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1.
In this study, catalytic performance of nanoferrites NiFe 2O 4 and Ni 0.3Zn 0.7Fe 2O 4 is reported. Nickel–ferrite and mixed nickel–zinc ferrite were successfully synthesized by combustion reaction using a conical reactor with production of 10 g per batch. Crystallinity and purity or quantitative analysis of the catalyst were checked by using X-ray diffraction and energy dispersive X-ray analysis. Surface chemistry was examined via Fourier transform infrared (FTIR) analysis; N 2 physisorption at 77 K was conducted to obtain textural properties of the catalyst; a thermogravimetric analysis, a scanning electron microscope and a transmission electron microscopy were used to check the thermal stability and morphology of the catalyst, respectively. The catalysts were used to convert soybean oil into biodiesel in a batch mode and the reaction mixture was analyzed using a pre-calibrated gas chromatograph (GC). The presence of a single-phase spinel structure in the synthesized nanoparticles was confirmed by the XRD results. The Ni 0.3Zn 0.7Fe 2O 4 had a lower surface area value of 71.5 m 2g −1 and higher saturation magnetization value of 31.50 emu/g than sample NiFe 2O 4 which had 87.6 m 2g −1 and 17.85 emu/g, respectively. Biodiesel yield of 94% was obtained with Ni 0.3Zn 0.7Fe 2O 4 and 49% was obtained with NiFe 2O 4. Better performance of Ni 0.3Zn 0.7Fe 2O 4 when compared to that of NiFe 2O 4 could be attributed to higher acidity of the former. Findings from this study suggest that the development of nickel-zinc ferrite nanoparticles as magnetic heterogeneous catalysts could provide an environmentally friendly platform for biodiesel production. 相似文献
2.
An easy method in a solvothermal system has been developed to synthesize nanostructured magnetite (Fe 3O 4)-loaded functionalized carbon spheres (CSs) and cobalt ferrite (CoFe 2O 4). Surface-tunable CSs loaded with iron oxide (Fe 3O 4) nanoparticles were prepared using an acetylferrocene Schiff base (OPF), whereas spinel cobalt ferrite (CoFe 2O 4) was synthesized via metal complexes of a ferrocenyl Schiff base with phenol moiety (Co-OPF). The formed composite powder was investigated using X-ray powder diffraction, Raman spectrometry, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry. It was found that most of the iron oxide nanoparticles were evenly distributed upon the surface of the CSs. Furthermore, the surface of the iron oxide-loaded CSs has large numbers of functional groups. Good saturation magnetization was achieved for the formed magnetic nanoparticles. 相似文献
3.
Magnetic CoFe 2O 4-functionalized graphene sheets (CoFe 2O 4-FGS) nanocomposites have been synthesized by hydrothermal treatment of inorganic salts and thermal exfoliated graphene sheets. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations show that cobalt ferrite nanoparticles with sizes of 10-40 nm are well dispersed on graphene sheets. OH − was recognized as a tie to integrate the inorganic salts with the graphene sheets, which made reaction started and developed on the surface of graphene sheets and formed cobalt ferrite nanoparticles on graphene sheets. The adsorption kinetics investigation revealed that the adsorption of methyl orange from aqueous solution over the as-prepared CoFe 2O 4-FGS nanocomposites followed pseudo-second-order kinetic model and the adsorption capacity was examined as high as 71.54 mg g −1. The combination of the superior adsorption of FGS and the magnetic properties of CoFe 2O 4 nanoparticles can be used as a powerful separation tool to deal with water pollution. 相似文献
4.
Cobalt, copper, and nickel ferrite spinel nanoparticles have been synthesized by using a combination of sonochemical treatment and combustion. The magnetic nanoparticles have been used as supports to prepare ~4 wt% palladium catalysts. The ferrites were dispersed in an ethanolic solution of Pd(II) nitrate by ultrasonication. The palladium ions were reduced to metallic Pd nanoparticles, which were then attached to the surface of the different metal oxide supports. Thus, three different catalysts (Pd/CoFe 2O 4, Pd/CuFe 2O 4, Pd/NiFe 2O 4) were made and tested in the hydrogenation of 2,4-dinitrotoluene (DNT). A possible reaction mechanism, including the detected species, has been envisaged based on the results. The highest 2,4-diaminotoluene (TDA) yield (99 n/n%) has been achieved by using the Pd/NiFe 2O 4 catalyst. Furthermore, the TDA yield was also reasonable (84.2 n/n%) when the Pd/CoFe 2O 4 catalyst was used. In this case, complete and easy recovery of the catalyst from the reaction medium is ensured, as the ferrite support is fully magnetic. Thus, the catalyst is very well suited for applicationy in the hydrogenation of DNT or other aromatic nitro compounds. 相似文献
5.
Nanostructured cobalt ferrite (CoFe2O4) has been synthesized by a two-step process, a facile ultrasonic-assisted solvothermal technique for Fe2Co-MOF preparation and subsequent calcination. X-ray diffraction (XRD) patterns confirm the formation of MIL-88A(Fe) structure of Fe2Co-MOF and the cubic spinel structure of CoFe2O4. Field emission scanning electron microscope (FESEM) images reveal that calcination process converts the spindle-like morphology of Fe2Co-MOF to yolk-shell CoFe2O4 microspheres. From Brunauer–Emmett–Teller (BET) analysis, the specific surface areas of 36.0 and 29.2 m2 g?1 are measured for Fe2Co-MOF and CoFe2O4, respectively. Vibrating sample magnetometer (VSM) analysis of CoFe2O4 displays high coercivity of 2500 Oe due to surface anisotropy. Conversion of Fe2Co-MOF to CoFe2O4 reduces the optical band gap from 1.92 to 1.77 eV. Electrochemical performance of Fe2Co-MOF and CoFe2O4 deposited on Ni foams (NFs) is examined by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) tests. Specific capacitances of 489.9 and 192.6 F g?1 have been achieved from GCD curves at a current density of 1 A g?1 for Fe2Co-MOF/NF and CoFe2O4/NF electrodes, respectively. Fe2Co-MOF/NF electrode exhibits more cyclic stability than CoFe2O4/NF electrode after 3000 cycles. 相似文献
6.
Magnetic nickel ferrite (NiFe 2O 4) was prepared by sol–gel process and calcined in the 2.45 GHz singlemode microwave furnace to synthesize nickel nanopowder. The sol–gel method was used for the processing of the NiFe 2O 4 powder because of its potential for making fine, pure and homogeneous powders. Sol–gel is a chemical method that has the possibility of synthesizing a reproducible material. Microwave energy is used for the calcining of this powder and the sintering of the NiFe 2O 4 samples. Its use for calcination has the advantage of reducing the total processing time and the soak temperature. In addition to the above combination of sol–gel and microwave processing yields to nanoscale particles and a more uniform distribution of their sizes. X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and vibrating sample magnetometer were carried out to investigate structural, elemental, morphological and magnetic aspects of NiFe 2O 4. The results showed that the mean size and the saturation magnetization of the NiFe 2O 4 nanoparticles are about 30 nm and 55.27 emu/g, respectively. This method could be used as an alternative to other chemical methods in order to obtain NiFe 2O 4 nanoparticles. 相似文献
7.
Nickel ferrite nanoparticle is a soft magnetic material whose appealing properties as well as various technical applications have rendered it as one of the most attractive class of materials; its technical applications range from its utility as a sensor and catalyst to its utility in biomedical processes. The present paper focuses first on the synthesis of NiFe 2O 4 nanoparticles through co-precipitation method resulting in calcined nanoparticles that were achieved at different times and at a constant temperature (773 k). Afterward, they were dispersed in water that was mixed by chitosan. Chitosan was bonded on the surface of nanoparticles by controlling the pH of media. In order to assess the structural and magnetic properties of nanoparticles, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analyses were conducted at room temperature. As per the results of XRD analysis, the pure NiFe 2O 4 was synthesized. Additionally, nanoparticles grew in size by extending the calcination process duration. TEM micrographs were used to determine the size and shape of particle; the obtained results indicate that the particle size was in a range of 17–30 nm and of a circular shape. The proper chitosan covering was also indicated by FTIR results. The VSM analysis also revealed that the saturated magnetization of NiFe 2O 4 nanoparticles stood in a range of 29 emu/g and 45 Q e. A stable maximum temperature ranging from 30 to 42 was successfully achieved within 10 min. Also, a specific absorption rate of up to 8.4 W/g was achieved. The study results revealed that the SAR parameter of the coated nickel ferrite nanoparticle is more than that of pure nickel ferrite or cobalt ferrite nanoparticles. 相似文献
8.
Nickel ferrite nanospheres were successfully synthesized by a reverse emulsion-assisted hydrothermal method. The reverse emulsion was composed of water, cetyltrimethyl ammonium bromide, polyoxyethylene(10)nonyl phenyl ether, iso-amyl alcohol and hexane. During the hydrothermal process, β-FeO(OH) and Ni 0.75Fe 0.25(CO 3) 0.125(OH) 2·0.38H 2O (INCHH) nanorods formed first and then transformed into nickel spinel ferrite nanospheres. The phase transformation mechanism is proposed based on the results of X-ray powder diffraction, transmission electron microscopy and energy-dispersive X-ray spectroscopy, etc. Nickel ferrite may form at the end of the INCHH nanorods or from the solution accompanied by the dissolution of β-FeO(OH) and INCHH nanorods. The X-ray photoelectron spectroscopy analysis shows that a few Fe 3+ ions have been reduced to Fe 2+ ions during the formation of nickel ferrite. The maximum magnetization of the nickel ferrite nanospheres obtained after hydrothermal reaction for 30 h is 55.01 emu/g, which is close to that of bulk NiFe 2O 4. 相似文献
9.
Nano-sized nickel ferrite (NiFe 2O 4) was prepared by hydrothermal method at low temperature. The crystalline phase, morphology and specific surface area (BET) of the resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen physical adsorption, respectively. The particle sizes of the resulting NiFe 2O 4 samples were in the range of 5–15 nm. The electrochemical performance of NiFe 2O 4 nanoparticles as the anodic material in lithium ion batteries was tested. It was found that the first discharge capacity of the anode made from NiFe 2O 4 nanoparticles could reach a very high value of 1314 mAh g −1, while the discharge capacity decreased to 790.8 mAh g −1 and 709.0 mAh g −1 at a current density of 0.2 mA cm −2 after 2 and 3 cycles, respectively. The BET surface area is up to 111.4 m 2 g −1. The reaction mechanism between lithium and nickel ferrite was also discussed based on the results of cycle voltammetry (CV) experiments. 相似文献
10.
Magnetic nanoparticles of NiFe 2O 4-Pd composites have been synthesized using a simple, low cost, sol-gel auto-combustion method. As-prepared samples were sintered at 800 ℃ for 6 h in order to develop the crystalline phase. X-ray diffraction confirmed the spinel structure of the ferrite samples. Structural morphology and size of the nanoparticles were evaluated using a field emission scanning electron microscope. Magnetic hysteresis loops were obtained at 300 and 100 K using a physical properties measurement system. The value of saturation magnetization was observed to decrease at the temperatures with the increase of Pd contents up to 5% but then a sudden rise in saturation magnetization was observed for the addition of 10% Pd in NiFe 2O 4. 相似文献
11.
Nickel ferrite nanoparticles have several possible applications as cathode materials for rechargeable batteries, named “lithium-ion” batteries. In this study, NiFe 2O 4 was prepared by microwave induced thermohydrolysis. The obtained nanoparticles were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), BET method, transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). All the results show that the microwave one-step flash synthesis leads in a very short time to NiFe 2O 4 nanoparticles with elementary particles size close to 4-5 nm, and high specific surfaces (close to 240 m 2/g). Thus, microwave heating appears as an efficient source of energy to produce quickly nanoparticles with complex composition as ferrite. 相似文献
12.
Background Nickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe 2O 4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated. Methods For investigation of the inhibition effect of surfactant on NiFe 2O 4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples. Results The results of XRD and ICP-AES show that the products were pure NiFe 2O 4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm -1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe 2O 4 nanoparticles were in the range of 39.60 emu/g and 15.67 Q e that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature. Conclusions Nanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe 2O 4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature. Graphical abstract 相似文献
13.
In this study, CoFe 2O 4/Sawdust and NiFe 2O 4/Sawdust magnetic nanocomposites were synthesized using a hydrothermal method, and then characterized using X-ray powder diffraction, Infrared, scanning electron microscopy, Brunauer–Emmett–Teller/Barrett–Joyner–Halenda, and vibrating-sample magnetometer techniques. In this study, unmodified sawdust (US), modified sawdust (MS), unmodified CoFe 2O 4/sawdust (UCS), modified CoFe 2O 4/sawdust (MCS), unmodified NiFe 2O 4/sawdust (UNS), and modified NiFe 2O 4/Sawdust (MNS) magnetic nanocomposites, which are inexpensive, economical, environmentally friendly absorbents, and have a high selective hydrophobic, were used for the removal of oil from the water surface. The results show that the UCS, MCS, UNS, and MNS magnetic nanocomposites can selectively absorb the oil spreading on the water surface, due to its superhydrophobicity and superoleophilicity, and can be easily collected from water under the influence of a magnetic field. In addition, the results showed that the absorbents reach their equilibrium at the 30-min mark. Among all the absorbents, the MNS magnetic nanocomposite showed the maximum absorption capacity (18.172 g/g) at the 40-min mark. The results of the kinetic studies showed that the second-order kinetic equation with the highest correlation coefficient had the best fit with the experimental results. 相似文献
14.
Ferrites-spinels of the MFe 2O 4 type (M = Co, Ni, Zn), produced by glycine-nitrate combustion were studied. A physicochemical study of ferrite samples was performed by X-ray fluorescence analysis, scanning electron microscopy, X-ray phase analysis, and X-ray spectroscopy. The average size of the coherent scanning region was found to be (nm): 28 ± 2 for CoFe 2O 4, 32 ± 2 for NiFe 2O 4, and 26 ± 2 for ZnFe 2O 4. Magnetic characteristics were determined by the NMR method. The specific residual magnetization, specific saturation magnetization, and coercive force were, respectively, 14.1 A m 2 kg ?1, 20.1 A m 2 kg ?1, 31800 A m ?1 for CoFe 2O 4; 4.4 A m 2 kg ?1, 23.1 A m 2 kg ?1, 6550 A m ?1 for NiFe 2O 4; and 5.1 A m 2 kg ?1, 18.3 A m 2 kg ?1, 3200 A m ?1 for ZnFe 2O 4. Their magnetic properties show that the resulting ferrospinel powders can be used in the following fields of technology: CoFe 2O 4 in those areas where heat transfer is necessary (hyperthermia) and in development of data storage media; NiFe 2O 4 and ZnFe 2O 4 in those areas where low heat exchange is necessary, ZnFe 2O 4 for fast remagnetization and NiFe 2O 4 as a core or shell for transportation of other substances. The ferrospinel samples compare well in magnetic properties with their foreign commercial analogs, which makes these compounds commercially viable. 相似文献
15.
Phase-pure spinel-type magnetic nickel ferrite (NiFe 2O 4) nanocrystals in the size range of 4 to 11 nm were successfully synthesized by a fast and energy-saving microwave-assisted approach. Size and accessible surface areas can be tuned precisely by the reaction parameters. Our results highlight the correlation between size, degree of inversion, and magnetic characteristics of NiFe 2O 4 nanoparticles, which enables fine-tuning of these parameters for a particular application without changing the elemental composition. Moreover, the application potential of the synthesized powders for the electrocatalytic oxygen evolution reaction in alkaline media was demonstrated, showing that a low degree of inversion is beneficial for the overall performance. The most active sample reaches an overpotential of 380 mV for water oxidation at 10 mA cm −2 and 38.8 mA cm −2 at 1.7 V vs. RHE, combined with a low Tafel slope of 63 mV dec −1. 相似文献
16.
This research study aims to remove hazardous anionic azo dyes (Congo red (CR)) from aqueous solutions via a simple adsorption method using a poly(3-aminobenzoic acid/graphene oxide/cobalt ferrite) nanocomposite (P3ABA/GO/CoFe 2O 4) as a novel and low-cost nanoadsorbent, as synthesized by a simple and straightforward polymerization method. Typically, 3-aminobenzoic acid (3ABA), as monomer, was chemically polymerized with graphene oxide (GO) and cobalt ferrite (CoFe 2O 4) in an aqueous acidic medium containing an ammonium persulfate initiator. The adsorbent P3ABA/GO/CoFe 2O 4 nanocomposite was characterized using various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, energy-dispersive analysis by X-ray and Brunauer–Emmett–Teller, vibrating sample magnetometer, and zeta potential techniques. These techniques confirmed the interaction between the poly(3-aminobenzoic acid) with GO and CoFe 2O 4 due to the presence of π-π interactions, hydrogen bonding, and electrostatic forces. Herein, the removal efficiency of dye from aqueous solution by the adsorbent was studied according to several parameters such as the pH of the solution, dye concentration, dosage of adsorbent, contact time, and temperature. The adsorption of the dye was fitted using a Langmuir model (R 2 between 0.9980 and 0.9995) at different temperatures, and a kinetic model that was pseudo-second order (R 2 = between 0.9993 and 0.9929) at various initial concentrations of CR dye. In addition, the data revealed that the P3ABA/GO/CoFe 2O 4 nanocomposite exhibited a high adsorption capacity (153.92 mg/g) and removal for CR dye (98 %) at pH 5. Thermodynamic results showed the adsorption process was an endothermic and spontaneous reaction. It was found that, in terms of reusability, the P3ABA/GO/CoFe 2O 4 adsorbent can be used for up to six cycles. In this study, P3ABA/GO/CoFe 2O 4 nanocomposites were found to be low cost, and have an excellent removal capability and fast adsorption rate for CR from wastewater via a simple adsorption method. Moreover, this adsorbent nanocomposite could be simply separated from the resultant solution and recycled. 相似文献
17.
Cobalt ferrite layered double hydroxide (LDH) nanoparticles with cubic structure were synthesized by the co-precipitation method: addition of NaOH solution to a solution of Co 2+ and Fe 3+. Formation of nanoparticles was confirmed by XRD, SEM, TEM, PSA, FT-IR, TGA, DSC, and magnetic characteristics were measured using VSM. Crystals produced by calcination at 900°C possessed high coercivity and pronounced physical and chemical stability. Nanoparticles of CoFe 2O 4 formed outer layers with poor crystallization on the surface of cobalt ferrite nanocrystals. 相似文献
18.
In this work the synthesis of CoFe 2O 4-SiO 2 and NiFe 2O 4-SiO 2 nanocomposites was studied via the sol–gel method, using the polymerized complex route. The polymerized precursors obtained
by the reaction of citric acid, ethylene glycol, tetraethylorthosilicate, ferric nitrate, and cobalt nitrate or nickel chloride
were characterized by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. NMR and IR spectra of the precursors,
without and with metallic ions, show the formation of polymeric chains with ester and ether groups and complexes of metal-polymeric
precursor. The nanocomposites were obtained by the thermal decomposition of the organic fraction and characterized by X-ray
diffraction (XRD) and vibrating sample magnetometry (VSM). XRD patterns show the formation of CoFe 2O 4 and NiFe 2O 4 in an amorphous silica matrix above 400 °C in both cases. When the calcination temperature was 800 °C the particle size of
the crystalline phases, calculated using the Scherrer equation, reached ∼35 nm for the two oxides. VSM plots show the ferrimagnetic
behavior that is expected for this type of magnetic material; the magnetization at 12.5 KOe of the CoFe 2O 4-SiO 2 and NiFe 2O 4-SiO 2 compounds was 29.5 and 17.4 emu/g, respectively, for samples treated at 800 °C. 相似文献
19.
Cobalt ferrite magnetic nanoparticles (CoFe 2O 4-MNPs) were synthesized by hydrothermal and co-precipitation methods using different precursors such as nitrates, chlorides, and acetates, at different concentrations with/without surfactant under different growth conditions. The structural and morphological analyses reveal the formation of a single-phase CoFe 2O 4 in nanoplatelet-shaped NPs with average particle size between 11 and 26 nm depending on synthesis condition. The specific surface area of these NPs obtained by hydrothermal method was ~ 34 m 2 g ?1. Electrochemical performances of the obtained nanoparticles in a three-electrode configuration with a 6 M KOH electrolyte revealed a specific capacitance ( C s) of 429 F/g at 0.5 A/g, with excellent capacitance retention of 98.8% after 6000 cycles at 10 A/g for the electro-active NPs synthesized by hydrothermal method at 200 °C for 18 h. 相似文献
20.
铁酸镍(NiFe 2O 4)中的镍原子抑制其光芬顿催化活性. 然而,活性炭(AC)能激活其光芬顿催化活性,结果导致复合催化剂AC-NiFe 2O 4在过氧化氢存在时可见光辐射下也可催化氧化氨氮. 用X射线衍射(XRD),透射电镜(TEM),傅里叶变换红外(FTIR)光谱,紫外-可见漫反射光谱(UV-Vis DRS),比表面积和振动样品磁强计对催化剂进行了表征. 光催化降解氨氮的实验表明,该复合催化剂在10 h内氨氮的降解率可达到91.0%,而同样条件下没有催化剂时氨氮的去除率只有24.0%. 对照实验表明,裸铁酸镍在可见光辐射下,氨氮的降解率只有30.0%. 这表明活性炭加速了氨氮的氧化速率. 动力学研究表明,氨氮的氧化遵循一级反应动力学规律,其表观反应动力学常数为3.538×10 -3 min -1. 机理研究表明,氨氮的氧化是通过生成HONH 2 中间体,然后转化为NO 2- .8次循环实验表明该复合催化剂容易分离、可循环使用、且催化活性十分稳定. 因此,该催化剂具有潜在的应用价值. 相似文献
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