Nickel and cobalt ferrites nanoparticles: synthesis,study of magnetic properties and their use as magnetic adsorbent for removing lead(II) ion

Nano-sized nickel ferrite (NiFe₂O₄) and cobalt ferrite particles (CoFe₂O₄) were successfully synthesized using a hydrothermal method. Techniques of X-ray diffraction, scanning electron microscope, Fourier transform infrared spectrometer, energy dispersive X-ray spectroscopy, vibrating sample magnetometer and transmission electron microscope have been used to characterize and study the as-synthesized NiFe₂O₄ and CoFe₂O₄ products. The results showed that the average size of the nickel and cobalt ferrite nanoparticles is smaller than 10 and 100 nm, respectively. The results of magnetic measurement showed that the synthesized NiFe₂O₄ and CoFe₂O₄ nanoparticles were superparamagnetic and soft ferromagnetic materials, respectively. Study of adsorption behavior showed that these nanoparticles can act as a good adsorbent for removing Pb²⁺.     

Microwave-assisted one-step hydrothermal synthesis of pure iron oxide nanoparticles: magnetite, maghemite and hematite

A simple, rapid, one-step synthesis way of pure iron oxide nanoparticles: magnetite (Fe₃O₄), maghemite (γ-Fe₂O₃) and hematite (α-Fe₂O₃) was investigated. Nanoparticles were prepared by microwave synthesis, from ethanol/water solutions of chloride salts of iron (FeCl₂ and FeCl₃) in the presence of sodium hydroxide NaOH. X-ray powder diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize these nanoparticles.     

Synthesis and characterization of Co<Subscript>0.8</Subscript>Zn<Subscript>0.2</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoparticles

Cobalt zinc ferrite, Co_0.8Zn_0.2Fe₂O₄, 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 Co_0.8Zn_0.2Fe₂(C₄H₂O₄)₃·6N₂H_4. The Curie temperature of the ‘as-prepared oxide’ was determined by AC susceptibility measurements.     

Thermal behavior of Co<Subscript>x</Subscript>Fe<Subscript>3−x</Subscript>O<Subscript>4</Subscript>/SiO<Subscript>2</Subscript> nanocomposites obtained by a modified sol–gel method

The thermal behavior of Co_xFe_3?xO₄/SiO₂ nanocomposites obtained by direct synthesis starting from nonahydrate ferric nitrate and hexahydrate cobalt nitrate in different ratios with and without the addition of 1,4-butanediol was studied. For the synthesis of Co_xFe_3?xO₄ (x = 0.5–2.5) dispersed in the silica matrix a wide Co/Fe molar ratio was used. The decomposition processes, formation of crystalline phases, gases evolvement and mass changes during gels annealing at different temperatures were assessed by thermal analysis. The absence of succinate precursor and a low mass loss were observed in the case of the gel obtained in the absence of 1,4-butanediol. In case of gels obtained using a stoichiometric ratio of Co/Fe, no clear delimitation between Co and Fe succinates was observed, while for samples with a Fe or Co excess, the formation of the two succinates was observed. The evolution of the crystalline phase after annealing (673, 973 and 1273 K) investigated by X-ray diffraction analysis and Fourier transformed infrared spectrometry revealed that in samples with Fe excess, stoichiometric Fe/Co ratio or low Co excess, the cobalt ferrite (CoFe₂O₄) was obtained as a single phase, while in samples with higher cobalt excess, olivine (Co₂SiO₄) as a main phase, cobalt oxide and CoFe₂O₄ as secondary phases were obtained after annealing at 1273 K. The SEM images confirmed the nanoparticles embedding in the silica matrix, while the TEM and X-ray diffraction data showed that the obtained nanoparticles’ size was below 10 nm in most samples.     

Study on synthesis of superparamagnetic spinel cobalt ferrite nanoparticles as layered double hydroxides by co-precipitation method

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 Co²⁺ and Fe³⁺. 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 CoFe₂O₄ formed outer layers with poor crystallization on the surface of cobalt ferrite nanocrystals.     

Electrochemical performance of spindle-like Fe2Co-MOF and derived magnetic yolk-shell CoFe2O4 microspheres for supercapacitor applications

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.

     

Synthesis of graphene oxide supported copper–cobalt ferrite material functionalized by arginine amino acid as a new high–performance catalyst

A novel Cu_0.5Co_0.5Fe₂O₄@Arg–GO catalytic system was successfully prepared by immobilization of copper substituted cobalt ferrite nanoparticles on arginine–grafted graphene oxide nanosheets, in which ferrite moiety acts as an oxidation catalyst and arginine has the role of base catalyst. Also, arginine amino acid was used to modify the surface of graphene oxide nanosheets which the prepared support can improve dispersion and uniform loading of nanoparticles. The prepared nanocomposite was characterized by flame atomic absorption spectroscopy (FAAS), inductively coupled plasma optical emission spectrometer (ICP–OES), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT–IR), ultraviolet–visible spectroscopy (UV–vis), Raman spectroscopy, thermogravimetric analysis (TGA), x–ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The prepared Cu_0.5Co_0.5Fe₂O₄@Arg–GO nanocomposite was used as an efficient catalyst for one–pot tandem oxidative synthesis of 2–phenylbenzimidazole derivatives in good yields.     

Reactivity of nanoparticles; interaction between zinc and copper oxide nanoparticles and iron ions in an alkaline medium

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 (ZnFe₂O₄ and CuFe₂O₄) or core/shell nanoparticles (Fe₃O₄/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 Fe₃O₄/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 Fe₃O₄/ZnO nanoparticles.     

Preparation of magnetic CoFe2O4-functionalized graphene sheets via a facile hydrothermal method and their adsorption properties

Magnetic CoFe₂O₄-functionalized graphene sheets (CoFe₂O₄-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 CoFe₂O₄-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 CoFe₂O₄ nanoparticles can be used as a powerful separation tool to deal with water pollution.     

Nicotinic acid-supported cobalt ferrite-catalyzed one-pot synthesis of substituted chromeno[3,4-b]quinolines

One-pot synthesis of substituted chromeno[3,4-b]quinoline derivatives was developed by three-component reaction of aldehydes, dimedone or 1,3-cyclohexadione, and 4-aminocoumarin in the presence of nicotinic acid-supported cobalt ferrite [CoFe₂O₄@SiO₂@Si(CH₂)₃Cl@NA] as a novel magnetic catalyst in chloroform at reflux conditions. Nicotinic acid-supported cobalt ferrite was characterized via Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and vibrating sample magnetometry. Moreover, the catalyst could be easily recovered by magnetic separation and recycled up to five times without significant loss of its catalytic activity. The products formed in excellent yields over appropriate reaction times under environmentally friendly conditions. High efficiency and easy isolation of the catalyst from products by simple magnetic attraction are some of the considerable advantages of this procedure.     

Prenucleation formations in control over synthesis of CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocrystalline powders

Nanocrystalline cobalt ferrite powders were synthesized by hydrothermal treatment of co-precipitated hydroxides in the conditions of an external heating of the autoclave and under microwave heating of the reaction medium. In the microwave-heating mode, the prenucleation clusters formed under ultrasonic treatment of a suspended mixture of cobalt and iron hydroxides is transformed into CoFe₂O₄ nanocrystals during the first minute of synthesis at a temperature satisfying the equilibrium-existence conditions of cobalt ferrite. In the case of a slow external heating of the autoclave, there is no effect of this kind, which is attributed to the disintegration of the prenucleation clusters before the dehydration of the hydroxides to give crystalline cobalt ferrite becomes thermodynamically favorable. The main factor determining the increase in the formation rate of crystallites of CoFe₂O₄ nanopowders and the decrease in their size is the generation of prenucleation centers in the starting mixture of cobalt and iron hydroxides.     

Bacitracin‐Conjugated Superparamagnetic Iron Oxide Nanoparticles: Synthesis,Characterization and Antibacterial Activity

Bacitracin‐conjugated superparamagnetic iron oxide (Fe₃O₄) nanoparticles were prepared by click chemistry and their antibacterial activity was investigated. After functionalization with hydrophilic and biocompatible poly(acrylic acid), water‐soluble Fe₃O₄ nanoparticles were obtained. Propargylated Fe₃O₄ nanoparticles were then synthesized by carbodiimide reaction of propargylamine with the carboxyl groups on the surface of the iron oxide nanoparticles. By further reaction with N₃‐bacitracin in a Cu^I‐catalyzed azide–alkyne cycloaddition, the magnetic Fe₃O₄ nanoparticles were modified with the peptide bacitracin. The functionalized magnetic nanoparticles were characterized by powder X‐ray diffraction, X‐ray photoelectron spectroscopy, TEM, zeta‐potential analysis, FTIR spectroscopy and vibrating‐sample magnetometry. Cell cytotoxicity tests indicate that bacitracin‐conjugated Fe₃O₄ nanoparticles show very low cytotoxicity to human fibroblast cells, even at relatively high concentrations. In view of the antibacterial activity of bacitracin, the biofunctionalized Fe₃O₄ nanoparticles exhibit an antibacterial effect against both Gram‐positive and Gram‐negative organisms, which is even higher than that of bacitracin itself. The enhanced antibacterial activity of the magnetic nanocomposites allows the dosage and the side effects of the antibiotic to be reduced. Due to the antibacterial effect and magnetism, the bacitracin‐functionalized magnetic nanoparticles have potential application in magnetic‐targeting biomedical applications.     

Rapid removal of anionic organic dye from contaminated water using a poly(3-aminobenzoic acid/graphene oxide/cobalt ferrite) nanocomposite low-cost adsorbent via adsorption techniques

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/CoFe₂O₄) 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 (CoFe₂O₄) in an aqueous acidic medium containing an ammonium persulfate initiator. The adsorbent P3ABA/GO/CoFe₂O₄ 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 CoFe₂O₄ 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 (R² between 0.9980 and 0.9995) at different temperatures, and a kinetic model that was pseudo-second order (R² = between 0.9993 and 0.9929) at various initial concentrations of CR dye. In addition, the data revealed that the P3ABA/GO/CoFe₂O₄ 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/CoFe₂O₄ adsorbent can be used for up to six cycles. In this study, P3ABA/GO/CoFe₂O₄ 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.     

Glycolic acid-supported cobalt ferrite-catalyzed one-pot synthesis of pyrimido[4,5-b]quinoline and indenopyrido[2,3-d]pyrimidine derivatives

Herein, one-pot synthesis of pyrimido[4,5-b]quinoline and indenopyrido[2,3-d]pyrimidine derivatives was developed by the three-component reaction of aldehydes, 6-amino-1,3-dimethyluracil, and 1,3-dicarbonyl compounds in the presence of glycolic acid-supported cobalt ferrite CoFe₂O₄@SiO₂@Si (CH₂)₃NHCOOCH₂COOH as a novel magnetic catalyst in ethanol at reflux conditions. Glycolic acid-supported cobalt ferrite was characterized via Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometer (VSM). Moreover, the catalyst was easily recovered with magnetic separation and recycled at least for five times without significant loss of its catalytic activity. The products were formed in excellent yields over appropriate reaction times under environmentally friendly conditions. The high efficiency and easy isolation of catalyst from products with an external permanent magnet are some of the remarkable advantages of this method.     

Synthesis and characterization of ultrafine spinel ferrite obtained by precursor combustion technique

Nanoparticles of the spinel ferrite, Co_0.6Ni_0.4Fe₂O₄ have been synthesized by the precursor combustion technique. This synthetic route makes use of a novel precursor viz. metal fumarato hydrazinate which decomposes autocatalytically after ignition to yield nanosized spinel ferrite. The X-ray powder diffraction of the ??as prepared?? oxide confirms the formation of monophasic nanocrystalline cobalt nickel ferrite. 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 fixed as Co_0.6Ni_0.4Fe₂(C₄H₂O₄)₃·6N₂H₄. The Curie temperature of the ??as prepared?? oxide was determined by ac susceptibility measurements.     

Fabrication of flexible graphene oxide paper-like adsorbent doped with magnetite nanoparticles for removal of dyes

Organic dyes are used in many industries, e.g., textile, cosmetics and food. Hence, contamination of organic dyes to water sources is a critical issue. To reduce water pollution by organic dyes, we propose a paper-like adsorbent with a practical and economical production procedure. Subsequently, a flexible adsorbent was produced using a one-step approach by vacuum filtration of graphene oxide (GO) and iron oxide nanoparticles (Fe₃O₄-NPs) containing dispersion through a membrane and quoted as GO/Fe₃O₄ paper. For comparison, GO paper was also prepared using the same procedure. Both papers were characterized using UV–VIS absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, electron diffraction X-ray analysis, X-ray photoelectron spectroscopy, and powder X-ray diffraction techniques. At the steady-state conditions, GO/Fe₃O₄ and GO papers were performed as adsorbent for cationic dyes of methylene blue, neutral red, and anionic dyes of methyl orange and fluorescein. In general, the removal efficiency of GO/Fe₃O₄ paper was higher than that of GO paper for adsorption of all dyes and this adsorbent revealed satisfactory adsorption properties for cationic dyes when compared to anionic dyes.

     

Fe3O4磁性纳米粒子的超声包金及其表征

超声条件下, 在乙醇分散的3-氨丙基三乙氧基硅烷(APTES)功能化的磁性Fe₃O₄纳米粒子和四氯合金酸的混合溶液中滴加柠檬酸钠, 成功地制备了磁性Fe₃O₄/Au复合纳米粒子. 采用X射线粉末衍射仪(XRD)、紫外吸收可见光谱(UV-Vis)、带有电子能谱仪(EDS)的扫描电子显微镜(SEM)、透射电子显微镜(TEM)、光电子能谱(XPS)、超导量子干涉仪(SQUID)等方法, 对复合粒子的形态、结构、组成以及磁学性质进行了表征. 结果表明: 在此条件下制得的复合粒子粒径在30 nm左右, 室温下磁化强度可达63 emu/g.     

Synthesis,characterization and application of sulfonic acid supported on ferrite–silica superparamagnetic nanoparticles

In this study, the synthesis of sulfonic acid supported on ferrite–silica superparamagnetic nanoparticles (Fe₃O₄@SiO₂@SO₃H) as a nanocatalyst with large density of acidic groups is suggested. This nanocatalyst was prepared in three steps: preparation of colloidal iron oxide magnetic nanoparticles (Fe₃O₄ MNPs), coating of silica on Fe₃O₄ MNPs (Fe₃O₄@SiO₂) and incorporation of sulfonic acid as a functional group on the surface of Fe₃O₄@SiO₂ nanoparticles (Fe₃O₄@SiO₂@SO₃H). The properties of the prepared magnetic nanoparticles were characterized using transmission electron microscopy, infrared spectroscopy, vibrating sample magnetometry, X‐ray diffraction and thermogravimetric analysis. Finally, the applicability of the synthesized magnetic nanoparticles was tested as a heterogeneous solid acid nanocatalyst for one‐pot synthesis of diindolyloxindole derivatives in aqueous medium. Oxindole derivatives were produced by the coupling of indole and isatin compounds with good to high yields (60–98%). Copyright © 2016 John Wiley & Sons, Ltd.     

The structure and magnetic properties of cobalt ferrite nanoparticles synthesized in a system of direct micelles of amphiphiles by means of ion flotoextraction

A method for obtaining nanoparticles in a system of direct micelles of amphiphiles using ion flotoextraction for concentrating ions from diluted water solutions is developed. Nanoparticles of the composition CoFe₂O₄ with a structure close to spinel are obtained. It is established that the particles consist of two components: well-formed phases of cobalt ferrite CoFe₂O₄ and its amorphous analog. It is shown that the nanoparticles have a maximum size distribution ranging from 4 to 6 nm; on a carbon substrate, they self-organize into a periodic colloidal structure. It is concluded that nanosized CoFe₂O₄ powder has a blocking temperature of about 45 K, a magnetic moment of about 0.85–0.9μ_B at a temperature of 0 K, and the Neöl temperature lies in the range of 110 to 250 K.     

Iron Oxide Nanoparticles: Biosynthesis,Magnetic Behavior,Cytotoxic Effect

Iron oxide nanoparticles have attracted much attention because of their superparamagnetic properties and their potential applications in many fields such as magnetic storage devices, catalysis, sensors, superparamagnetic relaxometry (SPMR), and high-sensitivity biomolecule magnetic resonance imaging (MRI) for medical diagnosis and therapeutics. In this study, iron oxide nanoparticles (Fe₂O₃ NPs) have been synthesized using a taranjabin (camelthorn or persian manna) aqueous solution. The synthesized Fe₂O₃ NPs were identified through powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), field energy scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), vibrating-sample magnetometer (VSM) and Raman technics. The results show that the nanoparticles have a hexagonal structure with 20 to 60 nm in size. The cytotoxic effect of the synthesized nanoparticles has been tested upon application against lung cancer cell (A549) lines. It was found that there is no cytotoxic activity at lower concentrations of 200 μg/mL. The ability of the synthesized nanoparticles for lead removal in wastewaters was tested. Results show that highest concentration of adsorbent (50 mg/L) has maximum removal efficiency (96.73 %). So, synthesized Fe₂O₃ NPs can be a good candidate to use as heavy metals cleaner from contaminated waters.