scholarly journals Raman and TGA Study of Carbon Nanotubes Synthesized Over Mo/Fe Catalyst on Aluminium Oxide, Calcium Carbonate and Magnesium Oxide Support

2013 ◽  
Vol 2 (4) ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Ezekiel D. Dikio ◽  
Albert J. Kupeta ◽  
Force T. Thema

A comparative study of the effect of magnesium oxide and calcium carbonate as support material in the synthesis of carbon nanotubes using the catalyst Fe/Co is presented. The synthesized carbon nanotubes were characterized with Raman spectroscopy, scanning electron spectroscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), and energy dispersive spectroscopy (EDS). The morphology of the carbon nanotubes synthesized with magnesium oxide as support material gives rise to carbon nanotubes with consistent and well-defined structure unlike that synthesized with calcium carbonate. TheID/IGratio of synthesized carbon nanotubes (CNTs) was 0.8544 for magnesium oxide supported compared to 0.8501 for calcium carbonate supported carbon nanotube.


Author(s):  
Fairooz Kareem ◽  
Mahasin Al-Kadhemy ◽  
Asrar Saeed

Absorption and fluorescence spectroscopy techniques were applied to investigate the photophysical characteristics of acridine orange (AO) dye in solvents that included distilled water, dimethyl sulfoxide (DMSO), acetone and ethanol in various concentrations (1×10-4–1×10-6) M. All of the samples were served at room temperature. The relationships between various parameters describing the strength of optical transitions in atoms and molecules were reviewed. This study expresses various viewpoints by describing how concentration and solvent affect the dye's absorption and fluorescence spectra. The absorption spectra of AO exhibit a band at (490 nm), except for DMSO, which shifts more towards red by 5 nm. The fluorescence spectra show a blue shift in AO aqueous solution around 6 nm until (0.5×10-4) M, followed by a red shift at around 7 nm at (1×10-6) M. There is a blue shift in (1×10-5) M for DMSO at around 4 nm, then a 10 nm red shift in higher concentrations as well as a 9 nm red shift in acetone and 6 nm in ethanol. Adding magnesium oxide nanoparticles (MgO NPs) quenched AO in both absorption and fluorescence spectra, whereas maximum fluorescence and intensity increased when aluminium oxide nanoparticles (Al2O3 NPs) were added to the solution. KEYWORDS Laser dye, absorption spectrum, fluorescence spectrum, MgO NPs, Al2O3 NPs


2014 ◽  
Vol 788 ◽  
pp. 28-33
Author(s):  
Peng Deng ◽  
Yu Qin Liu ◽  
Wen Gui Yao ◽  
Hong Wen Ma

In this paper, a new process for the production of the primary magnesium is introduced using the dolomite as the raw material. The magnesia and calcium carbonate were prepared from dolomite by acidification. The content of magnesium oxide can reach 98.92% about the magnesia obtained. The magnesia is used to produce primary magnesium by aluminothermic reduction under vacuum condition. The reduction ratio of MgO can be up to 86.14% under the temperature of 1200°C for 5hrs, briquetting pressure of 10MPa and the molar ratio of MgO to Al of 3:2. The content of magnesium is more than 99.90%. The major phases in the briquette residue are corundum and spinel, which can be used as refractory.


2002 ◽  
Vol 81 (6) ◽  
pp. 1098-1100 ◽  
Author(s):  
Won Seok Kim ◽  
Whikun Yi ◽  
SeGi Yu ◽  
Jungna Heo ◽  
Taewon Jeong ◽  
...  

2008 ◽  
Vol 8 (11) ◽  
pp. 5748-5752
Author(s):  
S. Krishnamurthy ◽  
T. Donnelly ◽  
N. McEvoy ◽  
W. Blau ◽  
J. G. Lunney ◽  
...  

We report the growth of carbon nanotubes on the size controlled iron catalytic nanoparticles. The nanotubes were grown by thermal chemical vapour deposition (CVD) in the temperature range 600–850 °C. The Fe films were deposited on silicon by pulsed laser deposition in vacuum. Atomic force microscopy measurements were performed on the catalytic nanoparticles. The topography of the catalytic nanoparticles shows the homogenous distribution of Fe catalyst. We observe the nanotubes are produced only at temperatures between 650 and 800 °C, and within this narrow temperature regime the yield of nanotubes reaches a maximum around 750 °C and then declines. Raman measurements illustrate a high G/D peak ratio indicating good nanotube quality. By further defining the size of the catalyst the diameter of these carbon nanotubes can be controlled.


2017 ◽  
Vol 95 (9) ◽  
pp. 935-941 ◽  
Author(s):  
Shunichi Nishimura ◽  
Tomoyuki Tajima ◽  
Tatsuki Hasegawa ◽  
Tomoaki Tanaka ◽  
Yutaka Takaguchi ◽  
...  

A new dendritic dispersant of carbon nanotubes (CNTs) was synthesized and applied for the noncovalent functionalization of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). The 1,10-bis(decyloxy)decane core of the poly(amidoamine) dendrimer strongly adhered to the sidewalls of CNTs to form CNT/dendrimer supramolecular nanocomposites having many carboxyl groups (–COOH) on the surface. Then, crystallization of calcium carbonate (CaCO3) by the CO2 diffusion technique in aqueous environments using the CNT/dendrimer supramolecular nanocomposites as scaffolds afforded monodisperse spherical CNT/CaCO3 nanohybrids consisting of CNTs and calcite nanocrystals. The morphologies of the SWCNT/CaCO3 hybrids and MWCNT/CaCO3 hybrids were almost the same.


2011 ◽  
Vol 402 ◽  
pp. 293-296
Author(s):  
Kai Wang ◽  
Jian Li ◽  
R.G. McDonald ◽  
R.E. Browner

In this study, the iron precipitation and associated nickel loss from synthetic ferric and nickel sulphate solutions were investigated. Two types of common neutralizing agents, magnesium oxide and calcium carbonate were applied in the investigation. The results indicated that pH and temperature had significant impacts on nickel loss during the iron precipitation process, whereas the type of neutralizing agents had little effect. It was found that increasing in pH and temperature resulted in more nickel loss in the pH range of 2 to 4 and temperature range of 25 to 85 °C. Mineralogical examination by XRD indicated that the iron precipitates were combinations of schwertmannite, ferrihydrite and goethite. In addition, more crystalline goethite was formed from the ferric solutions when no nickel was present, indicating that nickel might play a role in inhabiting the crystallization of goethite.


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