Size Of Magnetite Nanoparticles Research Articles

Magnetite nanoparticles from representative coal fired power plants in China: Dust removal capture and their final atmospheric emission

Information on the emission of coal combustion-sourced magnetite nanoparticles (MNPs) is lacking, which is critical for their health-related risks. In this study, MNPs in coal fly ashes (CFAs) from various coal-fired power plants (CFPPs) in China equipped with various dust removal devices were extracted and quantified using single particle ICP-MS. The number concentrations of MNPs in CFAs captured by dust removal increased with stage, while their size decreased. Among all the dust removal devices, electrostatic-fabric-integrated precipitators showed the best removal of MNPs. Furthermore, throughout all the coal combustion by-products in a typical CFPP, MNPs in EFA (fly ash escaped from the stack) showed the highest number concentration (1.2 × 107 particles/mg) and lowest size (78 nm). Although the mass of CFA escaping through the stack is extremely low, it still had an emission rate of 1.9 × 1015 particles/h, contributing 3.56 % of the total emissions of MNPs in number. In addition, the purity of MNPs and their associated toxic metals showed a size-dependent variation pattern. As the particle size of MNPs decreased, the proportion of Fe in MNPs increased from 43 % in bottom ash (BA) to 84 % in EFA, while the abundance of trace toxic metals in EFA was 3.3 times higher than that of BA. These MNPs with the highest purity can adsorb elevated concentrations of toxic metals, and can be discharged directly into the atmosphere, posing a risk of synergistic toxicity.

Fabrication of Magnetic Nanocomposites Using Natural Polymer Coating to Grain and Ciprofloxacin

In this study, we try to stabilize magnetic nanoparticles (Fe3O4) with natural granular polymer (granular mucilage as a natural, biocompatible and biodegradable coating) and then load the drug ciprofloxacin on these nanoparticles. Then, structural, magnetic, physicochemical, colloidal and antibacterial properties of the samples using various characterization tools and tests such as X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) analysis, FEE-SEM field scanning electron microscopy (SEM) Vibrating Sample Magnetometry (VSM), Infrared Fourier Analysis (FTIR), Optical Spectroscopy (UV-Vis), Dynamic Light Scattering (DLS), Nanoparticle Specific Surface (BET) and Testing The antibacterial property of disk diffusion must be investigated [21]. XRD results as well as structural analysis of the samples confirm the magnetite phase with high purity. The results of FE-SEM and TEM analyzes indicate spherical morphology and very small size of magnetite nanoparticles (average 13 nm). The results of DLS analysis show a hydrodynamic diameter of 81.9 to 119.2 nm for magnetic nanoparticles with different structures. Zeta potential values ​​for magnetic nanoparticles are between -0.28 and -55.2 mV, indicating suitable colloidal stability of the nanoparticles for biological applications. The VSM results indicate the high saturation magnetization of the samples as well as the small amounts of the forcing field and the residual magnetization of the samples, which indicates the superpromagnetic property of the nanoparticles.

A New Concept for Adsorption Studies Using a Brush-Type Adsorbent (Magnetite Coated Animal Fibers)

ABSTRACT The brush-type adsorbent is an innovative material that provides significant advantages to adsorption processes and contains effective and diversifiable materials such as nanomaterials. The adsorbent can be separated from the environment by a single movement and it brings practicality, convenience, and low-cost to batch and column systems. The brush fibers were successfully coated with the adsorptive materials obtained from Fe(II)/Fe(III), Ag(I), Cu(II), Zn(II), and Ni(II) solutions. The particle size of magnetite nanoparticles formed on brush fibers is about 60 nm. SEM-EDX analysis showed that uncoated brush fibers mainly contained carbon, oxygen, and sulfur. Also, magnetite nanoparticles are spherical and contain iron and oxygen. The adsorbents have high removal efficiencies (80–94%) for arsenic, cadmium, lead, molybdenum, selenium, and thallium. The pseudo first-order, the pseudo second-order, Elovich, and the intraparticle diffusion kinetic models were fitted to the experimental data. The pseudo-second-order mechanism was predominant (R2 = 0.99–1.00) for all the elements, and the adsorptions are chemical in nature. The adsorbent can be produced for various purposes, in different contents and sizes. The use of this brush-type adsorbent for water and air pollutants will contribute to both the environment and the economy by facilitating and reducing the adsorption stages.

Iron acquisition and mineral transformation by cyanobacteria living in extreme environments.

Iron is an essential micronutrient for most living organisms, including cyanobacteria. These microorganisms have been found in Earth's driest polar and non-polar deserts, including the Atacama Desert, Chile. Iron-containing minerals were identified in colonized rock substrates from the Atacama Desert, however, the interactions between microorganisms and iron minerals remain unclear. In the current study, we determined that colonized gypsum rocks collected from the Atacama Desert contained both magnetite and hematite phases. A cyanobacteria isolate was cultured on substrates consisting of gypsum with embedded magnetite nanoparticles. Transmission electron microscopy imaging revealed a significant reduction in the size of magnetite nanoparticles due to their dissolution, which occurred around the microbial biofilms. Concurrently, hematite was detected, likely from the oxidation of the magnetite nanoparticles. Higher cell counts and production of siderophores were observed in cultures with magnetite nanoparticles suggesting that cyanobacteria were actively acquiring iron from the magnetite nanoparticles. Magnetite dissolution and iron acquisition by the cyanobacteria was further confirmed using large bulk magnetite crystals, uncovering a survival strategy of cyanobacteria in these extreme environments.

Green Synthesis of Unsaturated Fatty Acid Mediated Magnetite Nanoparticles and Their Structural and Magnetic Studies

The green, cost-effective and sustainable synthesis of nanomaterials has been a key concern of scientists and researchers. In this view, MNPs were prepared using a sapota plant leaf extract and the surface of the magnetite nanoparticles was engineered with unsaturated fatty acids. The first report on the effect of unsaturation on the size and magnetic properties of magnetite nanoparticles (MNPs), prepared by the co-precipitation method, has been studied by coating surfactants on MNPs based on their unsaturation from zero to three (lauric acid, oleic acid, linoleic acid, linolenic acid). The size effect and magnetic properties of MNPs coated with a surfactant have been studied in comparison with uncoated magnetite nanoparticles. After the surface modification of the magnetite particle, it is necessary to check whether the magnetic property has been restored or not. Therefore, the magnetic property was studied. The presence of a surfactant on the surface of MNPs was confirmed by Fourier-transform infrared spectroscopy (FTIR), which was later confirmed by scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The atomic structure was studied by X-ray diffraction (XRD) and the size of uncoated and surfactant-coated MNPs was determined by transmission electron microscopy (TEM) and the Scherrer equation by following XRD data. The magnetization property was analyzed by a vibrating sample magnetometer (VSM) at 10, 100 and 300 K and both bared and surfactant-coated MNPs exhibited a superparamagnetic nature at room temperature. The saturation magnetization (Ms) study shows that MNPs coated with a surfactant have a lower saturation magnetization value in comparison to uncoated NPs, confirming surface layering. Because the magnetic fluid has been stabilized in the aqueous medium, the double-layer model is expected to prevail.

Influence of synthesis conditions on the structure and size of magnetite nanoparticles in coprecipitation method without stabilizer in one system

The unique properties of magnetite (Fe3O4) nanoparticles (MNPs) have promoted a wide range of applications in various fields, but specifying and defining the preparation conditions of MNPs with the desired monodispersed size are still challenges. This paper discusses systematically the influence of synthesis conditions on the structure and size of MNPs in the coprecipitation method without a stabilizer in one system. The ammonium hydroxide (NH4OH)/iron (III) (Fe3+) ratio, iron (III)/iron (II) (Fe2+) ratio, initial concentration of hydrochloric acid (HCl), total concentration of iron ions, reaction temperature, aging time and washing times were investigated. The surface of magnetite crystals was easily oxidized at high ammonium hydroxide/iron (III) ratios, and the high pH value of the reaction system can induce a large crystalline size. The hydrodynamic diameter of MNPs was efficiently controlled by the equilibrium between Derjaguin–Landau–Verwey–Overbeek (DLVO) forces and non-DLVO forces. An appropriate initial concentration of hydrochloric acid and a higher reaction temperature can reduce the crystalline size due to the decelerated nucleation rate. The aging time and the total concentration of iron affected the crystalline size positively. Noticeably, the pH value of the MNP dispersion in distilled water would remarkably reduce after each washing by centrifugation due to surface absorption of the hydroxy group. This research provided fundamental support for the reproducible preparation of MNPs in the coprecipitation method.

Green synthesis, characterization and antibacterial activity of iron oxide nanoparticles derived fromSolanum nigrum leaf extract

In order to create iron nanoparticles, extract from Solanum nigrum was used. By using UV/Vis absorptionspectroscopy, X-ray diffraction spectroscopy, and SEM examination, the produced iron nanoparticles were identified. Iron oxide nanoparticles exhibit a distinctive absorption peak in the UV/Vis spectrum between 200 and 300 nm. Theaverage particle size of magnetite nanoparticles, as determined by the X-ray diffraction method, was found to be 24.1nm. By using the well diffusion method, it was discovered that the synthetic iron nanoparticles have antibacterial action against harmful bacteria such Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, and Klebsiellapneumoniae. This biosynthetic method has been discovered to be economical, environmentally benign, and promisingfor use in a variety of fields. Keywords: Iron nanoparticles, Solanum nigrum, antibacterial activity

Synthesis and characterization of chalcone based benzoxazine-magnetite nanocomposites

Here, we proposed an approach to develop magnetic chalcone based benzoxazine using different contents of magnetite nanoparticles. A chalcone containing benzoxazine was prepared from 3-(4-hydroxyphenyl)-1-phenylprop-2-en-1-one), stearyl amine and paraformaldehyde through Mannich condensation reaction in a cosolvent of ethanol/toluene (1/1)(v/v). The chemical structure of the prepared benzoxazine monomer was confirmed by FTIR and 1H NMR. Both monomer and monomer mixed with different contents of magnetite were exposed to UV irradiation to induce dimerization via [2p + 2p] cycloaddition followed by thermal curing of oxazine moiety. The crystal structure of magnetite nanoparticles was studied by X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) was used to examine the surface morphology of the resulted materials. The average size of magnetite nanoparticles was determined by transmission electron microscope (TEM) to be 30–40 nm. The magnetization properties of these materials were measured by vibrating sample magnetometer (VSM). The thermal properties of thermosets were evaluated and compared with nanocomposites using TGA and DSC. The thermosets exhibited good thermal stability and improved with increasing the magnetite contents in the feed.

Magnetite nanoparticles synthesized using grape fruit extract: synthesis, morphology, hyperthermia application and catalytic activity in hydrogen peroxide decomposition

The paper presents a simple one-step "green" approach to the synthesis of magnetite nanoparticles. The magnetite nanoparticles were synthesized using fruit extract obtained from grape peels and grape pulp. The formation of magnetite nanoparticles was confirmed by X-ray diffraction analysis (XRD), infrared spectroscopy (IR), Mössbauer spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The crystallites sizes of magnetite nanoparticles are 7 and 14 nm for Fe3O4-peel and Fe3O4-pulp samples, respectively. Scanning electron microscopy images show that the samples consist of agglomerated nanoparticles. The synthesized magnetite nanoparticles showed good prospects for their use in magnetic hyperthermia. SAR values ​​of 0.488 W/g and 1.330 W/g for Fe3O4-peel and Fe3O4-pulp samples, respectively. The synthesized magnetic nanoparticles show excellent colloidal stability in the aqueous solutions. The maximum hyperthermia temperatures are 42.28 °C and 42.48 °C for Fe3O4-peel and Fe3O4-pulp samples, respectively. Studies of the catalytic activity of magnetite were performed in decomposition of hydrogen peroxide in a batch mode. The degrees of H2O2 decomposition are 67.5% and 65.25% for the Fe3O4-peel and Fe3O4-pulp samples respectively. The high catalytic activity of the synthesized samples makes them promising candidates for the decomposition of hydrogen peroxide in wastewater disinfection.

Catalytic activity of magnetite and its magnetic heating properties

Magnetite (Fe3O4) nanoparticles have been successfully synthesized using cetyltrimethylammonium bromide (CTAB). The stabilizing agent CTAB reduces agglomeration of magnetic nanoparticles in solution. The formation of Fe3O4 nanoparticles was confirmed by X-ray diffractometry, IR spectroscopy and Mössbauer spectroscopy. The average crystallite size of magnetite nanoparticles was found to be 14.41 nm. The catalytic activity of the obtained magnetite have been tested in a batch reactor. Due to favourable redox properties and low crystallite size, magnetite nanoparticles have high catalytic activity in the decomposition of H2O2. The degree of H2O2 decomposition was 77.41% in 120 min. The induction heating of synthesized Fe3O4 nanoparticles have been investigated. At magnetite concentration of 40 mg/ml, the specific absorption rate is equal 14.57 W/g.

Wettability of Magnetite Nanoparticles Guides Growth from Stabilized Amorphous Ferrihydrite.

Crystal formation via amorphous precursors is a long-sought-after gateway to engineer nanoparticles with well-controlled size and morphology. Biomineralizing organisms, like magnetotactic bacteria, follow such a nonclassical crystallization pathway to produce magnetite nanoparticles with sophistication unmatched by synthetic efforts at ambient conditions. Here, using in situ small-angle X-ray scattering, we demonstrate how the addition of poly(arginine) in the synthetic formation of magnetite nanoparticles induces a biomineralization-reminiscent pathway. The addition of poly(arginine) stabilizes an amorphous ferrihydrite precursor, shifting the magnetite formation pathway from thermodynamic to kinetic control. Altering the energetic landscape of magnetite formation by catalyzing the pH-dependent precursor attachment, we tune magnetite nanoparticle size continuously, exceeding sizes observed in magnetotactic bacteria. This mechanistic shift we uncover here further allows for crystal morphology control by adjusting the pH-dependent interfacial interaction between liquidlike ferrihydrite and nascent magnetite nanoparticles, establishing a new strategy to control nanoparticle morphology. Synthesizing compact single crystals at wetting conditions and unique semicontinuous single-crystalline nanoparticles at dewetting conditions in combination with an improved control over magnetite crystallite size, we demonstrate the versatility of bio-inspired, kinetically controlled nanoparticle formation pathways.

Investigation of Magnetic Properties of Magnetic Poly (glycidyl methacrylate) Microspheres: Experimental and Theoretical

Biocompatible magnetic poly (glycidyl methacrylate) microsphere is a novel nanocomposite with a myriad of promising bioapplications. Investigation of their characteristics by experimental analysis methods has also been carried out in the past. However, a survey of the magnetic anisotropy constant has not been mentioned and the influence of the poly (glycidyl methacrylate) polymer matrix on the Fe3O4 magnetite nanoparticles embedded inside has also not been discussed. Moreover, the accurate characterization of the magnetite nanoparticle size distribution remains challenging. In this paper, we present an effective approach was used to solve these problems. First of all, we combine both experiment and theory to estimate the effective magnetic anisotropy constant. Besides that, we implement an accurate method to determine magnetite nanoparticle size distribution in the magnetic poly (glycidyl methacrylate) microspheres composite nanomaterial.

Magnetoactive Compound Based on Humic Acid and Magnetite as a Sorbent for Heavy Metals

In the process of in situ synthesis using ultrasound, a magnetoactive sorbent based on humic acid and magnetite was produced for the extraction of heavy metals from industrial wastewater by magnetic solid-phase extraction. When exposed to ultrasound, substances are dispersed, which results in an increase in the specific surface area of the studied sorbent and the opening of inaccessible pores on its surface. Humic acid, which is part of the magnetoactive sorbent, is a stabilizer of the size of magnetite nanoparticles. The composition and sorption properties of a magnetoactive compound with respect to heavy metal ions Pb(II), Cu(II), Zn(II), Sr(II), Fe(III), and Al(III) were investigated. The dependence of the sorption value of the studied metal ions on the temperature and pH of the waste water was examined, the sorption capacity of the magnetoactive compound and the degree of waste water purification were determined. It was found that the maximum extraction of metal ions Pb(II), Cu(II), Al(III), Zn(II), Sr(II), Fe(III) from wastewater occurs at 25°C and pH 6.5, after additional sorption post-treatment, the content of Pb(II), Cu(II) and Zn(II) ions decreases by more than 15 times, and of Al(III), Pb(II), and Fe(III) ions, more than 12 times. The maximum degree of water purification from metal ions Pb(II), Cu(II), Al(III), Zn(II), Sr(II), and Fe(III) is 98.8, 83.1, 81.5, 78.1, 69.5, and 42.5%, respectively.

Lysine as Size-Control Additive in a Bioinspired Synthesis of Pure Superparamagnetic Magnetite Nanoparticles

Magnetite nanoparticles (MNPs) are being used in a number of nanotechnological applications, especially biomedical, both in diagnosis and in therapeutics such as hyperthermia agents and as drug nanocarriers for targeted chemotherapy. However, the development of efficient methodologies to produce novel MNPs with the specific requirements needed for biomedical applications is still challenging. In this context, biomimetic approaches taking use of magnetosome proteins expressed as recombinant and/or polyamino acids are becoming of great interest. In fact, these protocols give rise to magnetite nanoparticles of adequate size, magnetic properties and surface functionalization that make them compatible for biomedical applications. In this respect, herein we show for the first time that lysine (Lys), unlike other amino acids like arginine (Arg), is able to exert a control over the size of MNPs produced in water and at room temperature. This control occurs through the stabilization of the magnetite nuclei by the lateral ammonium group of Lys. The strength of such stabilization allows a further release of these previously bonded nuclei to allow the further growth of the larger ones, thus resulting in larger crystals compared to those obtained by using Arg or no amino acids at all. MNPs obtained by the mediation of this amino acid are fairly large (30 nm) while being superparamagnetic at room temperature. They present an isoelectric point of 4, which may allow the coupling/release of these MNPs to other molecules based on electrostatic interaction, a large magnetic moment per particle and high magnetization saturation. This study highlights the effects that biological additives have in the process of magnetite biomineralization and goes along the line of previous reports using magnetosome proteins and polyamino acids.

Utilization of Neem Leaf Extract on Biosynthesis of Iron Oxide Nanoparticles.

The present work reports the successful synthesis of biosynthesized iron oxide nanoparticles (Fe3O4-NPs) with the use of non-toxic leaf extract of Neem (Azadirachta indica) as a reducing and stabilizing agent. The successful synthesis was confirmed by infrared spectra analysis with strong peak observed between 400–600 cm−1 that corresponds to magnetite nanoparticles characteristics. X-ray diffraction (XRD) analysis revealed that iron oxide nanoparticles were of high purity with crystalline cubic structure phases in nature. Besides, the average size of magnetite nanoparticles was observed to be 9–12 nm with mostly irregular shapes using a transmission electron microscope (TEM) and was supported by field emission scanning electron microscope (FESEM). Energy dispersive X-ray analysis shown that the elements iron (Fe) and oxygen (O) were present with atomic percentages of 33.29% and 66.71%, respectively. From the vibrating sample magnetometer (VSM) analysis it was proven that the nanoparticles exhibited superparamagnetic properties with a magnetization value of 73 emu/g and the results showed superparamagnetic behavior at room temperature, suggesting potential applications for a magnetic targeting drug delivery system.

Magnetite Nanoparticles in Hybrid Micelles of Polylactide-block-polyethylene Oxide and Sodium Dodecyl Sulfate in Water

Magnetite nanoparticles have been obtained in hybrid micelles of polylactide-block-polyethylene oxide (PL-b-PEO) and sodium dodecyl sulfate (SDS) in a one-stage process. Dynamic light scattering, transmission electron microscopy, and small-angle X-ray scattering data show that hybrid micelles form micellar associates, and the size of magnetite nanoparticles in hybrid micelles of the block-copolymer varies from 0.5 to 10 nm. The specific magnetization of solid samples has been measured.

Structure and Magnetic Properties of Nanopowders of Iron Oxides and Hybrid Nanopowders of the Core–Shell Type Based on Them

The results are presented from complex phase structural and magnetic studies for uncoated and hybrid nanopowders based on iron oxide of the core–shell type (Fe3−xO4@SiO2). Their phase and structural characteristics are determined along with their and morphologies. It is shown that the nanopowders are nonstoichiometric magnetite Fe3+[Fe 1-3 x 2+ Fe 1+2 x 3+ Vx]О4 in which there are volume and surface regions that differ by the electronic state of their iron ions. The results from magnetic measurements reveal a relationship between the dispersity and magnetic properties of nanopowders. The change in the thickness of a defect surface layer and its specific magnetization is analyzed quantitatively as a function of the mean size of magnetite nanoparticles and the presence of a coating. The resulting dependences are constructed and analyzed.

Microwave Assisted Synthesis and Oxidation Resistance of Sm3+ Doped Fe3O4 Nanoparticles

In this study, pure and Sm3+ doped Fe3O4 nanoparticles were prepared via a microwave assisted synthesis in water solution. The samples were characterized by TEM, XRD, XANES, and VSM techniques. The structure and morphology, Fe and Sm oxidation states, the oxidation resistance and magnetic properties of pure and Sm doped Fe3O4 nanoparticles were studied. TEM and XRD results show that Sm doped Fe3O4 nanoparticles have a good dispersion and are smaller than pure Fe3O4 nanoparticles. The Fe and Sm oxidation states of pure and Sm doped Fe3O4 nanoparticles were studied by means of XANES analysis. The magnetic properties of Sm doped Fe3O4 nanoparticles determined by VSM exhibit superparamagnetic behavior with high saturation magnetization. It was found that Sm doping in a small amount makes it possible not only to reduce the sizes of magnetite nanoparticles but also to improve their oxidation resistance and increase their saturation magnetization value. These pure and Sm doped Fe3O4 magnetic nanoparticles are expected to be used in a number of biomedical applications.

Measurements of Pulsed 532 nm Laser Breakdown Spectroscopy of Synthesized Magnetite Nanoferrofluid

We describe the results of 532 nm pulse laser-induced breakdown spectroscopy (LIBS) of two samples of magnetite nanoparticles (SPIONs) nanoferrofluid synthesized at room (S1) and elevated temperatures (S2) and at three different laser energy levels and pulse frequency. The size of magnetite nanoparticles, size distribution, magnetic crystalline phase and magnetization were analyzed and measured using transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD) and vibrating sample magnetometry (VSM). The SPIONs showed a distribution between 4 - 22 nm with a peak about 12 nm and saturation magnetization of about 65 emu/g. The Saha-Boltzmann analysis of spectra for medium energy level (1050 mJ) yields plasma temperatures of (3881 ± 200) K and (26,047 ± 200) K for Fe I and OV as the lowest and highest temperatures respectively. A range of corresponding electron density (Ne-) of (0.47 - 6.80) × 1020, (0.58 - 8.30) × 1020 and (0.69 - 9.96) × 1020 cm-3 were determined at 860, 1050 and 1260 mJ respectively using the estimated CCD pictures. The results confirmed a higher elements ratio for S1 than S2 and the signal intensity indicated a non-linear behaviour as a function of pulse frequency with the maximum ratio value at 3 Hz. At higher frequency of 6 Hz no such turning point was observed. The highest and lowest temperatures corresponded to Fe I and OV respectively. The LIBS technique can be utilized to study, characterize and determine the elements ratio required in most applications involving the synthesizing process.

Size-dependent magnetic responsiveness of magnetite nanoparticles synthesised by co-precipitation and solvothermal methods

Abstract The dependence of the magnetic responsiveness on magnetite nanoparticle size has been studied. Monodisperse magnetite nanoparticles of 10 nm diameter were prepared by an ultrasonically enhanced co-precipitation procedure. A carboxyl-functionalised solvothermal approach was applied to synthesise magnetite nanoparticles with an average size of 30 nm. The particle sizes and their distribution have been determined by analysing TEM images and considering nanoparticle formation mechanisms. The magnetic characterisation revealed an inverse dependence between the magnetite nanoparticle size and its ability to respond to external magnetic fields, which was explained by the decrease of magnetic dipoles inside the tailing-away crystal of the magnetite nanoparticles. Negligible hysteresis with a small value of 5 Oe was found for the 10 nm nanoparticles, while the larger value of 80 Oe was determined for the 30 nm nanoparticles.