In this work, we report the synthesis of magnetic sulfur-doped Fe3O4 nanoparticles (Fe3O4:S NPs) with a novel simple strategy, which includes low temperature multicomponent mixing and high temperature sintering. The prepared Fe3O4:S NPs exhibit a much better adsorption performance towards Pb(II) than bare Fe3O4 nanoparticles. FTIR, XPS, and XRD analyses suggested that the removal mechanisms of Pb(II) by Fe3O4:S NPs were associated with the process of precipitation (formation of PbS), hydrolysis, and surface adsorption. The kinetic studies showed that the adsorption data were described well by a pseudo second-order kinetic model, and the adsorption isotherms could be presented by Freundlich isotherm model. Moreover, the adsorption was not significantly affected by the coexisting ions, and the adsorbent could be easily separated from water by an external magnetic field after Pb(II) adsorption. Thus, Fe3O4:S NPs are supposed to be a good adsorbents for Pb(II) ions in environmental remediation. 相似文献
A procedure for the synthesis of carbon-encapsulated multilayer magnetite and zirconium oxide–magnetite nanoparticles that form porous nanostructures, for use as biocompatible sorbents, is proposed. The properties, composition, dimensions, particle shapes, surface morphology, and magnetic characteristics of the products are studied. 相似文献
Fe3O4 nanorods and Fe2O3 nanowires have been synthesized through a simple thermal oxide reaction of Fe with C2H2O4 solution at 200–600°C for 1 h in the air. The morphology and structure of Fe3O4 nanorods and Fe2O3 nanowires were detected with powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy.
The influence of temperature on the morphology development was experimentally investigated. The results show that the polycrystals
Fe3O4 nanorods with cubic structure and the average diameter of 0.5–0.8 μm grow after reaction at 200–500°C for 1 h in the air.
When the temperature was 600°C, the samples completely became Fe2O3 nanowires with hexagonal structure. It was found that C2H2O4 molecules had a significant effect on the formation of Fe3O4 nanorods. A possible mechanism was also proposed to account for the growth of these Fe3O4 nanorods.
Supported by the Fund of Weinan Teacher’s University (Grant No. 08YKZ008), the National Natural Science Foundation of China
(Grant No. 20573072) and the Doctoral Fund of Ministry of Education of China (Grant No. 20060718010) 相似文献
As the solubility is a direct measure of stability, this study compares the solubilities of ZnFe2O4, Fe3O4 and Fe2O3 in high temperature water. Through literature analysis and formula derivation, it is shown that it is reasonable to assume ZnFe2O4 and Fe(OH)3 coexist when ZnFe2O4 is dissolved in water. Results indicated that the solubility of ZnFe2O4 is much lower than that of Fe2O3 or Fe3O4. The low solubility of ZnFe2O4 indicates that it is more protectively stable as an anticorrosion phase. Moreover, the gap between the solubility of ZnFe2O4 and that of Fe3O4 or Fe2O3 was enlarged with an increase of temperature. This means that ZnFe2O4 is more protective at higher temperatures. Further analysis indicated that with the increase of temperature, the solubility of ZnFe2O4 changed little while those of Fe2O3 or Fe3O4 changed a lot. Little change of the solubility of ZnFe2O4 with increase of temperature showed that ZnFe2O4 is stable. The very low and constant solubility of ZnFe2O4 suggests that it is more protective than Fe2O3 and Fe3O4, especially in water at higher temperature. 相似文献
A procedure was suggested for recovering and concentrating phenols (phenol, 4-nitrophenol, 2-chlorophenol, and pentachlorophenol) from aqueous solution using a newly synthesized sorbent: magnetite nanoparticles modified with hyper-cross-linked polystyrene. The sorbent particle size, limiting sorption, specific surface area, and saturation magnetization were determined. A novel concentrating cartridge that ensures sorption under dynamic conditions using the magnetic sorbent was developed, and its performance was evaluated. The dynamic sorption allows quantitative recovery of phenols with a concentration factor of 530–1360. 相似文献
The study of superparamagnetic Fe3O4/Ag nanocomposites have received great research attention due to their wide range of potential applications in biomedicine. In this report, an easy microemulsion reaction was employed to synthesis Fe3O4/Ag nanocomposites with self-aggregated branch like nanostructures. The Fe3O4 nanoparticles were initially prepared and subsequently AgNO3 was reduced as Ag by chemical reduction method. The results showed that the average size of the Fe3O4/Ag nanocomposites were in the range of 10 ± 2 nm. These nanoparticles were self-aggregated as a branch like nanostructure. The optical properties of Fe3O4 nanoparticles were modified with surface plasmon resonance of Ag nanoparticles. The observed saturation magnetization of superparamagnetic Fe3O4/Ag nanocomposites were 40 emu/g. 相似文献
Nanobiotechnology has opened a new and exciting opportunities for exploring urea biosensor based on magnetic nanoparticles (NPs) mainly Fe3O4 and Co3O4. These NPs have been extensively exploited to develop biosensors with stability, selectivity, reproducibility and fast response time. This review gives an overview of the development of urea biosensor based on Fe3O4 and Co3O4 for in vitro diagnostic applications along with significant improvements over the last few decades. Additionally, effort has been made to elaborate properties of magnetic nanoparticles (MNPs) in biosensing aspects. It also gives details of recent developments in hybrid nanobiocomposite based urea biosensor. 相似文献
Using Fe3O4 nano-particles as seeds, a new type of Fe3O4/Au composite particles with core/shell structure and diameter of about 170 nm was prepared by reduction of Au3+ with hydroxylamine in an aqueous solution. Particle size analyzer and transmission electron microscope were used to analyze
the size distribution and microstructure of the particles in different conditions. The result showed that the magnetically
responsive property and suspension stability of Fe3O4 seeds as well as reduction conditions of Au3+to Au0are the main factors which are crucial for obtaining a colloid of the Fe3O4/Au composite particles with uniform particle dispersion, excellent stability, homogeneity in particle sizes, and effective
response to an external magnet in aqueous suspension solutions. UV-Vis analysis revealed that there is a characteristic peak
of Fe3O4/Au fluid. For particles with d(0.5)=168 nm, the λmax is 625 nm. 相似文献
New nanomagnetic coordination compound, Cu(salal)@DA@ Fe3O4, was synthesized by bonding between the Cu(II) complex and Fe3O4 nanoparticles. The Cu complex has two aldehyde groups. The surface of Fe3O4 nanoparticles was modified by the dopamine molecules and the amine group of dopamine is free. Therefore, the Cu complex is covalently anchored to Fe3O4 nanoparticle by the formation of imine bonds between the aldehyde and amine groups. On the other hand, a Cu-Schiff base complex is immobilized on nano-Fe3O4 by dopamine as a bridge. Consequently, the homogeneous Cu complex is easily converted to the heterogeneous-magnetic compound in this project. The Cu complex, Fe3O4 and new nanocomposite were characterized by general techniques such as FTIR, TGA, XRD, FESEM, MAP and EDS. The average crystallite size of Fe3O4 and Cu(salal)@DA@ Fe3O4 were calculated by Scherrer’s formula and they are 18.52 and 24.69 nm, respectively. These results indicated the average crystallite size of Fe3O4 nanomaterials is slightly increased by surface modification by Cu complex. The FESEM images show a tiny spherical mushroom morphology for both nanocompounds, and the EDS analysis confirms the presence of Fe, Cu, C and O in the nanomagnetic coordination composite. The catalytic properties of these compounds were studied and compared to oxidation of benzyl alcohol by 30% H2O2 at room temperature. The results show that the catalytic properties Cu complex and Fe3O4 were enhanced by cooperation of both compounds in a nanocoordination composite. 相似文献
Summary The adsorption of 99Tc on the adsorbers Fe, Fe2O3 and Fe3O4 was studied by batch experiments under aerobic and anoxic conditions. The effects of pH and CO32- concentration of the simulated ground water on the adsorption ratios were also investigated, and the valences of Tc in solution after the adsorption equilibrium were studied by solvent extraction. The adsorption isotherms of TcO4- on the adsorbers Fe, Fe2O3 and Fe3O4 were determined. Experimental results have shown that the adsorption ratio of Tc on Fe decreases with the increase of pH in the range of 5-12 and increases with the decrease of the CO32- concentration in the range of 10-8M-10-2M. Under aerobic conditions, the adsorption ratios of 99Tc on Fe2O3 and Fe3O4 were not influenced by pH and CO32-concentration. When Fe was used as adsorbent, Tc existed mainly in the form of Tc(IV) after equilibrium and in the form of Tc(VII) when the adsorbent was Fe2O3 or Fe3O4 under aerobic conditions. The adsorption ratios of Tc on Fe, Fe2O3 and Fe3O4 decreased with the increase of pH in the range of 5-12 and increased with the decrease of the CO32- concentration in the range of 10-8M-10-2M under anoxic conditions. Tc existed mainly in the form of Tc(IV) after equilibrium when Fe, Fe2O3 and Fe3O4 was the adsorbent under anoxic conditions. The adsorption isotherms of TcO4- on the adsorbers Fe, Fe2O3 and Fe3O4 are fairly in agreement with the Freundlich’s equation under both aerobic and anoxic conditions. 相似文献
A new support for Pd(II) was synthesized via the functionalization of Fe3O4 nanoparticles with N-(2-aminoethyl)acetamide. PdCl2 was anchored to the support for obtaining a heterogeneous magnetically recoverable catalyst for Pd(II). High yield and excellent selectivity were obtained for the green epoxidation of styrene derivatives using H2O2 as a green oxidant in H2O as the solvent at 100 °C. Also, the recovered catalyst is applicable for four times without significant decrease in yield. 相似文献
The authors describe magnetic nanoparticles consisting of an Fe3O4 core and a poly(methacrylic acid) coating for dispersive solid phase extraction (DSPE) of arsenic prior to its determination by hydride-generation microwave plasma AES (HG-MP-AES). The particles have an average size of 25 nm, can be prepared at low costs, and provide improved operational safety in combination with plasma generation. The methods allows arsenic to be determined with detection limits (at 3σ/m) of 3.0 ng?L?1 for As(III) and of 10.0 ng?L?1 of As(V). Recoveries of (spiked) samples range from 99.0 to 102%. This is the first report on the use of HG-MP-AES for speciation and preconcentration of arsenic using DSPE. The method displays detection limits that come close to those of ICP-OES and ICP-MS.
Graphical abstract A core/shell Fe3O4@poly(methacrylic acid) coated sorbent was synthesised and employed to the speciation of arsenic prior to its determination by hydride-generation microwave plasma atomic emission spectrometry.
Monodisperse and porous nonstoichiometric Zn ferrite can be prepared by a solvothermal method. Such non-Zn ferrite was used to be the precursor for synthesis of ZnFe2O4/Fe2O3 composite via calcination at 600°C for 3 h in air. X-ray powder diffractometer (XRD) and Energy Dispersive Spectrometer (EDS) proved the nonstoichiometry of Zn ferrite synthesized by solvothermal method and the formation of ZnFe2O4/Fe2O3 composite via calcination. TEM image showed that non-Zn ferrite spheres with wormlike nanopore structure were made of primary nanocrystals. BET surface area of non-Zn ferrite was much higher than that of ZnFe2O4/Fe2O3 composite. Saturation magnetization of non-Zn ferrites was significantly higher than that of ZnFe2O4/Fe2O3 composites. Calcination of non-Zn ferrite resulted in the formation of large amount of non-magnetic Fe2O3,which caused a low magnetization of composite. Because of higher BET surface area and higher saturation magnetization, non-Zn ferrite presented better Cr6+ adsorption property than ZnFe2O4/Fe2O3 composites. 相似文献
The interaction between stabilizers and nanoparticles is one of the important factors to prepare stable magnetic fluids. The
magnetic nano-size Fe3O4 core with single domain and the average grain size around 8–12 nm were prepared by chemical precipitation method. The O/Fe
molar ratio of the particle surface was measured by X-ray photoelectron spectroscopy (XPS). The heat effects of stabilizers
adsorption on nanoparticles were measured by solution calorimetry. The excess amount of oxygen was possibly the result of
the hydroxygen formed on the surface of the nanoparticles. The heat effects showed that compounds containing carboxyl groups
can be adsorbed chemically on magnetite by forming chemical bonds. The other stabilizers involving NH-groups, such as polyethylene-imine,
can be adsorbed physically. The exothermic value is about half of the former case.
Supported by the National Natural Science Foundation of China (Grant No. 50476039), and Guangdong Provincial Department of
Science and Technology (Grant No. 2004A10-703001) 相似文献
This investigation examines the magnetorheological (MR) characteristics of Fe3O4 aqueous suspensions. Magnetite particles (Fe3O4) were synthesized using a colloidal process and their sizes were determined to be normally distributed with an average of
10 nm by TEM. Experimental results reveal that the MR effect increases with the magnetic field and suspension concentration.
The yield stress increases by up to two orders of magnitude when the sample is subjected to a magnetic field of 146 Oe/mm.
In comparison with other published results, concerning a concentration of approximately 10–15% v/v, this study demonstrates
that the same increase can be obtained with a concentration of nano-scale particles as low as 0.04% by volume. The viscosity
was increased by an order of magnitude while the shear rate remained low; however, the increase decayed rapidly as the shear
rate was raised. Finally, the MR effect caused by DC outperformed that caused by AC at the same current. 相似文献
A new approach to the synthesis of hybrid nanoparticles based on magnetic Fe3O4 nanoparticles and CdS quantum dots, combining magnetic and luminescence properties, has been suggested. Conditions for preparation of their stable aqueous suspensions have been found, and their optical properties have been studied. Nanocomposites produced at the molar ratio Fe3O4: CdS = 5: 1, which exhibited the luminescence properties) and gave stable aqueous suspensions, have turned out to be most promising. The results are evidence that the synthesized nanoparticles can be used for the development of visualizing agents for in vitro biomedical research. 相似文献
A yolk–shell-structured sphere composed of a superparamagnetic Fe3O4 core and a carbon shell (Fe3O4@HCS) was etched from Fe3O4@SiO2@carbon by NaOH, which was synthesized through the layer-by-layer coating of Fe3O4. This yolk–shell composite has a shell thickness of ca. 27 nm and a high specific surface area of 213.2 m2 g?1. Its performance for the magnetic removal of tetracycline hydrochloride from water was systematically examined. A high equilibrium adsorption capacity of ca. 49.0 mg g?1 was determined. Moreover, the adsorbent can be regenerated within 10 min through a photo-Fenton reaction. A stable adsorption capacity of 44.3 mg g?1 with a fluctuation <10% is preserved after 5 consecutive adsorption–degradation cycles, demonstrating its promising application potential in the decontamination of sewage water polluted by antibiotics. 相似文献
Cobalt zinc ferrite, Co0.8Zn0.2Fe2O4, nanoparticles have been synthesized via autocatalytic decomposition of the precursor, cobalt zinc ferrous fumarato hydrazinate.
The X-ray powder diffraction of the ‘as prepared’ oxide confirms the formation of single phase nanocrystalline cobalt zinc
ferrite nanoparticles. The thermal decomposition of the precursor has been studied by isothermal, thermogravimetric and differential
thermal analysis. The precursor has also been characterized by FTIR, and chemical analysis and its chemical composition has
been determined as Co0.8Zn0.2Fe2(C4H2O4)3·6N2H4. The Curie temperature of the ‘as-prepared oxide’ was determined by AC susceptibility measurements. 相似文献
Fe3O4/Au composite particles with core/shell structure were prepared by reduction of Au3+ with hydroxylamine in the presence of an excess of Fe3
O4 as seeds. The resultant colloids, with an average diameter of less than 100 nm, were obtained; the remaining non-reacted
Fe3O4 seeds can be removed by treatment with diluted HCl solution. The Fe3O4/Au colloids exhibit a characteristic peak of UV-visible spectra, which largely depend on the size of the particle and the
suspension medium. The localized surface plasmon resonance peaks red shift and broaden with increased nanoparticle diameter
or increased solvent ionic strength. The optical property is very important in the establishment of means for the detection
of biomolecules. 相似文献
A new chemical approach for the fabrication of Fe3O4 embedded ZnO magnetic semicondutctor composite is reported. The method consists in increasing the pH of the synthesis solution by the thermal decomposition of urea instead of using common alkaline agents, such as NaOH and NH4OH. The material (Fe3O4@ZnO) was used as a platform for the fabrication of highly dispersed gold nanoparticles (~5?nm). The catalytic efficiency of the material, Fe3O4@ZnO@Au, was tested in the photodegradation of Rhodamine-B solutions, and prominent catalytic efficiency, stability, and recycling were achieved. A single portion of the catalyst could be used up to five times without significant loss of activity and its photodegradation efficiency was considered high even after the 12th cycle (56%). Catalyst separation after each batch could be easily achieved because of the intrinsic magnetic property of the material. Leaching monitoring of free Zn species during the fabrication of the catalyst suggests that the use of urea decreased substantially the formation of non-magnetic-semiconducting species and provided a higher mass yield of the magnetic composite compared to an analogous protocol using NaOH. The catalyst was also characterized by detailed structural and chemical analyses, such as transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and vibration sample magnetometer (VSM).