Dispersed Iron Particles Research Articles

Monitoring of suspended matter in the Dnipro River within Zaporizhzhia city, the main trends of 2022

The article presents the results of monitoring observations on the temporal distribution of the qualitative and quantitative components of the Dnipro River suspended matter within Zaporizhzhia city. The research on the territory of this powerful industrial center of Ukraine with a developed metallurgical complex was carried out from 2015 up to 2019 and from the end of 2021 to the present time. The main task of the research was determining the distribution of iron and a group of heavy metals of anthropogenic origin in the composition of the river suspension, and identifying the connections of their concentrations and forms with the natural conditions of the region. Sedimentary matter from the water flows of Dnipro River within research area was sampled once per month using sedimentary traps developed by authors. The methods of electron microscopy (with microprobe analysis) and laser diffraction analysis were used to study the suspension granulometric and chemical composition in the Center for Shared Use of Scientific Equipment of the IGS NASU. SEM studies were carried using scanning electron microscope SEM JEOL-6490 LV (Jeol Ltd., Japan) with an energy dispersive spectrometer of the X-ray microanalysis system INCA Energy+ (Oxford Instruments plc., Great Britain). Particle size analysis was determined using the laser particle size analyzer Mastersizer 2000 with a Hydro 2000S wet dispersion module (Malvern Ins. Ltd, UK).The study results of the samples taken in the first year of hostilities in Ukraine revealed a number of features which were not observed in the previous series of studies. Those peculiarities are the following ones: reduction in the intensity of sedimentary matter accumulation; decrease of technogenic components in the suspension content (in particular, the amount of ferrous metals, changes in the ratio of condensed and dispersed iron particles of silt size, as well as the component composition of fragments of alloys of non-ferrous and ferrous metals). The obtained results may indicate the sensitivity of the component composition of the suspension to changes in the external environment in general, as well as the significant impact of the anthropogenic component on the distribution of iron in suspended matter.

CO2-FT activity of Fe7C3 in FeZnK/ZrO2 catalysts synthesized by using citric acid: Effect of pretreatment gas

Here in, FeZnK/ZrO2 catalysts were synthesized by using citric acid (CA) chelation method. These catalysts were pretreated under H2(g) or CO(g) or CO/H2(g) for 2 h at 350 °C and subsequently tested in CO2-FT reaction at 300 °C and 2.0 MPa. The resultant fresh or spent samples were characterized by using BET-SA, XRD, TPD, TPR, XPS, HR-TEM, SEM-mapping-EDX and Mossbauer techniques. Improved textural properties (SA/pore width) and uniformly dispersed iron particles were obtained in FeZnK/ZrO2 catalysts through CA chelating method as established by BET-SA and SEM-mapping results respectively. The carbidization under CO/H2(g) produced Fe7C3 phase due to the ease reduction of dispersed iron oxides in CA catalyst as evidenced by XRD, HR-TEM and Mossbauer results. On the other hand, CA catalyst carbidized under CO(g) exhibited Fe7C3/Fe phases suggests inadequate carbidiztion of reduced iron species in agreement with H2-TPD results. Among the CO/H2 gas pretreatment ratio (0.45, 0.93 and 1.25), Fe7C3 with optimum particle size of 30.0 nm was achieved at CO/H2(g) = 0.93. Two fold increase in the –C2-C4= olefins yield (7.29 mmol gcat−1 h−1) over conventional impregnation catalyst (3.24 mmol gcat−1 h−1) was observed for CA catalyst. It was associated with stable Fe7C3 phase existed in a greater extent on the surface (Fe-C = 0.21 atom.%) in close vicinity to K (0.25 atm.%) and resulted in dissociative activation of adsorbed CO2/H2(g). In the present study, citric acid chelating method followed by CO/H2 gas pretreatment at 350 °C for only 2 h generated stable Fe7C3/ZrO2 unlike, literature reports (5–10 h pretreatment) and has the potential for further developments in CO2-FT process.

Enhanced Effect of the Mesoporous Carbon on Iron Carbide Catalyst for Hydrogenation of Dimethyl Oxalate to Ethanol

AbstractDue to the low activity of bulk Fe5C2 catalyst in the hydrogenation of dimethyl oxalate to ethanol, a supported Fe5C2 catalyst was designed and prepared with mesoporous carbon as the carrier. For a comparison, two iron carbide catalysts supported on activated carbon and microporous carbon were also prepared. Based on the characterization results of IR, XRD, H2‐TPR, CO‐TPD, XPS and MES, the oxygen‐containing functional groups (especially COOH group) on the surface of the carbon supports inhibit the formation of iron carbides, which are regarded as the active sites and play the key role in the hydrogenation of dimethyl oxalate to ethanol. However, the mesoporous carbon exhibits a more positive effect on the dispersion of iron particles than the other two carbon supports. As a result, the as‐prepared mesoporous catalyst presents an excellent activity (the ethanol yield of 85.8 %) and stability in the hydrogenation of dimethyl oxalate. This work suggests a practical strategy in fabricating a supported iron carbides catalyst for the chemosynthesis of ethanol via DMO hydrogenation from syngas.

Selectively forming light olefins via macroporous iron-based Fischer–Tropsch catalysts

A highly dispersed macroporous iron-based catalyst (Fe/S80-E) was developed by the modification of a macroporous silica (80 nm) surface with ethylene glycol before the impregnation of iron precursors. Due to higher diffusion efficiency and highly dispersed iron particles, this kind of catalyst presents superb catalytic performance in Fischer–Tropsch synthesis with high selectivity of light olefins (46.2 c-mol%) as well as high activity (CO conv. 63.4 %) without any promoters. The obtained catalysts were characterized by N2 physisorption, mercury intrusion porosimetry, XRD, TEM, XPS, TPR and in situ DRIFT.

Study of Adsorption Doxorubicin by Iron-Carbon Composite Powders

Method of electric-spark dispersion of iron particles in water, ethyl alcohol, phosphoric acid solution and hexane has been applied to produce composite magnetic nanosized powders. Their phase composition, dispersity, magnetic susceptibility, and adsorption-desorption properties towards anti-tumor remedy doxorubicin have been studied. It is shown that the obtained powder in hexane has the highest adsorption capacity towards doxorubicin. This is probably the evidence of surface compound formation. It is durable adsorption complex, which is formed from carbonyl and amine groups of organic cations and vacant orbitals of iron d-sublevel. The powder, obtained in hexane, can be dissolved in human blood plasma and amino acid solutions: possible time of iron elimination from human organism is smaller than 10 days. It is shown possibility of application iron-carbon sorbent is in quality of magnetic carrier doxorubicin to cancer cells.

Microstructure formation during the annealing of iron nitrides

The thermal metastability of iron nitride was exploited to fabricate thin-film microstructures applicable to left-handed metamaterials. A granular thin film containing dispersed iron particles was prepared by post-annealing an rf-sputter-deposited Fe0.5Al0.5N thin film with a wurtzite-type structure in a nitrogen atmosphere at 450 °C. The obtained samples showed magnetic resonance in the microwave region. Laser direct writing was also applied in a nitrogen atmosphere to an rf-sputter-deposited Fe0.7Al0.3N thin film. 200 μm-wide, 300 Ω cm iron metal lines were drawn in a host nitride film of approximately 2 kΩ cm. Combining and optimizing the above negative permeability and permittivity values should provide left-handed materials with a negative refractive index.

Advanced Materials from Natural Materials: Synthesis of Aligned Carbon Nanotubes on Wollastonites

The growth of carbon nanotubes (CNTs) on natural materials is a low-cost, environmentally benign, and materials-saving method for the large-scale production of CNTs. Directly building 3D CNT architectures on natural materials is a key issue for obtaining advanced materials with high added value. We report the fabrication of aligned CNT arrays on fibrous natural wollastonite. Strongly dispersed iron particles with small sizes were produced on a planar surface of soaked fibrous wollastonite by a reduction process. These particles then catalyzed the decomposition of ethylene, leading to the synchronous growth of CNTs to form leaf- and brush-like wollastonite/CNT hybrids. The as-obtained hybrids could be further transformed into porous SiO(2)/CNT hybrids by reaction with hydrochloric acid. Further treatment with hydrofluoric acid resulted in aligned CNT arrays, with purities as high as 98.7 %. The presented work is very promising for the fabrication of advanced materials with unique structures and properties that can be used as fillers, catalyst supports, or energy-absorbing materials.

Mössbauer Investigation of Highly Dispersed Iron Particles in Crazed Porous Polymers

Formation and stability of highly dispersed iron particles in crazed porous polymer matrices were studied. The iron-polymer composites obtained were characterized by different morphologies and dimensions of iron particles. The phase content of the iron constituent in a composite studied by Mossbauer spectroscopy was shown to depend on the type of the iron salt and the method of introduction of the initial reagents into a polymer.

スズ―鉄合金めっき負極を用いた次世代リチウム二次電池の作製とその充放電特性

Charge-discharge behaviors for tin-12% iron alloy films on electrolytic copper foils prepared by electroplating, which were low cost and made of environmentally friendly alloy, were investigated for X-ray a diffraction measurement, cyclic voltammetry and charge-discharge tests. Tin-12% iron alloy plating anodes showed a discharge capacity of 374 mAh/g after 50 cycles with metallic lithium as counter electrodes. From the results of cyclic voltammograms for tin-12% iron alloy plating anodes, the current value for lithium deposition increased around 0.26 V in the first cycle and increased around 0.68 V in the second cycle. The current value for lithium deposition in tin plating anodes increased around 0.66 V in the first cycle. These results suggested that iron was separated from tin-iron alloy plating film in the first charge and electric conductivity of tin-lithium intermetallic compounds formed bycharge-discharge reactions was improved by the dispersion of iron particles between these compounds. At a discharge rate of 5C(50 A/m2) tin-12% iron alloy plating anodes showed a discharge capacity of 285 mAh/g after 50 cycles and was applicable for high discharge rate. A coin-type cell(CR 2032) with a tin-12% iron alloy plating anode and a LiCoO2 cathode showed a discharge capacity of 273 mAh/g and coulombic efficiency of 90.4% after 95 cycles in charge-discharge tests at a constant charge capacity of 302 mAh/g. Therefore, tin-12% iron alloy plating anodes can be expected to substitute for carbon as high capacity anodes for advanced lithium secondary batteries.

96/05850 Effect of iron catalysts on hydrogenation pathways in direct coal liquefaction

The effect of a collnnerciany available, high surface area nanometer size iron oxide (SFIO) catalyst on the pathway by which hydrogen is added to a subbituminous coal during direct lquefaction was studied under a variety of conditions. This unique iron oxide, prepared by pyrolyzing volatilized iron carbonyl to produce a finely divided product, is characterized as y-F%03 having a surface area of -300 m'/g and particle size of 1-3 nm. Liquefying Wyodak coal in tetralin (0.5 hrs, 415 C, 2.3 tetralinldry coal, 6.89 Mpa & cold) containing 1.2 wt % Fe as SFIO resulted in an increase in o v d coal conversion (77 to 83%) with most of the increase in product being in formation of THF soluble-pentane insoluble Addhg an excess of sulfur to convext the iron to pyrrhotite funher increases conversion to 85% along with a decrease in the THF solublepentane insoluble fraction. The presence of catalyst increases the amount of hydrogen added to the product as dihydrogen (HJ relative to the amount from tetralin via the H-donor pathway. In the absence of *t, 60% was added as adding 1.2% Fe increased H2 addition to 67%; adding 3 mol Shnol Fe to 1.2% Fe further increased & addition to 82%. Introduction Through the use of various types of catalysts, high yields of distillate fuels have been pmduced in pilot plants firomlowerast subbituminous coal.' The use of high surface area, small particle catalysts has been one area that has been extensively explored in an effort to maximize yields and reduce the cost of catalyst. Fe has been of particular interest as a dispersed catalyst because of its abundance, low cost and its environmental acceptability. Various approaches have been used for preparing disposable nanometer size Fe catalysts, among which are nirmmdm ' aerosols,*a9 hydrothermal disproportionation of sulfides, and precipitation of sulfated oxyhydroxides. Highly dispersed iron particles, in various forms as oxides and oxyhydroxides, have been shown to retain their small size upon conversion to pyrrhotite under coal hydroliquefaction condition^.*^^'^ In OUT laboratory, a specially prepared Commercially available supexfine Fe oxide (SFTO) was found to have high activity for coal conversion and excellent selectivity for producing distillate product. In the study reponed hae, the activity of this catalyst for conversion of a Wyodak coal in teualin was compared with a nnich Lower surface a m Fe oxide prepared from AiusNther spray roast processing of spent acid from steel pickling.I4 The effect of these catalysts on the pathways by which hydrogen (H) is added to the coal and its products was investigated. Experimental Samples of the subbituminous coal and powdered iron oxides used at the Wilsonville Advanced Coal Liquefaction Facility in Run 263Jl4 were supplied by CONSOL, Inc. The Wyodak coal from the Black Thunder mine in Wright, Wyoming was ground to -200 mesh, M e d and stored under nitrogen at 4 C. Proximate and ultimate analyses are presented in Table I. The average moisture content measured at the beginning of each run was 21.9 f 0.72 wt % of as-received coal. Two iron oxide catalysts were used. One, a sample of SFIO provided by MACH I, Inc., King of P r U S k PA, contained 63 wt % Fe with a y-F%03 structure, average particle size of 1-3 nm, and nitrogen BET surface area of 300 t~?/g.'~ The second, from Bailey Engineers, Fairfield, AL, (IO) was 99% Fq03 with 0.35 wt % manganese oxide being the largest impurity. The material had a structure of a-FqO,, nitrogen BET surface area of 8.6 d/g , an average particle size of -140 nm, and bulk density 26 times greater than SFIO (1.37 vs. 0.052 ghl ) . Carbon black (CB) was purchased from UIC, Inc. and had a fixed carbon content of 93% with a nitrogen BET surface area of 90 m'/g. ~ u e f a c t b n eXperiments were conducted by adding 3 gratns of coal 5.4 grams of tea&, and catalyst to a 50 mL microautoclave. When used, dimethyl disulfide @MDS) was added at a ratio of 3.0 moles S per mole Fe. The reactor was sealed, pressurized with Hz to 6.89 MPa, and immersed in a fluidized sand bath set at the V@.%kd temperatun while continuously agitating at a rate of 400 cycles per minute. After the specified reaction period the microautoclave was rapidly cooled in a sand bath at room temperature. Gaseous products

Magnetroviscoelastic behavior of composite gels

AbstractDynamic viscoelasticity of silicone gels having many lines of dispersed iron particles under the influence of external magnetic fields was studied. The particulate composite enhanced its elastic modulus by action of magnetic fields. The magnetroviscoelastic behavior was caused by the cohesive forces between magnetically polarized particles and was analyzed using a simple model of induced dipole‐induced dipole interactions. The presented results provide insight into the relationship between macroscopic viscoelastic behavior of the composite gels and the microscopic bondings between dispersed particles. © 1995 John Wiley & Sons, Inc.

Characterization of Carbon in Mechanically Alloyed C-10 at%Fe Powder

Mechanical alloying (MA) of iron and graphite was performed for C-10 at%Fe alloy by the use of a conventional ball mill. The structure of mechanically alloyed samples were examined by X-ray diffraction, transmission electron microscopy. A spectrometric approach to the change of structure during the milling process was carried out by carbon Kα X-ray-emission band spectroscopy and electron energy loss spectroscopy. Finely dispersed iron particles with a grain size of about 10 nm into graphite powder particles were obtained after 1000 h of MA. Spectrometric results suggested that fracturing of graphite of graphite crystal progressed by three steps ; fracturing along the hexagonal plane, fracturing the hexagonal networks and amorphization. The electron state of carbon atom in the ball milled sample was energized to form sp 3 hybrid orbital, after applying pressuring.

Mössbauer study of FeAlO layers obtained by ion-beam deposition and ion implanation

FeAlO layers were prepared at different temperatures (between 20 °C and 600 °C) by ion implantation and ion-beam sputtering. By the use of conversion electron Mössbauer spectroscopy it was possible to observe the charge states of iron atoms and then to determine the effect of the temperature on the compound formation. In the two fabrication processes small iron particles and FeAl 2O 4 are produced. However, at 20 °C some differences are observed in the chemical state: Fe(IV) and α-Fe are detected in implanted layers only. From 400 °C the main effect of temperature is to favour the formation of dispersed iron particles in alumina with bigger precipitates for ion-implanted samples.

Study of the activation process and catalytic behaviour of a supported iron ammonia synthesis catalyst

A 3 wt% iron-supported catalyst has been prepared by free adsorption of K 4[Fe(CN) 6] precursor on acid-modified γ-alumina. The catalyst activation was studied by in situ X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and mass-spectrometry techniques. Thermal treatments under vacuum of H 2 : He flow produce the removal of cyanide ligands mainly as HCN and the formation of well dispersed Fe 2+ species which easily interact with the support. However, an activation under H 2:N 23:1 flow up to 673 K produces the elimination of cyanide ligands and formation of ammonia; small, well dispersed iron particles are obtained simultaneously. This activation process raises the initial K/Fe atomic surface ratio from 4.37 to 6.1. Chemisorption of dinotrogen species on potassium-rich small iron particles is related with an infrared absorption found at 2043 cm -1, which appears under H 2:N 23:1 activation conditions above 573 K. Catalytic behaviour in the ammonia-synthesis reaction has been studied in a flow reactor under pressure. A catalytic activity at 30 bar and 723 K as 405 mmol NH 3 per iron gram per hour has been determined.

Surface characterization of carbon-supported iron catalysts for carbon monoxide hydrogenation: Influence of catalyst distribution and coal minerals

The iron catalysed carbon monoxide hydrogenation (Fischer–Tropsch synthesis) has been studied by on-line combination of a chemical microreactor working under technical conditions with surface analytical methods (photoelectron spectroscopy, secondary ion and thermal desorption mass spectrometry, ion scattering spectroscopy, electron and x-ray microscopy). In contrast to other sample preparation methods, deposition of Fe(CO)5 onto carbon substrates leads to a surface shell with highly dispersed iron particles. Metallic iron, which is the most important species in the reaction, is formed by reduction of the samples in H2 atmosphere at elevated temperature. A reduction time of 16 h is required to achieve complete reduction of residual FeO at the interface between iron and the carbon support. The activity and selectivity of the catalyst is mainly determined by the existence of a mobile potassium phase which segregates to the surface. A high potassium concentration shifts the selectivity towards long chains, a low concentration lowers the total activity. Degradation of the catalyst during the reaction mainly occurs by two processes: the gradual oxidation of metallic iron to FeO and sintering of iron to larger particles. Iron oxidation can be reversed by reactivation in H2. Sintering cannot be prevented completely, but seems to be delayed by a high Al content in the carbon substrate.

Magnetic and Mossbauer studies of finely dispersed iron particles

Magnetic and Mossbauer measurements have been used to study the superparamagnetic behaviour of a magnetic fluid containing iron particles. Electron micrographs show the particles to form a Gaussian distribution with median diameter Dp=65 AA, sigma =12 AA whilst magnetic analysis gives the median diameter Dvm=60+or-5 AA at 80K and Dvm=55+or-5 AA at 300K. Superparamagnetic behaviour was evident for the magnetic measurements at both 80 and 300K. The Mossbauer spectrum at 86K contained two lines which were associated with the superparamagnetic iron core and the FeO coating. The FeO line showed no evidence of magnetic ordering when the coating was thin ( approximately=10 AA) but this was apparent when the coating thickness was increased by prolonged oxidation.

Electron-microscopic investigations of highly dispersed iron powders obtained by the electroemulsion method

Depending upon the electrolysis conditions and the rate of movement of the emulsion the form, dispersion, degree of aggregation, and specific surface of highly dispersed iron particles change. The electroemulsion method makes it possible to obtain 0.15–0.25~m metal particles close to monodispersed.

The Crystal Structure of Iron Particles Dispersed in a Glasslike Carbon Matrix

Abstract Ultra-fine iron particles were dispersed in a glasslike carbon matrix by the heat treatment of acetylferrocenefurfural resins. The dispersed iron particles were investigated by means of X-ray and electron diffraction analyses and by means of electron microscopy. In resins heat-treated at 400 °C, iron particles of varying diameters were observed by means of electron microscopy. The crystal structure of the iron particles was analyzed by means of X-ray and electron diffractions. Finely subdivided iron particles were identified as hexagonal, close-packed (hep) and expanded, body-centered cubic (bec) irons. The hep iron is the high-pressure phase of iron metal. The ultra-fine iron particles were coagulated to larger particles by heat treatment above 400 °C. The size of their unit cell was the same as that of standard bec iron.

Decomposition of water by highly dispersed iron particles during ore crushing

1. It has been established experimentally that when quartz, feldspar, mica, and other minerals are crushed in steel (iron) mills, considerable amounts of hydrogen are evolved from the pulp; this hydrogen can only originate from decomposition of water by very fine iron particles. 2. This phenomenon is undergoing detailed study to establish its role in ore flotation.

Dispersion hardening

The increase in yield strength of solid mercury due to dispersed iron particles is experimentally determined to be proportional to d (Λ − d) (1) and therefore a function only of d Λ , where d is the particle diameter and Λ is the spacing between centers of the particles. Since d/ Λ is proportional to ƒ 1 3 , where ƒ is the volume fraction of precipitate, these results show that the yield strength is a function only of the volume fraction of precipitate. In the case of coherent particles, the stressed region through which dislocations will not pass must be included. An investigation of the temperature dependence of the yield strength shows that the increase in yield strength at any absolute temperature T is proportional to d(T m − T) (Λ − d) , where T m is the melting point of the mercury matrix. The decrease in yield strength of overaged precipitation hardened systems is attributed to a loss in coherency between the matrix and precipitate and not to an increase in spacing between particles.