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1.
Thermal degradation of mixture of tetrabromobisphenol A (TBBA) and metal oxide (ZnO, Fe 2O 3, La 2O 3, CaO and CuO) has been studied under inert atmosphere. The formation of hydrogen bromide and brominated organic compounds is observed for pyrolysis of TBBA. The addition of metal oxide gives rise to considerable suppression of HBr as well as brominated organic compounds. The suppression owes to the bromination of oxides. The influence of oxide on thermal degradation of TBBA is discussed with emphasis on the conversion of bromine. 相似文献
2.
Decomposition of CCl 4 into diphenyl carbonate (DPC) was examined over metal oxides modified SiMCM-41. ZnO/SiMCM-41 and Fe 2O 3/SiMCM-41 showed high activity in DPC synthesis. Although many other metal oxides, such as La 2O 3, CuO, Al 2O 3 and alkali or alkaline earth oxide, were success in destruction of CCl 4, they displayed nearly no activity on DPC synthesis. ZnO/SiMCM-41 and Fe 2O 3/SiMCM-41 were characterized by X-ray diffraction (XRD), UV-Raman, 29Si MAS NMR and N 2 adsorption-desorption isotherms, and results showed that ferric and zinc oxide were supported onto SiMCM-41. The well ZnO
dispersion in SiMCM-41 channels and the weak electrostatic interaction between chlorine anion and Zn 2+ play an important role for the high activity of ZnO/SiMCM-41 in decomposition of CCl 4 into DPC. 相似文献
3.
Nanoparticles of CeO 2, Fe 3O 4, TiO 2 and ZnO get coated by hexadecyltriethoxysilane on refluxing the nanoparticles and the organosilane in a hydrocarbon solvent.
The organosilane-coated metal oxide nanoparticles give stable dispersions in hydrocarbon solvents due to their hydrophobic
surface. On heating in air, the organosilane-coated metal oxide nanoparticles yield to silica-coated core-shell type nanoparticles.
Dedicated to Late Professor F. A. Cotton. 相似文献
4.
Oxidation of ethylene was carried out over alumina-supported metal oxide catalysts and highly dispersed gold catalysts, respectively, under atmospheric pressure. The ethylene was completely oxidized to produce carbon dioxide and water with both metal oxide and gold catalysts. The activity of gold catalyst prepared by deposition method was much higher than that of supported metal oxide catalysts. Ultra-fine gold particles on Co 3O 4 were more active than on Al 2O 3. Fe 2O 3/Al 2O 3 and MnO 2/Al 2O 3 catalysts were more active than MoO 3/Al 2O 3 catalyst. The activity of the supported metal oxide catalysts was greatly enhanced by addition of gold particles. It was therefore considered that gold particles promote dissociative adsorption of oxygen and the adsorbed oxygen reacts with adsorbed ethylene on support adjacent to the active site. 相似文献
5.
The design of an efficient and green dye degradation technology is of great significance to mitigate water pollution as well as ecological damage. Fe 3O 4/CuO/ZnO/RGO was prepared by solvothermal synthesis and homogeneous precipitation. X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and vibrating-sample magnetometry (VSM) were used to characterize the samples, to explore the morphology and structural composition of the composites. To enhance the degradation efficiency, a dielectric barrier discharge (DBD)–Fe 3O 4/CuO/ZnO/RGO co-catalytic system was created based on the DBD plasma technology. Response surface methodology analysis results demonstrate that the degradation effect of DBD–Fe 3O 4/CuO/ZnO/RGO is optimal and the decolorization rate is 95.06 % when the solution pH is 3, conductivity is 0.5 mS/cm, the input voltage is 90 V, and Fe 3O 4/CuO/ZnO/RGO concentration is 0.18 g/L. Therefore, this study offers a novel method for dye degradation and confirms the viability of a DBD–Fe 3O 4/CuO/ZnO/RGO synergistic catalytic system. 相似文献
6.
New methods of obtaining products containing enzymes reduce the costs associated with obtaining them, increase the efficiency of processes and stabilize the created biocatalytic systems. In the study a catalytic system containing the enzyme α-amylase immobilized on ZnO nanoparticle and Fe3O4 nanoparticles was created. The efficiency of the processes was obtained with variables: concentrations of enzymes, temperatures and times, to define the best conditions for running the process, for which were determined equilibrium and kinetics of adsorption. The most effective parameters of α-amylase immobilization on metal oxides were determined, obtaining 100.8 mg/g sorption capacity for ZnO and 102.9 mg/g for Fe3O4 nanoparticles. Base on the best parameters, ZnO-α-amylase was investigated as an antimicrobial agent and Fe3O4-α-amylase was tested as a catalyst in the process of starch hydrolysis. As a result of the conducted experiments, it was found that α-amylase immobilized on Fe3O4 nanoparticles maintained high catalytic activity (the reaction rate constant KM?=?0.7799 [g/dm3] and the maximum reaction rate Vmax?=?8.660 [g/(dm3min)]). 相似文献
7.
Studies on Oxide Catalysts. XVI. Composition and Structure of Doped Zinc Oxide Catalysts Analytical, x-ray, textural, IR-spectroscopic, and MÖSSBAUER investigations of zinc oxide catalysts doped with Li 2O, Ga 2O 3 and Fe 2O 3 were conducted in order to reveal relations between electronic and catalytic properties. The mixtures ZnO/Li 2CO 3, ZnO/Ga 2O 3, ZnO/Fe 2O 3, and ZnO/ 57Fe(NO 3) 3, after the thermal pretreatment, always exist in the state of a polyphase solid system. In the ZnO/Li 2O system, only a very small part of the added lithium oxide is incorporated into the zinc oxide lattice by substitution. A second part of the Li 2O volatizes during the thermal pretreatment, and the greater part of it exists in the state of a separate solid phase in the catalyst and can be washed out by water. During the pretreatment, according to its temperature and duration, two-phase systems (ZnO, ZnMe 2O 4) or three-phase systems (ZnO, ZnMe 2O 4, Me 2O 3) are formed in the solid systems ZnO/Ga 2O 3 and ZnO/Fe 2O 3. For the reaction of both oxides forming a spinel, an electronic model is proposed. 相似文献
8.
The reactivity of zinc and copper oxide nanoparticles was investigated upon their interaction with iron oxides. It was ascertained
that, depending on the reaction conditions, nanoparticles of zinc and copper ferrites (ZnFe 2O 4 and CuFe 2O 4) or core/shell nanoparticles (Fe 3O 4/ZnO) are produced. Size, composition, and structure of the resulting nanoparticles were determined by transmission electron
microscopy and X-ray diffraction analysis. The average size of zinc and copper ferrite nanoparticles was ascertained to be
9–10 and 2–3 nm, respectively. For core/shell Fe 3O 4/ZnO nanoparticles, the average size is 20 nm. It was experimentally proved that the photoluminescence radiative characteristics
of ZnO nanoparticles are retained in core/shell Fe 3O 4/ZnO nanoparticles. 相似文献
9.
This work focussed on the optical, magnetic and photocatalytic properties of sol–gel-synthesized Fe 3O 4-doped ZnO nanospheres and was compared with pristine ZnO nanospheres. The crystalline phase of Fe 3O 4-doped ZnO nanospheres was studied with X-ray diffraction analysis and was well matched with standard pattern. Surface morphology was studied with HR-SEM images and EDAX spectrum. Furthermore, elemental mapping analysis was carried out to confirm the presence of Fe 3O 4 phase in Fe 3O 4-doped ZnO nanospheres. FT-Raman spectral studies show that a strong intense peak at 670 cm ?1 indicates the presence of Fe 3O 4 in Fe 3O 4-doped ZnO nanospheres. The mean crystallite size of Fe 3O 4-doped ZnO nanospheres was 34 nm as calculated by Debye–Scherrer’s formula which confirmed with HR-TEM image. The SAED pattern shows the presence of (100), (101), (102) and (202) of ZnO phase and (400) of Fe 3O 4 phase, confirming the crystalline nature of Fe 3O 4-doped ZnO nanospheres. The vibrating sample magnetometer (VSM) result shows that Fe 3O 4-doped ZnO nanospheres possess superparamagnetic nature and the composite nanospheres are magnetically separable. The optical properties have been studied by diffuse reflectance spectroscopy and time-resolved photoluminescence spectra. Implantation of Fe 3O 4 in ZnO nanospheres modifies the UV absorption edge, and it displays near-band gap emission and deep-level emission. The photocatalytic activity of Fe 3O 4-doped ZnO nanospheres studied against rhodamine B dye is found higher than that of pristine ZnO nanospheres which shows that Fe 3O 4-doped ZnO nanospheres are a promising photocatalyst. 相似文献
10.
Bio-oil from biomass pyrolysis is promising to be used as a sustainable biofuel and high-value-added chemical. However, the presence of high acid, water, and oxygenate causes corrosive properties, low higher heating value (HHV), and instability of the bio-oil component. Therefore, refining the bio-oil is essential to improve its quality. In this study, we introduced natural zeolite (HZ) impregnated with transition metal oxide (TMO) to refine the bio-oil using the hydrodeoxygenation method (HDO) at various catalyst ratios and temperatures. We find that ZnO/HZ 5% wt. shows the best catalytic performance, with the conversion of organic phase reaching ~ 50%. The refined bio-oil from Fe 2O 3, ZnO, and CuO has high-quality physicochemical properties with carbon, oxygen, water level, and HHV values are 37–52%, 40–53%, 8–27%, and 17–21 MJ/kg, respectively. This result represents a high catalytic performance for the hydrodeoxygenation process of bio-oil using natural zeolite-based transition metal oxide for better and low-cost biofuel production. 相似文献
11.
This research work includes the fabrication of iron oxide nanoparticles (Fe 2O 3 NPs) by green construction approach using Wisteria sinensis leaves extract. Due to its eco-friendly approach, the synthesis of iron oxide NPs (Fe 2O 3 NPs) using various plant sources, such as plant parts, and microbial cells have gained a lot of attention in recent years. Cost-effectiveness and ease of availability make Wisteria sinensis leaves extract a potential candidate for the construction of iron oxide NPs. The various key features like biocompatibility, non-toxicity capping, and stabilizing agents present in biological sources are advantageous for usage in a variety of applications. The phytoconstituents present in the leaf extract of Wisteria sinensis serve as reducing and stabilizing agents. The biologically fabricated (Fe 2O 3 NPs) were analyzed using FT-IR, XRD, UV–vis spectroscopy, and SEM. In the present work, the antioxidant and photocatalytic dye degradation efficiency of Fe 2O 3 NPs has been studied. The dye degradation efficiency of methylene blue dye was found to be 87% at 180 min upon exposure to sunlight. The capacity of Fe 2O 3 NPs to scavenge 2,2-diphenyl-1-picrylhydrazyl hydrate free radicals (DPPH) was examined using a UV–Vis spectrophotometer. The study compared the radical scavenging activity (RSA) of Fe 2O 3 nanoparticles (NPs) with that of the standard antioxidant ascorbic acid. The results demonstrated that Fe 2O 3 NPs have a greater ability to scavenge radicals than ascorbic acid. The half-maximal inhibitory concentration (IC50) of Fe 2O 3 NPs was observed to range from 0.12 to 0.17. Furthermore, Fe 2O 3 NPs displayed the highest antifungal activity, with an inhibition zone of 26.8 mm against F. oxysporum. These findings suggest that the biologically synthesized Fe 2O 3 NPs possess potent antimicrobial and dye degradation properties. 相似文献
12.
In this paper, we discuss the synthesis and electrochemical properties of a new material based on iron oxide nanoparticles stabilized with poly(diallyldimethylammonium chloride) (PDAC); this material can be used as a biomimetic cathode material for the reduction of H 2O 2 in biofuel cells. A metastable phase of iron oxide and iron hydroxide nanoparticles (PDAC–FeOOH/Fe 2O 3-NPs) was synthesized through a single procedure. On the basis of the Stokes–Einstein equation, colloidal particles (diameter: 20 nm) diffused at a considerably slow rate ( D = 0.9 × 10 ? 11 m s ? 1) as compared to conventional molecular redox systems. The quasi-reversible electrochemical process was attributed to the oxidation and reduction of Fe 3+/Fe 2+ from PDAC–FeOOH/Fe 2O 3-NPs; in a manner similar to redox enzymes, it acted as a pseudo-prosthetic group. Further, PDAC–FeOOH/Fe 2O 3-NPs was observed to have high electrocatalytic activity for H 2O 2 reduction along with a significant overpotential shift, Δ E = 0.68 V from ? 0.29 to 0.39 V, in the presence and absence of PDAC–FeOOH/Fe 2O 3-NPs. The abovementioned iron oxide nanoparticles are very promising as candidates for further research on biomimetic biofuel cells, suggesting two applications: the preparation of modified electrodes for direct use as cathodes and use as a supporting electrolyte together with H 2O 2. 相似文献
13.
Herein, we report a non-enzymatic glucose sensor field-effect transistor (FET) based on vertically-oriented zinc oxide nanorods modified with iron oxide (Fe 2O 3-ZNRs). Compared with ZnO-based non-enzymatic glucose sensors, which show poor sensing performances, modification of ZnO with Fe 2O 3 dramatically enhances the sensing behavior of the fabricated non-enzymatic FET glucose sensor due to the excellent electrocatalytic nature of Fe 2O 3. The fabricated non-enzymatic FET sensor showed excellent catalytic activity for glucose detection under optimized conditions with a linear range up to 18 mM, detection limits down to ~ 12 μM, excellent selectivity, good reproducibility and long-term stability. Moreover, the fabricated FET sensor detected glucose in freshly drawn mouse whole blood and serum samples. The developed FET sensor has practical applications in real samples and the solution-based synthesis process is cost effective. 相似文献
14.
A simple method for the preparation of metal‐oxide‐coated three‐dimensional (3D) graphene composites was developed. The metal–organic frameworks (MOFs) that served as the precursors of the metal oxides were first synthesized on the 3D graphene networks (3DGNs). The desired metal oxide/3DGN composites were then obtained by a two‐step annealing process. As a proof‐of‐concept application, the obtained ZnO/3DGN and Fe 2O 3/3DGN materials were used in a photocatalytic reaction and a lithium‐ion battery, respectively. We believe this method could be extended to the synthesis of other metal oxide/3DGN composites with 3D structures simply through the appropriate choice of specific MOFs as precursors. 相似文献
15.
Porous metal oxide (Co 3O 4, NiO, or ZnO) films were fabricated by a self-template method using layered hydroxide metal acetates (LHMA; metal = Co, Ni, or Zn) as templates. LHMAs were initially grown on glass substrates through a chemical bath deposition in methanolic-aqueous solutions of metal acetates at 60°C. The template films had a unique, nest-like morphology consisting of interlaced flake-like particles as a result of two-dimensional crystal growth of LHMAs in supersaturated solutions. The templates were successfully converted into porous Co 3O 4, NiO, or ZnO films by heating at 500°C for 10 min in air without microstructural deformation. 相似文献
16.
Superparamagnetic iron oxide particles with average size less than 20 nm were prepared by chemical co‐precipitation method in the air atmosphere. After that, polydimethyldiallyl ammonium chloride (PDDA) was used for wrapping iron oxide particles to obtain the core/shell nanocomposites. The parameters influencing properties of iron oxide particles and iron oxide/PDDA nanocomposites were investigated and optimized. The prepared iron oxide and nanocomposites were characterized by X‐ray diffraction (XRD) measurement, transmission electron microscopy (TEM), particle size and Zeta potential analyzer, Fourier transform infrared (FTIR) spectroscopy, and vibrating sample magnetometry (VSM), respectively. It was found that the iron oxide particles are cubic inverse spinel Fe 3O 4 with spherical shape. Superparamagnetic behavior of Fe 3O 4 with 73.114 emu/g is produced with NH 4OH as precipitator, and decreased to 58.583 emu/g for Fe 3O 4/PDDA nanocomposites. The Zeta potential of nanocomposites is positive value. The results showed that Fe 3O 4/PDDA nanocomposites have excellent future using as a carrier for bonding with some negative charged particles. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
17.
Gold metal particles were vacuum deposited onto the iron oxide surface and the effect of thermal treatment on the resulting Au/Fe 2O 3 samples at 30–800°C in vacuum and reaction media with different chemical compositions, i.e., 5 mbar of O 2, 5 mbar of CO, and 5 mbar of CO + 5 mbar of O 2, was studied by X-ray photoelectron spectroscopy. During the gold deposition, the increase in the intensity of the Au4 f line was shown to be accompanied by its shift toward lower binding energies, which is due to the increase in the particle size of gold. Starting from a certain amount of deposited gold, the binding energy Eb(Au4 f7/2) reaches the value typical of bulk gold metal. During the heating of Au/Fe 2O 3 in vacuum or a reaction medium, fine gold particles agglomerate into coarser ones, which is manifested in the decrease in the relative [Au]/[Fe] atomic ratio. The tendency of gold particles toward agglomeration depends on the composition of the reaction medium: the process proceeds most efficiently in the CO + O 2 mixture and less intensively in CO, and the highest stability was observed upon treatment in O 2. It is assumed that the decrease in the [Au]/[Fe] atomic ratio during the thermal treatment of Au/Fe 2O 3 in CO + O 2, CO, and vacuum could be not only due to agglomeration but also due to the encapsulation of the gold particles by the reduced fragments of the support. 相似文献
18.
Chitosan-based membranes filled with different metal oxide particles were prepared and their performance in ethanol dehydration process depending on the type of oxide and loading was discussed. For membrane preparation three oxides: TiO 2, Cr 2O 3 or Fe 3O 4 were selected. From experimental data suitable ethanol and water transport coefficients were evaluated. As shown in the results, applied fillers in different ways affect the separation properties. Presence of TiO 2 significantly affects the normalized total flux, increasing its value. On the other hand, addition of Fe 3O 4 influences most of all the separation factor, which is the among all investigated membranes. For membranes containing chromium(III) oxide as a filler, improvement in the separation properties is observed only in the case when the Cr 2O 3 content equals to 5 wt%. Above this concentration significant deterioration of separation properties is observed. The best performance has mixed-matrix membranes (MMMs) with magnetite, where the values of PSI are equal to 16.3 and 296.8 kg/m ?2 h µm for pristine and 15 wt% filler content, respectively. 相似文献
19.
Well-defined magnetic hybrid hollow capsules formed with magnetite (Fe 3O 4) and polyelectrolyte-multilayer films were successfully prepared through colloidal templating with layer-by-layer assembly of polyelectrolytes, followed by aqueous solution deposition of Fe 3O 4. Pd catalyst nanoparticles played an important role in the deposition of Fe 3O 4. Pd nanoparticles favorably adsorbed onto the polyelectrolyte layer with positively charged amino groups. Hollow capsules were obtained by the removal of the melamine–formaldehyde core particles. Although the processes were performed in aqueous solutions at temperatures less than 60 °C, X-ray diffraction patterns revealed that the deposited Fe 3O 4 was highly crystallized. The hollow capsules were stably dispersed in water; however, the capsules rapidly congregated around a locally applied magnet. 相似文献
20.
A comparative study of 1-octanol and 2-ethyl-1-hexanol transformations over silica supported NiO, MnO 2, Cr 2O 3, Fe 2O 3, and ZnO has been performed. Zinca containing catalyst was found to be the most active in dehydrogenation and dehydration
of the alcohols studied. ZnO dehydrogenating activity increased with supported oxide load. 相似文献
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