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Green rusts with brucite-like layers of hydroxide intercalated with anions constitute a family of diverse precursors for the synthesis of iron oxides via dehydration, but precise structural control of the resulting oxides with respect to the size and shape at the nanometer level remains challenging due to the easy oxidation of the ferrous species. Herein, we report a new synthetic strategy for the facile preparation of fibrous-like green rusts by using appropriate balancing anions (CO32− and SO42−) in ethylene glycol to regulate the morphology. Depending on the type of the intercalating anion, the green rusts were converted into hematite with fibrous- or plate-like shapes upon thermal activation. When evaluated in the reaction of NO reduction by CO, these iron oxides showed a prominent shape-dependent catalytic behavior. The fibrous-like Fe2O3 was much more catalytically active and structurally robust than the plate-like analogue. Combined spectroscopic and microscopic characterizations on the nanostructured iron oxides revealed that the superior performance of the fibrous-like Fe2O3 stemmed from a facile Fe2O3/Fe3O4 redox cycle and a higher density of active sites for NO activation.

Iron oxide copper-gold (IOCG) deposits are major sources of Cu, contain abundant Fe oxides, and may contain Au, Ag, Co, rare earth elements (REEs), U, and other metals as economically important byproducts in some deposits. They form by hydrothermal processes, but the source of the metals and ore fluid(s) is still debated. We investigated the geochemistry of magnetite from the hydrothermal unit and manto orebodies at the Mina Justa IOCG deposit in Peru to assess the source of the iron oxides and their relationship with the economic Cu mineralization. We identified three types of magnetite: magnetite with inclusions (type I) is only found in the manto, is the richest in trace elements, and crystallized between 459° and 707°C; type Dark (D) has no visible inclusions and formed at around 543°C; and type Bright (B) has no inclusions, has the highest Fe content, and formed at around 443°C. Temperatures were estimated using the Mg content in magnetite. Magnetite samples from Mina Justa yielded an average δ56Fe ± 2σ value of 0.28 ± 0.05‰ (n = 9), an average δ18O ± 2σ value of 2.19 ± 0.45‰ (n = 9), and Δ’17O values that range between –0.075 and –0.047‰. Sulfide separates yielded δ65Cu values that range from –0.32 to –0.09‰. The trace element compositions and textures of magnetite, along with temperature estimations for magnetite crystallization, are consistent with the manto magnetite belonging to an iron oxide-apatite (IOA) style mineralization that was overprinted by a younger, structurally controlled IOCG event that formed the hydrothermal unit orebody. Altogether, the stable isotopic data fingerprint a magmatic-hydrothermal source for the ore fluids carrying the Fe and Cu at Mina Justa and preclude significant input from meteoric water and basinal brines.

Fe-based catalysts are efficient systems for CO2 conversion via reverse water-gas shift (rWGS) reaction. Nevertheless, the nature of the active phase, namely metallic iron, iron oxide or iron carbide remains a subject of debate which our paper is meant to close. Fe0 is a much better catalyst for the rWGS than Fe3C. The activity of Fe0 can be promoted by the addition of Cs and Cu whose presence hinders iron carburisation while favouring both higher conversion and enhanced selectivity. When the samples are aged in the rWGS reaction mixture during stability test a new phase appear: Fe5C2, resulting in a more active but less selective catalysts than Fe0 for the rWGS reaction. Hence our results indicate that we could potentially achieve an optimal activity/selective balance upon finely tuning the proportion Fe/Fe5C2. Beyond the fundamental information concerning active phase we have observed the presence of advanced Fischer-Tropsch-like products at ambient pressure opening new opportunities for the design of hybrid rWGS/Fischer-Tropsch systems.

Molecular interactions between 4-OH-cinnamate and cetrimonium in solution result in improved adsorption of the cinnamate on mild steel, developing a protective mechanism against the diffusion of corrosive chloride to the oxide surface. Fundamental understanding of this mechanism should allow new design routes for the development of eco-friendly corrosion inhibitors.Via classic molecular dynamics, simulations were carried out for cetrimonium and 4-OH-cinnamate in aqueous solutions at different ionic strengths and the results were validated with experimental SAXS data. Self-aggregation of cetrimonium 4-OH-cinnamate on a hydrated hematite surface was then simulated and results were compared with cryo-TEM imaging for the same compound. Finally, the effect of the adsorbed aggregates on chloride diffusion to the oxide surface was modelled.Simulations showed the encapsulation of 4-OH-cinnamate into cetrimonium micelles, consistent with experiments. The newly formed micelles adsorb onto a hydrated iron oxide surface by forming hydrogen bonds between their carboxylate outer-shell groups and the surface hydroxyls. As the adsorbate concentrations increase, there is a morphological transition from spherical to wormlike adsorbed aggregates. The wormlike structure can block chloride ions, demonstrating a synergistic inhibitory mechanism between both cetrimonium and 4-OH-cinnamate. Encapsulation and delivery of active compounds to certain targets, such as carcinogenic tumors, have been well studied in biochemistry research, we demonstrate that the same mechanism can be applied to the design of efficient corrosion inhibitors, optimizing their delivery to the metal surface.

Hypothesis Some of the most promising fields of application of ionic liquid-based colloids imply elevated temperatures. Their careful design and analysis is therefore essential. We assume that tuning the structure of the nanoparticle-ionic liquid interface through its composition can ensure colloidal stability for a wide temperature range, from room temperature up to 200 °C. Experiments The system under study consists of iron oxide nanoparticles (NPs) dispersed in ethylmethylimidazolium bistriflimide (EMIM TFSI). The key parameters of the solid-liquid interface, tuned at room temperature, are the surface charge density and the nature of the counterions. The thermal stability of these nanoparticle dispersions is then analysed on the short and long term up to 200 °C. A multiscale analysis is performed combining dynamic light scattering (DLS), small angle X-ray/neutron scattering (SAXS/SANS) and thermogravimetric analysis (TGA). Findings Following the proposed approach with a careful choice of the species at the solid-liquid interface, ionic liquid-based colloidal dispersions of iron oxide NPs in EMIM TFSI stable over years at room temperature can be obtained, also stable at least over days up to 200 °C and NPs concentrations up to 12 vol% ( ≈ 30 wt%) thanks to few near-surface ionic layers.

Various advanced microwave absorbing materials have been developed for reducing/avoiding the harm of microwave radiation. Among them, core-shell structural nanomaterials have been widely fabricated for microwave absorption. However, the “structure-performance” relationship between shell thickness and microwave absorption performance is rarely reported. In this paper, we first explored the “structure-performance” relationship between shell thickness and microwave absorption performance, based on the core-shell α-Fe2O3@SiO2 nanoparticles with a constant α-Fe2O3-core size and changeable SiO2-shell thickness. With increasing the SiO2-shell thickness, the microwave absorption ability first increased, then decreased. Under a proper SiO2-shell thickness of 35 nm, α-Fe2O3@SiO2 sample achieved the strongest microwave absorbing ability with a reflection loss minimum value of –4.3 dB, better than that of pure α-Fe2O3 (–3.8 dB). This enhanced microwave absorption performance was mainly derived from the dielectric loss. Although the absolute value of the reflection loss was relatively low (–4.3 dB), this study shed an important reference on designing next-generation advanced iron oxide-based materials for microwave absorption.

Preparation of hierarchal structures of various dimensions in a single in-situ step is extremely challenging. However, they have gained huge attention for energy storage to electrocatalysis. Here, self-composed cerium iron oxide hierarchal structures are prepared using a novel in-situ process using urea as a ligand. The formed hierarchal structures are made of sheets, rods, and spherical particles. The deposition of the formed spherical particles on the surface of sheets and rods is observed. The prepared cerium iron oxide hierarchal structures are used as a catalyst for the electrooxidation of methanol. As an electrocatalyst, hierarchal structures showed a high specific current density of ∼274 mA cm–2. The observed onset potential for the cerium iron oxide is ∼0.44 V. The retention of ∼93.5% of the initial current density after 5000 consecutive seconds is observed. The iron present in cerium iron oxide hierarchal structures increases oxygen vacancies responsible for the observed superior methanol oxidation reaction activity. Results confirmed that hierarchal cerium iron oxide structures showed higher electrocatalytic activity than pristine cerium oxide and iron oxide materials.

The degradation of the anti-inflammatory ibuprofen (IBP) was evaluated by several advanced oxidation processes. IBP was treated by single ozonation and oxidation with hydrogen peroxide (H2O2), as well as a combination of these treatments. In order to improve the efficiency, the presence of catalysts such as original carbon nanotubes, labelled as CNT, and iron oxide supported on carbon nanotubes, named as Fe/CNT sample, was considered. The evolution of IBP degradation, mineralization and toxicity of the solutions was assessed. The formation of intermediates was also monitored. In the non-catalytic processes, IBP was faster removed by single ozonation, whereas no significant TOC removal was achieved. Oxidation with H2O2 did not present satisfactory results. When ozone and H2O2 were combined, a higher mineralization was attained (70% after 180 min of reaction). On the other hand, in the catalytic processes, this combined process allowed the fastest IBP degradation. In terms of mineralization degree, the presence of Fe/CNT increases the removal rate in the first hour of reaction, achieving a TOC removal of 85%. Four compounds were detected as by-products. All treated solutions presented lower toxicity than the initial solution, suggesting that the released intermediates during applied processes are less toxic.

Elucidation of reaction mechanisms in forming nanostructures is relevant to obtain robust and affordable protocols that can lead to materials with enhanced properties and good reproducibility. Here, the formation of magnetic iron oxide monocrystalline nanoflowers in polyol solvents using N-methyldiethanolamine (NMDEA) as co-solvent has been shown to occur through a non-classical crystallization pathway. This pathway involves intermediate mesocrystals that, in addition, can be transformed into large single colloidal nanocrystals. Interestingly, the crossover of a non-classical crystallization pathway to a classical crystallization pathway can be induced by merely changing the NMDEA concentration. The key is the stability of a green rust-like intermediate complex that modulates the nucleation rate and growth of magnetite nanocrystals. The crossover separates two crystallization domains (classical and non-classical) and three basic configurations (mesocrystals, large and small colloidal nanocrystals). The above finding facilitated the synthesis of magnetic materials with different configurations to suit various engineering applications. Consequently, the effect of the single and multicore configurations of magnetic iron oxide on the biomedical (magnetic hyperthermia and enzyme immobilization) and catalytic activity (Fenton-like reactions and photo-Fenton-like processes driven by visible light irradiation) has been experimentally demonstrated.

In this work, Ce and Cr/Co co-doped iron oxide (FeCeMOx, where M = Cr or Co) ferrites were investigated for high-temperature water-gas shift (HT-WGS) under industrially relevant pressures (20 bars). The Ce and Cr/Co bi-doping has greatly promoted the catalytic performance in comparison to the single Ce-doping. Especially, the FeCeCoOx ferrite demonstrated the best HT-WGS activity without any deactivation at a steam to CO ratio of 3.5. The ternary FeCeCrOx and FeCeCoOx catalysts also exhibited reasonably stable performance with a slight methanation activity (

In this research, we investigate the effects of pure and cobalt substitution on the size development, crystal erection, and attractive possessions of -Fe2O3 nanoparticles, which were synthesised using the Sol-Gel process. X-ray Diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and Fourier Transform Infrared Spectroscopy (FTIR) were used to analyse crystalline nature, magnitude, outline, and chemical composition of iron oxide (Fe2O3) nanoparticles (FT-IR). The change in direct band gaps is demonstrated by UV-Visible spectroscopy and compared to XRD findings. Furthermore, an XRD spectrum survey indicated that the material had a cubic structure. Scanning Electron Microscopy may be cast-off to characterise the morphologies and structures of iron oxides. The use of EDX to analyse elements revealed that cobalt doping had been successful. At room temperature, magnetic characteristics were resolute using a Vibrating Sample Magnetometer (VSM). Magnetic tests revealed that, when compared to pure and cobalt-doped nanoparticles, there is a significant difference. Furthermore, the doping content has a significant impact on magnetic characteristics.

The titanium-bearing iron sand (TIS) riches Fe, Ti and V elements and exhibits great value in ironmaking. The agglomeration of TIS is difficult due to complex mineralogical characteristics. In this study, the ball-milling pretreatment was conducted to improve the particle interface characteristics and promote the oxidation-consolidation behavior of TIS. The results show that the transition of TIS from spherical to polyhedral structure could disaggregate the interlocked gangue and iron oxide and produce large amounts powders adhering on the TIS surface, which promotes the interface behavior and increase the molten slag formation in oxidation-roasting. Besides, the introduced lattice defects of titanium hematite accelerate the oxidation and recrystallization behaviors, thereby strengthening consolidation and increasing the TIS pellet compressive strength with lowering bentonite addition. After ball-milling pretreatment and preparation parameters optimization, the TIS pellet exhibits favorable compressive strength, reducibility and softening-melting behavior, fully meeting the BF smelting requirements.

The effects of cobalt incorporation in spherical heterostructured iron oxide nanocrystals (NCs) of sub-critical size have been explored by colloidal chemistry methods. Synchrotron X-ray total scattering methods suggest that cobalt (Co) substitution in rock salt iron oxide NCs tends to remedy its vacant iron sites, offering a higher degree of resistance to oxidative conversion. Self-passivation still creates a spinel-like shell, but with higher volume fraction of the rock salt Co-containing phase in the core. The higher divalent metal stoichiometry in the rock salt phase, with increasing Co content, results in a population of unoccupied tetrahedral metal sites in the spinel part, likely through oxidative shell creation, involving an ordered defect-clustering mechanism, directly correlated to the core stabilization. To shed light on the effects of Co-substitution and atomic-scale defects (vacant sites), Monte Carlo simulations suggest that designed NCs, with desirable, enhanced magnetic properties (cf. exchange bias and coercivity), are developed with magnetocrystalline anisotropy raised at relatively low content of Co ions in the lattice. Growth of optimally performing candidates combines also a strongly exchange-coupled system, secured through a high volumetric ratio rock salt phase, interfaced by a not so defective spinel shell. In view of these requirements, Specific Absorption Rate (SAR) calculations demonstrate that the sufficiently protected from oxidation rock salt core and preserved over time heterostructure, play a key role in magnetically-mediated heating efficacies, for potential use of such NCs in magnetic hyperthermia applications., Main text of 23 pages, 12 Figures. Supplementary Information of 17 pages, 9 Figures, 4 Tables

The susceptibility of super paramagnetic iron oxide (SPIO) particles makes them a useful contrast agent for different purposes in MRI. These particles are typically quantified with relaxometry or by measuring the inhomogeneities they produced. These methods rely on the phase, which is unreliable for high concentrations. We present in this study a novel Deep Learning method to quantify the SPIO concentration distribution. We acquired the data with a new sequence called View Line in which the field map information is encoded in the geometry of the image. The novelty of our network is that it uses residual blocks as the bottleneck and multiple decoders to improve the gradient flow in the network. Each decoder predicts a different part of the wavelet decomposition of the concentration map. This decomposition improves the estimation of the concentration, and also it accelerates the convergence of the model. We tested our SPIO concentration reconstruction technique with simulated images and data from actual scans from phantoms. The simulations were done using images from the IXI dataset, and the phantoms consisted of plastic cylinders containing agar with SPIO particles at different concentrations. In both experiments, the model was able to quantify the distribution accurately.

The effects of adding iron oxide to ceramic glaze formulations were studied in this study. Iron oxide was added in different weight ratios into the reactive transparent glaze, reactive opaque glaze, and transparent glaze formulations. The iron oxide content in the glaze composition, the coloring mechanisms, the phase distributions, and surface properties at temperatures of 950–1000-1050-1200 °C in the oxidation firing medium were investigated. Scanning Electron Microscopy (SEM) to determine the microstructural and morphological characterizations of the test glazes, X-Ray Diffractometry (XRD) to determine the crystallographic properties and phases, and X-Ray Fluorescence (XRF) analyses to determine the elemental and chemical composition were performed. In addition to these, surface images were examined with Digital Microscope (DM) and Commission Internationale de l'Eclairage (CIE) L*a*b, and water absorption values were compared. In addition, taking into account environmental factors, a comparison of ceramic glazes with the same amount of waste iron oxide was also performed for same purpose. As a result of the studies, it was observed that the addition of iron oxide and/or waste iron oxide did not have a negative effect, and coloring effects on the glaze layer were observed at different rates and firing temperatures.

Murray-Darling Freshwater Research CentreMDFRC item.Filter-papers impregnated with iron oxides (“iron-strips”) are increasingly being used to estimate “bioavailable” phosphorus. This study shows that these strips, in addition to being able to adsorb phosphate ions, can also mediate the hydrolysis of a model organic phosphorus compound. It is proposed that the high correlation between bioavailable phosphorus and iron-strip available phosphorus is due in part to the strips' hydrolytic capability.

In this study, the anodized iron oxide films with micro-nano structure were prepared by a combination of heat treatment and anodization. The adjustment of these oxide films at the micron-scale was achieved by heat treatment on substrate to modify the position of the cementite and ferrite. The distribution and existing forms of carbon on cementite and ferrite determine the morphology of their respective anodization. It was found annealing at 300 °C can improve the crystallinity of iron oxide and maintain the original micro-nano structure. Although the crystal quality of iron oxide can be further improved with higher annealing temperature, it would result in the collapse of nanoporous structures and the reconstruction of the surface morphology. Furthermore, anodized samples made from those with lamellar ferrite and cementite show better specific capacitance. The iron oxide film on the annealed substrate obtained the highest specific capacitance of 35.3 mF/cm2 at a scan rate of 20 mV/s in our samples.

At present day, the actual physics behind the polarization mechanism in composite materials remains elusive. In this study, we introduce graphene oxide sheets, decorated with iron oxide nanoparticl...

Environmental remediation has become more effective when using nanotechnologies. In this study, iron oxide (α-Fe2O3) nanospheres with different cobalt doping levels (xCo-Fe2O3) were synthesised and applied in the heterogeneous activation of peroxymonosulfate (PMS) for the degradation of p-hydroxybenzoic acid (p-HBA). The catalyst (3Co-Fe2O3) with 3% Co doping exhibits the best performance for PMS activation, possibly because of the larger specific surface area and the tailored catalyst surface as confirmed by X-ray photoelectron spectroscopy (XPS). Reaction parameters were investigated to optimise the degradation efficiency. The metal ions leaching tests confirmed the higher stability of the catalyst, thanks to the leaching suppression by the doping of Co2+. The main contribution of free radicals (SO4•- and •OH) was confirmed by electron paramagnetic resonance (EPR) spectra, whereas partial contribution of oxygen anions and singlet oxygen (O2•-, 1O2) was observed during the quenching tests. Finally, a radical based degradation mechanism was proposed for the removal of p-HBA. It is expected to open up a novel perspective for the application of iron oxide as a potential catalyst for the removal of emerging contaminants.

Nanoadsorbents having large specific surface area, high pore volume with tunable pore size, affordability and easy magnetic separation gained much popularity in recent time. Iron-based nanoadsorbents showed higher adsorption capacity for different pollutant removal from water among other periodic elements. Spinel ferrite nanomaterials among iron-bearing adsorbent class performed better than single iron oxide and hydroxides due to their large surface area, mesoporous pore, high pore volume and stability. This work aimed at focusing on water treatment using magnesium ferrite (MgFe2O4) nanomaterials. Synthesis routes, properties and pollutant adsorption were critically investigated to explore the performance of magnesium ferrite in water treatment. Structural and surface properties were greatly affected by the factors involved in different synthesis routes and iron and magnesium ratio. Complete removal of pollutants through adsorption was achieved using magnesium ferrite. Pollutant adsorption capacity of MgFe2O4 and its modified forms was found several folds higher than Fe2O3 and Fe3O4 nanomaterials. In addition, MgFe2O4 showed strong stability in water than other pure iron oxide and hydroxide. Modification with graphene oxide, activated carbon, biochar and silica was demonstrated to be beneficial for enhanced adsorption capacity. Complex formation was suggested as a dominant mechanism for pollutant adsorption. These nanomaterials could be a viable and competitive adsorbent for diverse pollutant removal from water.

To gain a better understanding of the performance characteristics of a shaft furnace for hydrogen reduction of iron oxide pellets under operation with top gas recycling (TGR), a kinetic model was applied to investigate the coupled phenomena of gas-solid countercurrent reactive flow and heat transfer. The effects of operating parameters were studied for scenarios where the furnace is equipped with a single-row injection TGR system. The potential of a new TGR system featuring dual-row injection was also assessed preliminarily. The results showed that the productivity of the shaft furnace is much higher than in a syngas-based shaft furnace provided that a high mass flow of feed gas can be ensured to introduce adequate sensible heat. Hot charging of the pellets yielded an increase in the total energy consumption so the scope to reduce the gas mass flow by this method was found to be limited due to the poor heat utilization. By contrast, using a dual-row gas injection system was found to improve the performance, especially with respect to gas utilization and total energy consumption. This is chiefly attributed to a clear improvement in the thermochemical state of the furnace, which leads to a better utilization of the furnace volume.

Herein, a red iron oxide @ carbon fiber (RIO@CF) composite is prepared via a simple and effective single hydrothermal and calcination process. The physico-chemical characteristics of as-prepared electrode active materials are examined by X-ray photoelectron spectroscopy, high resolution field emission-scanning electron microscopy and field emission-tunneling electron microscopy analyses. When used as the anode material in the Li-ion battery, as-prepared RIO@CF composite have shown a specific capacity of 1138 mAh g−1 after 150 cycles with a capacity retention of 86% at a current density of 100 mA g−1. Moreover, a specific capacity of 825 mAh g−1 is achieved in the first cycle at a current density of about 5000 mA g−1. Thus, when compared to the pristine nano-cube-like red iron oxide (RIO) electrode material, the RIO@CF composite electrode exhibits an outstanding cyclic stability and rate capacity. This electrochemical enhancement facilitates effective lithium ion transport into the RIO@CF composite electrode, thus improving the electrical conductivity. In addition, the application of a homogeneous carbon fiber coating can provide effective contact between the electrode surface and the electrolyte to further benefit the electrochemical performance.

Constructing a distinctive electrochemical interface with low platinum content to boost the sluggish methanol electrooxidation kinetics is critical for commercializing the direct methanol fuel cells. Herein, we have synthesized highly active electrocatalysts with unique intermetallic-metal oxide interfaces through a facile pyrolysis method. Physical characterizations demonstrate that the obtained PtFe(1:2)@a-FeOx/NC-C catalyst with low platinum content of 7.2 wt% possesses an interfacial structure composed of face-centered tetragonal (L10) PtFe intermetallic nanoparticles accompanied with amorphous iron oxide. Electrochemical measurements show that the synthesized PtFe(1:2)@a-FeOx/NC-C catalyst not only exhibits excellent methanol electrooxidation activities with a mass activity of 1.48 A mg-1Pt and a specific activity of 2.34 mA cm-2Pt in acid medium, but also possesses better CO-tolerant performance and faster methanol oxidation kinetics compared with commercial Pt/C. The improved electrochemical performances may ascribe to the modified electronic structure by alloying platinum with iron and the special PtFe@a-FeOx interface, which render strong synergistic interactions between bimetallic PtFe nanoparticles and amorphous iron oxide. Consequently, the presented strategy offers new prospects into the construction of low-cost electrocatalysts with unique electrochemical interface for enhancing catalytic performances.

18% Ni-Co-Mo-Ti ferrous base alloys are special materials, widely used in the industry of isotopic enrichment after specific annealing and aging thermal treatment. The desirable high mechanical properties can then be attained by adequate aging heat treatment, answering the structural materials specifications required by defense applications in aerospace and nuclear engineering. For instance, the isotopic enrichment, in rocket engine envelope application, when associated with high temperature and chemical residues like acidic solutions, can induce corrosion and hydrogen embrittlement in martensitic microstructure. In order to limit these corrosion and hydrogen embrittlement phenomena, adherent and protective layers of iron oxides can be grown on the material’s surface by performing aging treatment in an adequate atmosphere. Due to its application in strategic areas, the characterization of these oxide layers in maraging steels is of importance as well as the understanding of their growth kinetics. For this purpose, several techniques, such as optical microscopy (OM), scanning electron microscopy (SEM), glow discharge optical emission spectroscopy (GDOES), microabrasive wear testing, hardness, grazing incidence X-ray diffraction (GIXRD), and X-ray photoelectron spectroscopy (XPS), have been performed for chemical and structural characterization of the oxide films formed after vapor exposed thermal aging at 510℃. The oxide layer consists of two sub-layers composed by magnetite ( $${Fe}_{3}{O}_{4}$$ ) and an external layer of hematite ( $${Fe}_{2}{O}_{3}$$ ). A thick interface between the oxide layer and the bulk is enriched in Ti and Mo, whereas the analyses of deep bulk material show an enriched area with Ni and Co.

El desarrollo de nuevos sensibilizadores para la degradación fotoquímica de contaminantes ha sido un foco de atención en los últimos años, es por ello que los nanomateriales han tomado una gran relevancia en este campo. En este contexto, se trabajó en la síntesis de un nuevo nanomaterial de óxido de hierro (Fe3O4) y plata (Ag), el cual fue obtenido en dos etapas; en primer lugar se sintetizaron las nanopartículas de magnetita (NPs) para luego adsorber plata sobre éstas obteniendo el nanocompuesto (NC) de Fe3O4/Ag. Se evaluó su capacidad como fotosensibilizador en la fotodegradación aireada del alcohol furfurílico, donde se observó la degradación del mismo aunque con una baja eficiencia.

Conversion reaction-based transition metal oxides have been considered as advanced anode materials for lithium batteries because of their high storage capacities; however, the initial lithiation/de...

A carboxyl-terminated fullerene pyrrolidine derivative was synthesized by 1, 3-dipolar cycloaddition of imine ylide (FP-COOH). UV-Vis, FT-IR and MALDI-TOF respectively verified the effective synthesis of compounds. The compound (FP-COOH) was used as an intermediate, and then the hydrothermal chemical bonding method was used to load ferric oxide on the compound (FP-COOH). Its purpose was to form a magnetic targeting carrier system (FP-IONP-COOH). Then use the non-covalent method to combine FP-IONP-COOH with doxorubicin. The ultimate goal was to improve the side effects of doxorubicin. The solubility experiments showed that both FP-IONP-COOH and FP-IONP-COOH/DOX had good water solubility. The investigation of magnetism showed that FP-IONP-COOH has good magnetism. Finally, in vitro release experiments further verified the targeting of FP-IONP-COOH/DOX. The cumulative release of DOX at 48 h could be as high as 82 %, whereas the accumulated release of FP-IONP-COOH/DOX at 48 h was only 48 %, and was able to continuously release for more than 120 h, demonstrating its good sustained release in vivo.

Magnetic iron oxide-silica shell nanocomposites (IONP@SiO2) have been prepared in a two-step procedure. IONPs were obtained by coprecipitation of iron salts, and coated by silica in sol-gel method under sonication. Two IONP/silica ratios and two drying methods, heating in oven and supercritical CO2 drying, were used. The samples were analyzed using X-ray diffraction (XRD), infrared spectroscopy, magnetic measurements, small-angle neutron scattering (SANS), nitrogen sorption, and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis (EDX). The iron oxide silica nanocomposites obtained via supercritical drying exhibited higher values of the specific surface area and of saturation magnetization compared to the samples synthesized with the same iron oxide content but obtained after drying at 60 °C. Pd(II) adsorption experiments were performed on the materials prepared by supercritical drying. The maximum adsorption capacity 6.5 mg/g showed that the materials can be used as good and cheap adsorbent for palladium ions from aquatic environment.

The WO3 is a promising photoanode material for photoelectrochemical (PEC) water oxidation. Loading co-catalysts is an effective strategy for favoring the charge transfer and light harvesting of WO3, which can in turn improve its PEC performance. Herein, the ferrihydrite (Fh), a kind of poorly crystalline iron oxide material, was loaded on the WO3 photoanode through a two-step hydrothermal synthesis. The obtained Fh/WO3 photoanode exhibited a remarkable photocurrent density of 0.6 mA/cm2 at 1.23 V (vs. RHE), which was 1.79 times higher than the bare WO3. For the Fh/WO3 photoanode, the bulk charge separation efficiency is 45.6% and the photoconversion efficiency is 0.066%, which are both higher than the bare WO3. The decorated Fh can form an additional interface between the WO3 and the electrolyte, which decreases the impedance and favors the charge transfer. Moreover, the Fh can function as a hole storage layer, which can temporarily store the photogenerated holes and induce the longer lifetime of charge carriers, thus improving the charge separation and water oxidation reaction kinetics.

A prototype electromagnetic vibrator, referred to here as E-Vib, was upgraded and developed for broadband hardrock and mineral exploration seismic surveys. We selected the iron oxide mine in Blötberget, central Sweden, for a test site in 2019 for the newly developed E-Vib because of the availability of earlier seismic datasets (from 2015 to 2016) for verification of its performance for hardrock imaging purposes. The two-dimensional data acquisition consisted of a fixed geometry with 550 receiver locations spaced at every 5 m, employing both cabled and wireless seismic recorders, along an approximately 2.7 km long profile. The E-Vib operated at every second receiver station (i.e. 10 m spacing) with a linear sweep of 2–180 Hz and with a peak force of 7 kN. The processing workflow took advantage of the broadband signal generated by the E-Vib in this challenging hardrock environment with varying ground conditions. The processed seismic section shows a set of reflections associated with the known iron oxide mineralization and a major crosscutting reflection interpreted to be from a fault system likely to be crosscutting the mineralization. The broadband source data acquisition and subsequent processing helped to improve signal quality and resolution in comparison with the earlier workflows and data where a drophammer seismic source was used as the seismic source. These results suggest new possibilities for the E-Vib source for improved targeting in hardrock geological settings.

Coatings have been used for a significant number of years in the Direct Reduction industry, and the ISO Cluster Index plays an important role in this context since it allows a better predictability of pellet performance in the industrial process. The present work developed a series of tests and characterization in order to better understand which materials, methods, and characteristics would be most relevant to decrease the clustering index. It was noticed that coating on green pellets is worse as compared to the conventional application method which coats the pellets after the hardening process in the pelletizing furnace. In an evaluation of predictive parameters, it was observed that the adhesion index and the sum of SiO2, Al2O3, CaO, and MgO content influence the clustering index response variable. Consequently, it was observed that the adhesion index is proportional to the microporosity and mesoporosity of the coating materials. Bauxite was the material that showed the best performance. Its differentials were the high content of Al2O3 combined with its high microporosity/mesoporosity, i.e., pores with diameter up to 50 nm.

The chemical precipitation was used to obtain carbon fibers (CF) with surface modified by magnetite particles (Fe3O4). Processing was carried out by employing up to three subsequent coating stages ...

Among iron oxide phases, magnetite Fe3O4 is often the preferred one for nanotechnological and biomedical applications because of its high saturation magnetization and low toxicity. Although there are several synthetic routes that attempt to reach magnetite nanoparticles NPs , they are usually referred as IONPs iron oxide NPs due to the great difficulty in obtaining the monophasic and stoichiometric Fe3O4 phase. Added to this problem is the common increase of size shape polydispersity when larger NPs D gt; 20 nm are synthesized. An unequivocal correlation between a nanomaterial and its properties can only be achieved by the production of highly homogeneous systems, which, in turn, is only possible by the continuous improvement of synthesis methods. There is no doubt that solving the compositional heterogeneity of IONPs while keeping them monodisperse remains a challenge for synthetic chemistry. Herein, we present a methodical optimization of the iron oleate decomposition method to obtain Fe3O4 single nanocrystals without any trace of secondary phases and with no need of postsynthetic treatment. The average dimension of the NPs, ranging from 20 to 40 nm, has been tailored by adjusting the total volume and the boiling point of the reaction mixture. Mössbauer spectroscopy and DC magnetometry have revealed that the NPs present a perfectly stoichiometric Fe3O4 phase. The high saturation magnetization 93 2 A m2 kg at RT and the extremely sharp Verwey transition at around 120 K shown by these NPs have no precedent. Moreover, the synthesis method has been refined to obtain NPs with octahedral morphology and suitable magnetic anisotropy, which significantly improves the magnetic hyperthemia performance. The heating power of properly PEGylated nano octahedrons has been investigated by AC magnetometry, confirming that the NPs present negligible dipolar interactions, which leads to an outstanding magnetothermal efficiency that does not change when the NPs are dispersed in environments with high viscosity and ionic strength. Additionally, the heat production of the NPs within physiological media has been directly measured by calorimetry under clinically safe conditions, reasserting the excellent adequacy of the system for hyperthermia therapies. To the best of our knowledge, this is the first time that such bulklike magnetite NPs with minimal size shape polydispersity, minor agglomeration, and exceptional heating power are chemically synthesized

The magnetic particles modified with silicon dioxide (SiO2) and amino groups (-NH2), as well as the magnetic particles modified with human serum albumin (HSA) were synthesized using the approaches we developed before and characterized by physico-chemical methods in this study. Plasminogen was chosen as a model protein since plasminogen plays a major role in the fibrinolytic system and plasminogen level correlates with different pathologies and conditions. For the first time it has been carried out qualitative and quantitative assessment of plasminogen nonspecific binding (noncovalent adsorption) by the particles in buffer and plasma solutions. The fibrinolytic activity of plasminogen on the surface of the particles has been measured by the aid of commercially available kits and appeared to be 28-30% of its initial value. Plasminogen desorption from the surface of particles was studied in phosphate buffer with NaCl and e-aminocaproic acid. Despite nonspecific plasminogen binding is an undesirable process, the data obtained is valuable for further modification of particles for high-specific proteins extraction from biological fluids or transport of plasminogen by the particles. The perspectives of particles modified with SiO2 and -NH2, and particles modified with HSA for isolation of protein analytes and their quantitative assessment thereafter have been discussed.

Mungbean is one of the important grain legumes and considered as ‘Green Pearl’ due to its nutritional significance. It is an excellent source of proteins and micronutrients and readily accessible to low income groups in arid and semi-arid regions of Africa and Asia. However, poor nutritional status of the soils in these regions limits the productivity and grain nutritional properties of mungbean. Seed priming with nutrient solutions was identified as viable and cost effective alternative to increase the crop productivity and grain nutritional properties and hence, an in-vitro experiment was conducted for optimizing the concentration of nano iron oxide (FeO) for seed priming in mungbean at Agricultural College, Bapatla, Acharya N.G.Ranga Agricultural University, Andhra Pradesh during 2018. Different concentrations of nano iron oxide were tested in completely randomized block design with three replications. The results revealed that, the nano iron oxide 50 ppm was found effective in increasing the germination percent, shoot length, root length, seedling vigour index and speed of germination of mungbean and has been considered as an optimum concentration for seed priming in mungbean.

The experiments of chemical looping gasification of biomass based on Fe2O3–CaO oxygen carrier were studied in a fixed bed reactor using sawdust as a biomass feedstock. It was found that compared to the parent Fe2O3 and CaO, the combined oxygen carriers of iron oxide and calcium oxide demonstrated the best activity for chemical looping gasification of biomass. When the mass ratio of sawdust:Fe2O3:CaO was 2:2:1, the maximum syngas yield could reach 531.3 mL g−1 sawdust at the reaction temperature of 850 °C. Furthermore, from the results of cycle experiments, SEM and XRD characterizations, it was found that Fe2O3 could provide oxygen for sawdust gasification, while CaO played a dual role of absorbing CO2 and catalysis at mild temperatures and reforming tars to syngas at high temperature. Fe2O3–CaO oxygen carriers exhibited good cycling characteristics during chemical looping biomass gasification.

—We study the relations between several selected elements present in the Sin Quyen IOCG deposit, Lào Cai, North Vietnam, and interpret the obtained correlations, especially with a coefficient higher than 0.7. The correlations with high coefficients are mainly observed for the elements belonging to the chalcophile group (Cu, Ag, Au, Te, and Bi) and for the relation between uranium and Ag, Au, Cu, Pb, and Bi. Although the S-, Fe-, and REE-bearing minerals are predominant in the studied deposit, no strong correlation between them and the other elements was observed, even with Cu. The phenomena are primarily explained based on the geochemical properties of the mentioned elements and the characteristics of IOCG deposits.

Solar thermochemical CO2-splitting (STCS) is a promising solution for solar energy harvesting and storage. However, practical solar fuel production by utilizing earth-abundant iron/iron oxides remains a great challenge because of the formation of passivation layers, resulting in slow reaction kinetics and limited CO2 conversion. Here, we report a novel material consisting of an iron-nickel alloy embedded in a perovskite substrate for intensified CO production via a two-step STCS process. The novel material achieved an unprecedented CO production rate of 381 mL g−1 min−1 with 99% CO2 conversion at 850 °C, outperforming state-of-the-art materials. In situ structural analyses and density functional theory calculations show that the alloy/substrate interface is the main active site for CO2 splitting. Preferential oxidation of the FeNi alloy at the interface (as opposed to forming an FeOx passivation shell encapsulating bare metallic iron) and rapid stabilization of the iron oxide species by the robust perovskite matrix significantly promoted the conversion of CO2 to CO. Facile regeneration of the alloy/perovskite interfaces was realized by isothermal methane reduction with simultaneous production of syngas (H2/CO = 2, syngas yield > 96%). Overall, the novel perovskite-mediated dealloying-exsolution redox system facilitates highly efficient solar fuel production, with a theoretical solar-to-fuel efficiency of up to 58%, in the absence of any heat integration.

In this study, we present a detailed investigation of a commercial iron-based high temperature water gas shift (HTWGS) catalyst (Johnson Matthey KATALCOTM 71-6) in a new application: the production of hydrogen from blast furnace gas (BFG), which originates from iron and steel manufacturing. During the lab-scale catalytic testing under BFG conditions the catalyst demonstrated: 1) high water gas shift activity and stability; 2) minimal methanation at reduced steam to CO ratios; 3) high resistance towards H2S impurities present in the feed. The results of post-characterization of the discharged samples confirm the robustness of KATALCO 71-6 towards BFG process conditions: no over-reduction of the catalytically active Fe3O4 phase and no formation of a less active FeS phase. An in situ X-ray absorption spectroscopy study revealed no over-reduction of the iron phase under BFG conditions and the stabilization of the iron phase by diffusion of chromium into the iron oxide matrix. The findings of this study demonstrate the suitability of the iron-based HTWGS catalyst KATALCO 71-6 for the production of hydrogen from BFG streams. Knowledge gained in this study is an essential step in the development and scale up of carbon capture and storage as well as carbon capture and utilization technologies, such as the sorption enhanced water gas shift (SEWGS) technology, aimed at reducing the CO2 footprint during steel manufacturing.

Production of single-phase materials with multifunctional properties is still a challenge faced by material scientists. In addition, obtaining high spin polarization efficiency in the materials that exhibit multifunctional properties is a big issue. A novel approach is suggested in this work for obtaining multifunctionality and spin polarization in the same material. This approach has combined the effect of microwave radiations and aluminum (Al) doping in iron oxide thin films during synthesis. Combined effect of microwave radiations and Al doping results in controlling / tuning the structural transitions in iron oxide thin films. Pristine and 2–10 wt% Al doped iron oxide thin films are prepared and studied in detail. Raman analysis shows that 2 and 4 wt% Al concentration results in γ-Fe2O3 + Fe3O4 phase with 71.3% and 64.5% of γ-Fe2O3 content, respectively. XRD and Raman analyses confirm the transition from γ-Fe2O3 to Fe3O4 thin films at Al concentrations of 6–10 wt%. Structural transformation shows that microwave radiations catalyzes that Al3+ions to occupy the vacancies on B sites of iron oxide thus, lead to the formation of Fe3O4. Observation of Verwey transition ~ 126 K also supports the transition in phases of iron oxide with increase in saturation magnetization from 251.3emu/cm3 (pristine films) to 405.6emu/cm3 (8 wt% Al concentration). High dielectric constant of ~ 135.5 (log f = 5.0) is observed for 8 wt% Al concentration. Conductivity and detailed impedance & modulus analyses depict Mott’s hopping phenomenon along with presence of different relaxation times. Coupling between magnetic and dielectric properties is observed at room temperature. Magnetoresistance curves indicate spin polarization efficiency of ~24%.

Being a novel energy storage medium, ice slurry has the advantage of good fluidity, high latent heat and heat transfer efficiency, which has a broad application prospect. In this work, the ice making characteristics of different types of additives (MgCl2, ethylene glycol and magnetic iron oxide nanoparticles) in a binary ice system by vacuum flash evaporation under the action of solid adsorption were experimentally investigated. Subcooling, flash rate, ice packing factor, latent heat and thermal conductivity were measured to evaluate the performance of ice production. The results showed that 0.075% wt of iron oxide nanoparticles and 1% wt of MgCl2 are more suitable to be used as additives for binary ice preparation than ethylene glycol, with the former outperforming the latter. Under optimal conditions, compared with pure water for ice making, the subcooling degree of iron oxide nanofluid was reduced by 55.80%, and the thermal conductivity and ice packing factor were increased by 98.80% and 54.22%, respectively. The subcooling degree of the MgCl2 solution was reduced by 37.52% and the ice packing factor was improved by 59.51%. Meanwhile, DSC tests showed that the latent heat of the nanofluid was almost independent of the nanoparticle concentration. However, the increase of MgCl2 solution would cause the decrease of latent heat. In addition, high concentrations of additives can inhibit ice crystal nucleation and growth, but a certain concentration of additives facilitates ice crystal refinement in vacuum ice making process, which is conducive to the transportation of ice slurry.

The energy conversion in Earth’s surface environments over geological history heavily involves the redox reactions of natural minerals. Natural Mn(III/IV) oxides and Mn2+(aq) is one of the most important redox couples that significantly dictate the electron flow in nature. Elucidating their formation and redox reactions is of critical importance for understanding numerous elemental cycles and the evolution of redox environments on Earth and other planets. Previous studies generally consider biotic processes as the dominant oxidation pathway for Mn2+(aq) in natural environments. In this study, we demonstrate rapid abiotic oxidation of Mn2+(aq) through photocatalytic reactions in the presence of natural Fe oxide minerals at rates comparable to those of currently known biotic/abiotic oxidation processes. Fe oxide minerals not only facilitate the electron transfer, but also serve as templates for the heterogeneous nucleation of tunnel structured Mn oxides. This finding highlights an important yet previously overlooked abiotic process on the formation of Mn oxides, which offers a new pathway for explaining the commonly observed co-occurrence of Fe and Mn oxide minerals in nature and the origin of diverse structures of Mn oxides.

Transition-metal oxides have shown renewed interest as promising electrode materials for high-performance electrochemical energy storage devices. However, applications of these devices are hindered by the instability of the electrode materials, which is originated from the electrochemical redox reactions induced phase transition between materials with different chemical stoichiometries. Herein, the Pourbaix diagram was constructed to predict ways of inhibiting this undesirable phase transition by using iron oxides as a prototypical model. Appropriate metal dopant (e.g., Ni) doping in the iron oxide was theoretically and experimentally found to present single phase under an extra-wide range of applied potential in alkaline aqueous solutions. Typically, the designed material (NixFe3-xO4) presents high cycling stability with capacitance retention of 94.3% over 5,000 cycles at a current density of 20 A/g when working as a supercapacitor anode. A configured asymmetric supercapacitor with the designed anode exhibits an almost 100% performance retention after 10,000 charging-discharging cycles. This success proposed a new perspective to enhance the stability of electrochemical electrodes for energy storage devices.

The exploration of new red pigments based on transition elements is of great practical value in the field of inorganic pigments, since the red coloured pigments have unique applications in paints, ceramic tiles, cosmetics, etc. Here we mainly reported a new class of eco-friendly red pigments based on substituted Li3AlMnO5 (LAMO) and briefly state about the other rock salt layered structure Li3GaMnO5 (LGMO). The solid-state synthesized powders were crystallized to monoclinic structure having MnIV(1)2b and MnIV(2)4g site. The absorption bands in the synthesized samples mainly arises due to the octahedrally coordinated MnIVO6 in the 4g site. Among the synthesized samples, LAMO: 0.10Ti4+ showed exemplary chromatic properties. The doping of tetravalent Ti4+ ions in the Mn4+ sites altered the MnIV(2)O6 bond lengths and increased the crystal field around the absorption band attributed to the 4A2g→4T2g transitions. The ball milled LAMO: 0.10Ti4+shows the a* value of 40.05, which is higher than that of the commercially available red iron oxide pigments (a* = 28.9). Meanwhile, the brighter red powder LAMO: 0.10Ti4+ demonstrated appreciable thermal and chemical stability. From the thermal evaluating study, we observed that, LAMO: 0.10Ti4+ pigment coated roof panels showed a temperature difference of (3.2 °C) compared to the bare roof panel (3.7 °C). We estimated the coating's performance of the LAMO: 0.10Ti4+ in concrete block, metal plate and ceramic tile. In these substrates, the pigment possesses distinctly elevated NIR‐reflectance, which makes these materials worthwhile for cool coating applications.

In this study, we applied iron (-oxide) incorporated carbide nanofiber composites as heterogeneous catalysts with wide visible-light absorption ability, catalytic reactivity, and catalytic stability for the highly efficient decomposition performance. Notably, water vapor activated iron (-oxide) incorporated carbide nanofiber catalyst (Act-Fe-CNF) showed high crystalline Fe3O4 phase, saturation magnetization point (17.76 emu/g), and large surface area (508.2 m2/g). In water vapor activation, Fe3C particles inside carbide nanofiber oxidized and aggregated to larger Fe3O4 particles, thereby forming a meso/macroporous structure and improving surface area offering more available active sites for catalytic reactivity. Under both UV-/real solar-light irradiation, it was demonstrated that the Act-Fe-CNF catalysts exhibited unprecedentedly excellent removal capabilities (>98%, [k] = 4.06 h−1) for rhodamine B, leading to complete water purification. Interestingly, the AF-CNFs catalysts also showed strong antimicrobial activities against gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) under incandescent-light irradiation. These results indicated that the Act-Fe-CNF catalysts might have utility in important environmental and bio-medical applications.

Factors such as particle type and its loading have been previously studied in tailoring the efficiency of particles-modified polymeric membranes for water treatment. However, the role of particle sizes in membrane modification is often overlooked. Thus, in this work, two commercial iron oxide (Fe 3 O 4 ) particles (i.e., 50–100 nm and