediment total organic carbon (TOC) was investigated, both for sediments examined in this study as well as for previously reported values using the same extraction conditions. It was found that TOC does not correlate to selective SFE, which indicates that the use of TOC to predict bioavailability is questionable. 相似文献
109.
Synthesis and Characterization of Cobalt-Carbon Core-Shell Microspheres in Supercritical Carbon Dioxide System 下载免费PDF全文
The synthesis of cobalt-carbon core-shell microspheres in supercritical carbon dioxide system was investigated. Cobalt-carbon core-shell microspheres with diameter of about 1 μm were prepared at 350 oC for 12 h in a closed vessel containing an appropriate amount of bis(cyclopentadienyl)cobalt powder and dry ice. Characterization by a variety of techniques, including X-ray powder diffraction, X-ray photoelectron spectroscopy, Transmission electron microscope, Fourier transform infrared spectrum and Raman spectroscopy analysis reveals that each cobalt-carbon core-shell microsphere is made up of an amorphous cobalt core with diameter less than 1 μm and an amorphous carbon shell with thickness of about 200 nm. The possible growth mechanism of cobalt-carbon core-shell microspheres is discussed, based on the pyrolysis of bis(cyclopentadienyl)cobalt in supercritical carbon dioxide and the deposition of carbon or carbon clusters with odd electrons on the surface of magnetic cobalt cores due to magnetic attraction. Magnetic measurements show 141.41 emu/g of saturation magnetization of a typical sample, which is lower than the 168 emu/g of the corresponding metal cobalt bulk material. This is attributed to the considerable mass of the carbon shell and amorphous nature of the magnetic core. Control of magnetism in the cobalt-carbon core-shell microspheres was achieved by annealing treatments. 相似文献
110.
溶质在超临界流体中的溶解度与流体的密度密切相关。本文采用微扰硬球链理论对纯CO2及CO2-正戊烷、CO2-正庚烷、CO2-正癸烷体系在不同条件下的密度进行计算,计算值与文献给出的实验值符合很好。 相似文献