Showing papers on "Magnetite published in 2018"
TL;DR: The distinctive structure and the heavy metal ions removal property of magnetic nanocomposites reflect their prospective application in water treatment.
156 citations
TL;DR: Granular activated carbon (GAC) or magnetite could promote methane production from organic wastes, but their roles in enhancing anaerobic sludge digestion have not been clarified as discussed by the authors.
152 citations
TL;DR: In this paper, the influence of loading on graphite nanoplatelets/magnetite (GNP/Fe3O4)/epoxy composites with aligned under external magnetic field fillers and random fillers distribution has been developed.
Abstract: Novel graphite nanoplatelets/magnetite (GNP/Fe3O4)/epoxy composites with aligned under external magnetic field fillers and random fillers distribution have been developed. The influence of loading ...
103 citations
TL;DR: Metric analysis using Scopus and Web of Science databases from 2003 to 2018 showed that applied research involving magnetite from MTB in some form has been focused mainly in biomedical applications, particularly in magnetic hyperthermia and drug delivery.
Abstract: Magnetotactic bacteria (MTB) biomineralize magnetosomes, which are defined as intracellular nanocrystals of the magnetic minerals magnetite (Fe3O4) or greigite (Fe3S4) enveloped by a phospholipid bilayer membrane The synthesis of magnetosomes is controlled by a specific set of genes that encode proteins, some of which are exclusively found in the magnetosome membrane in the cell Over the past several decades, interest in nanoscale technology (nanotechnology) and biotechnology has increased significantly due to the development and establishment of new commercial, medical and scientific processes and applications that utilize nanomaterials, some of which are biologically derived One excellent example of a biological nanomaterial that is showing great promise for use in a large number of commercial and medical applications are bacterial magnetite magnetosomes Unlike chemically-synthesized magnetite nanoparticles, magnetosome magnetite crystals are stable single-magnetic domains and are thus permanently magnetic at ambient temperature, are of high chemical purity, and display a narrow size range and consistent crystal morphology These physical/chemical features are important in their use in biotechnological and other applications Applications utilizing magnetite-producing MTB, magnetite magnetosomes and/or magnetosome magnetite crystals include and/or involve bioremediation, cell separation, DNA/antigen recovery or detection, drug delivery, enzyme immobilization, magnetic hyperthermia and contrast enhancement of magnetic resonance imaging Metric analysis using Scopus and Web of Science databases from 2003 to 2018 showed that applied research involving magnetite from MTB in some form has been focused mainly in biomedical applications, particularly in magnetic hyperthermia and drug delivery
103 citations
TL;DR: In this paper, a Panzhihua (China) magnetite was used as a low-cost oxygen carrier for chemical looping reforming of methane (CLRM) in an isothermal redox experiment using methane as reducing fuel and steam as an oxidizing gas.
90 citations
TL;DR: It was concluded that CIP elimination was mainly occurred through heterogeneous Fenton procedure which included the adsorption and oxidation phases in which the hydroxyl radicals (OH) played a significant role.
89 citations
08 Mar 2018
TL;DR: Li et al. as mentioned in this paper proposed a chitosan-coated magnetite with Covalently Grafted Polystyrene Based Carbon Nanocomposites for Hexavalent Chromium Adsorption.
Abstract: 46 | Eng. Sci., 2018, 1, 46–54 © Engin 1 Shanghai Key Lab of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, Shanghai 200092, People’s Republic of China. E-mail: hongbogu2014@tongji.edu.cn 2 Integrated Composites Laboratory (ICL), Department of Chemical & Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee, 37966, USA MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, Shaanxi Key Laboratory of Macromolecular Science and Technology, Department of Applied Chemistry, School of Science, Northwestern Polytechnical University, Xi’ an, Shaanxi, 710072, P. R. China. E-mail: gjw@nwpu.edu.cn Chitosan-coated-magnetite with Covalently Grafted Polystyrene Based Carbon Nanocomposites for Hexavalent Chromium Adsorption
85 citations
TL;DR: In this paper, a modified one-step method under CO2 atmosphere for the purification of toxic dye, using the mixture of FeCl3·6H2O and peanut shells as precursor.
79 citations
TL;DR: The inner layer was identified by Transmission Electron Microscopy (TEM) as Fe3O4 (magnetite) and was always present over time despite it being less stable than iron sulfide as discussed by the authors.
77 citations
TL;DR: In this article, the catalytic performance of iron oxides in 2,4,4′-trichlobiphenyl (PCB28) degradation following an order of goethite, magnetite, hematite, and hydrated iron(III) oxide was observed.
77 citations
TL;DR: Experiments suggest that magnetite precipitation on early Mars was accompanied by the release of H2 that may have helped to warm the planet and stabilize liquid water at the Martian surface.
Abstract: The Curiosity rover has documented lacustrine sediments at Gale Crater, but how liquid water became physically stable on the early Martian surface is a matter of significant debate. To constrain the composition of the early Martian atmosphere during sediment deposition, we experimentally investigated the nucleation and growth kinetics of authigenic Fe-minerals in Gale Crater mudstones. Experiments show that pH variations within anoxic basaltic waters trigger a series of mineral transformations that rapidly generate magnetite and H2(aq). Magnetite continues to form through this mechanism despite high partial pressure of carbon dioxide (pCO2) and supersaturation with respect to Fe-carbonate minerals. Reactive transport simulations that incorporate these experimental data show that groundwater infiltration into a lake equilibrated with a CO2-rich atmosphere can trigger the production of both magnetite and H2(aq) in the mudstones. H2(aq), generated at concentrations that would readily exsolve from solution, is capable of increasing annual mean surface temperatures above freezing in CO2-dominated atmospheres. We therefore suggest that magnetite authigenesis could have provided a short-term feedback for stabilizing liquid water, as well as a principal feedstock for biologically relevant chemical reactions, at the early Martian surface.
TL;DR: In this article, a comparative analysis of the adsorption and photo-degradation performance of goethite and magnetite was conducted to investigate the mechanism and process of PMG degradation in the environment.
TL;DR: In this paper, magnetic nanocomposites are synthesized by loading reduced graphene oxide (RG) with two components of nanoparticles consisting of titanium dioxide (TiO2) and magnetite (Fe3O4) with varying amounts.
TL;DR: The removal of basic violet 10 (BV10), which is known as a cationic dye, from aqueous solution was studied by employing a heterogeneous sono-Fenton process over the nano-sized magnetite (Fe3O4) which was prepared by the milling of magnetite mineral using a high-energy planetary ball milling process.
TL;DR: In this article, a facile electrochemical route for the synthesis of lanthanide-doped magnetite nanoparticles was provided. But the results proved the suitability of the electrosynthesized nanoparticles for use in supercapacitors.
Abstract: Sm3+-doped magnetite (Fe3O4) nanoparticles were synthesized through a one-pot facile electrochemical method. In this method, products were electrodeposited on a stainless steel (316L) cathode from an additive-free 0.005 M Fe(NO3)3/FeCl2/SmCl3 aqueous electrolyte. The structural characterizations through X-ray diffraction, field-emission electron microscopy, and energy-dispersive X-ray indicated that the deposited material has Sm3+-doped magnetite particles with average size of 20 nm. Magnetic analysis by VSM revealed the superparamagnetic nature of the prepared nanoparticles (Ms = 41.89 emu g−1, Mr = 0.12 emu g−1, and H
Ci = 2.24 G). The supercapacitive capability evaluation of the prepared magnetite nanoparticles through cyclic voltammetry and galvanostat charge–discharge showed that these materials are capable to deliver specific capacitances as high as 207 F g−1 (at 0.5 A g−1) and 145 F g−1 (at 2 A g−1), and capacity retentions of 94.5 and 84.6% after 2000 cycling at 0.5 and 1 A g−1, respectively. The results proved the suitability of the electrosynthesized nanoparticles for use in supercapacitors. Furthermore, this work provides a facile electrochemical route for the synthesis of lanthanide-doped magnetite nanoparticles.
TL;DR: In this paper, different commercial hematite powders, normally used as Fe precursor in laboratory synthesis of Fe-containing oxides, were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM).
Abstract: Magnetic techniques are suitable to detect iron oxides even in trace concentrations. However, since several iron oxides may be simultaneously present in natural and synthetic samples, mixtures of magnetic particles and magnetic interactions between grains can complicate magnetic signatures. Among the iron oxide minerals, hematite (α-Fe2O3) and magnetite (Fe3O4) are the most common. In this work, different commercial hematite powders, normally used as Fe precursor in laboratory synthesis of Fe-containing oxides, were characterized using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The effects of different concentrations of the hematite and magnetite on the magnetic properties of a set of mixtures (from 1 to 10 wt% magnetite) were then investigated by measuring the hysteresis loops, first order reversal curves (FORCs), thermal demagnetization, and isothermal remanent magnetization (IRM) curves. The three commercial hematite powders presented differ...
TL;DR: In this article, micro-to nano-structural and chemical data of hydrothermal magnetite from the Los Colorados iron oxide-apatite deposit in Chile were reported.
Abstract: Magnetite from hydrothermal ore deposits can contain up to tens of thousands of parts per million (ppm) of elements such as Ti, Si, V, Al, Ca, Mg, Na, which tend to either structurally incorporate into growth and sector zones or form mineral micro- to nano-sized particles. Here, we report micro- to nano-structural and chemical data of hydrothermal magnetite from the Los Colorados iron oxide–apatite deposit in Chile, where magnetite displays both types of trace element incorporation. Three generations of magnetites (X–Z) were identified with concentrations of minor and trace elements that vary significantly: SiO2, from below detection limit (bdl) to 3.1 wt%; Al2O3, 0.3–2.3 wt%; CaO, bdl–0.9 wt%; MgO, 0.02–2.5 wt%; TiO2, 0.1–0.4 wt%; MnO, 0.04–0.2 wt%; Na2O, bdl–0.4 wt%; and K2O, bdl–0.4 wt%. An exception is V2O3, which is remarkably constant, ranging from 0.3 to 0.4 wt%. Six types of crystalline nanoparticles (NPs) were identified by means of transmission electron microscopy in the trace element-rich zones, which are each a few micrometres wide: (1) diopside, (2) clinoenstatite; (3) amphibole, (4) mica, (5) ulvospinel, and (6) Ti-rich magnetite. In addition, Al-rich nanodomains, which contain 2–3 wt% of Al, occur within a single crystal of magnetite. The accumulation of NPs in the trace element-rich zones suggest that they form owing to supersaturation from a hydrothermal fluid, followed by entrapment during continuous growth of the magnetite surface. It is also concluded that mineral NPs promote exsolution of new phases from the mineral host, otherwise preserved as structurally bound trace elements. The presence of abundant mineral NPs in magnetite points to a complex incorporation of trace elements during growth, and provides a cautionary note on the interpretation of micron-scale chemical data of magnetite.
TL;DR: In this article, structural fingerprinting and scanning transmission electron microscopy and electron energy loss spectroscopy analysis was used to prove that magnetite is the dominant soil-formed ferrite.
Abstract: In the world-famous sediments of the Chinese Loess Plateau, fossil soils alternate with windblown dust layers to record monsoonal variations over the last ∼3 My. The less-weathered, weakly magnetic dust layers reflect drier, colder glaciations. The fossil soils (paleosols) contain variable concentrations of nanoscale, strongly magnetic iron oxides, formed in situ during the wetter, warmer interglaciations. Mineralogical identification of the magnetic soil oxides is essential for deciphering these key paleoclimatic records. Formation of magnetite, a mixed Fe2+/Fe3+ ferrimagnet, has been linked to soil redox oscillations, and thence to paleorainfall. An opposite hypothesis states that magnetite can only form if the soil is water saturated for significant periods in order for Fe3+ to be reduced to Fe2+, and suggests instead the temperature-dependent formation of maghemite, an Fe3+-oxide, much of which ages subsequently into hematite, typically aluminum substituted. This latter, oxidizing pathway would have been temperature, but not rainfall dependent. Here, through structural fingerprinting and scanning transmission electron microscopy and electron energy loss spectroscopy analysis, we prove that magnetite is the dominant soil-formed ferrite. Maghemite is present in lower concentrations, and shows no evidence of aluminum substitution, negating its proposed precursor role for the aluminum-substituted hematite prevalent in the paleosols. Magnetite dominance demonstrates that magnetite formation occurs in well-drained, generally oxidizing soils, and that soil wetting/drying oscillations drive the degree of soil magnetic enhancement. The magnetic variations of the Chinese Loess Plateau paleosols thus record changes in monsoonal rainfall, over timescales of millions of years.
TL;DR: In this article, a simple, time-saving and low energy-consuming, microwave-assisted synthesis of iron oxide nanoparticles, is presented, where the nanoparticles were prepared by microwave assisted synthesis using polyethylene glycol (PEG) or PEG and β-cyclodextrin (β-CD)/water solutions of chloride salts of iron in the presence of ammonia solution.
Abstract: The development of magnetite and maghemite particles in uniform nanometer size has triggered the interest of the research community due to their many interesting properties leading to a wide range of applications, such as catalysis, nanomedicine-nanobiology and other engineering applications. In this study, a simple, time-saving and low energy-consuming, microwave-assisted synthesis of iron oxide nanoparticles, is presented. The nanoparticles were prepared by microwave-assisted synthesis using polyethylene glycol (PEG) or PEG and β-cyclodextrin (β-CD)/water solutions of chloride salts of iron in the presence of ammonia solution. The prepared nano-powders were characterized using X-Ray Diffraction (XRD), Transition Electron Microscopy (TEM), Fourier-transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Vibrating Sample Magnetometer (VSM), X-Ray Photoelectron Spectroscopy (XPS) and Thermal analysis (TG/DSC). The produced nanoparticles are crystallized mostly in the magnetite and maghemite lattice exhi...
TL;DR: In this article, the authors studied the mechanical and biologocal properties of the bredigite-magnetite (Ca 7 MgSi 4 O 16 -Fe 3 O 4 ) nanocomposite with various amounts of magnetite (0, 10, 20 and 30. %).
TL;DR: In this paper, the removal of copper ions by magnetic Fe3O4/carbon nanotube (CNT) composite adsorbents, prepared by co-precipitation method, in aqueous solution has been investigated.
Abstract: The removal of copper ions by magnetic Fe3O4/carbon nanotube (CNT) composite adsorbents, prepared by co-precipitation method, in aqueous solution has been investigated. The influence of magnetite loading (35.5‒64.1 wt.%) onto oxidized CNT support on the adsorption capacity and regeneration efficiency is investigated. The adsorption isotherms of Cu2+ ions are well characterized by Langmuir, Freundlich, and Dubinin–Radushkevich models within the temperature range of 303‒323 K. The decoration of magnetic Fe3O4 significantly enhances the removal efficiency, equilibrium rate constant, and adsorption capacity, as analyzed by these models. The appropriate loading of magnetite nanoparticles on the CNT supports not only increases adsorption capacity but also facilitates regeneration efficiency. Accordingly, the Fe3O4/CNT composite can be used as an effective adsorbent for rapid removal of Cu2+ ions from aqueous solution.
TL;DR: The catalytic activity of sulfides oxidation showed that this atom-economical protocol provided great yields of various sulfones and allowed the sulfide function reaction conducting under the mild conditions thus to prevent the sulfides being over-oxidized to sulfoxides.
TL;DR: In this article, the chemical stabilization and reutilization of iron-rich slag from copper metallurgy, by the manufacturing of glass-ceramic foams was explored, which exhibited a ferrimagnetic behavior, that could be exploited in electromagnetic shielding applications.
TL;DR: The discovery of magnetism by the ancient Greeks was enabled by the natural occurrence of lodestone, a magnetized version of the mineral magnetite as discussed by the authors, which is a type of magnetite.
Abstract: The discovery of magnetism by the ancient Greeks was enabled by the natural occurrence of lodestone – a magnetized version of the mineral magnetite. Nowadays, natural minerals continue to inspire t...
01 Jan 2018
TL;DR: In this article, the authors used trace element concentrations in magnetite and pyrite, Fe and O stable isotope abundances of magnetite, H isotopes of magnetites and actinolite, and Re-Os systematics of the magnetite from the Los Colorados Kiruna-type iron oxide-apatite (IOA) deposit in the Chilean iron belt to develop a new genetic model that explains IOCG and IOA deposits as a continuum produced by a combination of igneous and magmatic-hydrothermal processes.
Abstract: Iron oxide copper-gold (IOCG) and Kiruna-type iron oxide-apatite (IOA) deposits are commonly spatially and temporally associated with one another, and with coeval magmatism. Here, we use trace element concentrations in magnetite and pyrite, Fe and O stable isotope abundances of magnetite and hematite, H isotopes of magnetite and actinolite, and Re-Os systematics of magnetite from the Los Colorados Kiruna-type IOA deposit in the Chilean iron belt to develop a new genetic model that explains IOCG and IOA deposits as a continuum produced by a combination of igneous and magmatic-hydrothermal processes. The concentrations of [Al + Mn] and [Ti + V] are highest in magnetite cores and decrease systematically from core to rim, consistent with growth of magnetite cores from a silicate melt, and rims from a cooling magmatic-hydrothermal fluid. Almost all bulk δ 18 O values in magnetite are within the range of 0 to 5‰, and bulk δ 56 Fe for magnetite are within the range 0 to 0.8‰ of Fe isotopes, both of which indicate a magmatic source for O and Fe. The values of δ 18 O and δD for actinolite, which is paragenetically equivalent to magnetite, are, respectively, 6.46 ± 0.56 and-59.3 ± 1.7‰, indicative of a mantle source. Pyrite grains consistently yield Co/Ni ratios that exceed unity, and imply precipitation of pyrite from an ore fluid evolved from an intermediate to mafic magma. The calculated initial 187 Os/ 188 Os ratio (Osi) for magnetite from Los Colorados is 1.2, overlapping Osi values for Chilean porphyry-Cu deposits, and consistent with an origin from juvenile magma. Together, the data are consistent with a geologic model wherein (1) magnetite microlites crystallize as a near-liquidus phase from an intermediate to mafic silicate melt; (2) magnetite microlites serve as nucleation sites for fluid bubbles and promote volatile saturation of the melt; (3) the volatile phase coalesces and encapsulates magnetite microlites to form a magnetite-fluid suspension; (4) the suspension scavenges Fe, Cu, Au, S, Cl, P, and rare earth elements (REE) from the melt; (5) the suspension ascends from the host magma during regional extension; (6) as the suspension ascends, originally igneous mag-netite microlites grow larger by sourcing Fe from the cooling magmatic-hydrothermal fluid; (7) in deep-seated crustal faults, magnetite crystals are deposited to form a Kiruna-type IOA deposit due to decompression of the magnetite-fluid suspension; and (8) the further ascending fluid transports Fe, Cu, Au, and S to shallower levels or lateral distal zones of the system where hematite, magnetite, and sulfides precipitate to form IOCG deposits. The model explains the globally observed temporal and spatial relationship between magmatism and IOA and IOCG deposits, and provides a valuable conceptual framework to define exploration strategies.
TL;DR: The results indicated that the cationic (including Fe2+, Fe3+ and U(VI)) migrate to cathode side under the electric field and the uranium was incorporated or adsorbed by Fe3O4 which was generated at cathode while the pH ranges between 2-7.
TL;DR: In this paper, the effects of pH and surface modifications on the colloidal and chemical stabilities of nanosized magnetite (Fe3O4), maghemite (γ-Fe2O3), and hematite (α-Fe 2O3) are investigated.
Abstract: Nanoparticle (NP) stability in aqueous environments is dependent upon many parameters including environmental conditions, NP concentrations as well as NP intrinsic characteristics. In this study, the effects of pH and surface modifications on the colloidal and chemical stabilities of nanosized magnetite (Fe3O4), maghemite (γ-Fe2O3) and hematite (α-Fe2O3) are investigated. Because changes in surface charge affect the size distribution of NP, pH plays a key role in driving the colloidal stability. More NP aggregation is observed at pH values close to the pH of zero point of charge (pHzpc). Coating of magnetite with humic acid (HA) and phosphatidylcholine (PC) affects the electrostatic interactions and then the colloidal behavior of NP. The rapid transformation of magnetite into maghemite through air oxidation results in significant modification of both surface charge and specific surface area of NP. Because the maghemite almost exclusively formed μm-scale aggregates, the colloidal stability of magnetite is expected to be hindered in oxic environments. For hematite, the particle size distribution data emphasize the influence of both pH and intrinsic surface properties in colloidal stability. These findings may have strong implications for an accurate prediction of the transformation and mobility of Fe-nanoparticles under environmentally relevant conditions and thus their fate in nature.
TL;DR: Ruthenium(0) nanoparticles supported on bare or silica-coated magnetite are prepared by impregnation of ruthenia(III) ions followed by their reduction with aqueous solution of sodium borohydride on the surface of support as mentioned in this paper.
TL;DR: In this article, the phase composition of the magnetite and maghemite phases of iron oxide magnetic nanoparticles is analyzed using Moser's equation of O(n 2 ).
Abstract: Iron oxide magnetic nanoparticles produced by chemical synthesis are usually composed of both magnetite and maghemite phases. Information about the phase composition is typically obtained using Mos...
TL;DR: In this article, a multi-functional nanocomposites based on magnetite nanoparticles, chitosan nanoparticles and polythiophene for efficient and selective mercury (II) removal from its aqueous solution.