Nanosized Iron Oxide Research Articles

Nanosized Iron Oxide Uniformly Distributed on 3D Carbon Nanosheets: Efficient Adsorbent for Methylene Blue

Magnetic carbon materials as adsorbents for dye removing have attracted increasing attention because of their magnetic separation feature. However, the immobilization of large magnetic particles on a carbon matrix greatly decreases the available sites for adsorption, resulting in a low adsorption capacity. The synthesis of magnetic carbon materials as adsorbents for dye adsorption with high adsorption capacity remains challenging. Herein, porous carbon (PC) was firstly synthesized through the calcination of macroporous acrylic type cation exchange resin. The as-prepared PC was applied as a matrix to deposit nano-sized Fe3O4 nanoparticles (MPC) via a facile one-pot solvothermal strategy. The nano-sized Fe3O4 nanoparticles (5.19 nm in diameter) are uniformly distributed on the PC surface. The MPC possesses an exceptional performance for methylene blue removal (qe = 214.4 mg g−1) at room temperature, outperforming most previous magnetic carbon adsorbents. The large surface area of the MPC originated from the combined advantages of PC and nano-sized Fe3O4 must be ascribed to the high performance of MPC composite toward methylene blue adsorption.

(Invited) Iron Catalyst Facilitated Synthesis of Ammonia from N2 and Water at High Efficiency By Electrolysis

An electrosynthetic process to produce ammonia that avoids the greenhouse gas carbon dioxide is presented here. The electrocatalytic process combines water and nitrogen directly to generate ammonia at high coulombic efficiency. Catalyst enhancements were studied and improved on from our early advances,1-5by varying particle size, catalyst calcination preparation conditions, variation of catalyst carbon conductive matrix support, type and amounts of additives for better carbon coating of the catalyst, etc. Two sets of iron oxide catalysts were probed, nano-sized iron oxides and micron sized nano-oxides formed by calcination of micron sized iron metal particles. A 2µm nano-graphite carbon as the catalyst coating yields higher rates of ammonia than larger sized carbons or iron oxides without the coating. The catalysts from iron metal were made by first mixing iron powder (sized either 1-3 µm, 6-10µm, ~74µm,~149µm, ~841µm). Subsequently, the catalyst was converted to iron oxide coated partially with nano-graphiteby calcination (heating in air at a series of increasing stepped temperatures). Ammonia syntheses were investigated in two configurations (1) with free catalyst suspended in the electrolyte, and (2) with the catalyst confined to the cathode. The ammonia electrosynthesis was conducted between nickel and Monel electrodes in concentrated Na0.5K0.5OH electrolyte. The coulombic efficiency of the electrosynthesis, ηNH3, is measured by comparing the applied charge (the integrated constant current) to the 3 Faraday efficiency per mole of measured synthesized NH3.The highest performance (efficiency and ammonia rate of production) at 100°C was achieved by the catalyst synthesized with 1-3µm iron and prepared with nano-graphite coating. At 100 °C for catalysts prepared respectively with either 1-3µm, 6-10µm, ~74µm,~149µm, ~841µm iron powder, the synthesis coulombic efficiencies ηNH3 are 47%, 39%, 34%, 31%, 25%respectively and maximum ammonia formation rates are 4.7×10−9, 3.8×10−9, 3.4×10−9, 3.0×10−9, 2.4×10−9mol·(s·cm2)−1respectively. Lower temperature and/or confining the catalyst to the cathode will permit future cell variations such as polymer membrane separations in the synthesis cell. The synthesis is also effective at a lower temperature of 60°C, the formation rate using the 1-3µmiron with nano-graphite prepared catalyst is 2.2 mol·(s·cm2) −1with 21% ηNH3. Smaller sized catalysts can be effective, but are a challenge to confine in a stable configuration at the cathode. Rather than dispersing the catalyst in the electrolyte, we also introduce here a configuration that confines the catalyst to the cathode region. This consists ofsealed tea-bag shape Monel mesh cathode separated into 8 individual layers confining equal amounts of catalyst within each layer. At 60°C, the formation rate is 2.3×10−9mol·(s·cm2)−1with 23.7% ηNH3. The catalyst is stablized for ammonia synthesis ata current density of 3 mA/cm2. (1) Licht, S. Cui, B. Wang, Li, F.-F. Lau, J. Lui., S. Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3.Science2014, 345, 637-640. (2) Li, F.-F. Licht, S. Advances in understanding the mechanism and improved stability of the synthesis of ammonia from air and water in hydroxide suspensions of nanoscale Fe2O3. Inorg. Chem., 2014, 53, 10042-10044. (3) Cui, B. Zhang, J. Liu, S.,Liu, X., Xiang, W. Liu, L., Xin, H., Lefler, M. J. Licht, S. Electrochemical synthesis of ammonia directly from N2and water over iron-based catalysts supported on activated carbon. Green Chem., 2017, 19, 298-304. (4) Peng, P., Li, F.-F., Liu, X., Ren, J. Stuart, J., Lefler, M., Johnson, M., Vicini, J., Licht, S.. Chemical transformation of Fe, air & water to ammonia: variation of reaction rate with temperature, pressure, alkalinity, and iron. ChemRxiv.org,posted 31.07.2018. (5) Li, F.-F., Singhal, R., Ren, J., Johnson, Lefler, M., Licht, Solar electrochemical thermal process (STEP ammonia: Optimization of the electrolysis conditions. ChemRxiv.org,posted 25.06.2018. Illustration: The ammonia synthesis from water and nitrogen, avoiding the emission of carbon dioxide, and illustrated using a multi-layer cathode configuration via the mechanism: Cathode: Fe2O3+ 3H2O + 6e−→ 2Fe + 6OH− Anode: 6OH−→ 3／2 O2(g) + 3H2O + 6e− Chemical: 2Fe + N2+ 3H2O → 2NH3+ Fe2O3 Net: N2+ 3H2O → 2NH3+ 3／2 O2 Figure 1

A comparative study on applicability of nano-sized iron(II, III) oxide in ultrasonicated Fenton process

A comparative study on applicability of nano-sized iron(II, III) oxide in ultrasonicated Fenton process

Influence of nanosized iron oxides (II, III) on conversion of biodegradated oil

In the given paper, we evaluate the efficiency of iron oxide (magnetite in the form of water suspension) nanoparticles (50-120 nm) in intensification of cracking reactions of heavy components of biodegradated oil. The physical simulation of thermal influence on heavy oil in the presence of synthesized catalyst (concentration = 0.3%) was carried out in autoclave at temperature ranges of 150-300°С and reaction period of 24 hours. According to the results of SARA-analysis and dynamic viscosity measurements, the destructive hydrogenation processes that were catalyzed by iron oxide were conducted already at 200°С. However, the significant effect was achieved at 300°С (the degree of viscosity reduction was higher than 67%).

Nondestructive Chemical Analysis of the Iron-Containing Protein Ferritin Using Raman Microspectroscopy.

Ferritin is a ubiquitous intracellular iron storage protein of animals, plants, and bacteria. The cavity of this protein acts like a reaction chamber for natural formation and storage of nano-sized particles via biomineralization. Knowledge of the chemical composition and structure of the iron core is highly warranted in the fields of nano technologies as well as biomolecules and medicine. Here, we show that Raman microspectroscopy (RM) is a suitable nondestructive approach for an analysis of proteins containing such nano-sized iron oxides. Our approach addresses: (1) synthesis of suitable reference materials, i.e., ferrihydrite, maghemite and magnetite nanoparticles; (2) optimization of parameters for Raman spectroscopic analysis; (3) comparison of Raman spectra from ferritin with apoferritin and our reference minerals; and (4) validation of Raman analysis by X-ray diffraction and Mössbauer spectroscopy as two independent complementary approaches. Our results reveal that the iron core of natural ferritin is composed of the iron(III) hydroxide ferrihydrite (Fe2O3 ∙ 0.5 H2O).

Chemistry of iron nitrate-based precursor solutions for spray-flame synthesis.

Understanding the chemistry of iron-based metal-organic precursor solutions for spray-flame synthesis is a key step to developing inexpensive and large scale applications for gas-phase synthesized, nano-sized iron oxide particles. Owing to the large variety of available organic solvents and iron compounds, the choice of a suitable precursor-solvent pair is challenging. Systematic investigations of the precursor chemistry of iron-based systems are currently not available. This work aims at filling this gap by providing a detailed spectroscopic analysis of mixtures containing iron(iii) nitrate nonahydrate and alkyl alcohols (C2-4). Moreover, the impact of adding 2-ethylhexanoic acid is explored. The FTIR spectra reveal the formation of carboxylates and allow deriving information about the coordination of the metal-carboxylate complexes. The stability of the precursor solutions is investigated by monitoring precipitation phenomena and turbidity. Furthermore, gas chromatography is employed to provide additional information on oxidation products and esters as well as to aid the interpretation of the FTIR data. It is found that the formation of esters has an enhancing effect on iron sorption and, thus, it promotes precursor stability.

A Microfluidic ExoNANO for Efficient Isolation and Chemiluminescence Quantitative Immunoassay of Exosomes

Background: Although exosomes are potential diagnostic and therapeutic biomarkers for diverse diseases, efficient and sensitive technologies for exosomes isolation and detection are still lacking. Methods: In this study, we construct a microfluidic system (ExoNANO) for exosomes separation using CD63 antibody conjugated nano-sized superparamagnetic iron oxide particles (SIOP) and microfluidic isolation column. Further, a chemiluminescence immunoassay (CLIA) strategy was established for exosomal protein detection. Findings: Results show that microfluidic ExoNANO reveals high isolation efficiency (94%) and allows quantitative analysis of exosomes in the range of 2.92×105 to 2.80×108 particles/μL with a limit of detection (LOD) of 2.63×105 particles/μL from as little as 1μL serum sample. Using microfluidic ExoNANO, we quantified exosomes in serum, cell culture media (CM), saliva, ascitic fluid and cerebrospinal fluid (CSF) samples. Interpretation: We developed microfluidic ExoNANO, which could pave the way for routine, rapid isolation and quantitative analysis of exosomes in clinical application. Funding Statement: This study was supported by grant from the National Natural Science Foundation of China (Grant nos. 81271917, 81802571), Natural Science Foundation of Zhejiang province (Grant nos. LY14H200002, LY15H200002 and LY16H160023). Declaration of Interests: The authors declare: There does not exist any conficts of interest. Ethics Approval Statement: Serum samples of healthy individuals and cerebrospinal fluid, ascitic fluid, and saliva samples were obtained from the Second Affiliated Hospital of Zhejiang University School of Medicine. Research protocols were approved by the Ethical Committees for Clinical Research of supporting institutions, and all patients provided written informed consent for the use of their samples for experimentation.

Nanosize Fex Oy @SBA-3: A Comparative Study Between Conventional and Microwave Assisted Synthesis.

The present study is focussed on development of highly dispersed nanosize iron oxide (FexOy) particles within the uniform mesopore channels of SBA-3. Herein we report a comparative study between conventional incipient wetness and microwave assisted synthesis routes adopted to devise nanoparticles. The developed materials are characterised by following X-ray diffraction, high resolution transmission electron microscopy, proton induced X-ray emission, diffuse reflectance UV-visible spectroscopy, thermogravimetry and Fourier transform infrared spectroscopy. Mesoporous siliceous SBA-3 was prepared at room temperature to obtain samples with good crystallinity and ordered pore structure. Pore channels of SBA-3 were used as nanoreactor for developing iron oxide nanoparticles. Iron oxide nanoparticles developed under microwave activation showed uniform distribution within the SBA-3 structure along with retaining the orderness of the pore architecture. On the contrary, iron oxides developed under incipient wetness method followed by conventional heating resulted in agglomeration of nanoparticles along with significant loss in SBA-3 pore structure. Proton induced X-ray emission studies revealed the extremely high purity of the samples and almost thrice higher amount of iron oxide particles are encapsulated within the host by microwave assisted preparation as compared to incipient/conventional heating method.

Iron Oxide Nanoparticles in Soils: Environmental and Agronomic Importance

The iron (Fe) oxide particles affect a wide range of important environmental processes related to soil fertility and plant growth. They often occur as aggregates, mineral nanoparticles or as nanoscale coatings on other grains in the soil, where they may also control the fate and transport of nutrients such as phosphate, sulfate, molybdate and pollutants (arsenic or chromium). Solubilization of Fe from minerals control iron availability for plant growth; this process is regulated by chemical mechanisms (pH and dissolution-precipitation), sometimes mediated by biological interactions at rhizosphere scale, of both Fe crystalline and poorly ordered Fe oxide minerals. In cold and temperate climate the organic carbon storage and the Fe minerals are highly correlated, possibly because the interactions of nano-size iron oxide particles with humic substances. The aims of this review are to summarize the main findings and the classical iron soil chemistry and to propose chemical and biological relationships with the hope of stimulating new model in soil fertility.

Magnetite loaded cross-linked polystyrene composite particles prepared by modified suspension polymerization and their potential use as adsorbent for arsenic(III)

Magnetic particles have attracted much interest because they can be easily guided under the influence of magnetic field and are considered suitable in biomedical as well as in separation technology. In this work, magnetite (Fe3O4) loaded cross-linked polystyrene (PS) composite particles are prepared by a novel suspension polymerization of styrene and divinylbenzene (DVB) in presence of nanosized iron oxide (Fe3O4) particles dispersed in n-octane. The structure and surface properties are systematically characterized using FTIR, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermogravimetric analyses (TGA). The morphology and surface structure reveal that Fe3O4 nanoparticles are mostly dispersed within the P(S-DVB) copolymer layer. Finally the applicability of Fe3O4/P(S-DVB) composite polymer particles as adsorbent for toxic element like trivalent arsenic (As) has been investigated. Fe3O4/P(S-DVB) composite polymer particles exhibited good sorption efficiency compared to reference P(S-DVB) copolymer particles.

Developing Nanomaterials for Ironmaking Processes: Theory and Practice

Ironmaking processes take three main forms namely; blast furnace, direct reduction and direct smelting processes. Ironmaking is energy intensive sector as it requires huge amount of natural resources. It is also very important for the worldwide economy where it provides the backbone for construction, transportation and manufacturing. Many factors are strongly affecting the developing of ironmaking processes such as energy consumption, materials costs, and environment problems. These factors should be considered when discussing any new trend for developing ironmaking processes. The present work handles the current status and future of ironmaking processes. The technical and economic environment that motivates the development of these processes will be also clarified. The manuscript is designated to investigate theoretically and practically the possibility of using nanomaterials in ironmaking processes. Nano-sized iron oxides can be considered a promising source for deceasing energy consumption in iron and steel industry. The reduction of iron oxide is the most important processes in ironmaking and usually operated at relatively high temperatures. The nanopowder of iron oxide could be charged to a blast furnace together with the blast, much like the current pulverized coal injection technology. In that case, the reducibility of blast furnace burdens will be improved and consequently the energy consumption for reduction will be declined. Accordingly, minimizing the energy consumption will greatly influence the gross energy consumption of iron and steel production.

Toxicity assessment of magnetosomes in different models

Magnetosomes are nanosized iron oxide particles surrounded by lipid membrane synthesized by magnetotactic bacteria (MTB). Magnetosomes have been exploited for a broad range of biomedical and biotechnological applications. Due to their enormous potential in the biomedical field, its safety assessment is necessary. Detailed research on the toxicity of the magnetosomes was not studied so far. This study focuses on the toxicity assessment of magnetosomes in various models such as Human RBC’s, WBC’s, mouse macrophage cell line (J774), Onion root tip and fish (Oreochromis mossambicus). The toxicity in RBC models revealed that the RBC’s are unaltered up to a concentration of 150 µg/ml, and its morphology was not affected. The genotoxicity studies on WBC’s showed that there were no detectable chromosomal aberrations up to a concentration of 100 µg/ml. Similarly, there were no detectable morphological changes observed on the magnetosome-treated J774 cells, and the viability of the cells was above 90% at all the tested concentrations. Furthermore, the magnetosomes are not toxic to the fish (O. mossambicus), as no mortality or behavioural changes were observed in the magnetosome-treated groups. Histopathological analysis of the same reveals no damage in the muscle and gill sections. Overall, the results suggest that the magnetosomes are safe at lower concentration and does not pose any potential risk to the ecosystem.

Pickering emulsion polymerized magnetite-poly(methyl methacrylate) composite particles and their magnetorheology

Magnetic poly(methyl methacrylate) (PMMA)/Fe3O4 composite nanoparticles were fabricated by Pickering emulsion polymerization using nano-sized iron oxide (Fe3O4) particles as a solid stabilizer that had been synthesized initially from a hydrothermal process. High-resolution scanning electron microscopy was applied to characterize the morphology of the materials. Fourier transformation infrared spectroscopy confirmed the chemical structure of both pure Fe3O4 and PMMA/Fe3O4 composites. The magnetic properties and atomic and molecular structure of a crystal of the materials were examined by vibration sample magnetometry and X-ray diffraction, respectively. The magnetorheological (MR) features of both pure Fe3O4 and PMMA/Fe3O4 nanoparticles dispersed in mineral oil under a magnetic field were characterized by a rotational rheometer. The dynamic yield stress was higher than the elastic stress under external magnetic field. The PMMA/Fe3O4 composite-based MR fluid showed good dispersion stability, while exhibiting typical MR characteristics for the applied magnetic field dependent yield stress with a slope of 1.5.

Synthesis of Nano-Sized Silicon Oxide, Iron Oxide and Carbonates from Chrysotile Asbestos.

The objectives of this study were to investigate the physicochemical dissolution of chrysotile asbestos and to synthesize nano-sized materials and carbonate minerals from the asbestos via acid dissolution and pH changes. Chrysotile asbestos powder was dissolved in 3 different acids, HCl, HThe objectives of this study were to investigate the physicochemical dissolution of chrysotile asbestos and to synthesize nano-sized materials and carbonate minerals from the asbestos via acid dissolution and pH changes. Chrysotile asbestos powder was dissolved in 3 different acids, HCl, H₂SO₄, and HNO₃, and the solutions were then titrated using NH₄OH and reacted with CO₂. The residual material and precipitates were examined with XRD and TEM-EDS. ICP-AES analysis was also used to investigate the chemical makeup of the solution. The concentration of Mg in the solution was about 1,280 mg/L. The chrysotile became noncrystalline silica after acid treatment (pH = 0). At pH 8.6 and 9.5, the precipitates were amorphous iron oxide and nesquehonite [Mg(HCO3)(OH)·2(H₂O)] after reaction with CO₂. The particle size of the precipitates ranged from 2 to 500 nm. These results indicate that dissolution of chrysotile asbestos using HCl, H₂SO4, and HNO3 can chemically alter chrysotile fibers. Also, the dissolved materials can be used as precursors for other materials such as silica, iron oxide, and carbonates. This process may be useful for the synthesis of silica and iron oxides and for mineral carbonation for carbon sequestration. SO4, and HNO₃, and the solutions were then titrated using NH4OH and reacted with CO₂. The residual material and precipitates were examined with XRD and TEM-EDS. ICP-AES analysis was also used to investigate the chemical makeup of the solution. The concentration of Mg in the solution was about 1,280 mg/L. The chrysotile became noncrystalline silica after acid treatment (pH = 0). At pH 8.6 and 9.5, the precipitates were amorphous iron oxide and nesquehonite [Mg(HCO₃)(OH)·2(H₂O)] after reaction with CO₂. The particle size of the precipitates ranged from 2 to 500 nm. These results indicate that dissolution of chrysotile asbestos using HCl, H₂SO₄, and HNO3 can chemically alter chrysotile fibers. Also, the dissolved materials can be used as precursors for other materials such as silica, iron oxide, and carbonates. This process may be useful for the synthesis of silica and iron oxides and for mineral carbonation for carbon sequestration.

Active targeting theranostic iron oxide nanoparticles for MRI and magnetic resonance-guided focused ultrasound ablation of lung cancer.

Despite its great promise in non-invasive treatment of cancers, magnetic resonance-guided focused ultrasound surgery (MRgFUS) is currently limited by the insensitivity of magnetic resonance imaging (MRI) for visualization of small tumors, low efficiency of invivo ultrasonic energy deposition, and damage to surrounding tissues. We hereby report the development of an active targeting nano-sized theranostic superparamagnetic iron oxide (SPIO) platform for significantly increasing the imaging sensitivity and energy deposition efficiency using a clinical MRgFUS system. The surfaces of these PEGylated SPIO nanoparticles (NPs) were decorated with anti-EGFR (epidermal growth factor receptor) monoclonal antibodies (mAb) for targeted delivery to lung cancer with EGFR overexpression. The potential of these targeted nano-theranostic agents for MRI and MRgFUS ablation was evaluated invitro and invivo in a rat xenograft model of human lung cancer (H460). Compared with nontargeting PEGylated SPIO NPs, the anti-EGFR mAb targeted PEGylated SPIO NPs demonstrated better targeting capability to H460 tumor cells and greatly improved the MRI contrast at the tumor site. Meanwhile, this study showed that the targeting NPs, as synergistic agents, could significantly enhance the efficiency for invivo ultrasonic energy deposition in MRgFUS. Moreover, we demonstrated that a series of MR methods including T2-weighted image (T2WI), T1-weighted image (T1WI), diffusion-weighted imaging (DWI) and contrast-enhanced T1WI imaging, could be utilized to noninvasively and conveniently monitor the therapeutic efficacy in rat models by MRgFUS.

The Disruption of an OxyR-Like Protein Impairs Intracellular Magnetite Biomineralization in Magnetospirillum gryphiswaldense MSR-1.

Magnetotactic bacteria synthesize intracellular membrane-enveloped magnetite bodies known as magnetosomes which have been applied in biotechnology and medicine. A series of proteins involved in ferric ion transport and redox required for magnetite formation have been identified but the knowledge of magnetosome biomineralization remains very limited. Here, we identify a novel OxyR homolog (named OxyR-Like), the disruption of which resulted in low ferromagnetism and disfigured nano-sized iron oxide crystals. High resolution-transmission electron microscopy showed that these nanoparticles are mainly composed of magnetite accompanied with ferric oxide including α-Fe2O3 and 𝜀-Fe2O3. Electrophoretic mobility shift assay and DNase I footprinting showed that OxyR-Like binds the conserved 5′-GATA-N{9}-TATC-3′ region within the promoter of pyruvate dehydrogenase (pdh) complex operon. Quantitative real-time reverse transcriptase PCR indicated that not only the expression of pdh operon but also genes related to magnetosomes biosynthesis and tricarboxylic acid cycle decreased dramatically, suggesting a link between carbon metabolism and magnetosome formation. Taken together, our results show that OxyR-Like plays a key role in magnetosomes formation.

Shape-dependent magnetic and microwave absorption properties of iron oxide nanocrystals

Synthesis of uniform magnetic nanocrystals with tunable shape is valuable to investigate the microwave absorption properties that depend closely on the shape and size. In this study, we utilize an efficient method to synthesize nano-sized iron oxide nanocrystals with different shapes through thermal decomposition of Fe(acac)3 in oleylamine. While the spherical Fe3O4 nanocrystals display a typical superparamagnetic behavior at room temperature, the triangular nanoplates exhibit a blocking behavior at an unexpected high temperature. The antiferromagnetic-ferrimagnetic core-shell structure of FeO@Fe3O4 nanocubes presents exchange bias behavior. We also investigate the high frequency properties of all samples by a network analyzer. Compared to spherical and cubic shapes, the triangular Fe3O4 nanoplates exhibit significantly enhanced microwave absorption performance in terms of strong reflection loss and wide bandwidth. Moreover, the triangular Fe3O4 nanoplates have obvious dielectric and magnetic resonance behaviors responding to the microwave at the frequency range of 2–18 GHz. The dielectric and magnetic resonance behaviors may be derived from the interface polarization and exchange resonance. The minimum reflection loss of triangular Fe3O4 nanoplates reaches −32.1 dB at 11.7 GHz and the bandwidth less than −10 dB is from 10.6 to 13.3 GHz at a thickness of 2.5 mm.

Effective removal of glyphosate from water by resin-supported double valent nano-sized hydroxyl iron oxide

The double valent composite resin (DR) was prepared within nano-sized Fe(ii) and Fe(iii) hydroxyl oxide crosslinking polystyrene anion exchanger resin for efficient glyphosate removal from water.

Features of reduction and chemisorption properties of nanosized iron(III) oxide

Nanosized iron(III) oxide with an average particle size of 8–10 nm has been synthesized by the thermolysis of iron(III) acetylacetonate using diphenyl ether as a dispersion medium. Reduction processes in a hydrogen atmosphere in the presence of nanosized iron oxide and natural mineral hematite (Fe2O3) have been studied by the temperature-programmed reduction method. The activation energies of the reduction processes have been determined by the Kissinger method; it has been shown that, in the case of nano-Fe2O3, the activation energies are several times higher than the respective values observed for hematite. The adsorption properties of nano-Fe2O3 and hematite have been studied; the isosteric heats of chemisorption of hydrogen and carbon monoxide on the surface of these samples have been determined.

Magnetic (ethylene-octene) elastomer composites obtained by extrusion

Most research on magnetorheological elastomer (MRE) composites is focused on achieving the best magnetic and magnetorheological properties of composites. Less attention is paid to obtain adequate strength properties. The aim of this study was to receive MRE composites with the best mechanical characteristics. Thermoplastic ethylene–octene rubber composites, filled with different magnetoactive particles were reported. The use of extrusion method instead of traditional preparation processes (two-roll mill, mixer) of composites was also presented. Ferromagnetics: micro- and nano-sized iron oxides, as well as gamma iron oxide and carbonyl iron powder were found to be an active fillers improving both mechanical and magnetic properties of rubber. Application of extrusion process affected mechanical properties of MRE composites and the dispersion of magnetic fillers. Dynamic mechanical analysis (DMA) indicates the presence of strongly developed secondary structure in vulcanizates. Studies investigated by vibration sample magnetometer (VSM) proved that all composites exhibit adequate magnetic properties, predispose them for plenty of applications with the most promising being nowadays tunable vibration absorbers. POLYM. ENG. SCI., 57:520–527, 2017. © 2016 Society of Plastics Engineers