Effect Of Iron Content Research Articles

Effect of Iron Content in Alumina-Supported Palladium Catalysts and Their Reduction Conditions on Diclofenac Hydrodechlorination in an Aqueous Medium

Effect of Iron Content in Alumina-Supported Palladium Catalysts and Their Reduction Conditions on Diclofenac Hydrodechlorination in an Aqueous Medium

Effect of content and spin state of iron on electronic properties and floatability of iron-bearing sphalerite: A DFT+U study

Iron is an impurity widely occurred in sphalerite, and its effect on sphalerite flotation is complex. In this work, the effects of iron content and spin state on electronic properties and floatability of iron-bearing sphalerite are comprehensively studied using density functional theory Hubbard U (DFT+U) calculations combined with coordination chemistry flotation. The band gap of ideal sphalerite is 3.723 eV, and thus electron transition is difficult to occur, resulting in poor floatability. The results suggest the band gap of sphalerite decreases with increasing iron content. For low iron content, the decreased band gap facilitates electron transition; at this case, Fe2+ in a high-spin state possesses one π electron pair, which can form a weak π-backbonding with xanthate, causing increasing floatability. However, for medium and high iron-bearing sphalerite, with the further decrease of band gap, Fe2+ is oxidized to Fe3+ due to electrochemical interaction, and hence π-backbonding is eliminated, leading to lower floatability of iron-bearing sphalerite, which is consistent with the flotation experimental results. This work could give a deeper understanding of how sphalerite flotation behaviors are affected by iron content.

Effect of Iron Content on High Strength and Environmentally Friendly Water-Permeable Bricks Prepared from W-Mo Tailing and Iron Slags

Effect of Iron Content on High Strength and Environmentally Friendly Water-Permeable Bricks Prepared from W-Mo Tailing and Iron Slags

EFFECT OF Fe CONTENT ON THE STRUCTURAL AND MAGNETIC PROPERTIES OF TERNARY (Ni60Co40)100−xFex NANOMATERIALS SYNTHESIZED BY HYDROTHERMAL ROUTE

The effect of iron content on the structure, morphology and magnetic properties of (Ni[Formula: see text]Co[Formula: see text])[Formula: see text]Fe[Formula: see text] powders synthesized by hydrothermal method has been studied. Several samples have been elaborated for different Fe content ([Formula: see text] = 0, 3, 5, 7, 10 and 13.5). The as- prepared samples have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometry (VSM). From XRD spectra and for all Fe content, we have shown the presence of both face centered cubic (FCC) and Hexagonal (HCP) nanosized phases. The lattice parameter increases with increasing Fe content and the grains size varies with Fe content to reach a minimum value of 32 nm for (Co[Formula: see text]Ni[Formula: see text])[Formula: see text]Fe[Formula: see text]. From hysteresis curves, we have extracted the saturation magnetization, Ms, and the coercivity, Hc. We noticed that Ms increases and then decreases as a function of Fe content. The values of Hc vary from 156 Oe to 186 Oe depending on the particles shape.

Microtwin evolution and grain boundary phase formation in iron-rich 2:17-type Sm-Co magnets: The effect of iron content

Iron-rich 2:17-type Sm-Co magnets are expected to possess a high energy product due to their elevated saturation magnetization. However, achieving high energy in manufactured magnets poses a challenge, and the mechanism by which the microstructure is affected by the iron content remains unclear. Here, we investigate the microstructure of 2:17-type Sm-Co magnets with varying iron contents in both single solid-solution precursors and aged magnets. Our study indicates that a higher iron content results in microtwin structures with a lower dislocation density in the 1:7H precursor phase, leading to an increased energy barrier and decreased driving force during the subsequent phase transformation. As a result, the 1:7H phase does not completely decompose, causing an increase in the intermediate phases. Furthermore, the impact of iron content on the 1:7H phase causes the aged magnets to have insufficient cell boundaries and massive grain boundary phases. Our study provides an understanding on the iron-rich 2:17-type Sm-Co magnets through the manipulation of the free energies and the defects in the solid-solution precursors.

Effect of Iron Content on Thermal Conductivity of Ferropericlase: Implications for Planetary Mantle Dynamics

AbstractWe have simultaneously measured thermal conductivity (λ) and thermal diffusivity (κ) for polycrystalline ferropericlase with different Fe contents (Fp3, Fp5, Fp10, Fp20, Fp30 and Fp50) up to 23 GPa and 1100 K by a pulse heating method. Experiment results reveals that even small amounts of Fe in ferropericlase can strongly reduce the thermal conductivity by several times at low temperature compared with MgO periclase. With increasing Fe in ferropericlase, both their pressure and temperature dependence decrease. λ of Fe‐bearing ferropericlase is not sensitive to temperature compared with silicates and shows a tendency of first increasing and then decreasing with increasing temperature. A universal equation was derived to estimate λ of ferropericlase with arbitrary composition under mantle conditions. The low λ values of Fe‐rich ferropericlase can explain one possible origin of ultralow velocity zones. This study suggests that Fe content in ferropericlase is an important factor controlling the cooling history of terrestrial planets.

The Effect of Iron Content on the Ammonia Selective Catalytic Reduction Reaction (NH3-SCR) Catalytic Performance of FeOx/SAPO-34.

Iron-based catalysts are regarded as promising candidates for the ammonia selective catalytic reduction reaction (NH3-SCR) which show good catalytic activity at medium and high temperatures, whereas SAPO-34 molecular sieves have a micro-pore structure and are ideal catalyst carriers. In this paper, four FeOx/SAPO-34 molecular sieve catalysts with different iron contents (Fe = 1%, 2%, 3%, 4%) were prepared using an impregnation method. The effect of iron content on the surface properties and catalytic activity was investigated by a series of characterization techniques including XRD, SEM, BET, XPS, H2-TPR and NH3-TPD. Iron species in the FeOx/SAPO-34 catalysts exist in the form of isolated iron ions or well-dispersed small crystals and iron oxide species clusters. With the addition of iron content, the integrity of CHA (chabazite) zeolite structure remained, but the crystallinity was affected. The FeOx/SAPO-34 catalyst with 3% Fe loading showed a relatively flat surface with no large-diameter particles and strong oxidation-reduction ability. Meanwhile, more acidic sites are exposed, which accelerated the process of catalytic reaction. Thus, the FeOx/SAPO-34 catalyst with 3% Fe showed the best NO conversion performance among the four catalysts prepared and maintained more than 90% NO conversion efficiency in a wide temperature range from 310 °C to 450 °C.

Iron-copper interaction in soil spectra and its effect on the estimation of copper content

It is important to clarify the iron-copper interaction pattern to effectively extract the characteristic bands and improve the inversion accuracy of copper content in soil. In this study, based on experimental samples, spectral feature analysis and analysis of variance (ANOVA) were used to deeply uncover the iron-copper interaction pattern. And used natural samples to build a random forest model to analyze the effect of interaction patterns on inversion accuracy. The results of the study showed that the effect of iron content in soil on spectral reflectance varied with copper content in soil, and similarly, the effect of copper content in soil on spectral reflectance varied with iron content in soil. The effect of iron, copper and their interaction on the spectral reflectance of soil varied with the wavelength. In the wavelength from 400 to 2,500 nm, the effect of iron on the spectral features was more than copper, and in the characteristic wavelength of iron (600–700 nm), even more than 5 times that of copper, the effect of iron on the spectral reflectance played a major role, and the iron content in soil must be considered in the inversion of copper content in soil. The Pearson correlation coefficient method was used as the selected characteristic wavelength, the selected wavelength was used as the independent variable, and the copper content in the soil was the dependent variable. Inversion model was built by the random forest algorithm, and the determination coefficient was 0.73. Under the condition of considering the interaction, the coefficient of determination was 0.87. It was shown that the characteristic wavelength was selected by considering the iron-copper interaction, which can better characterize the response signal of copper in soil. This paper provided a new idea for the accurate inversion of copper content in soil, which can provide technical support for the rapid detection of copper content in soil.

Catalytic Performance and Sulfur Dioxide Resistance of One-Pot Synthesized Fe-MCM-22 in Selective Catalytic Reduction of Nitrogen Oxides with Ammonia (NH3-SCR)-The Effect of Iron Content.

The catalytic performance of Fe-catalysts in selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) strongly depends on the nature of iron sites. Therefore, we aimed to prepare and investigate the catalytic potential of Fe-MCM-22 with various Si/Fe molar ratios in NH3-SCR. The samples were prepared by the one-pot synthesis method to provide high dispersion of iron and reduce the number of synthesis steps. We have found that the sample with the lowest concentration of Fe exhibited the highest catalytic activity of ca. 100% at 175 °C, due to the abundance of well-dispersed isolated iron species. The decrease of Si/Fe limited the formation of microporous structure and resulted in partial amorphization, formation of iron oxide clusters, and emission of N2O during the catalytic reaction. However, an optimal concentration of FexOy oligomers contributed to the decomposition of nitrous oxide within 250–400 °C. Moreover, the acidic character of the catalysts was not a key factor determining the high conversion of NO. Additionally, we conducted NH3-SCR catalytic tests over the samples after poisoning with sulfur dioxide (SO2). We observed that SO2 affected the catalytic performance mainly in the low-temperature region, due to the deposition of thermally unstable ammonium sulfates.

Effect of Iron Content on Microstructure and Mechanical Properties of Ti-Mo-Fe P/M Alloys

Effect of Iron Content on Microstructure and Mechanical Properties of Ti-Mo-Fe P/M Alloys

Magnetic Nanoparticles Supported on g‐C3N4 : An Efficient Heterogeneous Catalyst for Selective Transfer Hydrogenation of Furfural to Furfuryl alcohol

AbstractA series of economic and environmental benign g‐C3N4 supported magnetic ferrite nanoparticles (Fe3O4@g‐C3N4) were synthesized for the catalytic transfer hydrogenation of furfural (FF) into furfuryl alcohol (FFA) using ethanol as a source of hydrogen donor and solvent. The unique feature of high nitrogen content and locally conjugated structure of the g‐C3N4 have made it excellent support for loading of small sized ferrite nanoparticles. Excellent furfural conversion of 95.6 % was obtained with 100 % selectivity of the required product furfuryl alcohol over this Fe3O4@g‐C3N4 nanoparticles having mass ratio 0.2 of Fe3O4@g‐C3N4. The high surface properties, uniform dispersion of ferrite and very high ability of adsorption of furfural over g‐C3N4 attributed to the effective catalytic activity. The effect of iron content, catalyst amount, solvent, temperature and reaction time on the CTH of furfural were studied. The synthesized catalysts were characterised by various physic‐chemical, spectroscopic and microscopic techniques.

Effect of Iron Content on Corrosion Properties of Pure Titanium as Grain Refiner.

Microstructures and corrosion properties of pure titanium were characterized when iron was used as a grain refiner. The added Fe element acted as a strong grain refiner for pure titanium by forming β Ti phase at grain boundaries, and 0.15 wt% Fe was revealed to be a sufficient amount to make the grain size of pure titanium below 20 μm, which was the requirement for the desired titanium cathode. However, corrosion resistance was decreased with the Fe amount added. From the open circuit potential (OCP) results, it was obvious that the TiO2 stability against the reducing acid environment was deteriorated with the Fe amount, which seemed to be the main reason for the decreased corrosion resistance. Electrochemical impedance spectroscopy (EIS) results showed that both the decrease in the compact oxide film’s resistance (Rb) and the appearance of the outer porous film occurred as a result of the dissolution of the TiO2 layer, whose phenomena became more apparent as more Fe was added.

Proton magnetization relaxation in aqueous suspensions of composite silicon-iron nanoparticles for biomedical applications

Silicon-iron composite nanoparticles produced by arc-discharge plasma ablation method were characterized by scanning electron microscopy, dynamic light scattering, X-ray fluorescence diffractometry, and the effect of iron content and size of the nanoparticles on hydrogen nuclei magnetization relaxation were investigated by nuclear magnetic resonance relaxometry. It was shown that increasing in iron content during the synthesis leads to distortion of the spherical shape of the nanoparticles and increasing of their mean sizes from 140 nm to 350 nm. Nonlinear dependence of the longitudinal and transverse relaxivities from iron content was demonstrated. Increase in the iron concentration above 2.5 at. % leads to reduction of the both relaxivities, which can be explained by nonuniform distribution of iron and formation of iron containing agglomerates. It was shown that transverse and longitudinal relaxivities of the nanoparticles in their aqueous solutions inversely proportional from their hydrodynamic diameters in the range of 100 – 300 nm. The possibilities of using composite silicon-iron nanoparticles for biomedical applications are discussed.

Study of carbon dioxide hydrogenation to hydrocarbons over iron-based Catalysts: Synergistic effect

The full article will be published in the English version of the journal "Catalysis in Industry" No. 4, 2021.Hydrogenation of CO2 to CO and hydrocarbons is carried out over a wide range of catalysts. Group of VIIIB transition metals have proved high conversion and selectively for CO and methane. Meanwhile, low cost and effective catalysts are preferable in an industrial scale. In this work, the synergistic effect of iron content on the catalytic performance were investigated in carbon dioxide hydrogenation reaction. Incipient wetness impregnation procedure was used for the preparation of four γ-Al2O3 supported iron-based catalysts. BET, XRD, H2-TPR and TEM techniques were employed for the catalyst characterization. The evaluation of catalysts were carried out in a fixed bed reactor at the process conditions of temperature of 300 °C, pressure of 20 atm, H2 to CO2 ratio of 3 and GHSV of 3 nl.h–1·gCat–1. It was found that the promoter addition improves the activity of Fe catalyst for both Fischer – Tropsch synthesis (FTS) and Reverse Water Gas Shift (RWGS) reactions. The results showed that conversion of CO2 was from 15.6 to 35.6 % with major products of methane, C2 to C4, C5+ and CO. It was also found that impact of K and Ce promoters into iron catalyst showed the highest conversion and hydrocarbon yield due to the synergistic effect.

Conduction mechanisms and dielectric constant features of Fe doped ZnO nanocrystals

Fe doped ZnO nanocrystals (NCs) were synthesized from low cost sol gel method and the effect of iron content on their structural, transport and dielectric properties was studied. X-ray diffraction (XRD) measurements exhibit good crystalline quality of all the prepared NCs and a reduction of the crystallite size with Fe doping. Raman spectra confirmed the good crystallinity and revealed the formation of ferric phases for highly doped samples. Investigations of the impedance characteristics indicate that the samples are perfectly modulated from equivalent circuits using a constant phase element (CPE). Analysis of complex impedance and electrical modulus revealed a relaxation process dependent on temperature and of non-Debye type. Single activation energy was estimated for the electronic conduction, based on the Arrhenius plots. The conduction mechanism was governed from small polaron hopping in all the ZnO:Fe materials. The frequency dependence of the electric conductivity followed a simple Jonscher power behavior σac(ω)=σdc+Aωs (0.5≤ s ≤ 1), where the exponent s increased with temperature.The dielectric measurements, in both medium and high frequency regions, exhibited high dielectric constant values and low dielectric losses for all the samples, which could favor the use of Fe doped ZnO a as promising candidate for energy storage. The electrical modulus provides double relaxation times with low values. All the properties indicate that the ZnO:Fe material is suitable for device applications.

Effect of Iron content on the microstructure evolution, mechanical properties and wear resistance of FeXCoCrNi high-entropy alloy ‎system produced via MA-SPS

Abstract In the present study, the FexCoCrNi (x = 1, 1.3, 1.6) high entropy alloy (HEA) system was prepared by mechanical alloying (MA) and spark plasma sintering (SPS). The effect of iron content on the microstructure, mechanical properties, thermal behavior, and wear resistance of the FexCoCrNi (x = 1, 1.3, 1.6) HEA system was separately studied. It was found that all 3 alloys showed body-centered cubic (BCC) and face-centered cubic (FCC) solid solutions after 50 h of milling and an increase in the iron content was accompanied by an increase in the fraction of the BCC solid solution. Thermal stability of the FexCoCrNi (x = 1, 1.3, 1.6) HEA system was evaluated in the temperature range of 973–1273 K. The FCC structure was retained even after thermal exposure at 973, 1123, and 1273 K for all 3 alloys. The increase in Fe content led to a decrease in the sigma phase (FeCr or CoCr) formation temperature. The results of mechanical tests indicated that increasing Fe (1–1.6 mol) resulted in enhancement of ultimate tensile strength and hardness from 480 to 560 MPa and 320–400 Vickers, respectively. Wear resistance results demonstrated that the coefficient of friction (COF) and weight loss of this system decreases with increased Fe content. Moreover, the dominant wear mechanism changed from abrasive wear to adhesive wear.

Study on the depression mechanism of calcium on the flotation of high-iron sphalerite under a high-alkalinity environment

Although numerous studies on the flotation depression of sphalerite by calcium have been reported, certain issues warrant further investigation. Previous research works did not examine the role that the iron content of iron-bearing sphalerite plays in calcium depression and did not obtain direct and convincing microscopic evidence of calcium adsorption to support the depression of calcium-containing ions on iron-bearing sphalerite’s flotation. In this paper, the effects of iron content and the presence of calcium on iron-bearing sphalerite’s flotation depression under high alkalinity environment are studied using flotation tests, adsorption amount measurements, surface extraction, zeta potential measurements, time-of-flight secondary-ion mass spectrometry (TOF-SIMS) and density functional theory (DFT) calculations. The results show that increasing iron content or the presence of calcium will lead to an increase in the degree of flotation depression and will reduce the adsorption of copper and xanthate. Increasing iron content will cause the surface of iron-bearing sphalerite to adsorb more metal hydroxides (especially iron hydroxide) and calcium. The TOF-SIMS results confirmed the trend of calcium adsorption at the atomic level. DFT calculations show that the adsorption energy of CaOH+ on the surface of iron-substituted sphalerite is lower than that on the surface of ideal sphalerite. The following conclusions can be obtained through analysis of the aforementioned: Increase in the adsorption of hydroxides (especially iron hydroxide) and calcium significantly hinder the adsorption of copper and xanthate, and increase the hydrophilicity of high-iron sphalerite surface, which ultimately leads to an increase in the degree of flotation depression of high-iron sphalerite with increasing iron content.

The effect of iron content on properties of ZnO nanoparticles prepared by microwave hydrothermal method

Iron doped (in the range from 1 to 10 mol %) ZnO nanoparticles (NPs) were obtained by microwave hydrothermal method. The effects of iron content on morphology, crystal structure, optical and magnetic properties of ZnO nanoparticles were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), cathodoluminescence (CL), photoluminescence (PL) and magnetic measurements. XRD studies revealed presence of ZnFe2O4 foreign phase in NPs for iron doping concentrations above 5% placing the solubility limit of Fe in ZnO NPs near this value. The photoluminescence and cathodoluminescence spectra show an increase of the intensity ratio between near band edge (NBE) and deep level emission band (DLE) of ZnO, which is tentatively related by us with intrinsic cracking of ZnO crystals. The blue-shift of NBE band maxima was observed as a concentration of Fe dopant increases. The results of magnetic measurements indicate superparamagnetic behavior of nanoparticles.

Effect of iron content on microstructure and properties of FexNi2Co2CrTiNb high-entropy alloy coating

FexNi2Co2CrTiNb (x = 0, 0.5, 1, 2) high-entropy alloy coatings were fabricated on 45 steel by laser cladding. The phase, microstructure, hardness and wear resistance of FexNi2Co2CrTiNb coatings are studied systematically. The results behave that FexNi2Co2CrTiNb (x = 0, 0.5, 1, 2) coatings are composed of FCC and BCC solid solutions. When the Fe content increases from 0 to 2, the BCC phase in the coating increases significantly while the FCC phase decreases notably, the microstructure of FexNi2Co2CrTiNb coating evolves from coarse dendrites to the fine dendritic clusters in the general form of columnar or equiaxed crystals. The hardness of each FexNi2Co2CrTiNb (x = 0, 0.5, 1, 2) coating is much higher than that of the substrate. The highest hardness measured reaches up to 873.40 HV, which is about 3 times the hardness of the substrate. The average hardness of the FexNi2Co2CrTiNb coating presents an increasing trend with the increase of Fe content, the average hardness of Fe2Ni2Co2CrTiNb coating is 40.74 % higher than that of the Fe0Ni2Co2CrTiNb coating. Correspondingly, Fe2Ni2Co2CrTiNb coating with the highest hardness has the best wear resistance. The Fe2Ni2Co2CrTiNb coating with excellent wear resistance can be fully applied to various tools, molds and mechanical parts that require high hardness and superior wear resistance.

Effect of iron content on the wear behavior and adhesion strength of TiC–Fe nanocomposite coatings on low carbon steel produced by air plasma spray

In this study, the effect of Fe content on the abrasion behavior of TiC–Fe nanocomposite coatings applied on the CK45 steel substrate by air plasma spray method was investigated. For this purpose, milled TiC powder was prepared at 1, 2, 3 and 4 h milled TiC powder for 4 h was selected as the suitable sample. In the next step, a suitable sample mixture with different iron powder concentrations of 5, 10, 15, 20 and 25% was prepared by mechanical milling. The granulated mixture was applied to the substrate using air plasma spray technique. Microstructural and phase analyzes were performed using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). According to the results of Williamson-Hall calculations, the TiC crystallites' size decreased by 49 nm–29 nm, and network strain reached 0.16% by increasing milling time from 1 h to 4 h. Studies have shown that the coatings contain titanium carbide, iron oxide, and titanium oxide, with the number of phases formed depending on the amount of iron in the chemical composition. Investigation of the tribological properties of the coating layer showed that with increased iron content in the coating, the wear resistance of the samples is reduced. Hardness tests on coatings indicate that adding iron to nanocomposite from 5 to 25% reduces hardness from 1025 to 699 Hv. It can be argued that a slight increase in the adhesion strength of the coating to the substrate is due to increased wettability because of the formation of molten iron in the coating.