Search

[Display omitted] • Preparation of a biochar-iron oxide (BC-IO) composite via ultrasonication. • High specific surface area of BC-IO enables high heavy metal adsorption. • BC-IO outperformed unmodified BC in adsorption capacity. • BC-IO composite can be reused through adsorption and desorption. In this study, we aimed to develop an absorbent for efficient removal of heavy metals. We developed a composite (BC-IO x) using biochar (BC) obtained by carbonizing rice hull, a type of biomass, and iron(III) nitrate nonhydrate (IO). The bonding strength between BC and IO was increased through ultrasonication with high energy at 25 ℃ and a 2-h heat treatment process at 350 ℃. Brunauer-Emmett-Teller analysis showed that BC-IO x had an increased specific surface area, which was proportional to iron loading and provided an abundance of active heavy metal adsorption sites. This composite effectively removed Pb(II) and As(V). The addition of BC-IO 3 to Pb(II)-contaminated water for 120 min increased Pb(II) absorption capacity to 90.21 mg/g from 18.12 mg/g with unmodified BC. The As(V) adsorption capacity increased from 8.33 mg/g for unmodified BC to 65.34 mg/g for BC-IO 10. In addition, the potential adsorption mechanism was discussed using detailed chemical and physical analyses. The synthesis of a composite from biochar and iron oxide can inspire the cost-effective and straightforward production of heavy metal absorbents that can be utilized on a large scale. [ABSTRACT FROM AUTHOR]

Reverse loading of inert Al 2 O 3 support onto reactive FeO x nanoparticles generates nanocomposite with unusually improved reactivity and stability for H 2 O 2 activation and pollutant removal, compared to the analogue traditional nanocomposite which was prepared via the loading of FeO x nanoparticles onto inert Al 2 O 3 support. [Display omitted] • Reverse loading of inert Al 2 O 3 onto reactive FeO x to generate FeO x @Al 2 O 3 -R. • FeO x @Al 2 O 3 -R shows much improved reactivity in H 2 O 2 activation than its traditional analogue. • FeO x @Al 2 O 3 -R also shows greatly enhanced stability featuring suppressed ion leaching. • The inert Al ions modify the electronic environment and properties of the surface Fe reactive sites. Developing heterogeneous iron-based catalysts with superior reactivity and stability is a long-term goal for hydrogen peroxide (H 2 O 2) activation in Fenton-like technique for water remediation. Supported iron-based nanocomposites are of great interest due to their earth abundance, environmental friendliness, and tunable structure. However, existing iron-based Fenton catalysts are normally designed via the loading of iron-derived nanoparticles onto various inert substrates, where the surface reactive sites are hardly affected by the substrate. Here, we report the first example of reversely loaded FeO x -Al 2 O 3 nanocomposite via overturning the loading direction, i.e., loading inert Al 2 O 3 support onto reactive FeO x nanoparticles. The resultant FeO x @Al 2 O 3 -R catalyst demonstrated much improved reactivity for H 2 O 2 activation and bisphenol A removal (by 14 times in terms of first-order rate constant) than its analog FeO x /Al 2 O 3 -T, which was prepared via the loading of FeO x nanoparticles onto inert Al 2 O 3 support. Moreover, FeO x @Al 2 O 3 -R exhibited excellent stability with Fe leaching only one sixth of FeO x /Al 2 O 3 -T. Systematic characterization results revealed that the inert Al ions modify the electronic environment and properties of the surface Fe reactive sites. This work provides an alternative reverse loading strategy to traditional loading method for the preparation of iron-based nanocomposite catalyst that is highly efficient for H 2 O 2 activation and pollutant removal. [ABSTRACT FROM AUTHOR]

• The solid electrolyte of iron compound powder ingots can enhance battery capacity. • The ferrous chloride will be converted into Fe 8 O 8 (OH) 8 Cl 1.35 during the charge-discharge cycle. • After charging-discharging, an abnormal layer forms at the interface of solid electrolyte and electrode, leading to interface expansion, cracks, and reduced electrode adhesion. This study investigates a Fe/SSE/GF battery. Iron (Fe) as cathode material contains higher electrical capacity and competitive advantages. The solid-state electrolyte (SSE) material is sodium silicate powder mixed with iron compound powders. There are four types of iron compounds: 1) iron oxide, 2) chlorinated/Na-rich iron oxide, 3) Cl-rich iron oxide, 4) ferrous chloride, which are compared with sodium silicate powder. The negative electrode material is graphite film (GF). According to experiments, converting iron into iron oxide or ferric chloride can enhance battery capacity (beyond 200 mAh/g) and cycle life. The reliability of the Fe/SSE/GF battery was assessed by substituting sodium silicate powder with an iron compound electrolyte and adding binder (Polyvinyl Alcohol, PVA) into powder to enhance the performance of Fe/SSE/GF. This experimental research is not only innovative but also represents a significant milestone in the field of solid-state energy storage. [ABSTRACT FROM AUTHOR]

Three series of borosilicate glasses were prepared, ranging from simple ternary sodium borosilicate glasses (SCFe series), to complex borosilicate glasses (CCFe Series), to high-level radioactive waste analogue glasses (HAFe series). 57Fe Mössbauer and Fe K-edge XANES spectroscopies showed that the iron exists exclusively as Fe3+ in predominantly distorted tetrahedral structures ([4]Fe3+), with evidence for lower abundances of higher-coordinated [5 or 6]Fe3+. Raman, B K-edge XANES, and XPS spectroscopies qualitatively demonstrated that Fe3+ preferentially integrates into the borosilicate network through the silicate sub-network in the simple glasses, whereas in the complex glasses it preferentially integrates through the borate sub-network. The [4]B3+ fraction for the SCFe and CCFe glasses showed minimal changes as a function of Fe content, indicating that Fe concentration has no effect on boron coordination and is- therefore unlikely to be competing with [4]B3+ groups for charge compensation, qualitatively supporting the presence of competing tetrahedral avoidance hierarchies. [ABSTRACT FROM AUTHOR]

The occurrence of agglomeration due to particle sintering is one of the most significant technical issues hindering the direct reduction process of iron oxide fines (DRI) in a high-temperature fluidized bed. To get a better understanding of the agglomeration mechanism, the (de-)fluidization behavior of micron-sized iron oxide particles in a 3-D fluidized bed is investigated using Computational Fluid Dynamics coupled with a coarse-grained Discrete Element Method (CFD-cgDEM). The inter-particle cohesive force is considered as a temperature-dependent solid bridge force. The coarse-grained method is first verified by comparing results for different scaling factors. Subsequently, the effects of temperature on the bed pressure drop, void fraction distribution, particle velocity distribution, and agglomerate size are investigated. In conclusion, the developed model shows the capacity for reliable prediction of particle agglomeration behavior, which can shed light on the design of the DRI process in high-temperature fluidized beds. • Modeling agglomeration behavior of micron-sized combusted iron particles. • A coarse-grained method is extended to model cohesive dense gas-solid flows. • The inter-particle cohesive force is considered as a temperature-dependent solid bridge force. • Effects of temperature and solid bridge strength on bed dynamics are studied. [ABSTRACT FROM AUTHOR]

Understanding water absorbency in paper is challenging as fibre swelling and out-of-plane deformation occur simultaneously during liquid imbibition. Liquid absorption is commonly accessed by gravimetric tests, which provides limited information on the local spatial and temporal distribution of fluid in the substrate. In this work, we developed iron tracers to map liquid imbibition in paper by in situ precipitation of iron oxide nanoparticles during passage of the wetting front. The iron oxide tracers were found to be robustly attached to the cellulosic fibres. After liquid absorption tests, absorbency was investigated by mapping the distribution of iron in 3D using X-ray micro-computed tomography (μCT) and in 2D using energy-dispersive X-ray spectroscopy. We demonstrate a difference in tracer distribution between the wetting front and the fully saturated region supporting that imbibition proceeds in two phases, i.e. liquid percolation through the cell wall initially prior to filling of the external pore spaces. Critically, we demonstrate that these iron tracers enhance image contrast and allow for new imaging modalities in μCT for fibre networks. [Display omitted] [ABSTRACT FROM AUTHOR]

• Size effect of iron oxide NPs (NP10, NP20, NP30, and NP40) was investigated in pumpkin. • TEM and VSM analyses revealed root-to-shoot translocation of all tested NPs. • NP30 exhibits the highest translocation performance, while a negligible amount of NP10 and NP40 reached to the leaves. • The status of nutrient elements significantly altered depend on NP-type. • The findings could be important for selecting the most suitable NP size for agricultural practices. The ability of nanoparticles (NPs) to migrate in the plant body is an important issue to ensure that the NPs reach the desired tissue and to be able to select the most efficient NPs for agricultural applications. In this study, the size impact of four different iron oxide NPs (8–10, 18–20, 20–40, and 30–50 nm referred as NP10, NP20, NP30, and NP40, respectively) on their translocation in pumpkin was elucidated. To assess the root-to-shoot translocation, phloem sap was examined under transmission electron microscope (TEM). In addition, vibrating sample magnetometer (VSM) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses of stem and leaf tissues were performed to confirm size-dependent translocation. TEM and VSM analyses verified root-to-stem translocation of all tested NPs. The NPs treatment significantly altered the abundances of Mn, Cu, K, P, Al, Mg, and Na in tissues. The iron (Fe) content was abundant in plants treated with NP30 and NP20, and the lowest in plants treated with NP10 and NP40. Together with, only NP30 was found to be significantly translocated to the leaves, where it was 393 mg/kg in DW, about 2.3 times that of control. These findings pointed out the size-dependent translocation of NPs. It seems that biological barriers in the vascular bundle appear to restrict the migration, especially for NPs with an average size of 40 nm and above in pumpkins. These findings are important for selecting the most suitable size of iron oxide NPs for use in agricultural practices. [ABSTRACT FROM AUTHOR]

[Display omitted] • Strong Fe oxide (hematite), Cu, and REE mineralization (together with minor Au and locally U) suggests IOCG-type signatures. • Mineralization bears many signatures of the "classic" IOCG (-REE, U) deposits typical of Precambrian terranes but occurs in a Phanerozoic (Paleozoic) setting. • Mineralization is associated with transitional shoshonitic to A-type subvolcanic potassic granite intrusions emplaced in a post-collisional setting. • Mineralization occurs mainly in phyllic to carbonate-phyllic alteration assemblages. • A shallow level of mineralization possibly corresponds to an upper (to the uppermost) part of a vertically extended magmatic-hydrothermal system. The Ulandryk and related prospects in the Altaid orogenic belt (near the Russian-Mongolian border) comprise intense iron oxide (hematite), Cu, REE, and locally U mineralization and are estimated to contain in excess of 240 Mt iron oxide ores and 3.7 Mt copper. These prospects bear many signatures of the "classic" IOCG (-REE, U) deposits typical of Precambrian terranes but, in contrast, are situated in a Phanerozoic (Paleozoic) setting. They are related to the Early Devonian subvolcanic potassic granite stocks with transitional shoshonitic to A-type granite signatures suggesting a post-orogenic (post-collisional) setting, with some anorogenic (intracontinental to within-plate) affinity. The stocks have been intruded into a coeval local volcanic structure (a volcanic dome complicated by the central caldera) composed of Devonian trachyandesite, trachydacite, quartz latite, rhyolite, rhyolite-dacite, and dominant trachyrhyolite lavas, tuffs and subovolcanic porphyry intrusions. The granitic stocks are accompanied by magmatic and multi-staged hydrothermal breccias, zones of sodic (albite-quartz), potassic (quartz-K-feldspar), propylitic (quartz-albite-chlorite-amphibole) and dominant phyllic to carbonate-phyllic (quartz-sericite to quartz-sericite-carbonate) to possibly argillic (quartz-kaolinite) alteration, with intense development of hematite. Fluorite is also ubiquitous and locally abundant. The mineralization occurs in several wide (typically 60–100 m, up to 200 m) and extended (1.4–6 km) linear to arc-like paralleling steeply dipping zones of breccias surrounding the granite stocks, with the host rock and quartz fragments cemented by fine-grained quartz-hematite and coarser hematite (specularite) material. Copper-gold, REE, and locally U mineralization overprints hematite-rich zones. Wider quartz-sulfide stockworks with Cu-Au mineralization zones containing minor to trace hematite are also present. Quartz is generally abundant forming quartz-hematite veins, stockworks, and breccias (locally with crustiform texture), and zones of quartzite-like pervasive silicification (typically with sericite and clay minerals). Fluid inclusions in quartz contain daughter halite crystals and homogenize by halite dissolution after vapor bubble disappearance indicating a homogenous, high-salinity (35–45 wt%), Na-Ca-K-chloride, aqueous mineralizing fluid. The relatively low homogenization temperatures (∼200–260 °C) and generally subvolcanic-level pressure (∼0.2–0.5 kbar) conditions suggest a shallow level of mineralization possibly corresponding to an upper (to the uppermost) part of a vertically extended magmatic-hydrothermal system. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is a key trace element and a contaminant in many environments including mine tailings and acid mine drainage systems. Under oxic conditions Mo exists in a number of forms, including mono-molybdate (Mo(VI)O 4 2-) and various poly-molybdate species (e.g. Mo(VI) 7 O 24 6-) depending on the geochemical conditions (e.g. pH). The mobility and bioavailability of Mo is often controlled by sorption to mineral surfaces, including iron (oxyhydr)oxides e.g. hematite (Fe 2 O 3). This study uses adsorption isotherms, PHREEQC geochemical modeling, Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and X-ray Absorption Spectroscopy (XAS) to holistically characterise the molecular scale adsorption of molybdate to hematite as a function of pH (3−12) and Mo(VI) concentration (0.01 × 10−4 - 2 × 10−3 M). PHREEQC and ATR-FTIR indicated both pH and Mo concentration are important variables when forming mono- vs. poly- molybdate and suggest low pH (≤ 4) and high Mo(VI) concentration (≥ 5 × 10−4 M) contribute to the formation of a poly-molybdate surface species on the hematite surface. XAS found Mo adsorbed to hematite via an inner-sphere corner-sharing bidentate binuclear complex with an octahedral mono-molybdate structure at a Mo concentration of 0.6 × 10−4 M across the pH range, and at a Mo(VI) concentration of 5 × 10−4 M and pH over 5. This is the first direct observation of octahedrally coordinated Mo(VI) adsorption species on hematite, and this information has broad implications for the mobility and transport of Mo as a contaminant in the environment. [Display omitted] • Mo(VI) forms octahedral inner sphere adsorption complexes on hematite surface. • Polymolybdate is present at higher [Mo(VI)] and lower pH. • Monomeric surface complexes form at lower [Mo(VI)] and higher pH. • Implications for mobility and transport of Mo(VI) in the environment. [ABSTRACT FROM AUTHOR]

This study investigates the effect of iron oxide Fe 2 O 3 on the homogeneity, viscosity, and glass transition temperature (Tg) of peraluminous glasses. As-quenched glass samples elaborated at 1350 °C show an incorporation limit around 17.5 wt% of Fe 2 O 3 (10.4 mol%), while slowly cooled glass samples show a limit of 7.5 wt% of Fe 2 O 3 (4.2 mol%). Iron in the peraluminous glasses investigated was detected under three configurations: 6-fold coordinated 6Fe3+ in majority, 4-fold coordinated 4Fe3+ and 6-fold coordinated 6Fe2+. It was observed that Fe 2 O 3 addition has a strong fluidifying effect on peraluminous glasses and tends to slightly decrease the glass transition temperature Tg, depending on its thermal history. [ABSTRACT FROM AUTHOR]

• Utilization of Fe based catalysts for petroleum coke graphitization. • Properties comparison of graphitized petroleum coke and commercial graphite. • Graphitized petroleum coke shows good electrochemical properties in full cell LIB. Graphitic carbon materials are synthesized by mixing petroleum coke with Fe-based catalysts, followed with annealing under N 2 atmosphere at various iron-based catalysts at 1300 °C. We have found that the utilization of iron or iron oxide as catalyst lead to similar graphitic structure formation during heat treatment of petroleum coke. X-ray Diffraction (XRD) pattern showed that iron oxide catalyst leads to the formation of ordered graphitic structure. The use of iron-based catalyst tends to decrease the turbostratic peak, lead to a higher ordered graphite peak. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) showed that the morphology structure of graphite powder synthesized using iron or iron oxide is similar. From the full cell testing using NMC-622 cathode, the as-synthesized sample shows good electrochemical properties and comparable to graphite commercial. [ABSTRACT FROM AUTHOR]

Abstract: The electronic structure and the growth morphology of iron oxide thin films were studied by means of Synchrotron Radiation Photoelectron Spectroscopy (SRPES) and Low Energy Electron Diffraction (LEED). A thin well-ordered alumina film on a NiAl(110) single crystal surface as a template for iron oxide growth was employed. Two different methods of iron oxide film preparation were applied. In the first attempt, iron deposited at room temperature was subsequently annealed in oxygen. Even though a whole layer of iron was oxidized, an expected long-range order was not achieved. The second attempt was to perform reactive deposition. For this reason iron was evaporated in oxygen ambient at elevated substrate temperature. This method turned out to be more efficient. Diffused but clear LEED patterns of six-fold symmetry indicating hexagonal surface atoms arrangement were observed. From the PES measurements, binding energies for Fe2p for grown iron oxide film were established as well as energy distribution curves for the valence band. Growth curves based on Fe3p core-level peak intensities for iron and iron oxide were plotted identifying type of film growth for both deposition methods. Based upon these results we have found evidence for interdiffusion in the interface between alumina and iron oxide at the early stages of growth. Further deposition led to formation of Fe3O4(111) (magnetite) overlayer. Moreover, the quality of the film could also be improved by long-time annealing at temperatures not exceeding 575K. Higher annealing temperature caused disappearance of LEED pattern indicating loss of long-range ordering. [Copyright &y& Elsevier]

Abstract: Flue gases from coal, gas, or oil-fired power stations, as well as from several heavy industries, such as the production of iron, lime and cement, are major anthropogenic sources of global CO2 emissions. The newly proposed process for syngas production based on the tri-reforming of such flue gases with natural gas could be an important route for CO2 emission avoidance. In addition, by combining the carbothermic reduction of iron oxide with the partial oxidation of the carbon source, an overall thermoneutral process can be designed for the co-production of iron and syngas rich in CO. Water-gas shift (WGS) of CO to H2 enables the production of useful syngas. The reaction process heat, or the conditions for thermoneutrality, are derived by thermochemical equilibrium calculations. The thermodynamic constraints are determined for the production of syngas suitable for methanol, hydrogen, or ammonia synthesis. The environmental and economic consequences are assessed for large-scale commercial production of these chemical commodities. Preliminary evaluations with natural gas, coke, or coal as carbon source indicate that such combined processes should be economically competitive, as well as promising significant fuel saving and CO2 emission avoidance. The production of ammonia in the above processes seems particularly attractive, as it consumes the nitrogen in the flue gases. [Copyright &y& Elsevier]

Abstract: W/Fe bilayer metallic coatings are deposited by d.c. magnetron sputtering on an Fe substrate. Correlation between the deposition parameters and the film characteristics are investigated. The coatings exhibit small grain sizes and dense structure for high target power and low argon pressure, leading to well adhesive films. Bilayer post oxidation process is preformed in order to form Fe3O4 at the surface (W/Fe3O4). The ability of the Fe layer to be oxidised is also studied depending on the bilayer deposition parameters. [Copyright &y& Elsevier]

Fe4N crystals were exposed to intense electron beams at room temperature inside transmission electron microscopes (TEM) with base pressures of 10−5–10−6 Pa. The effects of irradiation on Fe4N along the [0 0 1], [0 1 1], [1 1 1] and [2 1 1] orientations were investigated in situ using selected area electron diffraction (SAED), high resolution electron microscopy (HREM), and electron energy loss spectroscopy (EELS). The dose rate of the electron beam for the irradiation experiments was in the range of 0.7–2×1024 e m−2 s−1. It was concluded that the initial Fe4N (γ′) transformed into Fe3O4 (O) with the cubic-to-cubic orientation relationship of (1 0 0)O//(1 0 0)γ′ and [0 0 1]O//[0 0 1]γ′. This transformation is electron-irradiation dependent, which suggests a controlled method to prepare local Fe3O4 crystals (magnetite) in a Fe4N film using an electron beam. [Copyright &y& Elsevier]

Magnetic and magnetotransport measurements were performed on gas-phase synthesized Fe nanoparticles subjected to surface oxidation and cold consolidation. Two samples were investigated with α-Fe volume fraction of 0.15 and 0.60. The sample with smaller metallic fraction is below the percolation threshold for metallic conduction and the conduction mechanism is dominated by thermally activated processes across the oxide. In this case, by lowering the temperature, an increase of the negative magnetoresistance is observed up to 5% at 50 K in a magnetic field of 70 kOe. The magnetoresistance dependence on the sample magnetization, temperature and sample composition is discussed considering the magnetic correlations present in these nanostrucuterd systems. [Copyright &y& Elsevier]