Journal articles on the topic 'Magnetite'
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Mohd Yusoff, Ahmad Huzaifah, Midhat Nabil Ahmad Salimi, and Mohd Faizal Jamlos. "A New XRD Method to Quantitatively Distinguish Non-Stoichiometric Magnetite: Influence of Particle Size and Processing Conditions." Advanced Engineering Forum 26 (February 2018): 41–52. http://dx.doi.org/10.4028/www.scientific.net/aef.26.41.
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Magnetite’s abilities rely on the quantitative phases present in the sample. Magnetite quality can strongly influence several physical properties, such as magnetism, catalytic performance, and Verwey transition. However, differentiation of magnetite and maghemite through the conventional X-ray diffractogram comparison are not relevant for the intermediate phases. In this study, the deviation from the ideal stoichiometric magnetite and the relative quantification of both phases were mathematically achievable through a new XRD technique. Various synthesis conditions were applied to obtain different crystallite sizes, in the range of 9 to 30 nm. Generally, the stoichiometric deviation and maghemite content would be significantly influenced by the final size, whereas system conditions (temperature of solution, agitation rate, and pH of solution) would only have minor significance. In this study, iron oxide nanoparticles prepared using the co-precipitation method was calculated to contain 100% magnetite for particles of 30.26 nm in size, while 100% maghemite was calculated for particles at 9.64 nm.
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Roh, Yul, Hee-Dong Jang, and Yongjae Suh. "Microbial Synthesis of Magnetite and Mn-Substituted Magnetite Nanoparticles: Influence of Bacteria and Incubation Temperature." Journal of Nanoscience and Nanotechnology 7, no. 11 (November 1, 2007): 3938–43. http://dx.doi.org/10.1166/jnn.2007.076.
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Microbial synthesis of magnetite and metal (Co, Cr, Ni)-substituted magnetites has only recently been reported. The objective of this study was to examine the influence of Mn ion on the microbial synthesis of magnetite nanoparticles. The reductive biotransformation of an akaganeite (β-FeOOH) or a Mn-substituted (2–20 mol%) akaganeite (Fe1–xMnxOOH) by Shewanella loiha (PV-4, 25 °C) and Thermoanaerobacter ethanolicus (TOR-39, 60 °C) was investigated under anaerobic conditions at circumneutral pH (pH = 7–8). Both bacteria formed magnetite nanoparticles using akaganeite as a magnetite precursor. By comparison of iron minerals formed by PV-4 and TOR-39 using Mn-mixed akaganeite as the precursor, it was shown that PV-4 formed siderite (FeCO3, green rust [Fe2+Fe3+(OH)16CO3·4H2O], and magnetite at 25 °C, whereas TOR-39 formed mainly nm-sized magnetite at 60 °C. The presence of Mn in the magnetite formed by TOR-39 was revealed by energy dispersive X-ray analysis (EDX) is indicative of Mn substitution into magnetite crystals. EDX analysis of iron minerals formed by PV-4 showed that Mn was preferentially concentrated in the siderite and green rust. These results demonstrate that coprecipitated/sorbed Mn induced microbial formation of siderite and green rust by PV-4 at 25 °C, but the synthesis of Mn-substituted magnetite nanoparticles proceeded by TOR-39 at 60 °C. These results indicate that the bacteria have the ability to synthesize magnetite and Mn-substituted magnetite nano-crystals. Microbially facilitated synthesis of magnetite and metal-substituted magnetites at near ambient temperatures may expand the possible use of specialized ferromagnetic nano-particles.
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Ngadenin, Ngadenin, Frederikus Dian Indrastomo, Widodo Widodo, and Kurnia Setiawan Widana. "Identifikasi Keterdapatan Mineral Radioaktif pada Urat-Urat Magnetit di Daerah Ella Ilir, Melawi, Kalimantan Barat." EKSPLORIUM 40, no. 1 (July 31, 2019): 33. http://dx.doi.org/10.17146/eksplorium.2019.40.1.5350.
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ABSTRAKElla Ilir secara administratif terletak di Kabupaten Melawi, Kalimantan Barat. Geologi regional daerah Ella Ilir tersusun atas batuan malihan berumur Trias–Karbon yang diterobos oleh batuan granitik berumur Yura dan Kapur. Keterdapatan mineral radioaktif di daerah tersebut terindikasi dari radioaktivitas urat-urat magnetit pada batuan malihan berumur Trias–Karbon dengan kisaran nilai 1.000 c/s hingga 15.000 c/s. Tujuan dari penelitian ini adalah menentukan jenis cebakan mineral bijih dan mengidentifikasi keterdapatan mineral radioaktif pada urat-urat bijih magnetit di daerah Ella Ilir. Metode yang digunakan adalah pemetaan geologi, pengukuran radioaktivitas, analisis kadar uranium, dan analisis mineragrafi beberapa sampel urat bijih magnetit. Litologi daerah penelitian tersusun oleh kuarsit biotit, metatuf, metabatulanau, metapelit, granit biotit, dan riolit. Sesar sinistral barat-timur dan sesar dekstral utara-selatan merupakan struktur sesar yang berkembang di daerah ini. Komposisi mineral urat-urat magnetit terdiri dari mineral-mineral bijih besi, sulfida, dan radioaktif. Mineral bijih besi terdiri dari magnetit, hematit, dan gutit. Mineral sulfida terdiri dari pirit, pirhotit, dan molibdenit sedangkan mineral radioaktif terdiri dari uraninit dan gumit. Keterdapatan urat-urat bijih magnetit dikontrol oleh litologi dan struktur geologi. Urat-urat magnetit pada metabatulanau berukuran tebal (1,5–5 m), mengisi rekahan-rekahan yang terdapat di sekitar zona sesar. Sementara itu, urat-urat magnetit pada metapelit berukuran tipis (milimetrik–sentimetrik), mengisi rekahan-rekahan yang sejajar dengan bidang sekistositas. Cebakan mineral bijih di daerah penelitian adalah cebakan bijih besi atau cebakan bijih magnetit berbentuk urat karena proses hidrotermal magmatik.ABSTRACTElla Ilir administratively located in Melawi Regency, West Kalimantan. Regional geology of Ella Ilir area is composed of metamorphic rocks in Triassic–Carboniferous age which are intruded by Jurassic and Cretaceous granitic rocks. Radioactive minerals occurences in the area are indicated by magnetite veins radioactivities on Triassic to Carboniferous metamorphic rocks whose values range from 1,000 c/s to 15,000 c/s. Goal of the study is to determine the type of ore mineral deposits and to identify the presence of radioactive mineral in magnetite veins in Ella Ilir area. The methods used are geological mapping, radioactivity measurements, analysis on uranium grades, and mineragraphy analysis of severe magnetite veins samples. Lithologies of the study area are composed by biotite quartzite, metatuff, metasilt, metapellite, biotite granite, and ryolite. The east-west sinistral fault and the north-south dextral fault are the developed fault structures in this area. Mineral composition of magnetite veins are consists of iron ore, sulfide, and radioactive minerals. Iron ore mineral consists of magnetite, hematit, and goetite. Sulfide minerals consist of pyrite, pirhotite, and molybdenite, while radioactive minerals consist of uraninite and gummite. The occurences of magnetite veins are controlled by lithology and geological structures. The magnetite veins in metasilt are thick (1.5–5 m), filled the fractures in the fault zone. Meanwhile, the magnetite veins in metapellite are thinner (milimetric–centimetric), filled the fractures that are parallel to the schistocity. The ore deposits in the study area are iron ore deposits or magnetite ore deposits formed by magmatic hydrothermal processes.
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Belov, Konstantin P. "Electronic processes in magnetite (or, "Enigmas of magnetite")." Uspekhi Fizicheskih Nauk 163, no. 5 (1993): 53. http://dx.doi.org/10.3367/ufnr.0163.199305c.0053.
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RAO, B. S. R., I. V. RADHAKRISHNA MURTHY, and Y. V. SUBBA RAO. "Results of a vertical magnetic survey near Karimnagar town, Karimnagar district, Andhra Pradesh." MAUSAM 25, no. 3 (February 21, 2022): 493–98. http://dx.doi.org/10.54302/mausam.v25i3.5263.
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Magnetic surveys were conducted around Karimnagar town of Andhra Fradesh to trace the quartz-magnetite bodies and to determine the exact nature of the unexposed dykes known to be running through the local college and the surrounding areas. The results clearly state that the underground bodies are only dolerites and quartz-magnetites do not occur anywhere except at three places. Laboratory studies indicate that the magnetism necessary to produc6 the observed anomalies could be easily attributed to dolerites.
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Roh, Y., H. Vali, T. J. Phelps, and J. W. Moon. "Extracellular Synthesis of Magnetite and Metal-Substituted Magnetite Nanoparticles." Journal of Nanoscience and Nanotechnology 6, no. 11 (November 1, 2006): 3517–20. http://dx.doi.org/10.1166/jnn.2006.17973.
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We have developed a novel microbial process that exploits the ability of Fe(III)-reducing microorganisms to produce copious amounts of extracellular magentites and metal-substituted magnetite nanoparticles. The Fe(III)-reducing bacteria (Theroanaerobacter ethanolicus and Shewanella sp.) have the ability to reduce Fe(III) and various metals in aqueous media and form various sized magnetite and metal-substituted magnetite nano-crystals. The Fe(III)-reducing bacteria formed metal-substituted magnetites using iron oxide plus metals (e.g., Co, Cr, Mn, Ni) under conditions of relatively low temperature (<70 °C), ambient pressure, and pH values near neutral to slightly basic (pH = 6.5 to 9). Precise biological control over activation and regulation of the biosolid-state processes can produce magnetite particles of well-defined size (typically tens of nanometers) and crystallographic morphology, containing selected dopant metals into the magnetite (Fe3−yXyO4) structure (where X = Co, Cr, Mn, Ni). Magnetite yields of up to 20 g/L per day have been observed in 20-L vessels. Water-based ferrofluids were formed with the nanometer sized, magnetite, and metal-substituted biomagnetite particles.
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Kahani, Seyed Abolghasem, and Zahra Yagini. "A Comparison between Chemical Synthesis Magnetite Nanoparticles and Biosynthesis Magnetite." Bioinorganic Chemistry and Applications 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/384984.
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The preparation of Fe3O4from ferrous salt by air in alkaline aqueous solution at various temperatures was proposed. The synthetic magnetites have different particle size distributions. We studied the properties of the magnetite prepared by chemical methods compared with magnetotactic bacterial nanoparticles. The results show that crystallite size, morphology, and particle size distribution of chemically prepared magnetite at 293 K are similar to biosynthesis of magnetite. The new preparation of Fe3O4helps to explain the mechanism of formation of magnetosomes in magnetotactic bacteria. The products are characterized by X-ray powder diffraction (XRD), infrared (IR) spectra, vibrating sample magnetometry (VSM), and scanning electron microscopy (SEM).
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Rahmayanti, Maya, Sri Juari Santosa, and Sutarno. "Sonochemical Co-Precipitation Synthesis of Gallic Acid-Modified Magnetite." Advanced Materials Research 1101 (April 2015): 286–89. http://dx.doi.org/10.4028/www.scientific.net/amr.1101.286.
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Gallic acid-modified magnetites were synthesized by one and two-step reactions via the newly developed sonochemical co-precipitation method. The two-step reaction included the formation of magnetite powder and mixing the magnetite powder with gallic acid solution, while the one-step reaction did not go through the formation magnetite powder. The obtained gallic acid-modified magnetites were characterized by the Fourier Transform Infrared (FTIR) spectroscopy, the X-Ray Diffraction (XRD) and the Scanning Electron Microscopy (SEM). More over, the magnetic properties were studied by using a Vibrating Sample Magnetometer (VSM). The characterization results showed that there were differences in crystalinity, surface morphology and magnetic properties of products that were formed by one and two-step reactions.
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Jackson, Mike J., and Bruce Moskowitz. "On the distribution of Verwey transition temperatures in natural magnetites." Geophysical Journal International 224, no. 2 (October 28, 2020): 1314–25. http://dx.doi.org/10.1093/gji/ggaa516.
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SUMMARY The Verwey transition in magnetite is a crystallographic phase transition occurring in the temperature range 80–125 K and depends on stoichiometry and cation substitution, which may in turn serve as an indicator of the conditions under which magnetite was formed or altered in nature. We have analysed the distribution of Verwey transition temperatures (TV) in a large set of samples (N = 1110) from a wide variety of rocks, sediments, and other natural and synthetic materials containing magnetite, mined from the database of the Institute for Rock Magnetism and from published studies. The analysis is restricted to measurements of remanence while warming through the transition from which TV was determined by the derivative method. Our analysis showed that the TV distribution exhibited a generally bimodal distribution of Verwey transition temperatures, both for the entire data set and for almost all of the lithological subsets. There is a sharp peak for values in the range 118–120 K, and a broad, relatively flat or polymodal distribution from about 98 to 118 K. The upper end of the distribution was sharp, with only a few values exceeding 124 K, and the tail on the lower end extended down to about 80 K. Virtually all of the sample types exhibited polymodal distributions, almost always with one peak near 120 K, and with one or more additional peaks at lower temperatures. Biogenic magnetites produced by magnetotactic bacteria had the lowest modal value of TV (100 K). Loesses (103.5 K) and igneous extrusives (102.5 K) also had low modal transition temperatures and distributions with dominant low-TV peaks. Lithological groups with the highest modal transition temperatures were modern soils (119.5 K), silicate minerals with exsolved magnetite (119 K) and sedimentary rocks (119 K). Numerical experiments confirmed that the derivative method for the determination of TV was reasonably robust and that the observed distributions cannot be explained as an artefact related to the determination of TV from individual thermomagnetic runs but rather is a general characteristic of natural magnetites. The results provide context for studies that interpret TV in particular samples in terms of natural processes or conditions during formation or alteration of magnetite.
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Agnestisia, Retno. "Synthesis & Characterization of Magnetit (Fe3O4) and Its Applications As Adsorbent Methylene Blue." Jurnal Sains dan Terapan Kimia 11, no. 2 (October 3, 2017): 61. http://dx.doi.org/10.20527/jstk.v11i2.4039.
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Synthesis, characterization and adsorption study of magnetite have beenconducted. Magnetite was synthesized by coprecipitation method. The characterizations of magnetite were carried out with spectroscopy FTIR (Fourier Transform Infrared) and XRD (X-ray diffraction). The adsorption study was conducted using a batch system with the studied adsorption study including optimum pH, optimum contact time and adsorption equilibrium. The results showed that coprecipitation method has succeeded to form magnetite that has magnetism properties. Magnetite can adsorbed methylene blue from aqueous phase, with the maximum adsorption at pH 5 and contact time of 90 minutes.Adsorption of methylene blue by magnetite follows the adsorption pattern of the Langmuir isotherm with the adsorption energy of 25.59 kJ/mol and adsorption capacity of 43.86 mg/g. The results of magnetite synthesis can accelerate the process of separating the adsorbent particles in a methylene blue solution using an external magnetic field.Keywords : magnetite, coprecipitation, adsorption, and methylene blue.
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Duran, Charley J., Sarah-Jane Barnes, Eduardo T. Mansur, Sarah A. S. Dare, L. Paul Bédard, and Sergey F. Sluzhenikin. "Magnetite Chemistry by LA-ICP-MS Records Sulfide Fractional Crystallization in Massive Nickel-Copper-Platinum Group Element Ores from the Norilsk-Talnakh Mining District (Siberia, Russia): Implications for Trace Element Partitioning into Magnetite." Economic Geology 115, no. 6 (September 1, 2020): 1245–66. http://dx.doi.org/10.5382/econgeo.4742.
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Abstract Mineralogical and chemical zonations observed in massive sulfide ores from Ni-Cu-platinum group element (PGE) deposits are commonly ascribed to the fractional crystallization of monosulfide solid solution (MSS) and intermediate solid solution (ISS) from sulfide liquid. Recent studies of classic examples of zoned orebodies at Sudbury and Voisey’s Bay (Canada) demonstrated that the chemistry of magnetite crystallized from sulfide liquid was varying in response to sulfide fractional crystallization. Other classic examples of zoned Ni-Cu-PGE sulfide deposits occur in the Norilsk-Talnakh mining district (Russia), yet magnetite in these orebodies has received little attention. In this contribution, we document the chemistry of magnetite in samples from Norilsk-Talnakh, spanning the classic range of sulfide composition, from Cu poor (MSS) to Cu rich (ISS). Based on textural features and mineral associations, four types of magnetite with distinct chemical composition are identified: (1) MSS magnetite, (2) ISS magnetite, (3) reactional magnetite (at the sulfide-silicate interface), and (4) hydrothermal magnetite (resulting from sulfide-fluid interaction). Compositional variability in lithophile and chalcophile elements records sulfide fractional crystallization across MSS and ISS magnetites and sulfide interaction with silicate minerals (reactional magnetite) and fluids (hydrothermal magnetite). Estimated partition coefficients for magnetite in sulfide systems are unlike those in silicate systems. In sulfide systems, all lithophile elements are compatible and chalcophile elements tend to be incompatible with magnetite, but in silicate systems some lithophile elements are incompatible and chalcophile elements are compatible with magnetite. Finally, comparison with magnetite data from other Ni-Cu-PGE sulfide deposits pinpoints that the nature of parental silicate magma, degree of sulfide evolution, cocrystallizing phases, and alteration conditions influence magnetite composition.
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Maher, Barbara A., and Roy Thompson. "Paleoclimatic Significance of the Mineral Magnetic Record of the Chinese Loess and Paleosols." Quaternary Research 37, no. 2 (March 1992): 155–70. http://dx.doi.org/10.1016/0033-5894(92)90079-x.
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AbstractThe origins of the magnetic susceptibility variations of the Chinese loess and paleosols are explored by scanning and transmission electron microscopy of magnetic extracts, and by magnetic modeling of magnetic hysteresis data, to provide quantified estimates of the major magnetic components. Microscopy identifies several distinct size and shape characteristics in the magnetic carriers. Lithogenic magnetites, intact and abraded, dominate the coarse-grained magnetic fraction. The smallest of the coarse grains is ∼ 2 μm. The remaining magnetic materal is ultrafine in size, with two types of magnetite particles present. Type A particles strongly resemble soil magnetites produced by inorganic precipitation. Type B particles, which occur rarely, are probably bacterial in origin. Quantitative modeling of these magnetic assemblages shows that over 90% of the susceptibility variations is accounted for by the superparamagnetic magnetite component. Compared to the loess units, the paleosols are richer in magnetite, particularly of superparamagnetic size, and have a threefold higher ratio of magnetite to hematite. We identify pedogenic formation of magnetite as the major contributor to the loess magnetic record. Matching this record against other paleoclimatic records, we find an extremely high correlation with the standard 18O record. The Chinese loess sequences record a very high resolution magnetic stratigraphy directly related to changing climate.
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Schüler, Dirk, and Edmund Baeuerlein. "Dynamics of Iron Uptake and Fe3O4 Biomineralization during Aerobic and Microaerobic Growth of Magnetospirillum gryphiswaldense." Journal of Bacteriology 180, no. 1 (January 1, 1998): 159–62. http://dx.doi.org/10.1128/jb.180.1.159-162.1998.
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ABSTRACT Iron uptake and magnetite (Fe3O4) crystal formation could be studied in the microaerophilic magnetic bacteriumMagnetospirillum gryphiswaldense by using a radioactive tracer method for iron transport and a differential light-scattering technique for magnetism. Magnetite formation occurred only in a narrow range of low oxygen concentration, i.e., 2 to 7 μM O2 at 30°C. Magnetic cells stored up to 2% iron as magnetite crystals in intracytoplasmic vesicles. This extraordinary uptake of iron was coupled tightly to the biomineralization of up to 60 magnetite crystals with diameters of 42 to 45 nm.
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Handayani, Ismi, Muhammad Abdur Rasyid, Rifdah Fadhilah, and Hyang Iman Kinasih Gusti. "Beneficiation Processing of Magnetite ore from Lampung as Dense Media for Dense Medium Separator in Coal Washing Plant." E3S Web of Conferences 543 (2024): 01006. http://dx.doi.org/10.1051/e3sconf/202454301006.
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Until recently, coal washing plants in Indonesia are still using imported magnetite from Australia as dense media for dense medium separator units. To be effectively utilized as a dense media, magnetite ore needs to be concentrated to remove gangue minerals so that the final product will have more than 95% magnetic content, 95% weight passing 53 microns, and relative density ranging from 4.9 – 5.2 g/cm3. Experimental studies have been performed at the Department of Metallurgical Engineering ITB to concentrate fine magnetite ores from Lampung Province. Two process routes were chosen: grinding-magnetic separation and magnetic separation-grinding. Products from the two routes were sieve size analyzed, assayed and characterized. Magnetism characteristic was analyzed with VSM and relative density was measured with pycnometer. The first process route products have maximum magnetic content of 99.1% and particle weight passing 53 microns of 95.7%, while the second route have magnetic content of 95.2% and particle passing 53 microns of 97.1%. Concentrates from both routes have the same relative density of 4.5 g/cm3. Characterization by XRF and AAS gives Fe content of 46.6% and 48.8% for the first route product, and 52.1% and 52.9% for the second route. Lampung magnetite ore gives lower magnetism characteristic compare to Australian magnetite ore. Finer particle size gave lower magnetic saturation value, hence lower magnetism.
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Zeng, Zhijie, Uzair Siddique, Miaojun Sun, Qin Gao, Yanting Chen, Lei Chen, and Zilong Li. "The Mineral Chemistry of Magnetite and Its Constraints on Ore-Forming Mechanism in the Sandaozhuang Skarn-Type W-Mo Deposit in East Qinling, China." Minerals 13, no. 8 (August 15, 2023): 1091. http://dx.doi.org/10.3390/min13081091.
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The Sandaozhuang super-large W-Mo deposit is located in the southern margin of the North China Craton, within the well-known East Qinling Mo mineralization belt, and is one of the typical skarn-type W-Mo deposits in China. Based on EMPA and LA-ICP-MS analyses, major and trace elements were presented, and the mineral chemistry of magnetite at various mineralization stages was discussed. Combining field observations, petrography, and geochemical characteristics, the magnetite at the Sandaozhuang deposit can be classified into three types, namely early-magmatic-stage high-temperature magnetite (Mag1), potassic-alteration-stage magnetite (Mag2), and retrograde-alteration-stage magnetite (Mag3). The Mag1 and Mag2 magnetites primarily occurred in granites in association with potassium (K) feldspar and biotite, whereas Mag3 is associated with metallic sulfide minerals that occurred mainly in vein-like structures in skarn. The three magnetites Mag1, Mag2, and Mag3 can be distinguished as having magmatic, magmatic–hydrothermal transition, and hydrothermal origins, respectively. All three types of magnetite exhibit a depletion of high-field-strength elements (HFSEs) such as Zr, Hf, Nb, Ta, and Ti, and large-ion lithophile elements (LILEs) including Rb, K, Ba, and Sr, compared to the mean continental crust composition. Conversely, they are enriched in elements such as Sn, Mo, V, Cr, Zn, and Ga. Mag3 showed no significant depletion of Co, Ni, Cu, and Bi, indicating that the influence of coexisting sulfides on the composition of magnetite at the Sandaozhuang deposit is limited. There are systematic variations in major and trace elements from Mag1 to Mag3, which exhibited similar patterns in trace element spider and rare earth element diagrams, and Y/Ho ratio, indicating a consistent source for the three types of magnetite. The changes in V and Cr contents and (Ti + V) vs. (Al + Mn) diagram of magnetite at the Sandaozhuang deposit reflected the evolution of ore-forming fluids with an initial increase in oxygen fugacity and a subsequent decrease, as well as a gradual decrease in temperature during skarn mineralization. The early high-temperature and high-oxygen-fugacity magmatic fluids became W and Mo enriched by hydrothermal fluid interaction. The rapid change in fluid properties during the retrograde alteration stage led to the precipitation of scheelite and molybdenite.
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Bailey, D. K., and S. Kearns. "High-Ti magnetite in some fine-grained carbonatites and the magmatic implications." Mineralogical Magazine 66, no. 3 (June 2002): 379–84. http://dx.doi.org/10.1180/0026461026630035.
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AbstractMagnetite is present in most carbonatites, and in the most abundant and best-known form of carbonatite, coarse-grained intrusions, it typically falls in a narrow composition range close to Fe3O4. A fine-grained carbonatite from Zambia contains magnetites with an extraordinary array of compositions (from 18–1% TiO2, 10–2% Al2O3, and 16–4% MgO) outranging previously-reported examples. Zoning trends are from high TiO2 to high Al2O3 and MgO. No signs of exsolution are seen. Checks on similar rocks from Germany, Uganda and Tanzania reveal magnetites with comparable compositions, ranges, and zoning. Magnetites from alkaline and alkaline ultramafic silicate volcanic rocks cover only parts of this array. Magnetite analyses from some other fine-grained carbonatites, reported in the literature, fall in the same composition field, suggesting that this form of carbonatite may be distinctive. The chemistry and zoning would be consonant with rapid high-temperature crystallization in the carbonatite melts, with the lack of exsolution pointing to fast quenching: this contrasts with coarse-grained intrusive carbonatites, in which the magnetite compositions are attributed to slow cooling, with final equilibration at low temperature. In some complexes, both forms of carbonatite, with their different magnetite compositions, are represented.
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Kumagai, Yuho, Norihiro Nakamura, Tetsuro Sato, Toshitaka Oka, and Hirokuni Oda. "Ferromagnetic Resonance Spectroscopy and Rock Magnetic Characterization of Fossil Coral Skeletons in Ishigaki Islands, Japan." Geosciences 8, no. 11 (November 2, 2018): 400. http://dx.doi.org/10.3390/geosciences8110400.
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Skeletons of hermatypic corals (e.g., Porites) might have enormous potential as a high-resolution paleomagnetic recorder owing to their rapid and continuous growth over hundreds of years at a rate of up to 2 cm/year, although typical corals show an extremely weak intensity of remanence and low stability. We found that coral tsunami boulders with negligible amounts of calcite on Ishigaki Island show a measurable intensity of remanence; thus, we attempted to characterize the magnetic assemblages in this coral skeleton to determine whether it is of biogenic or detrital magnetite using first-order reversal curve (FORC) measurements, ferromagnetic resonance (FMR) spectroscopy, and petrological observations through field-emission type scanning electron microscope (FE-SEM) with an acid treatment. The FMR derivative spectra of coral skeleton samples represent multiple derivative maxima and extended low-field absorption, indicating the presence of intact biogenic magnetite chains. FORC diagrams represent a “central ridge” signature with a vertical spread. These FMR and FORC features indicate the magnetization of these coral skeletons that are mainly created using intact biogenic magnetites and mixtures of grains from collapsed biogenic magnetites, pseudo-single domain grains, and multi-domain grains such as detrital magnetite. FE-SEM observations confirm the presence of a chain-like structure of iron oxides corresponding to the features of biogenic magnetite. Therefore, the magnetic mineral assemblage in coralline boulders from Ishigaki Island consists of dominant biogenic-origin single-domain magnetite and a trace amount of detrital component, indicating that fossil coral skeletons in Ishigaki Island have potential for utilization in paleomagnetic studies.
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Xu, Chun Hong. "The Development of Preconcentration Technology in Low-Grade Magnetite’s Beneficiation." Advanced Materials Research 361-363 (October 2011): 324–27. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.324.
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Exhaustion of high-grade magnetite resources and large demand for iron ore in the rapidly developing steel industry promotes the mining enterprises to exploit low-grade magnetite. Low-grade magnetite with a low content of valuable minerals is hard to be separated with the conventional separation process flow because of its high beneficiation costs. By preconcentration technology, enriching valuable minerals and discarding large amounts of gangue as soon as possible before grinding, low beneficiation costs can be achieved in low-grade magnetite’s beneficiation. After continuous researches and production practices and the development of relevant efficient crushing and separating equipments, preconcentration technology has made great progress: from crushing-dry magnetic separation technology to grinding-wet magnetic separation technology, then to ultrafine crushing-wet magnetic separation technology. Now preconcentration has become an indispensable stage in low-grade magnetite’s beneficiation.
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Aulia, Maudi. "Synthesis Of Mg/Al Hydrotalsite-Magnetite As CN- Ion Adsorbent On Wastewater Tapioca Industry." Stannum : Jurnal Sains dan Terapan Kimia 3, no. 2 (December 27, 2021): 69–75. http://dx.doi.org/10.33019/jstk.v3i2.2506.
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Cyanide compounds contained in tapioca industrial wastewater are relatively high, so it is necessary to reduce cyanide levels. This study utilizes the hydrotalcite-magnetite ability to adsorption of CN- ions. The composite formation process is carried out by mixing the magnetite phase at the stage of hydrotalcite-magnetite synthesis. The characterization of X-Ray Diffraction (XRD) shows reflection of the magnetite peak of 2θ 21.42°; 30,28°; 33.40°;35.65° and 37°. While the peak of hydrotalocites at an angle of 11.66° ; 23,33° ; 34,80° ; 60,92° ; and 62.21°. This result is supported by ir spectra on hydrotalocytes shown by O-H group at wave number 3441 cm-1, O=C-O at wave numbers 1359 cm-1, M-O and M-OH at wave numbers 964 cm-1, 797 cm-1 and 673 cm-1. Fe-O and Fe-OH absorption from magnetites at wave numbers 892 cm-1, 798 cm-1 and 629 cm-1. 0.4 grams of hydrotalcite-magnetite at 30 minutes of stirring absorbed 0.0490 mg/L of cyanide from tapioca liquid waste solution. The value of adsorption capacity is 0.022 mg/g and the adsorption efficiency is 87.96%. The hydrotalcite-magnetite adsorption method is superior to aerob and anaerobic methods using bacteria in the tapioca industry.
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Setianto, Setianto. "ANALISA KUANTITATIF CAMPURAN SENYAWA OKSIDA SEBAGAI DASAR IDENTIFIKASI KANDUNGAN BAHAN SUMBER DAYA ALAM Studi Kasus : Kandungan Mineral pada Pasir Besi di Pesisir Pantai Selatan, Jawa Barat." EKSAKTA: Berkala Ilmiah Bidang MIPA 18, no. 02 (November 30, 2017): 173–77. http://dx.doi.org/10.24036/eksakta/vol18-iss02/74.
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Pasir besi merupakan salah satu sumber daya alam yang melimpah di Indonesia terutama di pantai selatan Jawa Barat dan merupakan bahan dasar untuk bangunan serta industri logam.Kandungan mineral pasir besi tersebut umumnya adalah oksida logam seperti magnetit, hematit dan silika/kuarsa. Pada penelitian ini akan dilakukan analisa kuantitatif kandungan senyawa oksida logam (Fe2O3, Fe3O4) dan kuarsa (SiO2) sebagai identifikasi mineral bijih besi yang memiliki aspek ekonomis untuk industri logam.hasil analisa bahwa kandungan magnetite yang terdapat pada pasir besi secara kuantitatif dengan menggunakan X-Ray Diffraction (XRD) berbeda untuk setiap sampel. Untuk sampel pasir nonseparasi (TS) menghasilkan magnetite 24.27%, sampel tailing separasi ke-1 (SS1) menghasilkan magnetite 5.39% dan sampel consentrate separasi ke-3 (S3) menghasilkan 61.98%
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Farha, Ashraf H., Adil Alshoaibi, Osama Saber, and Shehab A. Mansour. "Novel Magnetite (Fe3O4)-Methylcellulose Nanocomposites Synthesized Using the Reverse Co-Precipitation Approach." Journal of Composites Science 8, no. 7 (July 20, 2024): 282. http://dx.doi.org/10.3390/jcs8070282.
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A simple approach was used to create Fe3O4-methylcellulose (MC) nanocomposites, which were then analyzed using XRD, FTIR, and FE-SEM to determine their structure. The effective factors for enhancing the ratio of magnetite NPs in the samples were investigated using RTFM and optical absorbance. Fe3O4 was synthesized utilizing the reverse co-precipitation technique and magnetic characteristics. Fe3O4/MC nanocomposites with magnetite/MC weight ratios of 0, 0.07, 0.15, and 0.25 have been developed. The diffraction pattern of magnetite is well indexed in accordance with the spinal reference pattern of Fe3O4 (space group: R¯3m), as confirmed by the Rietveld analysis of XRD data of magnetite NPs with an average crystallite size of 50 nm. Magnetite’s insertion into the MC network causes a red shift in the band gap energy (Eg) as the weight percentage of magnetite nanoparticles in the samples rises. The MC, MC-7, MC-15, and MC-25 samples have Eg values of 5.51, 5.05, 2.84, and 2.20 eV, respectively.
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Khachaturov, A. A., E. E. Potapov, S. V. Reznichenko, and A. N. Kovaleva. "Influence of iron ore concentrate (magnetite) on the kinetics of butadiene–styrene rubber-based blend curing in the presence of different accelerators." Fine Chemical Technologies 15, no. 5 (November 14, 2020): 46–53. http://dx.doi.org/10.32362/2410-6593-2020-15-5-46-53.
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Objectives. To investigate the possibility of using a cheaper ingredient, such as magnetite, in the synthesis of rubber compounds based on butadiene–styrene rubber by examining its effect on the process of sulfuric vulcanization of butadiene–styrene rubber in the presence of various accelerators.Methods. The influence of magnetite on the vulcanization kinetics was studied using an Alpha Technologies PRPA 2000 rotorless rheometer. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed using a Mettler Toledo TGA/DSC 2 device to evaluate the effect of magnetite on the butadiene–styrene rubber-based vulcanizates’ oxidation.Results. Magnetite was found to affect the kinetics of SBR-1500 butadiene–styrene rubber sulfuric vulcanization in the presence of thiazole-type accelerators (2-MBT, 2-MBS); in contrast, magnetite was inactive in the case of diphenylguanidine, sulfenamide T, and tetramethylthiuram disulfide. The obtained TGA/DSC data showed that magnetite has no significant effect on the butadiene–styrene rubber-based vulcanizates’ oxidation and thermal destruction.Conclusions. The obtained data confirmed magnetite’s capability to act as a butadiene–styrene rubber sulfuric vulcanization activator in the presence of various accelerators. The most significant effect was observed in the presence of thiazole-type accelerators.
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RED’KO, YANA, OLGA GARANINA, NATALIIA HUDZENKO, and NATALIIA DUDCHENKO. "PHYSICO-CHEMICAL PROPERTIES OF MAGNETITES IN NANOCOMPOSITES ON THE TEXTILE BASES." Fibres and Textiles 29, no. 3 (November 2022): 3–7. http://dx.doi.org/10.15240/tul/008/2022-3-001.
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The article is devoted to investigation of the physico-chemical properties of magnetites in nanocomposites on the textile bases. It studies of the structure and phase composition of nanocomposite materials on the polyamide and viscose textile bases. It is shown that magnetite particles synthesized in textile material with average sizes of 9.4 nm in viscose textile material and 9.7 nm in polyamide textile material. The influence of synthesis conditions on the size of magnetite nanocrystallites in textile material is established.
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Wolfinger, Thomas, Daniel Spreitzer, Heng Zheng, and Johannes Schenk. "Influence of a Prior Oxidation on the Reduction Behavior of Magnetite Iron Ore Ultra-Fines Using Hydrogen." Metallurgical and Materials Transactions B 53, no. 1 (December 21, 2021): 14–28. http://dx.doi.org/10.1007/s11663-021-02378-1.
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AbstractThe reduction behavior of raw and prior-oxidized magnetite iron ore ultra-fines with hydrogen was investigated. Reduction tests were conducted with a thermogravimetric analyzer in a temperature range from 873 K to 1098 K at 1.1 bar absolute, using hydrogen as reducing gas. The experimental results show that a prior oxidation of the magnetite has a positive effect on the reduction behavior because of changing morphology. The apparent activation energies show a turnaround to negative values, depending on the prior oxidation and degree of reduction. A multi-step kinetic analysis based on the model developed by Johnson–Mehl–Avrami was used to reveal the limiting mechanism during reduction. At 873 K and 948 K, the reduction at the initial stage is controlled by nucleation and chemical reaction and in the final stage by nucleation only, for both raw and pre-oxidized magnetites. At higher temperatures, 1023 K and 1098 K, the reduction of raw magnetite is mainly controlled by diffusion. This changes for pre-oxidized magnetite to a mixed controlled mechanism at the initial stage. Processing magnetite iron ore ultra-fines with a hydrogen-based direct reduction technology, lower reduction temperatures and a prior oxidation are recommended, whereby a high degree of oxidation is not necessary.
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Chopdekar, R. V., G. Hu, A. C. Ford, and Y. Suzuki. "Magnetics and magnetoresistance in epitaxial magnetite heterostructures." Journal of Electronic Materials 33, no. 11 (November 2004): 1254–58. http://dx.doi.org/10.1007/s11664-004-0149-z.
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Moilanen, M., E. Hanski, J. Konnunaho, T. Törmänen, S. H. Yang, Y. Lahaye, H. O’Brien, and J. Illikainen. "Composition of iron oxides in Archean and Paleoproterozoic mafic-ultramafic hosted Ni-Cu-PGE deposits in northern Fennoscandia: application to mineral exploration." Mineralium Deposita 55, no. 8 (January 11, 2020): 1515–34. http://dx.doi.org/10.1007/s00126-020-00953-1.
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Abstract Using electron probe microanalyzer (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), we analyzed major and trace element compositions of iron oxides from Ni-Cu-PGE sulfide deposits hosted by mafic-ultramafic rocks in northern Fennoscandia, mostly focusing on Finland. The main research targets were the Archean Ruossakero Ni-(Cu) deposit; Tulppio dunite and related Ni-PGE mineralization; Hietaharju, Vaara, and Tainiovaara Ni-(Cu-PGE) deposits; and Paleoproterozoic Lomalampi PGE-(Ni-Cu) deposit. In addition, some reference samples from the Pechenga (Russia), Jinchuan (China), and Kevitsa (Finland) Ni-Cu-PGE sulfide deposits, and a barren komatiite sequence in the Kovero area (Finland) were studied. Magnetite and Cr-magnetite show a wide range of trace element compositions as a result of the variation of silicate and sulfide melt compositions and their post-magmatic modification history. Most importantly, the Ni content in oxide shows a positive correlation with the Ni tenor of the sulfide phase in equilibrium with magnetite, regardless of whether the sulfide assemblage is magmatic or post-magmatic in origin. The massive sulfide samples contain an oxide phase varying in composition from Cr-magnetite to magnetite, indicating that Cr-magnetite can crystallize directly from sulfide liquid. The Mg concentration of magnetites in massive sulfide samples is lowest among the samples analyzed, and this can be regarded as a diagnostic feature of an oxide phase crystallized together with primitive Fe-rich MSS (monosulfide solid solution). Our results show that magnetite geochemistry, plotted in appropriate discrimination diagrams, together with petrographical observations could be used as an indicator of potential Ni-(Cu-PGE) mineralization.
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Maher, Barbara A., Imad A. M. Ahmed, Vassil Karloukovski, Donald A. MacLaren, Penelope G. Foulds, David Allsop, David M. A. Mann, Ricardo Torres-Jardón, and Lilian Calderon-Garciduenas. "Magnetite pollution nanoparticles in the human brain." Proceedings of the National Academy of Sciences 113, no. 39 (September 6, 2016): 10797–801. http://dx.doi.org/10.1073/pnas.1605941113.
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Biologically formed nanoparticles of the strongly magnetic mineral, magnetite, were first detected in the human brain over 20 y ago [Kirschvink JL, Kobayashi-Kirschvink A, Woodford BJ (1992) Proc Natl Acad Sci USA 89(16):7683–7687]. Magnetite can have potentially large impacts on the brain due to its unique combination of redox activity, surface charge, and strongly magnetic behavior. We used magnetic analyses and electron microscopy to identify the abundant presence in the brain of magnetite nanoparticles that are consistent with high-temperature formation, suggesting, therefore, an external, not internal, source. Comprising a separate nanoparticle population from the euhedral particles ascribed to endogenous sources, these brain magnetites are often found with other transition metal nanoparticles, and they display rounded crystal morphologies and fused surface textures, reflecting crystallization upon cooling from an initially heated, iron-bearing source material. Such high-temperature magnetite nanospheres are ubiquitous and abundant in airborne particulate matter pollution. They arise as combustion-derived, iron-rich particles, often associated with other transition metal particles, which condense and/or oxidize upon airborne release. Those magnetite pollutant particles which are <∼200 nm in diameter can enter the brain directly via the olfactory bulb. Their presence proves that externally sourced iron-bearing nanoparticles, rather than their soluble compounds, can be transported directly into the brain, where they may pose hazard to human health.
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Coltro, Monise Cristina Ribeiro Casanova, Warde Antonieta da Fonseca-Zang, Joachim Werner Zang, and Danilo César Silva e. Sousa. "Síntese, caracterização e estabilidade de nanopartículas de magnetita." Latin American Journal of Development 3, no. 4 (August 31, 2021): 2738–49. http://dx.doi.org/10.46814/lajdv3n4-075.
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Nanopartículas de ferro são muito utilizadas em diversas áreas de pesquisa. O elemento químico ferro (Fe), sendo o quarto elemento mais abundante na crosta terrestre, e a substância mineral magnetita, com propriedade magnética, apresentam aplicações nas áreas industrial, ambiental, biomédica e de novas tecnologias. Este trabalho apresenta processo de síntese de nanopartículas partindo-se de sais precursores, bem como a caracterização dos produtos e as rotas para estabilizá-los. Os sais químicos precursores utilizados foram o cloreto férrico (FeCl3) e o sulfato ferroso (FeSO4) na proporção de 2:1, sob agitação por ultrassom e pH ácido. Para formação do precipitado de nanopartículas usou-se solução aquosa de hidróxido de sódio (NaOH) de pH 12. A difratometria de raio-X, mostra a presença de magnetita (Fe3O4) indicada pelos picos característicos de difração em graus 2Ө = 18° (largo), 31° (fino), 36° (bem definido), 43,4°, 45°, 53,6°, 57,7°, 63,3°. A microscopia eletrônica de transmissão mostra a morfologia dos produtos da síntese. Fatores que influenciam a estabilidade das partículas são agitação, o ajuste de pH, condições de secagem. O tamanho médio das nanopartículas de magnetitas é de aproximadamente 15 nm.
Iron nanoparticles are widely used in several research areas. The chemical element iron (Fe), being the fourth most abundant element in the earth's crust, and the mineral substance magnetite, with magnetic properties, have applications in industrial, environmental, biomedical, and new technology areas. This work presents the process of synthesis of nanoparticles starting from precursor salts, as well as the characterization of the products and the routes to stabilize them. The precursor chemical salts were ferric chloride (FeCl3) and ferrous sulfate (FeSO4) in a 2:1 ratio, under ultrasound agitation and acidic pH. For the nanoparticles growth was applied aqueous solution of sodium hydroxide (NaOH) at pH 12. X-ray diffraction shows the presence of magnetite (Fe3O4) indicated by characteristic diffraction peaks in degrees 2Ө = 18° (wide), 31° (fine), 36° (well defined), 43.4°, 45°, 53.6°, 57.7°, 63.3°. Scanning electron microscopy shows the morphology of the synthesis products. Factors that influence the stability of the particles are agitation, the pH adjustment, and the conditions of drying. The average size of the magnetite nanoparticles is approximately 15 nm.
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Byrne, James M., and Matthieu Amor. "Biomagnetism: Insights Into Magnetic Minerals Produced by Microorganisms." Elements 19, no. 4 (August 1, 2023): 208–14. http://dx.doi.org/10.2138/gselements.19.4.208.
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Biomagnetism describes the biological origin of magnetism within living organisms. This phenomenon occurs due to the formation of iron-based minerals that exhibit magnetic ordering at room temperature. Perhaps the most studied form of biomagnetism originates in bacteria, especially magnetotactic bacteria that produce internal magnetite and greigite grains and iron-reducing bacteria that produce magnetite nanoparticles externally as a byproduct of iron respiration. These bacteria likely contribute to a significant proportion of environmental magnetite. The emergence of biomagnetism remains unclear, although it is thought that magnetotactic bacteria evolved this mechanism several billion years ago. Understanding how and why micro-organisms generate biomagnetism is helping to shed light on the origin of life on Earth and potentially on other planets. Biomagnetism is also of broad interest to industrial and environmental applications.
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Tsuchida, Takayuki, Jun Fukushima, and Hirotsugu Takizawa. "Decrease in the Crystallite Diameter of Solid Crystalline Magnetite around the Curie Temperature by Microwave Magnetic Fields Irradiation." Nanomaterials 11, no. 4 (April 11, 2021): 984. http://dx.doi.org/10.3390/nano11040984.
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A decrease in the crystallite diameter of ferrites irradiated with microwaves has been considered as a non-thermal effect of so-called de-crystallization; however, its mechanism has not been elucidated. We hypothesized that a decrease in the crystallite diameter is caused by interaction between the ordered spins of ferrite and the magnetic field of microwaves. To verify this, we focused on magnetite with a Curie temperature of 585 °C. Temperature dependence around this temperature and time dependence of the crystallite diameter of the magnetite irradiated with microwaves at different temperatures and durations were investigated. From the X-ray diffraction data, the crystallite diameter of magnetite exhibited a minimum value at 500 °C, just below the Curie temperature of magnetite, where the energy loss of the interaction between magnetite’s spins and the microwaves takes the maximum value. The crystallite diameter exhibited a minimum value at 5 min irradiation time, during which the microwaves were excessively absorbed. Transmission electron microscopy observations showed that the microstructure of irradiated magnetite in this study was different from that reported previously, indicating that a decrease in the crystallite diameter is not caused by de-crystallization but its similar phenomenon. A decrease in coercivity and lowering temperature of Verwey transition were observed, evidencing decreased crystallite diameter. This study can thus contribute to the development of the theory of a non-thermal effect.
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Wang, Chengyang, Jiajia Yu, Yunsheng Ren, Junkang Zhao, and Zhenjun Sun. "Ore Genesis of the Dongping Gold Deposit in the Northern Margin of North China Craton: Constraints from In-Situ Major, Trace Elemental Analysis of Magnetite and Pyrite." Minerals 12, no. 8 (July 31, 2022): 978. http://dx.doi.org/10.3390/min12080978.
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The Zhangxuan district in North China, also known as Northwestern Hebei “Golden Triangle,” develops many intrusion-hosted lode-gold deposits. The Dongping gold deposit in the Zhangxuan district is well known for its unique hosting of rocks and ore mineral assemblages. Magnetite and pyrite are common minerals that widely exist in ores of the Dongping deposit. To get a better understanding of the evolution of the ore-forming fluids responsible for mineralization, we report on an integrated study on the electron microprobe analysis (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of magnetite and pyrite from the deposit. The major results are as follows: The magnetite grains from the Dongping deposit show a variable content of major and trace elements such as Ti, Al, Si, Fe, Mn, Cr, Na, V, and Co, and the majority of the magnetite contain low Ti contents, revealing potential properties of hydrothermal magnetite. The flat time-resolved signals of LA-ICP-MS imply that the majority of trace elements in magnetite exist in the form of isomorphism, except for some incompatible trace elements. Magnetites from the Dongping deposit have compositional characteristics of hydrothermal origins, and the genetic discriminant diagrams of Ti–V, Ti–Ni/Cr or (Ca + Al + Mn)–(Ti + V) show that they may be originated from magma differentiated hydrothermal solutions. Co, Ni in pyrite from Dongping mainly enter the lattice via isomorphism, and Cu, Zn, Ag, W, Sn, Au, Pb, and Bi are partitioned into pyrite as micro/nano- mineral inclusions. The Co, Ni content, and the Ni/Co ratios, indicated that the temperature of the ore-forming fluids has decreased from Py-1 to Py-2, and the enrichment of Au in Py-2 may be related to the cooling and boiling of the fluids.
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Palamarchuk, M. S., D. Kh Shlyk, and S. Yu Bratskaya. "Influence of mechanochemical activation on dissolving model corrosion films formed on ion-exchange resins using Trilon B." Proceedings of Universities. Applied Chemistry and Biotechnology 11, no. 4 (January 10, 2022): 663–72. http://dx.doi.org/10.21285/2227-2925-2021-11-4-663-672.
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Inorganic deposits formed during operation and intermediate storage contain radionuclides, whose removal during the chemical decontamination of spent ion-exchange resins used in filters for special water purification at nuclear power plants has proved to be a challenge. In such deposits, radionuclides of the corrosion group (58.60Co, 54Mn, 51Cr) are typically located in the crystal lattice of poorly soluble iron oxides. The present work discusses the possibility of using mechanochemical activation in the decontamination of spent ion-exchange resins polluted with deposits of activated corrosion products from structural materials. Samples of natural and synthesised on the surface of the KU-2-8 cation exchanger in the presence of the 57Co label magnetites were used as model deposits. It was shown that an increase in the duration of mechanochemical activation leads to an increase in the dissolution rate of magnetite in model decontamination solutions based on еthylenediaminetetraacetic acid disodium salt (Trilon B) and nitric acid. It was shown that, when using Trilon B, magnetite dissolves more efficiently, which is explained by the interaction between the oxide surface and organic complexing agents. It can be assumed that solid-phase reactions occur during the mechanochemical activation of magnetite in the presence of dry reagents (Trilon B, oxalic, ascorbic and citric acids). Therefore, a poorly soluble shell formed on the oxide surface hinders the dissolution at a low magnetite/solution ratio. Unlike the reagent-free activation, for magnetite activated in the presence of oxalic acid, an increase in the solution/magnetite ratio promotes the dissolution of iron oxides. Using the example of a model cation exchanger, it was shown that the rate and efficiency of decontamination of spent ion-exchange resins polluted with deposits containing activated corrosion products increase significantly after mechanochemical activation in the presence of oxalic acid.
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Nchimi Nono, Katia, Alexander Vahl, and Huayna Terraschke. "Towards High-Performance Photo-Fenton Degradation of Organic Pollutants with Magnetite-Silver Composites: Synthesis, Catalytic Reactions and In Situ Insights." Nanomaterials 14, no. 10 (May 13, 2024): 849. http://dx.doi.org/10.3390/nano14100849.
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In this study, Fe3O4/Ag magnetite-silver (MSx) nanocomposites were investigated as catalysts for advanced oxidation processes by coupling the plasmonic effect of silver nanoparticles and the ferromagnetism of iron oxide species. A surfactant-free co-precipitation synthesis method yielded pure Fe3O4 magnetite and four types of MSx nanocomposites. Their characterisation included structural, compositional, morphological and optical analyses, revealing Fe3O4 magnetite and Ag silver phases with particle sizes ranging from 15 to 40 nm, increasing with the silver content. The heterostructures with silver reduced magnetite particle aggregation, as confirmed by dynamic light scattering. The UV–Vis spectra showed that the Fe:Ag ratio strongly influenced the absorbance, with a strong absorption band around 400 nm due to the silver phase. The oxidation kinetics of organic pollutants, monitored by in situ luminescence measurements using rhodamine B as a model system, demonstrated the higher performance of the developed catalysts with increasing Ag content. The specific surface area measurements highlighted the importance of active sites in the synergistic catalytic activity of Fe3O4/Ag nanocomposites in the photo-Fenton reaction. Finally, the straightforward fabrication of diverse Fe3O4/Ag heterostructures combining magnetism and plasmonic effects opens up promising possibilities for heterogeneous catalysis and environmental remediation.
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Norfolk, Laura, Andrea Rawlings, Jonathan Bramble, Katy Ward, Noel Francis, Rachel Waller, Ashley Bailey, and Sarah Staniland. "Macrofluidic Coaxial Flow Platforms to Produce Tunable Magnetite Nanoparticles: A Study of the Effect of Reaction Conditions and Biomineralisation Protein Mms6." Nanomaterials 9, no. 12 (December 4, 2019): 1729. http://dx.doi.org/10.3390/nano9121729.
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Magnetite nanoparticles’ applicability is growing extensively. However, simple, environmentally-friendly, tunable synthesis of monodispersed iron-oxide nanoparticles is challenging. Continuous flow microfluidic synthesis is promising; however, the microscale results in small yields and clogging. Here we present two simple macrofluidics devices (cast and machined) for precision magnetite nanoparticle synthesis utilizing formation at the interface by diffusion between two laminar flows, removing aforementioned issues. Ferric to total iron was varied between 0.2 (20:80 Fe3+:Fe2+) and 0.7 (70:30 Fe3+:Fe2+). X-ray diffraction shows magnetite in fractions from 0.2–0.6, with iron-oxide impurities in 0.7, 0.2 and 0.3 samples and magnetic susceptibility increases with increasing ferric content to 0.6, in agreement with each other and batch synthesis. Remarkably, size is tuned (between 20.5 nm to 6.5 nm) simply by increasing ferric ions ratio. Previous research shows biomineralisation protein Mms6 directs magnetite synthesis and controls size, but until now has not been attempted in flow. Here we report Mms6 increases magnetism, but no difference in particle size is seen, showing flow reduced the influence of Mms6. The study demonstrates a versatile yet simple platform for the synthesis of a vast range of tunable nanoparticles and ideal to study reaction intermediates and additive effects throughout synthesis.
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Hameed, Aneela, Hafiza Mehvish Mushtaq, and Majid Hussain. "Magnetite (Fe3O4) - Synthesis, Functionalization and its Application." International Journal of Food and Allied Sciences 3, no. 2 (May 25, 2018): 64. http://dx.doi.org/10.21620/ijfaas.2017264-75.
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<p>Nanoparticles are smaller than 100nm. Size of particle depends upon the method that is used for synthesis of nanoparticles. Magnetic nanoparticles consist of iron, cobalt and nickel and their chemical compounds. Their safety or toxicity is major concern for use in food. Magnetite, hematite and meghemite are types of magnetic nanoparticles. Magnetite (Fe3O4) common among the magnetic iron oxide nanoparticle that is used in food industry. Magnetite is getting popular due to its super paramagnetic properties and lack of toxicity to humans. Different methods are used to synthesize magnetic nanoparticles. Upon contact with air these particles loses magnetism and mono-dispersibility. To overcome this problem these nanoparticles are coated with natural or synthetic polymers, metals, organic and inorganic substances to create stable and hydrophilic nanostructures. Due to easy separation with magnet these magnetic nanoparticles are used as an affinity probe to remove bacteria from different food samples and have food related applications e.g, protein purification, enzyme immobilization and food analysis. These magnetic nanoparticles also used for removal of heavy metals and used in medical field.</p>
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Bobik, Magdalena, Irena Korus, Karol Synoradzki, Jacek Wojnarowicz, Dorota Biniaś, and Włodzimierz Biniaś. "Poly(sodium acrylate)-Modified Magnetite Nanoparticles for Separation of Heavy Metals from Aqueous Solutions." Materials 15, no. 19 (September 21, 2022): 6562. http://dx.doi.org/10.3390/ma15196562.
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Two types of magnetite nanoparticles: unmodified (Fe3O4 NPs), and modified with poly(sodium acrylate) (Fe3O4/PSA NPs) were synthesized by the co-precipitation method and characterized using different techniques: X-ray diffraction (XRD), transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), Brunauer–Emmett–Teller (BET) adsorption, Fourier-transform infrared spectroscopy (FTIR). Additionally, magnetic properties and the effect of pH on the zeta potential were analyzed for both types of nanoparticles. Magnetites were used as adsorbents for seven heavy metal ions (Zn(II), Cu(II), Ni(II), Cd(II), Pb(II), Cr(III), Cr(VI)) within the pH range of 3–7. Research revealed nanometric particle sizes, a specific surface area of 140–145 m2/g, and superparamagnetic properties of both tested materials. Moreover, the presence of PSA functional groups in modified magnetite was confirmed, which lowered the pH of the isoelectric point. Both types of magnetite were effective metal ion adsorbents, with metal cations more effectively removed on Fe3O4/PSA NPs and Cr(VI) anions on Fe3O4 NPs. The adsorption of most of the examined cations (performed at pH = 5) can be well described by the Langmuir isotherm model, whereas the adsorption of Cr(VI) ions on modified magnetite correlated better with the Freundlich model. The Dubinin–Radushkevich model confirmed that chemisorption is the predominant process. The adsorption of all metal ions was well-characterized by the pseudo-second-order kinetic model.
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Li, Jinhua, Nicolas Menguy, Christophe Gatel, Victor Boureau, Etienne Snoeck, Gilles Patriarche, Eric Leroy, and Yongxin Pan. "Crystal growth of bullet-shaped magnetite in magnetotactic bacteria of the Nitrospirae phylum." Journal of The Royal Society Interface 12, no. 103 (February 2015): 20141288. http://dx.doi.org/10.1098/rsif.2014.1288.
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Magnetotactic bacteria (MTB) are known to produce single-domain magnetite or greigite crystals within intracellular membrane organelles and to navigate along the Earth's magnetic field lines. MTB have been suggested as being one of the most ancient biomineralizing metabolisms on the Earth and they represent a fundamental model of intracellular biomineralization. Moreover, the determination of their specific crystallographic signature (e.g. structure and morphology) is essential for palaeoenvironmental and ancient-life studies. Yet, the mechanisms of MTB biomineralization remain poorly understood, although this process has been extensively studied in several cultured MTB strains in the Proteobacteria phylum. Here, we show a comprehensive transmission electron microscopy (TEM) study of magnetic and structural properties down to atomic scales on bullet-shaped magnetites produced by the uncultured strain MYR-1 belonging to the Nitrospirae phylum, a deeply branching phylogenetic MTB group. We observed a multiple-step crystal growth of MYR-1 magnetite: initial isotropic growth forming cubo-octahedral particles (less than approx. 40 nm), subsequent anisotropic growth and a systematic final elongation along [001] direction. During the crystal growth, one major {111} face is well developed and preserved at the larger basal end of the crystal. The basal {111} face appears to be terminated by a tetrahedral–octahedral-mixed iron surface, suggesting dimensional advantages for binding protein(s), which may template the crystallization of magnetite. This study offers new insights for understanding magnetite biomineralization within the Nitrospirae phylum.
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McCartney, Martha R., Ulysses Lins, Marcos Farina, Peter R. Buseck, and Richard B. Frankel. "Magnetic microstructure of bacterial magnetite by electron holography." European Journal of Mineralogy 13, no. 4 (July 18, 2001): 685–89. http://dx.doi.org/10.1127/0935-1221/2001/0013-0685.
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Singh, Rajendra Kumar, A. Perumal, Govind P. Kothiyal, and A. Srinivasan. "Evolution of Magnetism in CaO-SiO2-P2O5-Na2O-Fe2O3 Bioglass Ceramics." Materials Science Forum 587-588 (June 2008): 171–74. http://dx.doi.org/10.4028/www.scientific.net/msf.587-588.171.
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We report the evolution of magnetism in bioglass ceramics 41CaO.(52-x)SiO2.4P2O5. xFe2O3.3Na2O (2 ≤ x ≤ 10 mole % Fe2O3) prepared by melt quenching technique followed by heat treatment at 1050 oC. The structural investigation revealed the presence of magnetite phase in the heat treated samples with x ≥ 2 mole % Fe2O3. Room temperature magnetic measurements showed a very weak ferrimagnetic behaviour for the sample with x = 2 mole % of Fe2O3. Samples with x > 2 mole % of Fe2O3 exhibited magnetic behavior similar to soft magnetic materials with low coercivity. The evolution of magnetic properties in these samples as a function of Fe2O3 molar concentration is correlated with the amount of magnetite phase present in them.
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Kalebić, Barbara, Jelena Pavlović, Jelena Dikić, Aleksander Rečnik, Sašo Gyergyek, Nikola Škoro, and Nevenka Rajić. "Use of Natural Clinoptilolite in the Preparation of an Efficient Adsorbent for Ciprofloxacin Removal from Aqueous Media." Minerals 11, no. 5 (May 14, 2021): 518. http://dx.doi.org/10.3390/min11050518.
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The adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by natural zeolite, the calcium-rich clinoptilolite (CLI), and magnetite-coated CLI (MAG-CLI) was investigated. Both CLI and MAG-CLI showed a high adsorption affinity towards CIP at 283, 288 and 293 K at a pH of 5. Adsorption kinetics studied for the initial concentrations of 15–75 mg CIP dm−3 follow Lagergren’s pseudo-second order equation and the adsorption is best represented by the Langmuir model. The adsorption mechanism involves strong electrostatic interactions between negatively charged aluminosilicate lattice and the cationic form of CIP accompanied by an ion-exchange reaction. Magnetite coverage (approx. 12 wt.%) induces magnetism, which can facilitate the separation process. The coverage does not influence the adsorption activity of CLI. The leaching test showed that the MAG coating protects the adsorbent from CIP leaching. This is ascribed to interactions between the CIP carboxyl groups and magnetite nano-particles. Antibacterial tests showed strong antibacterial activity of the ciprofloxacin-containing adsorbents towards pathogenic E. coli and S. aureus.
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Ju, Dong Ying, and Pei Bian. "Development of Ferrite Magnetic Materials with High Strength by a Low-Temperature Sintering Method." Key Engineering Materials 317-318 (August 2006): 893–98. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.893.
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Magnetite (Fe3O4) ferrite magnetic materials have attracted attention arising by the chip coil electronic material. However, its industrial applications have been limited by the need for high temperature sintering under reduced pressure or vacuum. In order to develop the process method of low-cost and energy saving with high-strength and high magnetism of the magnet, in this paper, a new low-temperature sintering method using CO2 gas and adding a small amount of boric acid (H3BO3) is proposed. Here, the super fine magnetite powder was fabricated by decomposition from ferrous oxalate at 500 in CO2 gas. The ferrous oxalate was synthesized using iron chloride and ammonium oxalate through liquid phase precipitation. The magnetite powder compact was produced by Newton press and CIP (cold isostatic press) after adding a small amount of boric acid. In this study, the effects of the additive on the mechanical and magnetic properties of the sintered magnet were also evaluated. By characteristic evaluation of the magnet, the validity of the proposed new low-temperature sintering process and the optimal process conditions were confirmed.
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Aneela Hameed, Aneela Hameed, Hafiza Mehvish Mushtaq Hafiza Mehvish Mushtaq, Saeed Akhtar Saeed Akhtar, Tariq Ismail Tariq Ismail, Majid Hussain Majid Hussain, Ahsan Sattar Sheikh Ahsan Sattar Sheikh, and Zulfiqar Ali Merani and Abdul Ghafar Zulfiqar Ali Merani and Abdul Ghafar. "Potential of Functionalized Magnetite (Fe3O4) in Decontamination of Pathogenic Bacteria from Milk." Journal of the chemical society of pakistan 41, no. 6 (2019): 1014. http://dx.doi.org/10.52568/000825/jcsp/41.06.2019.
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Magnetite (Fe3O4) is getting popular due to its super-paramagnetic properties, high biocompatibility and lack of toxicity to humans. Magnetite (Fe3O4) nanoparticles have high surface energy thus these nanoparticles aggregate quickly. This aggregation strongly affects the efficiency of these nanoparticles. So these magnetite nanoparticles are coated with organic or inorganic substance to prevent aggregation. These coatings not only stabilize magnetic nanoparticles but can also be used for further functionalization. The aim of this study was to evaluate the efficiency of functionalized magnetite to remove pathogenic bacteria (E.coli and B.cereus) from milk considering binding capability of magnetite with bacterial cell wall. Magnetite (Fe3O4) was prepared by co-precipitation method and subsequently functionalized with oleic acid (OA) and ethylene diamine (EDA). In present study role of magnetite (Fe3O4) and functionalized magnetite (EDA-Fe3O4, OA-Fe3O4) in removal of pathogenic bacteria (E.coli and B.cereus) from milk was investigated. The morphology of functionalized magnetite was determined by Scanning Electron microscopy (SEM). Their removal efficiency was studied based on time (10, 20 and 30 minutes). Concentration of uncoated magnetite (Fe3O4) and coated magnetite (EDA-Fe3O4, OA-Fe3O4) was fixed at 4mg/50mL. Magnetite was successfully synthesized in range of and#177;3nm. Highest capturing efficiency (74.45%) of oleic acid magnetite (OA-Fe3O4) was observed for Bacillus cereus at 30 minutes. However for Escherichia coli, both ethylene-diamine magnetite (EDA-Fe3O4) and oleic acid magnetite (OA-Fe3O4) showed maximum capturing efficiency (61.65% and 63.91% respectively). It was concluded from the study that magnetite coated with oleic acid and ethylenediamine removed pathogenic bacteria from milk efficiently. However, more research is required to study the effect of these magnetic nanoparticles on nutritional composition of milk.
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Jin, Jianping, Xinran Zhu, Pengchao Li, Yanjun Li, and Yuexin Han. "Clean Utilization of Limonite Ore by Suspension Magnetization Roasting Technology." Minerals 12, no. 2 (February 17, 2022): 260. http://dx.doi.org/10.3390/min12020260.
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As a typical refractory iron ore, the utilization of limonite ore with conventional mineral processing methods has great limitations. In this study, suspension magnetization roasting technology was developed and utilized to recover limonite ore. The influences of roasting temperature, roasting time, and reducing gas concentration on the magnetization roasting process were investigated. The optimal roasting conditions were determined to be a roasting temperature of 480 °C, a roasting time of 12.5 min, and a reducing gas concentration of 20%. Under optimal conditions, an iron concentrate grade of 60.12% and iron recovery of 91.96% was obtained. The phase transformation, magnetism variation, and microstructure evolution behavior were systematically analyzed by X-ray diffraction, vibrating sample magnetometer, and scanning electron microscope. The results indicated that hematite and goethite were eventually transformed into magnetite during the magnetization roasting process. Moreover, the magnetism of roasted products significantly improved due to the formation of ferrimagnetic magnetite in magnetization roasting. This study has implications for the utilization of limonite ore using suspension magnetization roasting technology.
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Huzaira, Misbah, and R. Rox Anderson. "Magnetite tattoos." Lasers in Surgery and Medicine 31, no. 2 (August 2002): 121–28. http://dx.doi.org/10.1002/lsm.10075.
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Maher, Barbara. "Ubiquitous magnetite." Nature Geoscience 17, no. 1 (January 2024): 7. http://dx.doi.org/10.1038/s41561-023-01352-7.
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Belov, Konstantin P. "Electronic processes in magnetite (or, "Enigmas of magnetite")." Physics-Uspekhi 36, no. 5 (May 31, 1993): 380–91. http://dx.doi.org/10.1070/pu1993v036n05abeh002160.
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Özaytekin, İlkay, and Kamil Oflaz. "Synthesis and characterization of high-temperature resistant and thermally conductive magnetic PBI/Fe3O4 nanofibers." High Performance Polymers 32, no. 9 (May 22, 2020): 1031–42. http://dx.doi.org/10.1177/0954008320911985.
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In the present study, magnetite nanoparticles were added to an electrospinning solution of polyvinylidene fluoride (PVDF)/polybenzimidazole (PBI) polymers to prepare PBI/Fe3O4 nanofibers (NFs). The operating voltage of the electrospinning device was set to 15 kV, the distance between the needle and the plate was 10 cm, and the feed rate was set to 0.3 mL h−1. The microstructures of the as-prepared NFs were investigated by Fourier transform infrared spectrophotometry, atomic force microscopy, thermogravimetric analysis, and vibration sample magnetometry. Magnetite-doped PVDF/PBI NFs exhibited superior magnetism and saturation magnetization in the range of 1.5–5 emu g−1. It was observed that the thermal resistance of the fibers increased with the increasing amount of magnetic particles and nanocomposite fiber (NCF) 1 and NCF2 exhibited excellent thermal resistance up to 415°C and 450°C, respectively. The heat conduction coefficient of the fibers was measured at 4, 6, and 8 W. The thermal conductivity of the NFs increased with the increasing amount of magnetite nanoparticles, and the highest thermal conductivity coefficient for NCF2 (1.83 W mK−1) was measured at 4 W.
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Mansurov, Zulkhair, Gaukhar Smagulova, Bayan Kaidar, Aigerim Imash, and Aidos Lesbayev. "PAN—Composite Electrospun-Fibers Decorated with Magnetite Nanoparticles." Magnetochemistry 8, no. 11 (November 21, 2022): 160. http://dx.doi.org/10.3390/magnetochemistry8110160.
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The results of the synthesis of PAN(polyacrylonitrile)-magnetite composite fibers using the electrospinning method are presented. The electrospinning installation included a rotating drum collector for collecting fibers. Magnetite nanoparticles were synthesized using chemical condensation from an iron chloride solution. It was shown that homogeneous Fe3O4 magnetite nanoparticles with particle sizes of 6–16 nm could be synthesized using this method. Magnetite nanoparticles were investigated using X-ray diffraction analyses and transmission electron microscopy. Based on magnetite nanoparticles, composite PAN/magnetite fibers were obtained through electrospinning. The obtained composite fibers were investigated using scanning electron microscopy, X-ray diffraction analyses, and elemental analyses. It was shown that the magnetite nanoparticles were uniformly distributed on the surface of the fibers. A comparison of PAN fibers without any added magnetite to PAN/magnetite fibers showed that the addition of magnetite led to a decrease in the value of the fiber diameter at the same polymer concentration and under the same electrospinning process conditions.
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Sergii, Guzii, Arkhypenko Oksana, Odukalets Lyudmila, Prysiazhna Olena, and Rashkevich Nina. "Magnetite-ferrocyanide-copper sorbents for recovery of cesium ions from low-activity liquid radioactive waters." Material Science & Engineering International Journal 8, no. 1 (March 28, 2024): 15–18. http://dx.doi.org/10.15406/mseij.2024.08.00230.
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The article is devoted to the development of nanoscale sorbents based on copper ferrocyanide and magnetites for the removal of cesium, strontium, and heavy metal ions in their simultaneous presence in a multicomponent two-phase low-level radioactive solution containing complexing agents and surfactants. It they noted that the highest values of cesium ion removal from low-level radioactive water - 99.96% and 99.62% - are obtained with sorbents based on 100% copper ferrocyanide and a mixture of copper ferrocyanide and industrial magnetite in a ratio of 2 to 1. The efficiency of the sorbents in terms of the distribution coefficient is 2394 and 1589.7 ml/g, which ensures the purification of radioactive water from trace concentrations of cesium ions to values of 2394 and 265.11. These sorbents provide water purification to values less than 2 Bq/cm3, which is typical for 1-4 classes of water quality in terms of radiation safety of groundwater and surface water as sources of centralised drinking water supply. It is noted that sorption of cesium ions on copper ferrocyanide and magnetite is carried out in the presence of water molecules and hydroxo groups. It is shown that artificial magnetite in its pure form exceeds the sorption capacity of industrial magnetite. This is due to the difference in the phase composition and particle size of the crystals. The results obtained will be use as components of the technological process in the Plasma-Sorb technology developed at the State Institution "The Institute of Environmental Geochemistry" of the National Academy of Sciences of Ukraine for the treatment of low- and intermediate-level radioactive water from Ukrainian nuclear power plants.
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Hu, Pengfei, Long Liang, Yaoli Peng, Hesheng Yu, and Guangyuan Xie. "Recovery of Microcrystalline Graphite from Quartz Using Magnetic Seeding." Minerals 10, no. 1 (December 27, 2019): 24. http://dx.doi.org/10.3390/min10010024.
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Efficient beneficiation of microcrystalline graphite remains a challenge. Selective recovery of microcrystalline graphite from quartz using hydrophobized magnetite as magnetic seed is studied in this work. Magnetite was hydrophobized by the surface coating of sodium oleate. The hydrophobic agglomerates were then separated by magnetic separation. Sedimentation experiments were performed to study the adhesion of microcrystalline graphite and quartz to magnetite particles. The results showed that hydrophobized magnetite led to a higher microcrystalline graphite recovery than that of the original magnetite, due to the higher probability to bond with microcrystalline graphite. However, the hydrophobization of the magnetite surface had an insignificant effect on its interaction with quartz. The force analysis based on the extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory indicated that the total attractive interaction between hydrophobized magnetite and microcrystalline graphite were obviously stronger than that between hydrophobized magnetite and quartz, resulting in the selective aggregation between hydrophobized magnetite and microcrystalline graphite.