Mohd Shaban Ansari; Kashif Raees; Elham S. Aazam; M. Z. A. Rafiquee
Abstract
The kinetics of the oxidation of methylene blue (MB) by H2O2 in the presence of iron oxide nanoparticles has been studied. The nanoparticles of iron oxide (Fe3O4) were synthesized and characterized physico-chemical techniques. The XRD studies showed its crystalline nature. The VSM study was carried out ...
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The kinetics of the oxidation of methylene blue (MB) by H2O2 in the presence of iron oxide nanoparticles has been studied. The nanoparticles of iron oxide (Fe3O4) were synthesized and characterized physico-chemical techniques. The XRD studies showed its crystalline nature. The VSM study was carried out to determine the values of the magnetic saturation parameter ~ 40.00 emu/g. The particle were of spherical shape with particle size distribution centered at 12 ± 2 nm. The FT-IR spectra indicated the presence of peaks at 585 cm -1 and 459 cm -1 due to Fe-O bond vibrations. The peak at 3424 cm -1 was assigned to the O-H stretching vibration. The H-O-H bending appeared at 1631 cm -1 . The Fe3O4 nanoparticles enhanced the rate of degradation of MB. The oxidation rate increased with the increase in Fe3O4. At pH 3, the maximum rate of oxidation of MB was observed. The rate of reaction increased with the increase in [H2O2] in the absence of Fe3O4. But in the presence of Fe3O4, the rate constant versus [H2O2] showed peaked behaviour. The CTABr increased the rate of oxidation of MB by H2O2 in the presence of Fe3O4 nanoparticles.
Mohamed A. Elsayed; Hesham R. Tantawy; Amr A. Nada; Mohamed E. Elmowafy
Abstract
Due to intrinsic properties of graphene-like high electrical conductivity and large surface area, these properties make it an attractive matrix for composites. In this work, reduced graphene oxide (RG)/Fe3O4 (M)/Ag2CO3 (S) hybrid nano-composite (MRGS) has been effectively produced by coprecipitation ...
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Due to intrinsic properties of graphene-like high electrical conductivity and large surface area, these properties make it an attractive matrix for composites. In this work, reduced graphene oxide (RG)/Fe3O4 (M)/Ag2CO3 (S) hybrid nano-composite (MRGS) has been effectively produced by coprecipitation techniques. The prepared composites were investigated by powder X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (UV-vis/DRS), Raman and vibrating sample magnetometer (VSM). The prepared MRGS nano-composite shows significant enhancement in the degradation rate of Tartrazine dye (TZ) compared to commercial photo-catalyst such as TiO2. Meanwhile, the visible light absorption of the MRGS nano-composite is progressively refining with the increase of the percentage of Ag2CO3 on the surface of (RG). The obtained MRGS 75 photo-catalyst shows the best photo-catalytic activity for TZ under visible light irradiation. The close contact between Ag2CO3 and RG in the composite leads to accelerating the charge transfer on Ag2CO3 to RG and thus enhancing the photocatalytic activity. Additionally, the prepared composite displays superb separability and significant stability. Copyright © VBRI Press.
Zhenya Jiang; Yao Wang; Lifeng Yan
Abstract
WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic ...
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WO3@Graphene (WO3@GR) nanocomposite has been synthesized by using a simple sonochemical method, and the phosphotungstic acid was used as the source of the WO3 nanoparticles. The new catalyst was analyzed by means of FT-IR, XRD, TEM, and SEM-EDX. FT-IR spectrum of the new material reveals that sulfonic acid groups existed on the surface of graphene nanosheets. In addition, TEM image of WO3@GR indicates that the WO3 nano-particles in size of 5-10 nm have an uniform distribution on the surface of the graphene nanosheets. The as-prepared nanocomposite can be used as a catalyst for biomass conversion, and the catalytic hydrolysis of fructose was carried out at different experiment conditions, such as reaction temperature, reaction time and catalyst dosage. HPLC has been used to measure the compounds in product and their yield. It was found that the major products include HMF, formic acid, lactic acid, acetic acid, and maleic acid, and the maximum yield is 43.25% when the reaction was carried out at 160 o C with the ratio of fructose to catalyst is 8 in the presence of 20 ml of water for 2h. The results reveal that the WO3@GR nanocomposite is a potential catalyst for biomass conversion.
Omkar S. Kushwaha; C. V. Avadhani; R. P. Singh
Abstract
Acid doped polybenzimidazole membranes have emerged as an efficient electrolyte for high temperature polymer electrolyte membrane fuel cells (HTPEMFCs). The long term stability of polybenzimidazole membranes has been recognized as an important issue for commercial applications. Here, we report the oxidative ...
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Acid doped polybenzimidazole membranes have emerged as an efficient electrolyte for high temperature polymer electrolyte membrane fuel cells (HTPEMFCs). The long term stability of polybenzimidazole membranes has been recognized as an important issue for commercial applications. Here, we report the oxidative degradation of polybenzimidazole membranes. The photoirradiation of poly(2,2'-ethylene-5,5'-bibenzimidazole) (PBIE) under accelerated photodegradation conditions was carried out by ultraviolet (UV) rays (λ > 300 nm) and characterized by Fourier transform infra red (FT-IR) spectroscopy, scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD) and contact angle measurements (CAM). The thermal properties of PBIE membranes were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) which revealed a lowering in thermal stability after photodegradation. FT-IR spectra revealed high absorbance in the carbonyl region in photoirradiated membranes whereas SEM showed nano structures / defects on the polymer film surface. CAM results showed enhancement in hydrophilic behavior and WAXD revealed increase in amorphous nature upon irradiation.
Omkar S. Kushwaha; C. V. Avadhani; R. P. Singh
Abstract
High temperature polymer electrolyte membrane fuel cells (HTPEMFCs) are energy efficient systems with the potential to address all energy issues of present and future generations. Polybenzimidazole (PBI) based high temperature fuel cells are subject of high importance because PBI membranes are proved ...
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High temperature polymer electrolyte membrane fuel cells (HTPEMFCs) are energy efficient systems with the potential to address all energy issues of present and future generations. Polybenzimidazole (PBI) based high temperature fuel cells are subject of high importance because PBI membranes are proved to be one of the best candidates for high temperature fuel cell applications. The stability of PBI membranes has been identified as crucial issue for the long-term durability under oxidative conditions of fuel cells. The present investigation highlights the photo-oxidative degradation studies accomplished on polybenzimidazole based poly(2,2'-butylene-5,5'-bibenzimidazole) (PBIB) membranes. The PBIB polymer membranes are found suitable for both in high temperature fuel cells as well as other high temperature applications. In this research article, PBIB membranes were photoirradiated under polychromatic UV rays (λ > 290 nm). The photo-oxidative degradation of membranes was characterized by Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). FT-IR results showed significant amount of photo-oxidation and chemical degradation in fuel cell membranes which is proposed to be initiated by free radical mechanism. SEM images revealed development of nano-dimensional cracks and holes on surface of membranes which indicate structural and morphological degradation. The present study showed better results of accelerated photo-degradation as compared to the oxidative degradation results already reported in literature obtained chemically and thermally. Hence, the proposed photo-oxidative degradation method may be useful in determining stability, life time expectancy and degradation mechanism of fuel cell and other high performance membranes.
Shashi Kant;Amit Kumar
Abstract
Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission ...
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Zn1-xNixO (x=0, 0.5) nanoparticles were successfully prepared by sol gel method. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. Surface morphology of nanosystems was performed by Scanning Electron Microscopy (SEM) and High Resolution Transmission Emission Microscopy (TEM) .Due to doping of ZnO nanoparticles the absorption shifted towards the visible region from UV region .The absorption increases on doping in the visible region.The Photocatalytic activity of both the doped and undoped ZnO was analysed via degradation of Methylene Blue. The Methylene Blue decomposition rate of pure ZnO and Nickel doped ZnO nanoparticles were studied under UV –Visible region. In the visible region both pure and doped ZnO decomposed Methylene Blue.This confirms the potential application of ZnO Nanoparticles for removal of harmful dyes from waste water and drinking water.The doping has a pronounced effect on the photocatalytic activity of nanoparticles. The degradation rate of the dye increased in case of Ni doped ZnO nanospheres.
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