Nanosized Magnetite Particles Research Articles

In English

Iron-containing polypropylene (PP) composites were synthesized by precipitating iron(III) nitrate from aqueous solutions of varying concentrations onto a polypropylene matrix, followed by drying at ≤110°C and heating at ≤230°C temperatures. The resulting composites were characterized using scanning electron microscopy combined with energy-dispersive elemental analysis (SEM/EDS), X-ray diffractometry (XRD), and electron magnetic resonance (EMR).The study revealed that the composites obtained through thermal decomposition of iron(III) nitrate from aqueous solutions on a polypropylene matrix, with subsequent heat treatment at 220°C, form a two-phase system consisting of isotactic polypropylene and magnetite. SEM/EDS data showed a non-uniform distribution of the iron-containing component on the PP surface, even in samples with less than 1% by weight of the iron component. FMR spectra indicated the formation of superparamagnetic and ferromagnetic particles within the polypropylene matrix, attributed to nanosized magnetite particles of varying dimensions.Theoretical spectra were calculated using the Landau-Lifshitz-Gilbert equation, considering Lorentzian, Gaussian, and Dyson resonance signal shapes. These theoretical spectra, which accounted for the dependence of g-factor values and line widths of the FMR spectra on particle size, were adjusted to match the experimental data to clarify the magnetic resonance characteristics of the iron-containing particles.The study concluded that magnetite particles formed during the thermal decomposition of iron(III) nitrate deposited from an aqueous solution onto the polypropylene matrix do not interact significantly with the polypropylene. These particles remain mobile on the polymer surface and are prone to aggregation, posing challenges for achieving a uniform composite material.

Preparation of Magnetic Activated Carbons from Cassava Peel using H3PO4 and KOH Activation by Microwave Heating for Naphthol Blue-Black Adsorption

To address the separation problems and produce the reusable adsorbent, cassava peel magnetic activated carbon (MAC) prepared via microwave-assisted activation has been proposed to replace activated carbon (AC) for naphthol blue-black removal. To create MACs, ACs were embedded with nano-sized magnetite particles using co-precipitation methods. In this sense, 2 different activating agents (i.e., H3PO4 and KOH) have been used. H3PO4 activation provides a larger pore size and more functional groups, while KOH activation provides a larger surface area and higher porosity. The increase of H3PO4 concentration from 40 to 60 % leads to an increase in porosity as well as an increase in the weight ratio of KOH to char from 1 to 3. Impregnation magnetite to the ACs reduces surface area from 457.76 to 337.94 m2 g-1 for KOH activation, and from 360.65 to 232.74 m2 g-1 for H3PO4 activation, decreasing adsorption capacity from 97.5 to 97 % for KOH activation and from 99 to 98 % for H3PO4 activation. However, the adsorbent is easy to separate under the magnetic influence. The adsorption data of MAC by H3PO4 activation show suitability with the Redlich-Peterson isotherm model, suggesting that naphthol blue-black removal is not ideal monolayer adsorption, but a combination of physisorption and chemisorption processes that exhibit heterogeneity of naphthol blue-black adsorption on the surface of adsorbent. Meanwhile, for MAC by KOH activation, the Langmuir isotherm is more suitable. HIGHLIGHTS Cassava peel was used in the preparation of magnetic activated carbon The effect of microwave-assisted H3PO4 and KOH activation was discussed Prediction of isotherm models was proposed and compared GRAPHICAL ABSTRACT

The beneficial role of nano-sized Fe3O4 entrapped in ultra-stable Y zeolite for the complete mineralization of phenol by heterogeneous photo-Fenton under solar light

Highly efficient, separable, and stable magnetic iron-based-photocatalysts produced from ultra-stable Y (USY) zeolite were applied, for the first time, to the photo-Fenton removal of phenol under solar light. USY Zeolite with a Si/Al molar ratio of 385 was impregnated under vacuum with an aqueous solution of Fe2+ ions and thermally treated (500–750 °C) in a reducing atmosphere. Three catalysts, Fe-USY500°C-2h, Fe-USY600°C-2h and Fe-USY750°C-2h, containing different amounts of reduced iron species entrapped in the zeolitic matrix, were obtained. The catalysts were thoroughly characterized by absorption spectrometry, X-ray powder diffraction with synchrotron source, followed by Rietveld analysis, X-ray photoelectron spectroscopy, N2 adsorption/desorption at −196 °C, high-resolution transmission electron microscopy and magnetic measurements at room temperature.The catalytic activity was evaluated in a recirculating batch photoreactor irradiated by solar light with online analysis of evolved CO2. Photo-Fenton results showed that the catalyst obtained by thermal treatment at 500 °C for 2 h under a reducing atmosphere (FeUSY-500°C-2h) was able to completely mineralize phenol in 120 min of irradiation time at pH = 4 owing to the presence of a higher content of entrapped nano-sized magnetite particles. The latter promotes the generation of hydroxyl radicals in a more efficient way than the Fe-USY catalysts prepared at 600 and 750 °C because of the higher Fe3O4 content in ultra-stable Y zeolite treated at 500 °C. The FeUSY-500°C-2h catalyst was recovered from the treated water through magnetic separation and reused five times without any significant worsening of phenol mineralization performances. The characterization of the FeUSY-500°C-2h after the photo-Fenton process demonstrated that it was perfectly stable during the reaction. The optimized catalyst was also effective in the mineralization of phenol in tap water. Finally, a possible photo-Fenton mechanism for phenol mineralization was assessed based on experimental tests carried out in the presence of scavenger molecules, demonstrating that hydroxyl radicals play a major role.

Magnetic susceptibility of soft magnetic composite materials

A mathematical model is developed for the susceptibility of a composite of soft magnetic material, held together by a magnetic binder. The model ignores the volume average of the stray field in the binder, and allows for different volume fractions of soft magnetic particles, with different shape factors, yielding results directly analogous to those of Böttcher for dielectrics in Effective Medium Theory. A high and a low susceptibility is identified, with the composite susceptibility almost always equal to the low susceptibility term. The electrical analogy is that susceptibility corresponds to a non-dimensional electrical capacitor, with the high and low capacitors in series. The high susceptibility term results from weighted particle susceptibilities in series. The low susceptibility term is usually independent of particle susceptibility. This model is validated against both finite element calculations, and published data obtained from composites of titanomagnetite ironsand, industrial ferrite and nano-sized magnetite particles.

Fractionation of solid component of welding aerosol

The design of portable filtration device with electrostatic filter and description of its work, which provides the trapping efficiency about 99.5% and fractionation of the polydisperse aerosol to four fractions via particles’ electrical mobility, are presented. The samples of aerosol particles’ fractions are obtained under usual welding regimes by welding wire Св08Г2С in CO2 and their specific surface area, element and phase compositions, phase ratio and crystallite sizes are determined. The correlation between fraction’s element composition and its specific surface area is demonstrated – the iron content is decreased, and manganese and silicon contents are increased when specific surface area is increased. The polyphase content (Fe3O4, FeO, FeMn2O4 и a-Fe are determined) and presence of the monocrystal nanosized magnetite particles, wustite and iron-manganese spinel in the fraction samples are confirmed by the X-ray analysis. The silicon compounds in particles are in amorphous state. The possibility of utilization of the nanostructured aerosol particles are proposed as a result of experimental data analysis.

Development and Characterization of Fe3O4@Carbon Nanoparticles and Their Biological Screening Related to Oral Administration.

The current study presents the effect of naked Fe3O4@Carbon nanoparticles obtained by the combustion method on primary human gingival fibroblasts (HGFs) and primary gingival keratinocytes (PGKs)—relevant cell lines of buccal oral mucosa. In this regard, the objectives of this study were as follows: (i) development via combustion method and characterization of nanosized magnetite particles with carbon on their surface, (ii) biocompatibility assessment of the obtained magnetic nanoparticles on HGF and PGK cell lines and (iii) evaluation of possible irritative reaction of Fe3O4@Carbon nanoparticles on the highly vascularized chorioallantoic membrane of a chick embryo. Physicochemical properties of Fe3O4@Carbon nanoparticles were characterized in terms of phase composition, chemical structure, and polymorphic and molecular interactions of the chemical bonds within the nanomaterial, magnetic measurements, ultrastructure, morphology, and elemental composition. The X-ray diffraction analysis revealed the formation of magnetite as phase pure without any other secondary phases, and Raman spectroscopy exhibit that the pre-formed magnetic nanoparticles were covered with carbon film, resulting from the synthesis method employed. Scanning electron microscopy shown that nanoparticles obtained were uniformly distributed, with a nearly spherical shape with sizes at the nanometric level; iron, oxygen, and carbon were the only elements detected. While biological screening of Fe3O4@Carbon nanoparticles revealed no significant cytotoxic potential on the HGF and PGK cell lines, a slight sign of irritation was observed on a limited area on the chorioallantoic membrane of the chick embryo.

Rat Blood Leukocytes after Intravenous Injection of Chitosan-Modified Magnetic Nanospheres.

Nanosized magnetite particles (magnetic nanospheres) are a prospective basis for creation of new diagnostic and therapeutic agents. The structure of blood leukocytes and the leukocytic formula are studied in adult rats over a period of 120 days after a single intravenous injection of chitosan-modified nanosized magnetite particles. No effects of chitosan-modified magnetic nanospheres on the structure of rat blood leukocytes are detected. Injection of suspension of chitosan-modified magnetite nanospheres is associated with an increase in the levels of monocytes, segmented and stab neutrophils, and a decrease in lymphocyte counts in the blood of rats. The shifts in the leukogram parameters are transitory, the picture returned to normal by day 40 postinjection.

Examination of contact angles of magnetic fluid droplets on different surfaces in uniform magnetic field

The interactions between liquid–solid and liquid–gas phases can be characterized by measuring the contact angle between a solid surface and a liquid droplet. The wetting properties of magnetic fluids can be determined by contact angle measurements. In the case of these fluids the wetting properties are also affected by an external magnetic field. In our research we investigated the magnetic field induced deformation of water based magnetic fluid (Ferrotec EMG 700) droplets containing various amount of nanosized (~10 nm) magnetite particles on different surfaces. The contact angle measurements were conducted in a closed controlled environment on droplets placed on hydrophobic (silicone rubber coated silicon wafer) and hydrophilic (uncoated silicon wafer) surfaces. The droplets were photographed using a microscope camera and the contact angles were determined by image processing. The experimental data are discussed in the framework of a perturbative density functional theory.

Removal of U(VI) by sugar-based magnetic pseudo–graphene oxide and its application to authentic groundwater using electromagnetic system

Uranium U(VI) is toxic even at trace levels in aqueous solution and has adverse impacts on the health of human beings. In this study, a sugar-based magnetic pseudo-graphene oxide (SMGO) composite was prepared for the removal of U(VI) from groundwater by graphitization of sugar and ozonation, as well as synthesis with nano-size magnetite particles. To investigate the applicability of SMGO, U(VI)-spiked groundwater as well as U(VI)-contaminated groundwater samples were used in electromagnetic system. The pH-edge adsorption results suggest that adsorption occurs via an inner-sphere surface complex with an optimized pH of 4, where UO22+ is the dominant U(VI) species. The adsorption isotherm results confirmed that the adsorption of U(VI) onto SMGO occurred via a monolayer process on the homogeneous surface of SMGO and the maximum removal capacity of U(VI) was 28.2 mg/g. The high-gradient magnetic separation (HGMS) principle was applied to U(VI) removal using SMGO to facilitate recovery and the repeated use of the adsorbent during multiple batch cycles. The results indicated that the initial U(VI) concentration (439.1 μg/L) was reduced to a value less than the standard level of U(VI) for drinking water (30 μg/L) during six batch cycles and the separation efficiency was 95.2%. As such, SMGO and electromagnetic system using the HGMS principle are promising technologies for the removal of U(VI) in groundwater.

Preparation of High-purity 1,3-Diacylglycerol Using Performance-enhanced Lipase Immobilized on Nanosized Magnetite Particles

Early research on the nutritional value of 1,3-diacylglycerols (1,3-DAGs) has resulted in a significant interest in their synthesis. 1,3-DAGs can be produced chemically and biologically. In this work, a regioselective lipase from Rhizopus oryzae was efficiently immobilized on nanosized magnetite particles (NSM) in an oriented way, resulting in significant enhancement of activity. The specific hydrolytic and esterification activities of the immobilized enzyme were 1,660% and 260% of those of the free enzyme, respectively. The immobilized enzyme was then used to catalyze the esterification of oleic acid with glycerol in a solvent-free system for preparation of 1,3-DAG in a 1 L reactor. The catalytic process was studied in detail, the final concentration of 1,3-DAG reached >76% under the optimal condition when the molar ratio of oleic acid to glycerol was 2.8:1. The regioselectivities of free and immobilized enzyme were both >97%. The immobilized enzyme was reused for 55 cycles with only ∼30% activity loss at 30°C. The purity of 1,3-DAG was up to ∼95% (w/w) after a simple purification step with the recovery ratio ∼85%. This is the first report of efficient 1,3-DAG purification by neutralization without acyl migration.

Structure of Rat Testicles after Intravenous Injection of Nanosized Magnetite Particles.

The structure of the testicles was studied in adult rats in 120 days after a single intravenous injection of chitosan-modified (magnetic nanospheres) and lipid-modified (magnetoliposomes) nanosized magnetite particles. Perls histochemical reaction detected in the testicular interstitial connective tissue the cells which absorbed and accumulated magnetite nanoparticles. The dynamics of spermatogenesis index and the count of Perls+ cells in the rat testicles were traced throughout the experiment. The studied modified nanosized magnetite particles did not penetrate through the blood-testicle barrier in rats.

Preparation of Nimesulide magnetite nanoparticles for targeted drug delivery

Nimesulide is a relatively COX-2 selective, non-steroidal anti-inflammatory drug (NSAID) with analgesic and antipyretic properties. It is used for the treatment of acute pain, inflammation and for the symptomatic treatment of osteoarthritis. But nimesulide is banned in many countries due to liver failure. Thus the present study was aimed to develop a suitable dosage form to apply topically at inflammatory conditions, without affecting internal organs. This study covert nimesulide into magnetically modulated topical gel for topical application. The magnetic field over the applied area helps to retard the movement of drug into the deeper tissues. This results in accumulation of dosage form and delivery of drug at controlled rate in the target site. Nanosized magnetite particles were prepared for the study. The nimesulide drug has loaded over the magnetite particles using HPMC K15M, PVP and HPMC E5 rate controlling polymers. The polymer and its concentrations were optimized. The prepared drug loaded magnetite particles were converted into topical gel preparation.

Steam – Air Conversion of Heavy Oil in the Presence of Nanosized Metal Oxide Particles

The effect of suspended nanosized magnetite and hematite particles on the thermal degradation of heavy oil at 360°C in a steamair atmosphere was studied at various pressures. The highmolecularweight components of the oil were found to undergo degradation, leading to reduced oil viscosity. The effect of aluminum and zinc oxides used as additives to initiate hydrocarbon bond dissociation on this process was also investigated. The mechanisms for how change in composition components alters the conversion products relative to the initial oil were studied. Carrying out the process in the presence of additives at 11 MPa leads to reduced yield of aromatic end products with increased yield of oil hydrocarbons and the formation of gaseous products. Asphalticresin materials are also found to be reduced due to conversion in the presence of the additives. Rheological curves were determined for the conversion products and were used to show the change in the viscositytemperature characteristics.

Magnetic mesoporous silica for water remediation: Synthesis, characterization and application as adsorbent of molecules and ions of environmental concern

Magnetic mesoporous silicas (NSMSiO2) were synthesized by coating nano-sized magnetite (NSM) particles with mesoporous silica shells. The effects of the NSM loading on the morphology, charge development and adsorption properties of the synthesized composites were investigated. Both the shape and the size of aggregates strongly changed as NSM/SiO2 molar ratio increased, i.e., from plates to spherical-like particles, in agreement with reduction on the silica shell thickness. The shell acted as a protective agent that minimized alteration of the magnetite structure and avoided magnetite dissolution in acidic media. The composites have a significant adsorption capacity towards a humic acid and the cationic dye malachite green, showing that they can adsorb both, anionic and cationic species. HA seems to enter the pores and bind the NSM cores, whereas malachite green binds mainly the silica shell. The effect of Ca2+ concentration on the adsorption capacity of the synthesized composite was also evaluated and discussed. The magnetic property of the materials facilitates the recuperation of the adsorbent from aqueous environments.

Enhancing the separation of silica nanoparticles from backside grinding (BG) wastewater with synthesized magnetite

Abstract Fine nano-sized magnetite particles were synthesized and then used to treat backside grinding (BG) wastewater for the removal of silica nanoparticles (SiO 2 ). Batch experiments were conducted to examine the effects of the magnetite dosage, pH, stirring intensity (G) and duration (t d ), magnetic field strength and sedimentation time on the removal of SiO 2 . The optimum dosage of magnetite was determined as 16 mg/L, which had the best SiO 2 removal of about 97%, under the conditions of initial pH 5.9, stirring intensity 900 S −1 , stirring duration 30 min, sedimentation time 30 min and magnetic field strength 317 mT. The synthesis of nano-sized magnetite particles 10 nm in diameter led to a reduction in the magnetite dosage needed for the removal of SiO 2 . The pH was maintained at less than 10 to obtain the high SiO 2 removal mentioned above. When the pH was over 10, the Fe detached from magnetite particles which subsequently led to a decrease in SiO 2 removal. Magnetite aggregation was affected by both G and t d . Increasing the values of G and t d enhanced the removal of SiO 2 . When the multiple values of G and t d , i.e., Gt d reached 12,000, a SiO 2 removal of 95% was achieved. The relationship between the magnetic field strength and sedimentation time was also evaluated. An increase in the magnetic field strength improved the removal of SiO 2 . Specifically, the SiO 2 removal was greatly dependent on the sedimentation time when the magnetic field strength was weak. The results of this study can be used in the design and operation of a magnetite aggregation process to treat BG wastewater for the removal of SiO 2 .

Superparamagnetic nalidixic acid grafted magnetite (Fe3O4/NA) for rapid and efficient mercury removal from water

A new nanomaterial, nalidixic acid grafted magnetite (Fe3O4/NA), was synthesizedviaa chemical reaction with nano sized magnetite particles.

Facile preparation of acid-resistant magnetite particles for removal of Sb(Ⅲ) from strong acidic solution

A new facile coating strategy based on the hydrophobicity of methyl groups was developed to prevent nano-sized magnetite particles from strong acid corrosion. In this method, three steps of hydrolysis led to three layers of protection shell coating Fe3O4 nanoparticles. Filled with hydrophobic methyl groups, the middle layer mainly prevented the magnetic core from strong acid corrosion. These magnetite particles managed to resist 1 M HCl solution and 2.5 M H2SO4 solution. The acid resistant ability was higher than those reported previously. After further modification with amino-methylene-phosphonic groups, these magnetite particles successfully adsorbed Sb(III) in strong acid solution. This new strategy can also be applied to protect other materials from strong acid corrosion.

Optical Properties of Aggregated Magnetic Fluid: Birefringence and Light Scattering

The optical properties of colloidal solutions of nanosized magnetite particles in kerosene were studied by optical methods (birefringence and light scattering). The data on the birefringence kinetics in nonstationary magnetic fields is used to determine the size distribution of magnetite particles and aggregates. It is shown that the particle size distribution essentially depends on the type of magnetic moments of the particles and aggregates. Static and dynamic light scattering experiments confirm the conclusion about the existence of a significant fraction of nanoparticles in the form of aggregates with sizes of several tens of nanometers.

Accelerated methanogenesis from effluents of hydrogen-producing stage in anaerobic digestion by mixed cultures enriched with acetate and nano-sized magnetite particles

Potential for paddy soil enrichments obtained in the presence of nano-sized magnetite particles (named as PSEM) to promote methane production from effluents of hydrogen-producing stage in two-stage anaerobic digestion was investigated. The results showed that the addition of magnetite significantly accelerated methane production from acetate in a dose-independent manner. The results from high-throughput sequencing analysis revealed that Rhodocyclaceae-related species were selectively enriched, which were likely the key players for conversion of acetate to methane in PSEM. Compared to the paddy soil enrichments obtained in the absence of magnetite (named as PSEC), the maximum methane production rate in PSEM was significantly higher (1.5–5.5times higher for the artificial medium and 0.2–1.7times higher for the effluents). The accelerated methane production from the effluents indicated remarkably application potential of PSEM for improving performance of anaerobic digestion.

Iron metabolism after application of modified magnetite nanoparticles in rats.

The influence of modified nanosized magnetite (NSM) particles (magnetic microspheres coated with chitosan and magnetoliposomes) after a single intravenous infusion of their suspensions on iron metabolism in rats has been studied. Modern physical and chemical methods (X-ray fluorescence, dynamic light scattering, transmission electron microscopy) were used for standardization of the modified NSM particles (their size, structure, ζ-potential, and concentration were determined). Atomic emission spectroscopy was used to reveal the dynamics of iron content in rat liver, spleen, lungs, and kidneys during 120 days. Colorimetric and immunoturbidimetric methods were used to determine the concentrations of plasma iron and the proteins involved in its metabolism - ceruloplasmin, transferrin, and ferritin. Their dynamics throughout the experiments were studied.