Showing papers on "Magnetite published in 2010"
TL;DR: The magnetite-graphene hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem.
Abstract: Magnetite−graphene hybrids have been synthesized via a chemical reaction with a magnetite particle size of ∼10 nm. The composites are superparamagnetic at room temperature and can be separated by an external magnetic field. As compared to bare magnetite particles, the hybrids show a high binding capacity for As(III) and As(V), whose presence in the drinking water in wide areas of South Asia has been a huge problem. Their high binding capacity is due to the increased adsorption sites in the M−RGO composite which occurs by reducing the aggregation of bare magnetite. Since the composites show near complete (over 99.9%) arsenic removal within 1 ppb, they are practically usable for arsenic separation from water.
1,806 citations
TL;DR: In this article, three iron oxide polymorphs, hematite, maghemite, and magnetite, were produced on KBr substrates using a conventional electron beam deposition technique coupled with thermal annealing.
Abstract: Thin films of three iron oxide polymorphs, hematite, maghemite, and magnetite, were produced on KBr substrates using a conventional electron beam deposition technique coupled with thermal annealing. This method allowed for iron oxide thin films free from chemical precursor contaminants. The films were characterized using Fourier-transform infrared spectroscopy (FTIR), Raman microspectroscopy, and ellipsometry. These spectroscopic techniques allowed for a clear assignment of the phase of the iron oxide polymorph films produced along with an examination of the degree of crystallinity possessed by the films. The films produced were uniform in phase and exhibited decreasing crystallinity as the thickness increased from 40 to 250 nm.
653 citations
TL;DR: This review describes the synthesis, characterization and applications of a series of solids including silica supports, carbon nanotubes, alumina, organic polymers and other materials, mostly containing magnetite or paramagnetic metals.
376 citations
TL;DR: It is concluded that chitosan/magnetite nanocomposite beads could serve as a promising adsorbent not only for Pb( II) and Ni(II) (pH=4-6) but also for other heavy metal ions in wastewater treatment technology.
342 citations
TL;DR: The results indicate that the diatomite-supported/unsupported magnetite nanoparticles are readily prepared, enabling promising applications for the removal of Cr(VI) from aqueous solution.
335 citations
15 May 2010
TL;DR: Under the experimental conditions used, the materials reported here displayed high efficiency for Hg(2+) uptake (74%) even at contaminant levels as low as 50 μg l(-1), therefore these eco-nanomagnets show great potential for the removal of heavy metal ions of polluted water, via magnetic separation.
Abstract: The magnetic removal of Hg(2+) from water has been assessed using silica coated magnetite particles. The magnetite particles were first prepared by hydrolysis of FeSO(4) and their surfaces were modified with amorphous silica shells that were then functionalized with organic moieties containing terminal dithiocarbamate groups. Under the experimental conditions used, the materials reported here displayed high efficiency for Hg(2+) uptake (74%) even at contaminant levels as low as 50 μg l(-1). Therefore these eco-nanomagnets show great potential for the removal of heavy metal ions of polluted water, via magnetic separation.
329 citations
TL;DR: In this article, the suitability of magnetite nanoparticles for adsorption of heavy metal cation and its efficiency was investigated by graft polymerization with acrylic acid, which was then used for separation of metal cations.
269 citations
TL;DR: In this article, Raman spectroscopy is used to investigate magnetite nanoparticles dispersed in two types of b- cyclodextrin suspensions. But no hematite positions appear throughout that investigation.
208 citations
TL;DR: In this paper, the degree of stoichiometry in magnetite is quantitatively measured by determining the ratio of Fe2+ to Fe3+ using powder X-ray diffraction (pXRD).
Abstract: A solid solution can exist of magnetite (Fe3O4) and maghemite (γ-Fe2O3), which is commonly referred to as nonstoichiometric or partially oxidized magnetite. The degree of stoichiometry in magnetite is quantitatively measured by determining the ratio of Fe2+ to Fe3+. Magnetite stoichiometry ( x = Fe2+/Fe3+) strongly influences several physical properties, including the coercitivity, sorption capacity, reduction potential, and crystalline structure. Magnetite stoichiometry has been extensively studied, although very little work exists examining the stoichiometry of nanoparticulate samples (<<100 nm); when the stoichiometry was measured for nanoparticulate samples, it was not validated with a secondary technique. Here, we review the three most common techniques to determine magnetite stoichiometry: (1) acidic dissolution; (2) Mossbauer spectroscopy; and (3) powder X-ray diffraction (pXRD), specifically with nanoparticulate samples in mind. Eight samples of nonstoichiometric magnetite were synthesized with x ranging from 0 to 0.50 and with the particle size kept as similar as possible (BET specific surface area = 63 ± 7 m2/g; particle size ≈ 20 nm). Our measurements indicate excellent agreement between stoichiometries determined from Mossbauer spectra and by acidic dissolution, suggesting that Mossbauer spectroscopy may be a useful means for estimating magnetite stoichiometry in nanoparticulate, multi-phases samples, such as those found in the environment. A significant linear correlation was also observed between the unit-cell length ( a ) of magnetite measured by pXRD and magnetite stoichiometry, indicating that pXRD may also be useful for determining particle stoichiometry, especially for mixed phased samples.
206 citations
TL;DR: It is proposed that conceptual models that incorporate both redox and Fe2+ diffusion processes, rather than those that rely solely on diffusion of Fe2+, are more appropriate for understanding contaminant reduction by magnetite.
Abstract: The factors controlling rates of contaminant reduction by magnetite (Fe3O4) are poorly understood. Here, we measured the reduction rates of three ArNO2 compounds by magnetite particles ranging from...
194 citations
TL;DR: It is found that HA can adsorb to magnetite particles hence modifying their surface charge status, and fast aggregation, independent of solution chemistry, took place when the pH is close to the point zero charge (PZC) and the ionic strength is above the critical coagulation concentration (CCC).
TL;DR: The serpentinization of peridotite operates according to one or the other, or a combination, of two end-member mechanisms as discussed by the authors, with the result that the growth of Mg-rich antigorite can be accommodated by a compositional adjustment of olivine, eliminating the need to precipitate magnetite and evolve hydrogen.
Abstract: The serpentinization of peridotite operates according to one or the other, or a combination, of two end-member mechanisms. In low-temperature environments (50–300 °C), where lizardite is the predominant serpentine mineral, olivine is consumed by reaction with H2O but its composition (Mg#) remains unchanged. Mg-rich lizardite, magnetite, and dihydrogen gas (±brucite) are products of the reaction. At higher temperatures (400–600 °C), rates of MgFe diffusion in olivine are orders of magnitude faster, with the result that the growth of Mg-rich antigorite can be accommodated by a compositional adjustment of olivine, eliminating the need to precipitate magnetite and evolve hydrogen. This latter end-member mechanism probably best reflects the situation in the forearc mantle wedge.
TL;DR: In this paper, the role of Fe(II) in the oxidation of As(III) at the surface of magnetite and ferrihydrite under oxygenated conditions was investigated.
Abstract: To reduce the adverse effects of arsenic on humans, various technologies are used to remove arsenic from groundwater, most relying on As adsorption on Fe-(oxyhydr)oxides and concomitant oxidation of As(III) by dissolved O2. This reaction can be catalyzed by microbial activity or by strongly oxidizing radical species known to form upon oxidation of Fe(II) by dissolved O2. Such catalyzed oxidation reactions have been invoked to explain the enhanced kinetics of As(III) oxidation in aerated water, in the presence of zerovalent iron or dissolved Fe(II). In the present study, we used arsenic K-edge X-ray absorption near edge structure (XANES) spectroscopy to investigate the role of Fe(II) in the oxidation of As(III) at the surface of magnetite and ferrihydrite under oxygenated conditions. Our results show rapid oxidation of As(III) to As(V) upon sorption onto magnetite under oxic conditions at neutral pH. Moreover, under similar oxic conditions, As(III) oxidized upon sorption onto ferrihydrite only after additi...
TL;DR: In this article, a magnetite powder composed of uniform sub-micrometer spherical particles has been successfully synthesized by a hydrothermal method at low temperature, which shows a stable and reversible capacity of over 900 mAhg −1 during up to 60 cycles and good rate capability.
TL;DR: In this paper, the authors characterized the magnetic behavior of magnetite by determining the saturation magnetization, coercivity, remanent magnetization and susceptibility of synthetic magnetite using a superconducting quantum interference device (SQUID) and showed how these properties vary in the presence of surface-associated solutes such as tetramethylammonium (TMA) and ferrous (Fe(II)) cations.
Abstract: Synthetic nanomagnetite has been suggested as a potential reactant for the in situ treatment of contaminated groundwater. Although the application of magnetite nanoparticles for environmental remediation is promising, a full understanding of particle reactivity has been deterred by the propensity of the nanoparticles to aggregate and become colloidally unstable. Attractive magnetic interactions between particles are partially responsible for their aggregation. In this study, we characterized the magnetic behavior of magnetite by determining the saturation magnetization, coercivity, remanent magnetization, susceptibility, and blocking temperature of synthetic magnetite using a superconducting quantum interference device (SQUID). We show how these properties vary in the presence of surface-associated solutes such as tetramethylammonium (TMA(+)) and ferrous (Fe(II)) cations. More importantly, because magnetite readily reacts with O(2) to produce maghemite, we analyzed the effect of oxidation on the magnetic properties of the particles. Because maghemite has a reported magnetic saturation that is less than that of magnetite, we hypothesized that oxidation would decrease the magnitude of the magnetic attractive force between adjacent particles. The presence of TMA(+) and Fe(II) caused a change in the magnetic properties of magnetite potentially because of alterations in its crystalline order. Magnetite oxidation caused a decrease in saturation magnetization, resulting in less significant magnetic interactions between particles. Oxidation, therefore, could lead to the decreased aggregation of magnetite nanoparticles and a potential enhancement of their colloidal stability.
01 Dec 2010
TL;DR: In this article, the authors reported the results of a study of the early Archean BIFs from the Hamersley Basin, Australia and the early Isua Supracrustal Belt (ISB), Greenland.
Abstract: Banded Iron-Formations (BIFs) are voluminous chemical sediments that are rich in iron-oxide, carbonate and silica and whose occurrence is unique to the Precambrian. Their preservation in the geological record offers insights to the surface chemical and biological cycling of iron and carbon on early Earth. However, many details regarding the role of microbial activity in BIF deposition and diagenesis are unresolved. Laboratory studies have shown that reaction between carbon and iron through microbial iron respiration [2Fe2O3∙ nH2O + CH2O + 7H+ → 4Fe2+ + HCO3− + (2n + 4)H2O + chemical energy] can impart fractionation to the isotopic compositions of these elements. Here, we report iron (δ56Fe, vs. IRMM-014) and carbon isotopic (δ13C, vs. V-PDB) compositions of magnetite and of iron-rich and iron-poor carbonates in BIFs from the late Archean (~ 2.5 Ga) Hamersley Basin, Australia and the early Archean (~ 3.8 Ga) Isua Supracrustal Belt (ISB), Greenland. The range of δ56Fe values measured in the Hamersley Basin, including light values in magnetite and heavy values in iron-rich carbonates (up to + 1.2‰), are incompatible with their precipitation in equilibrium with seawater. Rather, the data together with previously reported light δ13C values in iron-rich carbonates record evidence for diagenetic reduction of ferric oxide precursors to magnetite and carbonate through microbial iron respiration (i.e., dissimilatory iron reduction, DIR). Iron and carbon isotope data of iron-rich metacarbonates from the ISB are similar to those of late Archean BIFs. The isotopic signatures of these metacarbonates are supportive of an early diagenetic origin despite metasomatic overprint, and preserve evidence of microbial iron respiration within the oldest recognized sedimentary rocks on Earth.
TL;DR: In this article, a new type of flexible carbon fabric supported magnetite multiwalled carbon nanotubes (Fe3O4-MWNTs) nanocomposite based supercapacitor was fabricated for the removal of high concentration of arsenic and desalination of seawater.
Abstract: A new type of flexible carbon fabric supported magnetite multiwalled carbon nanotubes (Fe3O4-MWNTs) nanocomposite based supercapacitor was fabricated for the removal of high concentration of arsenic and desalination of seawater. MWNTs were synthesized by a chemical vapor deposition (CVD) technique, purified by air oxidation and acid treatment followed by further functionalization. Decoration of magnetite (Fe3O4) nanoparticles over functionalized MWNTs surface was done by a chemical technique. Fe3O4-MWNTs nanocomposite was characterized using different characterization techniques. Electrochemical activity of the nanocomposite was analyzed for arsenite and arsenate ions containing water as well as for seawater by using cyclic voltametry (CV). Adsorption isotherms and kinetic characteristics of sodium, arsenate, and arsenite ion removal were studied. Performance of the filter made up of nanocomposite-based electrodes was examined by an inductive coupled plasma optical emission spectroscopy (ICP-OES) techniqu...
01 Mar 2010
TL;DR: The surface and bulk structures of a newly developed carbon-based iron-containing adsorbent for As(V) adsorption were investigated by using XRD, field emission scanning electronic microscopy, and X-ray photoelectron spectroscopy to demonstrate that the monoprotonated bidentate complexes were dominant on the surface of the MACF.
Abstract: The surface and bulk structures of a newly developed carbon-based iron-containing adsorbent for As(V) adsorption were investigated by using X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). XRD patterns of the adsorbents indicated that the modified activated carbon fiber (MACF) was a simple mixture of the raw activated carbon fiber (RACF) and magnetite. After modification, a porous film was formed on the surface of the MACF with nano-sized magnetite on it. The As(V) uptake on the MACF was highly pH dependent and was facilitated in acidic solutions. XPS studies demonstrated that the surface oxygen-containing functional groups were involved in the adsorption and that magnetite played a key role in As(V) uptake. The dominance of HAsO(4)(2-) in surface complexes and the pH effect on As(V) uptake demonstrated that the monoprotonated bidentate complexes were dominant on the surface of the MACF. No reduction of As(V) was observed on the surface of the ACFs.
TL;DR: In this article, a single iron precursor (iron(III) ethoxide) and an amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-poly(poly(methylene oxide) triblock copolymer (PEO100/PPO65/PEO 100) as a soft template were used to synthesize spherical mesoporous magnetite (Fe3O4) aggregates with wormhole-like pore structure.
Abstract: Spherical mesoporous magnetite (Fe3O4) aggregates with a wormhole-like pore structure were successfully synthesized for the first time using a single iron precursor (iron(III) ethoxide) and an amphiphilic poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymer (PEO100–PPO65–PEO100) as a soft template In this synthesis, the interaction between the iron precursor and the triblock copolymer self-assemblies in ethanol leads to the assembly of magnetite nanocrystals into spherical mesoporous aggregates These aggregates were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, standard and high-resolution transmission electron microscopy, 57Fe Mossbauer spectroscopy, and X-ray diffraction, confirming the formation of pure-phase Fe3O4 particles with monodisperse morphology (about 130 nm in diameter), three-dimensional wormhole-like mesopores, and highly crystalline spinel structure In addition, a formation mechanism for this material in the present system is proposed, based on the analysis of results The mesoporous magnetite has a high specific surface area of 1656 m2 g−1, and relatively large pores with a mean size of 52 nm The magnetic susceptibility data demonstrate that this material exhibits superparamagnetic behavior
TL;DR: This paper measured magnetization M continuously for stoichiometric and partially oxidized magnetites with average grain sizes of 37 and 220 nm during zero-field cycling of 25 T saturation isothermal remanent magnetization (SIRM) from 300 K to 20 K and back to 300 K.
Abstract: [1] In environmental, soil, and sediment magnetism, it is important to be able to estimate the degree of oxidation of magnetite grains We report a new method for finding the oxidation parameter z semiquantitatively from cooling-warming cycles of room temperature remanences We measured magnetization M continuously for stoichiometric and partially oxidized magnetites with average grain sizes of 37 and 220 nm during zero-field cycling of 25 T saturation isothermal remanent magnetization (SIRM) from 300 K to 20 K and back to 300 K Oxidized magnetites were obtained by heating stoichiometric magnetite in air at 100°C, 150°C, and 200°C In other experiments, SIRM was given at 10 K, and M was monitored during zero-field warming to 300 K In the oxidized magnetites, SIRM at first increases in cooling from 300 K and then decreases in approaching the Verwey transition The hump-like form is even more pronounced in the warming curves above TV For maghemite, the fully oxidized end member, we found reversible cooling-warming curves with no Verwey transition In partially oxidized grains, consisting of a maghemite surface layer and a largely unoxidized core, a Verwey transition is resolvable up to high degrees of oxidation Hallmarks of maghemitization include (1) a smeared-out Verwey transition shifted to lower temperatures when warming 20 K SIRM, (2) a shifted and broadened transition region in both cooling and warming of 300 K SIRM, and (3) humped cooling and warming curves of 300 K SIRM between 300 K and TV Property 3 has excellent diagnostic value It results from the combination of a slowly increasing M of maghemite and the rapid and nonlinear decrease in M of magnetite during cooling and is seen even for the slight initial oxidation of the reduced 37 nm magnetite Certain properties, such as the change in M in warming from 20 K to TV and the change in initial and final M values in a complete cooling-warming cycle, are roughly proportional to the oxidation parameter z However, the proportionality factors also depend on grain size d, which would have to be known independently in order to estimate z
TL;DR: In this article, a magnetite (Fe3O4) nanoparticle was synthesized using a solid state mechanochemical method and used for studying the sorption of uranium(VI) from aqueous solution onto the nanomaterial.
Abstract: Magnetite (Fe3O4) nanoparticle was synthesized using a solid state mechanochemical method and used for studying the sorption of uranium(VI) from aqueous solution onto the nanomaterial. The synthesized product is characterized using SEM, XRD and XPS. The particles were found to be largely agglomerated. XPS analysis showed that Fe(II)/Fe(III) ratio of the product is 0.58. Sorption of uranium on the synthesized nanomaterials was studied as a function of various operational parameters such as pH, initial metal ion concentration, ionic strength and contact time. pH studies showed that uranium sorption on magnetite is maximum in neutral solution. Uranium sorption onto magnetite showed two step kinetics, an initial fast sorption completing in 4–6 h followed by a slow uptake extending to several days. XPS analysis of the nanoparticle after sorption of uranium showed presence of the reduced species U(IV) on the nanoparticle surface. Fe(II)/Fe(III) ratio of the nanoparticle after uranium sorption was found to be 0.48, lower than the initial value indicating that some of the ferrous ion might be oxidized in the presence of uranium(VI). Uranium sorption studies were also conducted with effluent from ammonium diuranate precipitation process having a uranium concentration of about 4 ppm. 42% removal was observed during 6 h of equilibration.
TL;DR: A robust wet-chemical route to synthesize monosized octahedron-shaped magnetite (Fe3O4) nanoparticles with average sizes ranging from 8 to ∼430 nm was reported in this article.
Abstract: In this work, we report a robust wet-chemical route to synthesize monosized octahedron-shaped magnetite (Fe3O4) nanoparticles with average sizes ranging from 8 to ∼430 nm In other words, we are able to adjust the magnetic properties of the as-synthesized nanoparticles from superparamagnetic to single-domain to multidomain ferrimagnetic regimes We also demonstrate a simple solvent-evaporation assembly process to obtain either 2D monolayer or 3D microrod superstructures made of 21 nm-sized nanooctahedra by applying a weak magnetic field (∼006 T) in the horizontal or vertical direction, respectively The as-obtained 2D monolayer assembly not only exhibits a long-range translational order (hexagonal close packing) but also has a high degree of crystallographic orientational order (⟨111⟩ texture normal to the substrate) Large-area assemblies (up to 10 × 10 μm) can be formed on various substrates, for example, silicon substrates and carbon films of transmission electron microscopy copper grids, as demonstra
TL;DR: In this paper, the thermal conductivity of magnetite nanofluid has been studied as a function of transverse magnetic field and temperature, and the authors found almost 30% enhancements in thermal conductivities for 4.7% volume fraction.
Abstract: Magnetite nanofluid is synthesized using continuous chemical process. Powder x-ray diffraction and transmission electron microscopy show single phase spinel structure with size of 9.83 and 9.9 nm, respectively. Thermal conductivity of magnetite nanofluid has been studied as a function of transverse magnetic field and temperature. We found almost 30% enhancements in thermal conductivity for 4.7% volume fraction under transverse magnetic field. This result is explained on the basis of formation of continuous three-dimensional zipperlike structure of magnetic nanoparticles inside magnetic fluid. The temperature dependent thermal conductivity shows no enhancement in the temperature region of 25–65 °C.
TL;DR: In this paper, the properties, applications, and syntheses of three magnetic iron oxides (hematite, magnetite, and maghemite) are discussed and methods of preparation that allow control over the size, morphology, surface treatment and magnetic properties of their nanoparticles.
Abstract: Magnetic nanoparticles exhibit many interesting properties that can be exploited in a variety of applications such as catalysis and in biomedicine. This review discusses the properties, applications, and syntheses of three magnetic iron oxides – hematite, magnetite, and maghemite – and outlines methods of preparation that allow control over the size, morphology, surface treatment and magnetic properties of their nanoparticles. Some challenges to further development of these materials and methods are also presented.
TL;DR: In this article, an anion-assisted hydrothermal route for the production of magnetic iron oxide short nanotubes (SNTs) employing an an ion-assisted hydrogel route by simultaneously using phosphate and sulfate ions was proposed.
Abstract: We present a facile approach to the production of magnetic iron oxide short nanotubes (SNTs) employing an anion-assisted hydrothermal route by simultaneously using phosphate and sulfate ions. The size, morphology, shape, and surface architecture control of the iron oxide SNTs are achieved by simple adjustments of ferric ions concentration without any surfactant assistance. The result of a formation mechanism investigation reveals that the ferric ions concentrations, the amount of anion additive, and the reaction time make significant contributions to SNT growth. The shape of the SNTs is mainly regulated by the adsorption of phosphate ions on faces parallel to the long dimension of elongated α-Fe2O3 nanoparticles (c axis) during nanocrystal growth, and the hollow structure is given by the preferential dissolution along the c axis due to the strong coordination of the sulfate ions. Moreover, the as-synthesized hematite (α-Fe2O3) SNTs can be converted to magnetite (Fe3O4) and maghemite (γ-Fe2O3) ferromagneti...
TL;DR: These CNPs can still diffract visible lights when a magnetic field was applied, which is attributed to carbon coating and creating carboxyl groups on the surface of carbon shells introducing both a steric hindrance and electrostatic repulsions between magnetite nanoparticles.
Abstract: The core/shell structure of magnetite/carbon colloidal nanoparticles (CNPs) with average size about 190 nm has been prepared via a one-step solvothermal process using ferrocene as a single reactant. The composition, phase, and morphology of the nanostructure have been characterized by X-ray diffraction, and transmission electron microscopy. Magnetic measurements reveal the superparamagnetic nature of the material with a magnetization saturation of 40.2 emu/g at room temperature. Under the induction of an external magnetic field, strong diffraction in the visible light spectrum can be observed in a suspension of CNPs in ethanol and the diffraction wavelength varies with the strength of the external magnetic field. After being stored for eight months in an ethanol solution, these CNPs can still diffract visible lights when a magnetic field was applied, which is attributed to carbon coating and creating carboxyl groups on the surface of carbon shells introducing both a steric hindrance and electrostatic repulsions between magnetite nanoparticles.
TL;DR: The results indicated that the C-terminal region of the Mms6 protein has significant control over the morphology of magnetite crystals in the chemical synthetic method, and this method can, therefore, be useful as an alternative method of controlling the size and morphology of magnetsite crystals under ambient conditions.
TL;DR: In this paper, a facile, one-pot route to phase-pure Fe3C nanoparticles (mean diameter = 20 nm) that show a remarkably high saturation magnetization (∼130 emu/g) was reported.
Abstract: In this article, we report a facile, one-pot route to phase-pure Fe3C nanoparticles (mean diameter = 20 nm) that show a remarkably high saturation magnetization (∼130 emu/g), higher than iron oxide (Fe3O4) and comparable to that of bulk Fe3C (∼140 emu/g). A readily available biopolymer (gelatin) is used as a matrix to disperse an aqueous iron acetate precursor. On heating, the biopolymer induces nucleation of magnetite (Fe3O4) nanoparticles before decomposing to form a carbon-rich matrix. This then acts as a reactive template for carbothermal reduction of the magnetite nanoparticles to Fe3C at a moderate temperature of 650 °C. This method represents a considerable advance over previous reports that often use high-energy procedures or costly and hazardous precursors. These homogeneous, highly magnetic nanoparticles have many potential applications in biomedicine and catalysis.
TL;DR: In this article, the authors describe effective reagent combinations for removal of silicates by reverse cationic flotation from magnetic concentrate in magnetite ores processing, based on a hypothesis that a further development in reverse-cationic reagent flotation of iron ores implies a more detailed consideration of the nature of the Fe-bearing gangue minerals.
TL;DR: In this paper, a co-precipitation in an aqueous solution containing ferrous and ferric salts (1:2) at varying pH with ammonia as a base was found to influence the reaction mechanism for the formation of Fe3O4.