Synthesis Of Cobalt Ferrite Nanoparticles Research Articles

Synthesis of cobalt ferrite nanoparticles from thermolysis of prospective metal-nitrosonaphthol complexes and their photochemical application in removing methylene blue

In this study, cobalt ferrite (CoFe2O4) nanoparticles were synthesized by two novel methods. The first method is based on the thermolysis of metal-NN complexes. In the second method, a template free sonochemical treatment of mixed cobalt and iron chelates of α-nitroso-β-naphthol (NN) was applied. Products prepared through method 1 were spherical, with high specific surface area (54.39 m2 g−1) and small average crystalline size of 13 nm. However, CoFe2O4 nanoparticles prepared by method 2 were in random shapes, a broad range of crystalline sizes and a low specific surface area of 25.46 m2 g−1 though highly pure. A Taguchi experimental design was implemented in method 1 to determine and obtain the optimum catalyst. The structural and morphological properties of products were investigated by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, Brunauer–Emmett–Teller and dynamic laser light scattering. The crystalline size calculations were performed using Williamson–Hall method on XRD spectrum. The photocatalytic activity of the optimum nanocrystalline cobalt ferrite was investigated for degradation of a representative pollutant, methylene blue (MB), and visible light as energy source. The results showed that some 92% degradation of MB could be achieved for 7 h of visible light irradiation.

Synthesis of cobalt ferrite nanoparticles using spermine and their effect on death in human breast cancer cells under an alternating magnetic field

To compare heat generation under an AC magnetic field for inducing cancer cell death, CoFe2O4 and Fe3O4 nanoparticles with a diameter of ∼10nm were synthesized by hydrolysis in an aqueous solution containing the metal chlorides iron(III) chloride and cobalt(II) or iron(II) chloride, with spermine or N,N'-bis(3-aminopropyl)butane-1,4-diamine, as a base and a protective reagent. Both CoFe2O4 and Fe3O4 nanoparticles were incorporated into human breast cancer MCF-7 cells; the nanoparticles exhibited little toxicity on the cells. When the cells containing nanoparticles were subjected to an AC magnetic field, MCF-7 cell death was induced by heat generated from ∼10-nm CoFe2O4 nanoparticles but not from ∼10-nm Fe3O4 nanoparticles. An increase in coercivity derived from the substitution of Fe2+ with Co2+ facilitated the ability of the nanoparticles to induce cell death in human breast cancer cells under an AC magnetic field.

Oleate-based hydrothermal preparation of CoFe2O4 nanoparticles, and their magnetic properties with respect to particle size and surface coating

We present a facile and high-yield synthesis of cobalt ferrite nanoparticles by hydrothermal hydrolysis of Co–Fe oleate in the presence of pentanol/octanol/toluene and water at 180 or 220°C. The particle size (6–10nm) was controlled by the composition of the organic solvent and temperature.Magnetic properties were then investigated with respect to the particle size and surface modification with citric acid or titanium dioxide (leading to hydrophilic particles). The as-prepared hydrophobic nanoparticles (coated by oleic acid) had a minimum inter-particle distance of 2.5nm. Their apparent blocking temperature (estimated as a maximum of the zero-field-cooled magnetization) was 180K, 280K and 330K for the particles with size of 6, 9 and 10.5nm, respectively. Replacement of oleic acid on the surface by citric acid decreased inter-particle distance to less than 1nm, and increased blocking temperature by ca. 10K. On the other hand, coating with titanium dioxide, supported by nitrilotri(methylphosphonic acid), caused increase of the particle spacing, and lowering of the blocking temperature by ca. 20K. The CoFe2O4@TiO2 nanoparticles were sufficiently stable in water, methanol and ethanol.The particles were also investigated by Mössbauer spectroscopy and alternating-current (AC) susceptibility measurements, and their analysis with Vögel–Fulcher and power law. Effect of different particle coating and dipolar interactions on the magnetic properties is discussed.

Simultaneous degradation of phenol and paracetamol during photo-Fenton process: Design and optimization

In the present study, the photo-Fenton process was applied for the treatment of phenol and paracetamol in a binary system. The cobalt ferrite nanoparticles synthesized by microwave heating method were applied during photo-Fenton process. The nanoparticles were characterized by XRD and SEM analysis. The response surface methodology based on Box–Behnken design was used to evaluate and optimize the interactive effects of five operating variables including pH, initial concentrations of phenol and paracetamol, H2O2 concentration and cobalt nanoferrite dosage on the phenol and paracetamol degradation rates in photo-Fenton process. The results of experimental design indicated that the pH of 3.5, H2O2 concentration of 50mmol/L and cobalt nanoferrite dosage of 0.2g/L maximize the efficiency of phenol and paracetamol degradation rates at the time in photo-Fenton process. The maximum experimental phenol and paracetamol degradation efficiencies for initial concentrations of 20mg/L of phenol and paracetamol were found to be 95 and 85%, respectively. These values were in good agreement with the estimated values by the model in optimum conditions (94.5 and 84.4% for phenol and paracetamol degradation efficiencies). The obtained results demonstrated an excellent ability of synthesized cobalt ferrite nanoparticles to remove the phenolic compounds in photo-Fenton process.

Comparison study of phenol degradation using cobalt ferrite nanoparticles synthesized by hydrothermal and microwave methods

In the present study, the potential of synthesized cobalt ferrite nanoparticles using microwave (M-CF) and conventional hydrothermal (H-CF) methods for degradation of phenol was investigated during photo-Fenton-like process. The synthesized nanoparticles were characterized using powder X-ray diffraction, scanning electronic microscopy, and vibrating sample magnetometer analysis. The results showed that the microwave heating method produced smaller size nanoparticles with relatively narrower particle size distribution as well as stronger magnetic properties, compared with H-CF nanoparticles. The effect of photo-Fenton-like process parameters including UV light intensity (0–75 W), catalyst dosage (0–0.5 g/L), pH (2–5), hydrogen peroxide concentration (0–100 mmol/L), phenol initial concentration (20–500 mg/L), and temperature (35–55°C) on the phenol degradation was investigated. The kinetic data of phenol degradation using both synthesized nanoparticles were well fitted by pseudo-first-order kinetic model. The reaction times of phenol degradation over all ranges of phenol initial concentrations using M-CF catalyst were much smaller than those observed using H-CF catalyst. The obtained results indicated that the M-CF catalyst had a higher potential of phenol degradation compared with H-CF catalyst during photo-Fenton-like process.

Sonochemical Synthesis of Cobalt Ferrite Nanoparticles

Cobalt ferrite being a hard magnetic material with high coercivity and moderate magnetization has found wide-spread applications. In this paper, we have reported the sonochemical synthesis of cobalt ferrite nanoparticles using metal acetate precursors. The ferrite synthesis occurs in three steps (hydrolysis of acetates, oxidation of hydroxides, and in situ microcalcination of metal oxides) that are facilitated by physical and chemical effects of cavitation bubbles. The physical and magnetic properties of the ferrite nano-particles thus synthesized have been found to be comparable with those reported in the literature using other synthesis techniques.

Influence of the synthetic polypeptide c25-mms6 on cobalt ferrite nanoparticle formation

Nanoparticle syntheses utilizing biomimetic approaches have advanced in recent years. Polypeptides, with their ability to influence inorganic crystal growth, are a topic of great interest. Their effect on the particle formation has not been completely understood yet. Here we report a bioinspired synthesis of cobalt ferrite nanoparticles carried out in vitro under mild conditions using a short, synthetic polypeptide c25-mms6. The influence of c25-mms6 on the nanoparticle formation was investigated by comparing the particles synthesized with the polypeptide to particles synthesized under equivalent conditions without c25-mms6. A separation into D small,av = 10 nm small, superparamagnetic spheres and D big,av = 48 nm disc-like single-domain particles was observed. Non-stoichiometric cobalt ferrite particles with a shape-dependent stoichiometry were produced in the polypeptide-free synthesis. Stoichiometric D small,av = 10 nm CoFe2O4 spheres and D big,av = 60–70 nm Co2FeO4 ferromagnetic discs were obtained in the polypeptide-enhanced synthesis. The results indicate that the polypeptide acts as a catalyst during the multistep biomineralization process and allows the formation of stoichiometric phases which cannot be synthesized at room temperature using conventional bottom-up syntheses.

Synthesis of cobalt ferrite nanoparticles in continuous-flow microreactors

High quality CoFe2O4 nanoparticles were synthesized only in 16 min, continuously in two coupled microreactors. The first microreactor induced the fast homogenization of the reagents mixture at ambient temperature so Fe3+ and Co2+ hydroxides precipitate, while a second microreactor heated at 98 °C allowed the fast aging and the evolution of amorphous hydroxides into faceted and crystalline CoFe2O4.

Palladium nanoparticle supported on cobalt ferrite: An efficient magnetically separable catalyst for ligand free Suzuki coupling

Synthesis of Pd nanoparticle supported on cobalt ferrite magnetic nanoparticles has been achieved by direct addition of Pd nanoparticles during synthesis of cobalt ferrite nanoparticles by ultrasound assisted co-precipitation in the absence of any surface stabilizers or capping agent. The catalytic performance of the Pd incorporated cobalt ferrite nanoparticles was examined in Suzuki coupling reaction in ethanol under ligand free condition. The reaction undergoes with low catalyst loading (1.6 mol%) and the catalyst could be recovered using an external magnet and reused for multiple cycles with sustained catalytic activity.

Influence of the temperature in the electrochemical synthesis of cobalt ferrites nanoparticles

A new electrochemical method to synthesize cobalt ferrite nanoparticles has been developed. Magnetic measurement, Mössbauer spectroscopy, X-ray diffraction, inductive coupled plasma spectroscopy, and transmission electron microscopy were carried out to characterize the cobalt ferrites synthesized at different temperatures between 25°C and 80°C. These techniques confirm the efficiency of the electrochemical method. At room temperature a mixture of different compounds was obtained with a particle diameter around 20nm, while at 80°C the synthesis of cobalt ferrite leads to a stoichiometric spinel, with a crystallite size of 40nm measured by Scherrer equation. The temperature was defined as an important parameter to obtain stoichiometric ferrites and different diameters.

Solvothermal synthesis of cobalt ferrite nanoparticles loaded on multiwalled carbon nanotubes for magnetic resonance imaging and drug delivery

Multiwalled carbon nanotube (MWCNT)/cobalt ferrite (CoFe 2O 4) magnetic hybrids were synthesized by a solvothermal method. The reaction temperature significantly affected the structure of the resultant MWCNT/CoFe 2O 4 hybrids, which varied from 6 nm CoFe 2O 4 nanoparticles uniformly coated on the nanotubes at 180 °C to agglomerated CoFe 2O 4 spherical particles threaded by MWCNTs and forming necklace-like nanostructures at 240 °C. Based on the superparamagnetic property at room temperature and high hydrophilicity, the MWCNT/CoFe 2O 4 hybrids prepared at 180 °C (MWCNT/CoFe 2O 4-180) were further investigated for biomedical applications, which showed a high T 2 relaxivity of 152.8 Fe mM −1 s −1 in aqueous solutions, a significant negative contrast enhancement effect on cancer cells and, more importantly, low cytotoxicity and negligible hemolytic activity. The anticancer drug doxorubicin (DOX) can be loaded onto the hybrids and subsequently released in a sustained and pH-responsive way. The DOX-loaded hybrids exhibited notable cytotoxicity to HeLa cancer cells due to the intracellular release of DOX. These results suggest that MWCNT/CoFe 2O 4-180 hybrids may be used as both effective magnetic resonance imaging contrast agents and anticancer drug delivery systems for simultaneous cancer diagnosis and chemotherapy.

Synthesis of cobalt ferrite nano-particles and their magnetic characterization

Cobalt ferrite nano-particles (CoFe2O4) were synthesized by the co-precipitation method with ammonium hydroxide as an alkaline solution. The reactions were carried out at different temperatures between 20 and 80°C. The nano-particles have been investigated by magnetic measurements, X-ray powder diffraction and transmission electron microscopy. The average crystallite size of the synthesized samples was between 11 and 45nm, which was found to be dependent on both pH value of the reaction and annealing temperatures. However, lattice parameters, interplane spacing and grain size were controlled by varying the annealing temperature. Magnetic characterization of the nano-samples were carried out using a vibrating sample magnetometer at room temperature. The saturation magnetization was computed and found to lie between 5 and 67emu/g depending on the particle size of the studied sample. The coercivity was found to exhibit non-monotonic behavior with the particle size. Such behavior can be accounted for by the combination between surface anisotropy and thermal energies. The ratio of remanence magnetization to saturation magnetization was found to exhibit almost linear dependence on the particle size.

Micelle based synthesis of cobalt ferrite nanoparticles and its characterization using Fourier Transform Infrared Transmission Spectrometry and Thermogravimetry

Cobalt ferrite (CoFe 2O 4) nanoparticles of average size 4 nm with narrow size distribution are synthesized by reverse micelle approach. The nanoparticles are characterized using powder X-ray diffraction (XRD), Dynamic Light Scattering (DLS), Theromogravimetric analysis (TGA) and Fourier Transform Infrared Transmission Spectrometry (FTIR). Three successive transformations are observed in the thermogram that correspond to the loss of solvent and surfactant; onset of the amorphous to crystallize conversion; and isochemical transformation, i.e. migration of cations between octahedral and tetrahedral sites in the inverse spinel structure. The isochemical transformation is further confirmed by FTIR. The IR absorption bands observed at 460 and 615 cm −1 in the as-prepared CoFe 2O 4 nanoparticles correspond to the ferrite skeleton of octahedral and tetrahedral sites, respectively. The peak intensity at 615 and 460 cm −1 is shifted to 601 and 440 cm −1, respectively upon annealing at 320 and 400 °C. These results confirm migration of cations from the octahedral to the tetrahedral sites.

A Statistical Analysis to Control the Growth of Cobalt Ferrite Nanoparticles Synthesized by the Thermodecomposition Method

A statistical design of experiments was used to study the effect of reaction temperature and time on the synthesis of cobalt ferrite nanoparticles by the thermodecomposition method. A 24–2 factorial experimental design with two central points was used in which the control variables were the time and temperature of the nucleation and growth stages. Transmission electron microscopy, X-ray diffraction, inductively coupled plasma optical emission spectroscopy, and magnetic measurements were used for particle characterization. Cobalt-substituted ferrite (CoxFe3−xO4) nanoparticles with diameters between 9 nm and 13 nm were obtained by varying the nucleation temperature between 150°C and 250°C, the growth temperature between 300°C and 330°C, and the time in each stage between 60 min and 120 min. Statistical analysis showed that only the temperatures had an influence on the final particle size. The analysis of variance indicates that increase in the nucleation temperature resulted in decreased particle size, whereas the increase in temperature in the growth stage resulted in an increase in particle size. Additionally, statistical analysis showed that the growth temperature had an effect on Fe/Co ratio. An increase in the growth temperature produces a decrease in the Fe/Co ratio. Finally, a statistically significant correlation was found between particle diameter and saturation magnetization at 5 K and 300 K. No correlation was found between diameter and other magnetic properties.

Hyperthermic effect of magnetic nanoparticles under electromagnetic field

Magnetic nanoparticles have attracted increasingly attention due to their potential applications in many industrial fields, even extending their use in biomedical applications. In the latter contest the main features of magnetic nanoparticles are the possibility to be driven by external magnetic fields, the ability to pass through capillaries without occluding them and to absorb and convert electromagnetic radiation in to heat (Magnetic Fluid Hyperthermia). The main challenges of the current works on hyperthermia deal with the achievement of highly efficiency magnetic nanoparticles, the surface grafting with ligands able to facilitate their specific internalisation in tumour cells and the design of stealth nanocomposites able to circulate in the blood compartment for a long time. This article presents the synthesis of cobalt ferrite nanoparticles dispersed in diethylene glycol via the so called polyol strategy and the crystal size control through successive synthesis steps. Preliminary heat dissipation evaluations on the prepared samples were carried out and the question of how particles sizes affect their magnetic and hyperthermic properties was addressed as well. Furthermore we will present how surface chemistry can be modified in order to change the dispersity of the product without affecting magnetic and hyperthermic properties. .