Showing papers on "Magnetite published in 2021"
TL;DR: In this article, the main properties, applications, and synthesis methods of magnetite, together with the newest advancements in this field are presented, as well as a review of the main applications, applications and methods for magnetite.
60 citations
TL;DR: This work successfully fabricated a novel magnetic adsorbent, i.e., phosphate modified magnetite@ferrihydrite (Mag@Fh-P), and explored its potential application for Cd(II) removal from water, soil, and sediment.
42 citations
TL;DR: The results showed that high temperatures during the suspension reduction process were conducive to improving the reduction rate of the iron tailing, and the best kinetics model for this reduction reaction of iron tailings is the P1 model, which demonstrated a linear increase in the conversion degree with the extension of the reaction time.
39 citations
TL;DR: In this article, a microwave fluidization roasting method was developed for Oolitic hematite with an iron grade of 58.72% and an iron recovery of 89.32%.
38 citations
TL;DR: The adsorption studies illustrated that the elimination efficiency of lead ions was 80% by the prepared nanocomposite that includes a minimum amount of crosslinker, which demonstrated that the magnetic grafted oxidized cellulose nanofiber nanocomPOSite is a promising green adsorbent material to eliminate heavy metal ions.
33 citations
TL;DR: The use of magnetic nanoparticles in hyperthermia, that is, heating induced by alternating magnetic fields, is gaining interest as a noninvasive, free of side effects technique that can be considered as a co-adjuvant of other cancer treatments as discussed by the authors.
Abstract: The use of magnetic nanoparticles in hyperthermia, that is, heating induced by alternating magnetic fields, is gaining interest as a non-invasive, free of side effects technique that can be considered as a co-adjuvant of other cancer treatments. Having sufficient control on the field characteristics, within admissible limits, the focus is presently on the magnetic material. In the present contribution, no attempt has been made of using other composition than superparamagnetic iron oxide nanoparticles (SPION), or of applying surface functionalization, which opens a wider range of choices. We have used a hydrothermal synthesis route that allows preparing SPION nanoparticles in the 40 nm size range, with spherical, cuboidal or rod-like shapes, by minor changes in the synthesis steps. The three kinds of particles (an attempt to produce star-shaped colloids yielded hematite) were demonstrated to have the magnetite (or maghemite) crystallinity. Magnetization cycles showed virtually no hysteresis and demonstrated the superparamagnetic nature of the particles, cuboidal ones displaying saturation magnetization comparable to bulk magnetite, followed by rods and spheres. The three types were used as hyperthermia agents using magnetic fields of 20 kA/m amplitude and frequency in the range 136–205 kHz. All samples demonstrated to be able to raise the solution temperature from room values to 45 °C in a mere 60 s. Not all of them performed the same way, though. Cuboidal magnetic nanoparticles (MNPs) displayed the maximum heating power (SAR or specific absorption rate), ranging in fact among the highest reported with these geometries and raw magnetite composition.
33 citations
TL;DR: In this article, a novel method of pellet calcification roasting-H2SO4 leaching was proposed to efficiently separate and extract vanadium (V) from vanadium-titanium (V-Ti) magnetite concentrates.
Abstract: A novel method of pellet calcification roasting-H2SO4 leaching was proposed to efficiently separate and extract vanadium (V) from vanadium-titanium (V-Ti) magnetite concentrates. The leaching rate of V is as high as 88.98%, while the leaching rate of impurity iron is only 1.79%. Moreover, the leached pellets can be used as raw materials for blast furnace ironmaking after secondary roasting. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) analyses showed that V3+ was oxidized to V5+ after roasting at 1200 °C, and V5+ was then leached by H2SO4. X-ray diffraction (XRD) analyses and single factor experiment revealed a minimal amount of dissolved Fe2O3 during H2SO4 leaching. Therefore, a high separation degree of V and iron (Fe) from V-Ti magnetite concentrate was achieved through H2SO4 leaching. Compared with the traditional roasting-leaching process, this process can achieve a high selectivity of V and Fe, and has excellent prospects for industrial production.
31 citations
TL;DR: Mesoporous magnetite nanoparticles (Fe3O4NPs) were synthesized by using the leaf extract of Mussaenda erythrophylla (ME) by a cheap and simple method.
31 citations
TL;DR: In this paper, oleic acid (OA) was applied to Fe3O4 nanoparticles by a thermal decomposition method and the magnetic properties of the particles were investigated.
28 citations
TL;DR: The results suggest that hematite nanocrystals' superparamagnetic properties may be explored in multifunctional glass-ceramics applied in bone cancer treatment by hyperthermia allied to bone regeneration.
24 citations
TL;DR: In this article, a straightforward synthesis of magnetic graphene oxide (GO·Fe3O4) in very mild conditions was reported, and the results revealed the presence of magnetic nanoparticles (MNPs) in analyzed nanomaterial.
Abstract: In this work, we report a straightforward synthesis of magnetic graphene oxide (GO·Fe3O4) in very mild conditions. This methodology proved to be effective in obtain graphene oxide (GO) decorated with different amounts of incorporated magnetite. The characterizations reveal the presence of magnetic nanoparticles (MNPs) in analyzed nanomaterial. Despite several methods shown in the literature, this protocol enables the amount control of incorporated magnetite on the surface of GO. Experimental data shows that GO·Fe3O4 1:10 (mass:mass) demonstrates the highest adsorption capacity on the hydrochlorothiazide with a 67.86% removal of the contaminant and pH 7.0 as the favorable condition. The removal rate and adsorption capacity are dependent on the initial concentration of the HCTZ, amount and type of the adsorbent. Temperature, ionic strength, and solution pH in the adsorption were also studied. The pseudo-second-order and Freundlich models showed better adjustment of the experiment. Thermodynamic parameters indicated that the adsorption process is exothermic and occurred spontaneously. Magnetic nanoadsorbent proves to be an efficient alternative nanomaterial for removing hydrochlorothiazide from aqueous solutions, avoiding filtration and centrifugation steps.
23 Feb 2021
TL;DR: In this article, the effect of the gradual increase of cobalt content in Fe3O4 nanocolloids was investigated in-depth using XRD, XRF, XPS, FTIR, DLS, zeta potential, EMR, and VSM analyses.
Abstract: Magnetite nanoparticles are one of the most promising ferrofluids for hyperthermia applications due to the combination of unique physicochemical and magnetic properties. In this study, we designed and produced superparamagnetic ferrofluids composed of magnetite (Fe3O4, MION) and cobalt-doped magnetite (Cox-MION, x = 3, 5, and 10% mol of cobalt) nanoconjugates through an eco-friendly aqueous method using carboxymethylcellulose (CMC) as the biocompatible macromolecular ligand. The effect of the gradual increase of cobalt content in Fe3O4 nanocolloids was investigated in-depth using XRD, XRF, XPS, FTIR, DLS, zeta potential, EMR, and VSM analyses. Additionally, the cytotoxicity of these nanoconjugates and their ability to cause cancer cell death through heat induction were evaluated by MTT assays in vitro. The results demonstrated that the progressive substitution of Co in the magnetite host material significantly affected the magnetic anisotropy properties of the ferrofluids. Therefore, Co-doped ferrite (CoxFe(3−x)O4) nanoconjugates enhanced the cell-killing activities in magnetic hyperthermia experiments under alternating magnetic field performed with human brain cancer cells (U87). On the other hand, the Co-doping process retained the pristine inverse spinel crystalline structure of MIONs, and it has not significantly altered the average nanoparticle size (ca.∼7.1 ± 1.6 nm). Thus, the incorporation of cobalt into magnetite-polymer nanostructures may constitute a smart strategy for tuning their magnetothermal capability towards cancer therapy by heat generation.
TL;DR: The results demonstrate that the presence of Fe (II) substantially enhanced As removal from solution, and highlight a Fe(II)-induced mechanism through which highly mobile, toxic As(III) species are oxidized on the mineral surface to form As(V).
TL;DR: In this paper, the effect of reduction temperature, H2 concentration, reduction time and gas flow rate on the metallization degree of the reduced product were studied, and the phase compositions and microstructures of sample were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).
TL;DR: In this paper, microwave-assisted reduction roasting of a goethite-rich, reject iron ore waste stream (−2 mm) was used to produce a high-grade concentrate.
TL;DR: In this paper, the structure of the oxide scales formed on three ferritic/martensitic (F/M) steels, including HT9, T91 and CLA16 exposed to oxygen-saturated leadbismuth eutectic (LBE) at 400°C for 500 h has been studied.
TL;DR: In this article, a coupling mechanism of fast adsorption-direct reduction-indirect reduction was proposed, and a multi-step kinetic model was developed based on that, which had a much better fitting effect (0.936 d−1).
TL;DR: In this paper, the speciation of iron on crushed materials through spatially resolved micro-spectroscopic studies was analyzed by element-specific synchrotron-based techniques.
TL;DR: In this article, under the conditions (ethanol-type fermentation) employed, magnetite stimulated the secretion of extracellular polymeric substances (EPS) in the presence of magnetite and showed that the EPS secreted with magnetite had the higher electron accepting and electron-donating capacity than the EPS without magnetite.
TL;DR: In this paper, a facile and a low-cost chemical synthesis technique has been adopted to produce versatile, oxygen deficient, mesoporous maghemite (iron oxide) nanostructure.
TL;DR: In this article, an innovative utilization of red mud through co-roasting with coal gangue for separation and recycling of iron and aluminum minerals is presented under optimum coroasting conditions (550°C for 50min), an iron concentrate containing 5725% TFe (total iron content) with the recovery of 6522%, and an aluminum-rich product containing 2726% Al2O3 with recovery of 7137% were obtained after magnetic separation
TL;DR: In this article, the competitive adsorption geometries for arsenate and phosphate on magnetite surfaces over a pH range of 4-9 were investigated using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and two-dimensional correlation analysis (2D-COS).
Abstract: In the present study, the competitive adsorption geometries for arsenate and phosphate on magnetite surfaces over a pH range of 4–9 were investigated using in situ attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and two-dimensional correlation analysis (2D-COS). The adsorption energies and infrared vibrational frequencies of these surface complexes were also calculated by first-principles simulations. Arsenate and phosphate have different preferences for the magnetite surface in the presence of aqueous solvent at both acid and alkaline pH. For the adsorption of phosphate, mono-protonated monodentate mononuclear (MMM) complexes dominated at acid pH, while non-protonated bidentate binuclear (NBB) complexes were dominant at alkaline pH. Arsenate mainly formed bidentate binuclear (BB) complexes with some outer-sphere species, both of which were more prevalent at acid pH. The pre-absorbed inner-sphere arsenate species were scarcely affected by the introduction of phosphate. However, the pre-absorbed phosphate oxyanions, especially the MMM complexes, were significantly substituted by BB arsenate at the magnetite surfaces. The adsorption affinity of phosphate and arsenate species for magnetite surface was found to increase in the following order: MMM phosphate complex < NBB phosphate complex < BB arsenate complex, which was consistent with the calculated adsorption energies. The simulated infrared vibrational frequencies for the most favorable adsorption modes of each oxyanion display distinctive patterns, and their trends are in excellent agreement with experimental data.
The effects of pH, adsorption sequence, and mineral species on the competitive adsorption between arsenate and phosphate oxyanions are also discussed, and their different competing ability and stability on the magnetite surfaces can be ascribed to the variations in adsorption geometry and strength of binding. To the best of our knowledge, this is the first study aiming to distinguish the stability of the different phosphate and arsenate complexes on magnetite by employing a combined approach of in situ spectroscopy and DFT simulations. Our results provide molecular-level insight into the geometries and relative stabilities of the adsorption of phosphate and arsenate on magnetite surfaces, which is useful for interpretation of the mobility and bioavailability of these anions.
TL;DR: It is shown for the first time that biogenic Mt nanoparticles formed during fungal-mineral cultivation exhibit intrinsic peroxidase-like activity, which highlights an important, but unrecognized, catalytic activity of mineral nanoparticles produced byFungal-Mineral interactions and contribute substantially to the understanding of Mineral nanoparticles in natural ecosystems.
Abstract: Fungal-mineral interactions can produce large amounts of biogenic nano-size (~1-100 nm) minerals, yet their influence on fungal physiology and growth remains largely unexplored. Using Trichoderma guizhouense NJAU4742 and magnetite (Mt) as a model fungus and mineral system, we have shown for the first time that biogenic Mt nanoparticles formed during fungal-mineral cultivation exhibit intrinsic peroxidase-like activity. Specifically, the average peroxidase-like activity of Mt nanoparticles after 72 h cultivation was ~2.4 times higher than that of the original Mt. Evidence from high resolution X-ray photoelectron spectroscopy analyses indicated that the unique properties of magnetite nanoparticles largely stemmed from their high proportion of surface non-lattice oxygen, through occupying surface oxygen-vacant sites, rather than Fe redox chemistry, which challenges conventional Fenton reaction theories that assume iron to be the sole redox-active centre. Nanoscale secondary ion mass spectrometry with a resolution down to 50 nm demonstrated that a thin (<1 µm) oxygen-film was present on the surface of fungal hyphae. Furthermore, synchrotron radiation-based micro-FTIR spectra revealed that surface oxygen groups corresponded mainly to organic OH, mineral OH, and carbonyl groups. Together, these findings highlight an important, but unrecognized, catalytic activity of mineral nanoparticles produced by fungal-mineral interactions and contribute substantially to our understanding of mineral nanoparticles in natural ecosystems. This article is protected by copyright. All rights reserved.
TL;DR: In this article, the authors evaluate the compositions of fluids that formed the classic yet enigmatic Mt(-Ap) deposit at El Laco, northern Chile, and suggest that a major component of the liquid was derived from assimilation of evaporite-bearing sedimentary rocks during emplacement of andesitic magma at depth.
Abstract: The origins of Kiruna-type magnetite(-apatite) [Mt(-Ap)] deposits are contentious, with existing models ranging from purely hydrothermal to orthomagmatic end members. Here, we evaluate the compositions of fluids that formed the classic yet enigmatic Mt(-Ap) deposit at El Laco, northern Chile. We report evidence that ore-stage minerals crystallized from an Fe-rich (6–17 wt% Fe) sulfate melt. We suggest that a major component of the liquid was derived from assimilation of evaporite-bearing sedimentary rocks during emplacement of andesitic magma at depth. Hence, we argue that assimilation of evaporite-bearing sedimentary strata played a key role in the formation of El Laco and likely Mt(-Ap) deposits elsewhere.
TL;DR: In this paper, an electro-fenton system with magnetite coated stainless steel (SUS) mesh as cathode was developed and tested for removing methylene blue in wastewater, where surface roughening of SUS mesh with FeAl particles was carried out.
TL;DR: The role of 1,2-hexadecanediol, which mediates the particle nucleation and growth, is elucidated by infrared spectroscopy and the magnetic response and the structural features of the NPs for the two series of samples are correlated.
Abstract: Iron oxide nanoparticles (NPs) have been extensively used for both health and technological applications. The control over their morphology, crystal microstructure, and oxidation state is of great importance to optimize their final use. However, while mature in understanding, it is still far from complete. Here we report on the effect of the amount of 1,2-hexadecanediol and/or 1-octadecene in the reaction mixture on the thermal decomposition of iron(III) acetylacetonate in oleic acid for two series of iron oxide NPs with sizes ranging from 6 to 48 nm. We show that a low amount of either compound leads to both large, mixed-phase NPs composed of magnetite (Fe3O4) and wustite (FeO) and high reaction yields. In contrast, a higher amount of either 1,2-hexadecanediol or 1-octadecene gives rise to smaller, single-phase NPs with moderate reaction yields. By infrared spectroscopy, we have elucidated the role of 1,2-hexadecanediol, which mediates the particle nucleation and growth. Finally, we have correlated the magnetic response and the structural features of the NPs for the two series of samples.
TL;DR: The combined effect of zero valent iron (ZVI) and magnetite on semi-dry anaerobic digestion of swine manure was studied in this article, where the additive effect of ZVI+magnetite on methanogenesis was investigated.
TL;DR: A side-by-side comparison of four types of Fe(III) oxides including Fe( III)-citrate, ferrihydrite, hematite and magnetite to evaluate their effectiveness in methanogenic degradation of phenol showed that, amorphousFe(III)- citrate group showed the fastest phenol degradation and Fe2+ release among all the groups, followed by poorly crystalline ferriHydrite.
TL;DR: Magnetite nanoparticle-supported ionic liquid (IL@Fe3O4) catalysts with varying anions were synthesized via step-wise functionalization of Fe 3O4 nanoparticles as mentioned in this paper.
TL;DR: In this paper, the presence of trace amounts of dissolved cerium increases the porosity of hematite formed via fluid-induced, redox-independent replacement of magnetite (Fe3O4), thereby increasing the efficiency of coupled magnetite replacement, fluid flow, and element mass transfer.
Abstract: Reaction-induced porosity is a key factor enabling protracted fluid-rock interactions in the Earth’s crust, promoting large-scale mineralogical changes during diagenesis, metamorphism, and ore formation. Here, we show experimentally that the presence of trace amounts of dissolved cerium increases the porosity of hematite (Fe2O3) formed via fluid-induced, redox-independent replacement of magnetite (Fe3O4), thereby increasing the efficiency of coupled magnetite replacement, fluid flow, and element mass transfer. Cerium acts as a catalyst affecting the nucleation and growth of hematite by modifying the Fe2+(aq)/Fe3+(aq) ratio at the reaction interface. Our results demonstrate that trace elements can enhance fluid-mediated mineral replacement reactions, ultimately controlling the kinetics, texture, and composition of fluid-mineral systems. Applied to some of the world’s most valuable orebodies, these results provide new insights into how early formation of extensive magnetite alteration may have preconditioned these ore systems for later enhanced metal accumulation, contributing to their sizes and metal endowment. Trace amounts of Cerium can act as a catalyst by enhancing fluid-mediated magnetite alteration, which preconditions ore systems and could contribute to the large size and metal content of world-class ore deposits.