Thermal Diffusivity of Nanofluids Containing Au/Pd Bimetallic Nanoparticles of Different Compositions

2006 ◽  
Vol 6 (3) ◽  
pp. 685-690 ◽  
Author(s):  
J. F. Sánchez-Ramírez ◽  
J. L. Jiménez Pérez ◽  
A. Cruz Orea ◽  
R. Gutierrez Fuentes ◽  
A. Bautista-Hernández ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Thermal Lens ◽  
Bimetallic Nanoparticles ◽  
Colloidal Suspensions ◽  
High Resolution Electron Microscopy ◽  
Pd Nanoparticles ◽  
Molar Ratio ◽  
Theoretical Expression ◽  
Vis Spectroscopy ◽  
Transient Thermal

Colloidal suspensions of bimetallic Au/Pd nanoparticles were prepared by simultaneous reduction of the metal ions from their corresponding chloride salts with polymer (PVP) stabilizer. Thermal properties of water containing bimetallic nanoparticles with different nominal compositions (Au/Pd = 12/1, 5/1, 1/1, 1/5) were measured using the mode mismatched dual-beam thermal lens technique to determine the effect of particle composition on the thermal diffusivity of the nanofluids. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical expression for transient thermal lens. The thermal diffusivity of the nanofluids (water, containing Au/Pd bimetallic nanoparticles) is seen to be strongly dependent on the composition of the particles. The maximum diffusivity was achieved for the nanoparticles with highest Au/Pd molar ratio. A possible mechanism for such high thermal diffusivity of the nanofluids with bimetallic particles is given. UV-Vis spectroscopy, TEM and high-resolution electron microscopy (HREM) techniques were used to characterize the Au/Pd bimetallic nanoparticles.

Thermal Diffusivity of Multi-Walled Carbon Nanotubes Dispersed in Oleic Acid

2012 ◽  
Vol 21 ◽  
pp. 125-130 ◽  
Author(s):  
Alex Junior de Freitas Cabral ◽  
Clascídia Aparecida Furtado ◽  
Cristiano Fantini ◽  
Petrus Alcantara Jr.
Keyword(s):  
Carbon Nanotubes ◽  
Oleic Acid ◽  
Thermal Diffusivity ◽  
Thermal Lens ◽  
Theoretical Expression ◽  
Thermal Lens Spectrometry ◽  
Multi Walled Carbon Nanotubes ◽  
Spectrometry Technique ◽  
Transient Thermal ◽  
Walled Carbon Nanotubes

Suspensions of oleic acid with carbon nanotubes were prepared. Using a thermal lens experimental setup, the thermal diffusivity of oleic acid in presence of multi-walled carbon nanoparticles with different concentrations was measured. The results show that, the thermal diffusivity increases with the increase of nanotubes concentration, enhancing the thermal diffusivity in the solution. Modification in the thermal diffusivity as function of quantity of carbon nanotubes was investigated, for a constant volume of oleic acid 10 mL. The diffusivities were obtained by using the thermal lens spectrometry technique. The characteristic time constant of the transient thermal lens was obtained by fitting the theoretical expression to the experimental data.

Thermal Diffusivity Measurements in Fluids Containing Metallic Nanoparticles using Transient Thermal Lens

2006 ◽  
Vol 27 (4) ◽  
pp. 1181-1188 ◽  
Author(s):  
J. F. Sánchez Ramírez ◽  
J. L. Jiménez Pérez ◽  
R. Carbajal Valdez ◽  
A. Cruz Orea ◽  
R. Gutiérrez Fuentes ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Thermal Lens ◽  
Metallic Nanoparticles ◽  
Diffusivity Measurements ◽  
Transient Thermal

Preparation and Characterization of Bimetallic Nanoparticles Ptx-Pd1-x Supported on Silica

2006 ◽  
Vol 15-17 ◽  
pp. 559-563
Author(s):  
N. Castillo ◽  
L.A. García ◽  
A. Vázquez Z. ◽  
L. Díaz Barriga ◽  
R. Pérez
Keyword(s):  
Electron Microscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Properties ◽  
High Resolution Electron Microscopy ◽  
Pd Nanoparticles ◽  
Energy Dispersive ◽  
Palladium Chloride ◽  
Bright Field Image ◽  
X Ray ◽  
Resolution Electron

Ptx-Pd(1-x) nanoparticles supported on amorphous silica (SiO2) were prepared by wetness impregnation techniques with choroplatinic acid (H2PtCl6) and palladium chloride (PdCl4) with different concentrations of Pt and Pd at about 1% in overall metallic weight. The purpose of this study was to evaluate the physical properties as physisorption (BET), X Ray Diffraction XRD, High Resolution Electron Microscopy HREM, Transmission Electron Microscopy TEM couple with XEDS energy dispersive X-ray spectrometry and chemical properties to determine the activity in cyclohexene reaction of these materials supported. Bimetallic nanoparticles are made of a single solid solution of Pt and Pd atoms, and the particles diameter of about 3-5 nm was estimated by HREM and Bright field image, the Pt-Pd nanoparticles were found mainly to have truncated cuboctahedral shape with fcc packing,. by using energy dispersive X-ray spectrometry (XEDS) and their values were found to be close to the stochiometric relative concentrations in weight of the metals in the precursor aqueous solution.

Thermal Diffusivity Measurements in Edible Oils using Transient Thermal Lens

2006 ◽  
Vol 27 (6) ◽  
pp. 1890-1897 ◽  
Author(s):  
R. Carbajal. Valdez ◽  
J. L. Jiménez. Pérez ◽  
A. Cruz-Orea ◽  
E. San. Martín-Martínez
Keyword(s):  
Thermal Diffusivity ◽  
Thermal Lens ◽  
Edible Oils ◽  
Diffusivity Measurements ◽  
Transient Thermal

scholarly journals Biosynthesis and Cytotoxic Properties of Ag, Au, and Bimetallic Nanoparticles Synthesized Using Lithospermum erythrorhizon Callus Culture Extract

2021 ◽  
Vol 22 (17) ◽  
pp. 9305
Author(s):  
Yury Shkryl ◽  
Tatiana Rusapetova ◽  
Yulia Yugay ◽  
Anna Egorova ◽  
Vladimir Silant’ev ◽  
...  
Keyword(s):  
Metallic Nanoparticles ◽  
Au Nanoparticles ◽  
Bimetallic Nanoparticles ◽  
Molar Ratio ◽  
Biological Synthesis ◽  
Metal Nanostructures ◽  
Lithospermum Erythrorhizon ◽  
X Ray ◽  
Fibroblast Migration ◽  
Vis Spectroscopy

The present study reports a green chemistry approach for the rapid and easy biological synthesis of silver (Ag), gold (Au), and bimetallic Ag/Au nanoparticles using the callus extract of Lithospermum erythrorhizon as a reducing and capping agent. The biosynthesized nanoparticles were characterized with ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD) analysis, and transmission electron microscopy (TEM). Our results showed the formation of crystalline metal nanostructures of both spherical and non-spherical shape. Energy dispersive X-ray (EDX) spectroscopy showed the characteristic peaks in the silver and gold regions, confirming the presence of the corresponding elements in the monometallic particles and both elements in the bimetallic particles. Fourier-transform infrared (FTIR) spectroscopy affirmed the role of polysaccharides and polyphenols of the L. erythrorhizon extract as the major reducing and capping agents for metal ions. In addition, our results showed that the polysaccharide sample and the fraction containing secondary metabolites isolated from L. erythrorhizon were both able to produce large amounts of metallic nanoparticles. The biosynthesized nanoparticles demonstrated cytotoxicity against mouse neuroblastoma and embryonic fibroblast cells, which was considerably higher for Ag nanoparticles and for bimetallic Ag/Au nanoparticles containing a higher molar ratio of silver. However, fibroblast migration was not significantly affected by any of the nanoparticles tested. The obtained results provide a new example of the safe biological production of metallic nanoparticles, but further study is required to uncover the mechanism of their toxicity so that the biomedical potency can be assessed.

Green synthesis of mixed metallic nanoparticles using room temperature self-assembly

2017 ◽  
Vol 13 (2) ◽  
pp. 4671-4677 ◽  
Author(s):  
A. M. Abdelghany ◽  
A.H. Oraby ◽  
Awatif A Hindi ◽  
Doaa M El-Nagar ◽  
Fathia S Alhakami
Keyword(s):  
Self Assembly ◽  
Metallic Nanoparticles ◽  
Room Temperature ◽  
Bimetallic Nanoparticles ◽  
Reduction Process ◽  
Nano Particles ◽  
Nano Structure ◽  
Small Shift ◽  
Molar Ratios ◽  
Vis Spectroscopy

Bimetallic nanoparticles of silver (Ag) and gold (Au) were synthesized at room temperature using Curcumin. Reduction process of silver and gold ions with different molar ratios leads to production of different nanostructures including alloys and core-shells. Produced nanoparticles were characterized simultaneously with FTIR, UV/vis. spectroscopy, transmission electron microscopy (TEM), and Energy-dispersive X-ray (EDAX). UV/vis. optical absorption spectra of as synthesized nanoparticles reveals presence of surface palsmon resonance (SPR) of both silver at (425 nm) and gold at (540 nm) with small shift and broadness of gold band after mixing with resucing and capping agent in natural extract which suggest presence of bimetallic nano structure (Au/Ag). FTIR and EDAX data approve the presence of bimetallic nano structure combined with curcumin extract. TEM micrographs shows that silver and gold can be synthesized separately in the form of nano particles using curcumin extract. Synthesis of gold nano particles in presence of silver effectively enhance and control formation of bi-metallic structure.

Thermal Diffusivity Dependence with Highly Concentrated Graphene Oxide/Water Nanofluids by Mode-Mismatched Dual-Beam Thermal Lens Technique

2021 ◽  
Vol 42 (7) ◽  
Author(s):  
J. L. Jiménez-Pérez ◽  
G. López-Gamboa ◽  
J. F. Sánchez-Ramírez ◽  
Z. N. Correa-Pacheco ◽  
A. Netzahual‑Lopantzi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Thermal Diffusivity ◽  
Thermal Lens ◽  
Dual Beam

scholarly journals Carbothermal Synthesis of Ni/Fe Bimetallic Nanoparticles Embedded into Graphitized Carbon for Efficient Removal of Chlorophenol

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1417
Author(s):  
Min Zhuang ◽  
Wen Shi ◽  
Hui Wang ◽  
Liqiang Cui ◽  
Guixiang Quan ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Surface Passivation ◽  
Bimetallic Nanoparticles ◽  
Zero Valent Iron ◽  
Molar Ratio ◽  
Particle Sizes ◽  
Iron Corrosion ◽  
Graphitized Carbon ◽  
Nanoscale Zero Valent Iron ◽  
Iron Nickel

The reactivity of nanoscale zero-valent iron is limited by surface passivation and particle agglomeration. Here, Ni/Fe bimetallic nanoparticles embedded into graphitized carbon (NiFe@GC) were prepared from Ni/Fe bimetallic complex through a carbothermal reduction treatment. The Ni/Fe nanoparticles were uniformly distributed in the GC matrix with controllable particle sizes, and NiFe@GC exhibited a larger specific surface area than unsupported nanoscale zero-valent iron/nickel (FeNi NPs). The XRD results revealed that Ni/Fe bimetallic nanoparticles embedded into graphitized carbon were protected from oxidization. The NiFe@GC performed excellently in 2,4,6-trichlorophenol (TCP) removal from an aqueous solution. The removal efficiency of TCP for NiFe@GC-50 was more than twice that of FeNi nanoparticles, and the removal efficiency of TCP increased from 78.5% to 94.1% when the Ni/Fe molar ratio increased from 0 to 50%. The removal efficiency of TCP by NiFe@GC-50 can maintain 76.8% after 10 days of aging, much higher than that of FeNi NPs (29.6%). The higher performance of NiFe@GC should be ascribed to the significant synergistic effect of the combination of NiFe bimetallic nanoparticles and GC. In the presence of Ni, atomic H* generated by zero-valent iron corrosion can accelerate TCP removal. The GC coated on the surface of Ni/Fe bimetallic nanoparticles can protect them from oxidation and deactivation.

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