Relevant bibliographies by topics / Hematite

Academic literature on the topic 'Hematite'

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Published: 4 June 2021
Last updated: 30 July 2024

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Journal articles on the topic "Hematite"

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Alpochoritis, Georgios, Argiris Kolokithas Ntoukas, and Vasilios I. Georgakilas. "Hematene Nanoplatelets with Enhanced Visible Light Absorption; the Role of Aromatic Molecules." Molecules 29, no. 13 (June 29, 2024): 3115. http://dx.doi.org/10.3390/molecules29133115.

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Hematite has been considered an important candidate for the development of an efficient photoelectrocatalytic water-splitting system. One of the most serious obstacles that limits the efficiency of hematite is low absorption capacity in visible light. Herein, we report the production of hematene nanoplatelets from hematite ore with yields of up to 60%, using a low-cost, sustainable method that is based on the ultrasonic treatment of hematite ore in a water solution of a series of organic aromatic compounds. We show that the chemisorption of molecules with increased aromaticity on the surface of hematene resulted in the significant improvement of its visible light absorptivity, with an increase of up to 200%. As a result, using a water solution of terephthalaldehyde as a liquid medium, hematite ore was exfoliated to hematene nanoplatelets with a yield of 40% and remarkable stability in water. Due to this, hematene was easily drop-casted on glass forming homogenous thin films with strong absorptivity in the visible region.
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Kang, Myung Jong, Na Hyeon An, and Young Soo Kang. "Magnetic and Photochemical Properties of Cu Doped Hematite Nanocrystal." Materials Science Forum 893 (March 2017): 136–43. http://dx.doi.org/10.4028/www.scientific.net/msf.893.136.

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In this report, the magnetic and photochemical properties of Cu doped hematite nanocrystal was investigated intensively. The Cu doped hematite nanocrystals were prepared by hydrothermal method, changing the molar ratio of Cu precursors. The XRD and XPS techniques are used for revealing crystal and chemical state of Cu doped hematite nanocrystal. Raman spectroscopy was also used for confirming Cu atoms replacing Fe position in Cu doped hematite crystal. The UV-vis and UPS were used for assigning electronic band position for photocatalytic properties. Cu doped hematite showed the enhanced photocatalytic properties within photodegradation of methyl orange. Finally, by checking magnetic hysteresis loops of Cu doped hematites with VSM, it was revealed that the magnetic property of Cu doped hematite nanocrystal was increased after doping Cu into hematite nanocrystal, get the distortion of magnetic sub-lattices.
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Cabral, A. R., B. Lehmann, H. F. Galbiatti, and O. G. Rocha Filho. "Evidence for metre-scale variations in hematite composition within the Palaeoproterozoic Itabira Iron Formation, Minas Gerais, Brazil." Mineralogical Magazine 70, no. 5 (October 2006): 591–602. http://dx.doi.org/10.1180/0026461067050352.

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AbstractHematite is a mineral the chemical composition of which rarely differs significantly from stoichiometric Fe2O3. As such, little attention has been paid to the mineral chemistry of hematite in Precambrian iron formations, where hematite forms monomineralic high-grade orebodies. Electron microprobe analysis of hematite from two iron-ore deposits, Cauê (Itabira district) and Gongo Soco, in the Palaeoproterozoic Itabira Iron Formation, Quadrilátero Ferrífero of Minas Gerais, Brazil, has revealed distinct variations in chemical composition with respect to Ti and Cr. Hematite containing Ti and/or Cr is of very local occurrence in the itabirite unit and shows a spatial relationship to hematitic, palladiferous gold-bearing veins (known as ‘jacutinga’), occurring either within the veins (adjacent to, or included in, palladiferous gold grains) or in their vicinity. Where present, titaniferous hematite (to ∼1.3 wt.% TiO2) is lepidoblastic and defines a pervasive tectonic foliation (S1). In contrast, Ti-free, chromiferous hematite (to ∼6.4 wt.% Cr2O3) characteristically occurs as inclusions in palladiferous gold within S1-truncating ‘jacutinga’. Replacement of granoblastic, Ti-free, chromiferous martite with relicts of magnetite by lepidoblastic, Cr-depleted, titaniferous hematite proves that Cr and Ti were mobile during metamorphism. Chromium was ultimately fractionated into the hematite found in auriferous aggregates within cross-cutting ‘jacutinga’. A positive correlation between Cr and Pt in bulk-rock samples from the Itabira district suggests that Cr is a potential prospective guide for Au-Pd-Pt-bearing hematitic veins (‘jacutinga’).
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Su, Jinzhan, Jian Wang, Cong Liu, Bo Feng, Yubin Chen, and Liejin Guo. "On the role of metal atom doping in hematite for improved photoelectrochemical properties: a comparison study." RSC Advances 6, no. 104 (2016): 101745–51. http://dx.doi.org/10.1039/c6ra22895j.

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A systematic comparison study of various metal atoms doped hematites was performed to look into the effect of metal element doping on the photoelectrochemical (PEC) properties of hematite photoelectrodes.
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Gromadskaya, L. I., I. V. Romanova, O. A. Vyshnevskyi, and S. A. Kirillov. "Near-Stoichiometric Adsorption of Phosphate by Silica Gel Supported Nanosized Hematite." ISRN Inorganic Chemistry 2013 (July 16, 2013): 1–10. http://dx.doi.org/10.1155/2013/969746.

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Decreasing the size of oxide particles to nanoscale enables one to ensure maximal reaction rates and depths in the solid due to the enhancement of the specific surface area and the increase of the diffusion rate caused by shortening diffusion paths. For that reason, one may suggest that in the case of adsorption onto nanoparticles, the complete conversion of sorbents to stoichiometric compounds would become possible. Adsorption of phosphate ions onto nanosized hematite supported on silica gel surface has been studied. Modification of silica gel surface by hematite in the quantity of 0.62 and 1.25 mass% has been carried out by means of a citric acid aided method. The morphology of the samples obtained has been characterized using DTA, XRD, SEM, and low temperature desorption of nitrogen. It has been found in batch experiments that unlike natural and synthetic hematites, for which the limiting adsorption values do not exceed 14 mg/g, silica gel supported nanosized hematite adsorbs 400–2000 mg of the phosphate ions per gram, thus forming near-stoichiometric iron phosphates on the surface of the support. The degree of conversion of hematite to iron phosphates is greater in acidic media and at a lower surface coverage, when hematite crystallites are small and better accessible by adsorbate.
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Climo, Lawrence H. "Hematite." American Journal of Psychiatry 164, no. 4 (April 2007): 566–67. http://dx.doi.org/10.1176/ajp.2007.164.4.566.

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Torrent, J., U. Schwertmann, and V. Barron. "The reductive dissolution of synthetic goethite and hematite in dithionite." Clay Minerals 22, no. 3 (September 1987): 329–37. http://dx.doi.org/10.1180/claymin.1987.022.3.07.

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AbstractThe reductive dissolution by Na-dithionite of 28 synthetic goethites and 26 hematites having widely different crystal morphologies, specific surfaces and aluminium substitution levels has been investigated. For both minerals the initial dissolution rate per unit of surface area decreased with aluminium substitution. At similar aluminium substitution and specific surface, goethites and hematites showed similar dissolution rates. These results suggest that preferential, reductive dissolution of hematite in some natural environments, such as soils or sediments, might be due to the generally lower aluminium substitution of this mineral compared to goethite.
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Yoo, Jaemin, Dongkyu Lee, Jimo Lee, Taehyeong Kim, Hyungyu Jin, and Gunsu S. Yun. "Catalytic effect of laser-combined atmospheric pressure plasma in lowering the reduction temperature of hematite." RSC Advances 11, no. 56 (2021): 35489–93. http://dx.doi.org/10.1039/d1ra06858j.

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We report a novel method of controlling the oxidation state of hematite using microwave-driven atmospheric pressure plasma assisted by laser surface heating. The method lowers hematite's reduction temperature and accelerates the reduction speed.
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Secco, L., F. Nestola, A. Dal Negro, and L. Z. Reznitsky. "Crystal-chemical study of Rc natural oxides along the eskolaite – karelianite – hematite (Cr2O3–V2O3–Fe2O3) join." Mineralogical Magazine 72, no. 3 (June 2008): 785–92. http://dx.doi.org/10.1180/minmag.2008.072.3.785.

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AbstractSix natural crystals from the Sludyanka crystalline complex belonging to the eskolaite (Cr2O3)–karelianite (V2O3)–hematite (Fe2O3) solid solution were studied by means of X-ray diffraction and electron microprobe. The Fe3+-poor samples show a general increase in a and c cell parameters with increasing mean cationic radius (MCR), consistent with that shown by the synthetic crystals along the eskolaite–karelianite join. The Fe3+-richer sample deviates significantly from the behaviour shown by the Fe3+-poor ones, similar to synthetic and natural hematites; with increasing MCR, the a and c cell parameters increase linearly along the eskolaite-karelianite join. However, for the samples rich in Fe3+, from karelianite to hematite, a shows a slightly steeper slope whereas the c parameter decreases strongly. The octahedral distortion increases slightly as a function of MCR along the eskolaite-karelianite join, whereas it increases markedly for Fe3+-rich samples. The evolution of the octahedral edges and of the octahedral distortions as a function of MCR are responsible for the behaviour of the unit-cell parameters along the eskolaite-karelianite-hematite join.
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Liu, Xiaonan, Gang He, Jinshan Li, and Guangfu Yin. "The Synthesis and Mechanism of (001)-Orientated Hematite Nano Rings: A Combined Theoretical and Experimental Investigation." Nano 12, no. 09 (September 2017): 1750111. http://dx.doi.org/10.1142/s1793292017501119.

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In this study, we synthesized Hematite nano rings using hydrothermal treatment. The experimental results demonstrated that the (001)-orientated Hematite nano rings were produced in all of the obtained products. To determine the formation mechanism of the (001) orientation, the lowest three index crystal faces of Hematite, Hematite (001), Hematite (101), and Hematite (104), were investigated with the Cambridge Sequential Total Energy Package (CASTEP) within the Materials Studio software environment (MS5.5) using the density functional theory (DFT). Our theoretical results showed that Hematite (001), the Hematite crystal with the lowest surface energy, had the greatest Hematite nano ring growth. In addition, we present the growth process of the Hematite nano rings based on our experimental and theoretical results.
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Dissertations / Theses on the topic "Hematite"

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Lu, Baiqing. "Surface Reactivity of Hematite Nanoparticles." Thesis, Umeå universitet, Kemiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-90523.

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Medeiros, Alleyrand Sergio Ramos. "Efeito do método de preparação nas propriedades catalíticas de óxidos de ferro contendo alumínio." reponame:Repositório Institucional da UFBA, 2011. http://www.repositorio.ufba.br/ri/handle/ri/11138.

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Foi estudado o efeito do método de preparação nas propriedades catalíticas de óxidos de ferro contendo potássio com o objetivo de obter sólidos eficientes para catalisar a desidrogenação do etilbenzeno em presença de vapor d´água, a principal rota comercial para a produção de estireno. Este monômero é um produto químico de alto valor comercial utilizado na manufatura de polímeros e resinas, entre outras aplicações. Devido à toxidez dos catalisadores comerciais, existe a necessidade de investigar sólidos alternativos. As amostras baseadas em óxido de ferro contendo alumínio (Fe/Al (molar)= 10), ou não, foram preparados por hidrólise de nitrato de ferro e de alumínio com hidróxido de potássio pela adição de soluções: (i) do agente precipitante sobre a solução dos sais metálicos; (ii) dos sais metálicos (separadas) sobre a solução de hidróxido de potássio; (iii) dos sais metálicos (misturadas) sobre a solução do agente precipitante; (iv) dos sais metálicos (misturadas) e da solução do agente precipitante sobre a água; (v) do nitrato de ferro e da solução de hidróxido de potássio sobre a água, seguida de impregnação do gel obtido com solução de nitrato de alumínio; (vi) do nitrato de ferro e da solução de hidróxido de potássio sobre a água, seguida da impregnação do gel com solução de nitrato de alumínio e (vii) do agente precipitante sobre a solução do sal de ferro, seguido da impregnação com solução de nitrato de alumínio. As amostras foram caracterizadas por análise química, espectroscopia de infravermelho com transformada de Fourier, medidas de área de superficial específica, difração de raios X, redução a temperatura programada e espectroscopia fotoeletrônica de raios X. Os catalisadores foram avaliados em um microreator de leito fixo, a 1 atm e 530 ° C, utilizando uma razão molar vapor d´água/ etilbenzeno de 10. Após a reação, os catalisadores foram caracterizados por medidas de área superficial específica e difração de raios-X. Em todos os casos, foi produzida hematita (-Fe2O3) e não foi detectada nenhuma fase contendo potássio ou alumínio. Observou-se que a ação do alumínio sobre a hematita depende amplamente do método de preparação. A área superficial específica pode variar, dependendo da forma de introdução de alumínio no sólido: ela pode aumentar ou diminuir, dependendo do emprego da impregnação ou da precipitação, respectivamente. A redutibilidade dos sólidos também varia com o alumínio, dependendo do método de preparação; a amostra mais redutível é obtida pela adição da solução de hidróxido de potássio sobre a solução de nitrato de ferro e de alumínio, enquanto a menos redutível é obtida pela adição dos reagentes sobre a água, na ausência de alumínio. O método de preparação também afeta a ação do alumínio sobre a atividade de hematita na desidrogenação do etilbenzeno em presença de vapor. Em geral, quando o alumínio é adicionado ao sólido por precipitação são obtidos catalisadores mais ativos, em relação ao método de impregnação. Em todos os casos, o papel de alumínio, bem como do método de preparação, em afetar a atividade catalítica está mais relacionado à atividade intrínseca do que à área superficial específica. Dentre os métodos estudados, aquele em que uma solução de hidróxido de potássio é adicionada a uma solução de nitrato de ferro e alumínio, produziu catalisadores mais ativos em presença ou não de alumínio. Estes materiais apresentaram elevado rendimento a estireno, mas também foram seletivos aos subprodutos. O catalisador mais promissor para a produção de estireno foi aquele preparado por adição de uma solução de nitrato de ferro e alumínio a uma solução de hidróxido de potássio. Este método produziu um catalisador que levou ao rendimento a estireno mais elevado, com baixa seletividade a benzeno e tolueno e alta estabilidade, alcançada após 5000 s de reação.
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Dang, Mei-Zhen. "Moessbauer study of synthetic hematite aggregates." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7942.

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Synthetic hematite aggregates that result from a process that may have industrial and environmental relevance are studied by Mossbauer spectroscopy at room temperature and liquid nitrogen temperature. The Mossbauer results are compared to measurements involving chemical analysis, scanning electron microscopy, and X-ray diffraction on the same samples. Factors such as the crystalline quality of the hematite and the overall sample purity (wt%Fe$\sb2$O$\sb3)$ are followed as functions of the known synthesis conditions. Pure bulk hematite (high quality $\alpha$-Fe$\sb2$O$\sb3$) serves as a reference throughout. Mossbauer spectroscopy is useful in two ways in this problem: (i) it can detect and identify iron-bearing impurities (i.e. non-hematite Fe-compounds), and (ii) it gives much detailed microscopic information on the intra-sample hematite. We find that all of the sulphur seen by chemical analysis probably resides in an iron-bearing compound which, most often, is probably a quenstetite-like material: Fe$\sb2$(SO$\sb4)\sb3\cdot$nH$\sb2$O (n = 9-11). The synthesis conditions are understood to determine both the hematite yield (or sample purity: wt%Fe$\sb2$O$\sb3$) and the intra-hematite crystalline quality, in that these two factors are correlated. Our interpretation of the room temperature Mossbauer spectra resolves coexisting bulk-like and high-defect-density regions whose relative amounts and sample-dependent Mossbauer characteristics can be quantified accurately. On going to liquid nitrogen temperature, a Morin transition is seen to have occurred in all regions of the most bulk-like samples, to have occurred in some regions of intermediate samples, or not to have occurred at all in the samples with the highest defect-density hematites. This illustrates the intricate interplay between microstructural details and cooperative magnetism in hematite materials.
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Helgeson, Maria Rose. "Fe(II)-catalyzed recrystallization of hematite." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/1466.

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Hematite (α-Fe2O3) is a common, naturally occurring iron oxide, found throughout the earth's crust and atmosphere. Hematite is of interest to the scientific community because it is able to incite a reaction that produces hydrogen gas (H2), which is a form of clean energy (Bora et al., 2013). The composition of hematite in nature is also used to make inferences about conditions on early earth's surface (Guo et al., 2013). Hematite is useful for clean energy production and as an environmental indicator partly because of its apparent stability. However, some evidence suggests that hematite might not be as stable as previously thought. Many iron oxides undergo Fe atom exchange when they come into contact with aqueous Fe(II), as often occurs in nature (Pedersen et al., 2005, Jones et al., 2009, Gorski et al., 2012, Handler et al., 2009). This atom exchange can result in elements and nutrients being taken up or released from the iron oxides as they recrystallize (Frierdich & Catalano, 2012, Cwiertny et al., 2008, Boland et al., 2014). Although atom exchange has not been directly shown in hematite, it has been demonstrated that trace metals are released from hematite in the presence of aqueous Fe(II), implying that exchange may be occurring (Frierdich et al., 2011). Here, we directly demonstrate Fe atom exchange between hematite and aqueous Fe(II). This work provides knowledge concerning the surface chemistry of hematite that has important implications for clean energy production and the environment.
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Silva, Caio Luis Santos. "Efeito do gadolínio nas propriedades catalíticas de óxidos de ferro na reação de WGS." reponame:Repositório Institucional da UFBA, 2012. http://www.repositorio.ufba.br/ri/handle/ri/11726.

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Devido à necessidade de garantir o suprimento de energia através de tecnologias de conversão de energia mais limpas e mais eficientes, reduzindo a emissão de gases causadores do efeito estufa, o interesse pela reação de deslocamento de monóxido de carbono com vapor d´água (WGSR, water gas shift reaction) tem aumentado, especialmente devido ao seu papel nas células a combustível. A fim de obter catalisadores alternativos para essa reação, foi estudado o efeito da adição e do teor de gadolínio nas propriedades de catalisadores de óxido de ferro. As amostras foram preparadas pela hidrólise de nitrato de ferro e de gadolínio, seguida da lavagem do gel com uma solução de acetato de amônio para obter magnetita e com água para obter hematita. As amostras foram caracterizadas por termogravimetria, calorimetria diferencial de varredura, espectroscopia no infravermelho com transformada de Fourier, difração de raios X, medida da área superficial específica (B.E.T.) e redução à temperatura programada. Os catalisadores foram avaliados na WGSR a 1 atm, na faixa de 250 a 400 ºC, usando uma razão molar vapor d´água/gás de processo (3,7% CO, 3,7% CO2, 22,2% H2, 70,4% N2) igual a 0,6. As fases hematita e ferrita de gadolínio foram detectadas em todos os sólidos lavados com água, enquanto magnetita e ferrita de gadolínio foram encontradas naqueles lavados com acetato de amônio. No primeiro caso, a área superficial específica aumentou devido ao gadolínio, independente do seu conteúdo, um fato que foi relacionado ao seu papel como espaçador e/ou a uma causa de tensões na rede, produzindo partículas menores. Entretanto, em todos os sólidos baseados em magnetita, o gadolínio conduziu a uma diminuição da área superficial específica, devido à predominância da perovskita (ferrita de gadolínio), que apresenta valores tipicamente baixos. A adição de gadolínio facilita a redução de espécies Fe3+, em todos os catalisadores, mas aumenta a atividade apenas naquelas aquecidas sob ar. O sólido com Gd/Fe=0,1, aquecido sob ar, mostrou a mais alta atividade, provavelmente devido à area superficial específica aumentada devido ao gadolínio, que também facilitou a redução do ferro, tornando o ciclo redox mais fácil durante a WGSR. Além disso, os catalisadores baseados em hematita mostraram as atividades mais elevadas. Isto pode ser atribuído à predominância de hematita nesses sólidos, quando comparados a outros nos quais a ferrita de gadolínio foi a fase predominante. Isto significa que as espécies Fe3+, no ambiente da hematita, são mais ativas na reação de WGS que as espécies Fe4+, no ambiente da perovskita
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Dunn, James Albert. "Single Molecule Characterization of Peptide/Hematite Binding." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494014864020062.

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Ghopry, Samar A. "Magnetic Properties of Hematite (α-Fe2O3) Nanorods." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3662.

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At this study three samples of hematite nanorods were deposited on the silicon substrates with different varieties of glancing angle deposition techniques. One sample (S1) was prepared by using thermal deposition with partially ionized beam (PIB) and substrate rotation. The second sample (S2) was synthesized by using thermal deposition with PIB and no substrate rotation. The third sample (S3) was obtained by using E-beam deposition, PIB and rotating substrate. In addition, one sample of magnetite nanorods (S4) has been prepared in order to compare the magnetic properties of the two different iron oxides. S4 was prepared by using thermal deposition and fixed glancing angle deposition, but no PIB was applied. The hysteresis loop has been studied for all samples and the temperature dependent magnetic properties of one of the hematite samples and the magnetite been studied, too. The studies of the magnetic hysteresis for S1, S2, S3 and S4 showed that all of the samples have hysteresis loops but with dissimilar values of the saturation magnetization Ms, remanence MR, and coercivity HC. Furthermore, the hysteresis loops of all four samples showed different behaviors as the nanorods of the samples change the orientation with respect to the magnetic field. In addition to that fact, the hysteresis loop demonstrated that samples that have similar morphology have like behavior of the hysteresis loop. Also, it has found that S2 has the largest hysteresis loop of all hematite samples and it has large hysteresis loop in the perpendicular and parallel directions with the field as well. However, the magnetite hysteresis loops are significant larger than the ones of the hematite. Likewise, the studies of the temperature dependence magnetic properties of S2 and S4 showed that the ZFC and FC M-T curves of S1and S4 behaved differently when the direction of the nanorods changed from perpendicular to parallel with the field. In addition, the ZFC and FC M-T curves of hematite were different than the ZFC and FC M-T curves of magnetite.
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Kirwan, Luke J. "An investigation of polyacrylate adsorption onto hematite." Thesis, Curtin University, 2002. http://hdl.handle.net/20.500.11937/308.

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For the majority of tailings substrates, flocculant adsorption proceeds through hydrogen bonding of the amide functionalities with neutral surfaces. However, flocculation of Bayer process residue solids takes place in highly caustic liquors, typically using high molecular weight polyacrylates. This represents an almost unique situation, and implies a totally different adsorption mechanism. Direct examination of polyacrylate adsorption within the complex matrix of real liquors and a mixture of residue phases is difficult, making it necessary to focus on a model substrate (hematite) and synthetic liquors (pH 13 at high ionic strength). Previous spectral studies have used ex situ techniques, with sample drying potentially altering the adsorbed species, leading to inconclusive results. This study presents for the first time direct in situ evidence of polyacrylate adsorption onto hematite obtained by Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR) Spectroscopy. Adsorption and hence concentration of dilute polyacrylate solutions onto hematite-coated zinc selenide optics has provided spectra of adsorbed polymer under a range of conditions, unbiased by any contribution from the bulk polymer solution. Analysis of the polyacrylate carbon-oxygen stretching frequencies established differing modes of adsorption at low and high pH conditions. At pH 2 adsorption proceeded through bidentate chelation of the carboxylate to a surface ferric ion, facilitated through deprotonation of a carboxylic acid group and removal of a hematite surface hydroxyl group, i.e. chemisorption. Unshifted carboxyl peaks in the spectrum enabled the unadsorbed 'loops' and 'tails' to be distinguished from the adsorbed polymer, and represented at least 70% of the total polymer chain length.In contrast, at pH 13 adsorption of polyacrylate occurs via physisorption and was only possible with the addition of electrolyte. This adsorption was enhanced with increasing electrolyte concentrations up to 1 M NaCl. The hematite surface charge was negative at high pH, however with increasing ionic strength the specific adsorption of Na+ ions decreased the negative surface charge, and at very high salt concentrations the surface became positively charged. For electrolyte with different monovalent cations, polymer adsorption increased in the order Li+ > Na+ > Cs+. The identity of the monovalent cation had no effect on the polymer solution dimensions but the ability to reduce the magnitude of the hematite surface charge followed the same trend. This finding is consistent with the 'structure making - structure breaking' model proposed by Berube and de Bruyn. At both high and low pH, polyacrylate exhibited adsorption isotherms that are best described by the Langmuir expression. Surface coverage was greatest at low pH due to more available surface sites and the adsorbed polymer conformation (a greater fraction of loops and tails). Adsorbed conformation and hence maximum adsorption was independent of molecular weight at low pH, however at high pH maximum adsorption increased with increased molecular weight, indicating an adsorbed polymer configuration exhibiting a greater degree of loops and tails. While the individual carboxylate-surface interaction was stronger at low pH than high pH, both were relatively weak. Despite this, none of the polymers could be removed by washing, demonstrating the strength and irreversibility of the multi-attached polymer molecules.The stronger individual carboxylate-surface interactions at low pH is indicative of a higher activation energy of formation, and may be a contributing factor to the slower rate of adsorption at low pH. The rate of polyacrylate adsorption was dominated by mass transport limitations in all cases. The initial rate of adsorption was greater at lower polymer molecular weight, consistent with the relative polymer diffusion coefficients. This rate of adsorption was much less dependent on polymer molecular weight at high pH than at low pH, suggesting significantly different polymer-solvent interactions. It was clearly demonstrated that the sodium ion concentration within the high ionic strength Bayer liquors is more than sufficient to facilitate polyacrylate adsorption on bauxite residue. There is no need to postulate calcium bridging between the polymer and surface, as has been suggested in previous studies. Improved settling and clarity associated with the presence of calcium on residue surfaces is more likely due to enhanced particle coagulation prior to flocculation. FTIR-ATR has been shown to be an excellent tool for the in situ examination of polyacrylate adsorption onto hematite, and will be a powerful technique for the characterisation and subsequent comparison of the adsorption behaviour of other systems.
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Kirwan, Luke J. "An investigation of polyacrylate adsorption onto hematite." Curtin University of Technology, Department of Applied Chemistry, 2002. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=13689.

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For the majority of tailings substrates, flocculant adsorption proceeds through hydrogen bonding of the amide functionalities with neutral surfaces. However, flocculation of Bayer process residue solids takes place in highly caustic liquors, typically using high molecular weight polyacrylates. This represents an almost unique situation, and implies a totally different adsorption mechanism. Direct examination of polyacrylate adsorption within the complex matrix of real liquors and a mixture of residue phases is difficult, making it necessary to focus on a model substrate (hematite) and synthetic liquors (pH 13 at high ionic strength). Previous spectral studies have used ex situ techniques, with sample drying potentially altering the adsorbed species, leading to inconclusive results. This study presents for the first time direct in situ evidence of polyacrylate adsorption onto hematite obtained by Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR) Spectroscopy. Adsorption and hence concentration of dilute polyacrylate solutions onto hematite-coated zinc selenide optics has provided spectra of adsorbed polymer under a range of conditions, unbiased by any contribution from the bulk polymer solution. Analysis of the polyacrylate carbon-oxygen stretching frequencies established differing modes of adsorption at low and high pH conditions. At pH 2 adsorption proceeded through bidentate chelation of the carboxylate to a surface ferric ion, facilitated through deprotonation of a carboxylic acid group and removal of a hematite surface hydroxyl group, i.e. chemisorption. Unshifted carboxyl peaks in the spectrum enabled the unadsorbed 'loops' and 'tails' to be distinguished from the adsorbed polymer, and represented at least 70% of the total polymer chain length.
In contrast, at pH 13 adsorption of polyacrylate occurs via physisorption and was only possible with the addition of electrolyte. This adsorption was enhanced with increasing electrolyte concentrations up to 1 M NaCl. The hematite surface charge was negative at high pH, however with increasing ionic strength the specific adsorption of Na+ ions decreased the negative surface charge, and at very high salt concentrations the surface became positively charged. For electrolyte with different monovalent cations, polymer adsorption increased in the order Li+ > Na+ > Cs+. The identity of the monovalent cation had no effect on the polymer solution dimensions but the ability to reduce the magnitude of the hematite surface charge followed the same trend. This finding is consistent with the 'structure making - structure breaking' model proposed by Berube and de Bruyn. At both high and low pH, polyacrylate exhibited adsorption isotherms that are best described by the Langmuir expression. Surface coverage was greatest at low pH due to more available surface sites and the adsorbed polymer conformation (a greater fraction of loops and tails). Adsorbed conformation and hence maximum adsorption was independent of molecular weight at low pH, however at high pH maximum adsorption increased with increased molecular weight, indicating an adsorbed polymer configuration exhibiting a greater degree of loops and tails. While the individual carboxylate-surface interaction was stronger at low pH than high pH, both were relatively weak. Despite this, none of the polymers could be removed by washing, demonstrating the strength and irreversibility of the multi-attached polymer molecules.
The stronger individual carboxylate-surface interactions at low pH is indicative of a higher activation energy of formation, and may be a contributing factor to the slower rate of adsorption at low pH. The rate of polyacrylate adsorption was dominated by mass transport limitations in all cases. The initial rate of adsorption was greater at lower polymer molecular weight, consistent with the relative polymer diffusion coefficients. This rate of adsorption was much less dependent on polymer molecular weight at high pH than at low pH, suggesting significantly different polymer-solvent interactions. It was clearly demonstrated that the sodium ion concentration within the high ionic strength Bayer liquors is more than sufficient to facilitate polyacrylate adsorption on bauxite residue. There is no need to postulate calcium bridging between the polymer and surface, as has been suggested in previous studies. Improved settling and clarity associated with the presence of calcium on residue surfaces is more likely due to enhanced particle coagulation prior to flocculation. FTIR-ATR has been shown to be an excellent tool for the in situ examination of polyacrylate adsorption onto hematite, and will be a powerful technique for the characterisation and subsequent comparison of the adsorption behaviour of other systems.
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Santos, Manuela de Santana. "Efeito do lantânio nas propriedades de catalisadores de ferro para a produção de estireno." Instituto de Química, 2007. http://repositorio.ufba.br/ri/handle/ri/20530.

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Entre os intermediários utilizados na indústria petroquímica, o estireno é um dos mais importantes. Este monômero é empregado na produção de diferentes materiais poliméricos, sendo o poliestireno o mais importante. Desde 1930, a desidrogenação catalítica do etilbenzeno em presença de vapor d’água é mais importante via de produção de estireno. O catalisador clássico, baseado em óxido de ferro contendo potássio e cromo, entretanto, rapidamente desativa com o tempo, causando a necessidade de troca do catalisador a cada um ou dois anos. Como conseqüência, vários estudos estão sendo conduzidos com o intuito de descobrir dopantes alternativos que possam tornar o catalisador mais estável. Com esse objetivo, investigou-se neste trabalho, o efeito do lantânio e do método de preparação sobre as propriedades catalíticas da hematita. Amostras com diferentes razões molares ferro/lantânio (5, 10, 15 e 20) foram preparadas através do método sol-gel a partir de nitrato de lantânio, nitrato de ferro e hidróxido de amônio. Os catalisadores foram caracterizados por difração de raios X, medida de área superficial específica e redução à temperatura programada e avaliados na desidrogenação do etilbenzeno em presença de vapor d’água. Foi observado que as amostras mais ricas em lantânio (Fe/La = 5 e 10) se mostraram amorfas aos raios X, mas as outras eram formadas por hematita. Após a reação, detectou-se magnetita, em todas as amostras, hematita e um óxido de ferro e lantânio (FeLaO3). O lantânio evitou a sinterização dos sólidos, mas apenas nos catalisadores novos. Os catalisadores dopados com lantânio se mostraram mais ativos do que a hematita pura e este efeito aumentou com a quantidade de lantânio até o valor de Fe/La = 10; quantidades maiores desse dopante diminuiu a atividade. Esta melhoria do catalisador foi atribuída ao papel do lantânio em elevar a atividade intrínseca, assim como em estabilizar as espécies Fe+3, consideradas como a fase ativa. A fim de promover uma melhoria ainda maior desse catalisador, o efeito do tipo do agente precipitante foi também investigado, através da preparação de amostras com carbonato de sódio e potássio e hidróxido de sódio e potássio. Os catalisadores foram caracterizados pelas mesmas técnicas e também por espectroscopia fotoeletrônica de raios X e espectroscopia Mössbauer. O emprego de carbonato de sódio e potássio e hidróxido de sódio e potássio favoreceu a cristalização e a produção de sólidos com baixos valores de área superficial específica; a resistência contra redução aumentou. Também foi observado que sódio e potássio atuaram como promotores estruturais, sendo o potássio o mais eficiente, especialmente quando associado a espécies hidroxilas. O catalisador preparado com carbonato de potássio foi o mais ativo, um fato que foi atribuído à produção de ferrita de potássio na superfície das partículas, responsáveis pelo aumento da atividade dos sítios. O mais eficiente método de preparação desse sólido é a adição dos reagentes sobre a água; através da adição de carbonato de potássio aos nitratos de ferro e lantânio ou vice-versa foram obtidos catalisadores menos ativos. O catalisador foi mais ativo com conversão de 13% quando comparado a uma amostra comercial, que apresentou conversão de 9,0%, então é promissor para aplicação industrial
Among the intermediates used in petrochemical industry, styrene is by far one of the most important. This monomer is used for the production of different polymeric materials, the most important being polystyrene. Since 1930, the catalytic dehydrogenation of ethylbenzene in the presence of steam is the most important route for styrene production. The classical catalyst, based on iron oxide containing potassium and chromium, however, fastly deactivates with time, causing the need of replacing the catalyst each one or two years. As a consequence, several studies have been carried out in recent years aiming to get alternative dopants which could make the catalysts more stable. With this goal in mind, the effect of lanthanum and of the preparation method on the catalytic properties of hematite was investigated in this work. Samples with different iron to lanthanum molar ratio (5, 10, 15 and 20) were prepared by sol-gel method from lanthanum nitrate, iron nitrate and ammonium hydroxide. The catalysts were characterized by X-ray diffraction, specific surface area measurements and temperature programmed reduction and evaluated in the dehydrogenation of ethylbenzene in the presence of steam. It was found that the samples richest in lanthanum (Fe/La = 5 and 10) were amorphous to X-ray but the other were made off hematite. After reaction, magnetite, hematite and an iron and lanthanum oxide (FeLaO3) were detected in all the samples. Lanthanum avoided sintering but only for the fresh catalysts. The lanthanum-doped catalysts were more active than pure hematite and this effect increased with lanthanum amount up to Fe/La = 10; higher amounts of this dopant decreased the activity. This improvement of the catalysts was assigned to the role of lanthanum in increasing the intrinsic activity as well as in stabilizing the Fe+3 species, wich are supposed to be the active phase. In order to improve this catalyst even more, the effect of the kind of the precipitant agent was also investigated, by preparing samples with sodium and potassium carbonate and sodium and potassium hydroxide. The catalysts were characterized by the same techniques and also by X-ray photoelectron spectroscopy and Mossabuer spectroscopy. The use of sodium and potassium carbonate and hydroxide makes the crystallization easier and favors the production of solids with low specific surface areas; the resistance against reduction increased. It was also found that sodium and potassium were structural promoters, being potassium the most effective one, especially when associated with hydroxide species. The catalyst prepared with potassium carbonate was the most active one and this was assigned to the production of potassium ferrite on the particle surface, responsible for the increase of active of the sites. The most efficient way to prepare this solid is by adding all reagents to water; by adding potassium carbonate to the iron and lanthanum nitrate or vice-versa less active catalysts were produced. The catalyst was more active (13% of conversion) when compared to the commercial sample which showed 9% of conversion and thus is promising for industrial applications.
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Books on the topic "Hematite"

1

Taylor, Peter. Adsorption of aqueous silicate on hematite. Pinawa, Man: Whiteshell Laboratories, 1997.

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V, Morris Richard, and United States. National Aeronautics and Space Administration., eds. Lepidocrocite to maghemite to hematite: A way to have magnetic and hematitic martian soil. [Washington, D.C: National Aeronautics and Space Administration, 1998.

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V, Morris Richard, and United States. National Aeronautics and Space Administration., eds. Lepidocrocite to maghemite to hematite: A way to have magnetic and hematitic martian soil. [Washington, D.C: National Aeronautics and Space Administration, 1998.

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Peter, Taylor. Comparison of the solubilities of synthetic hematite (a-Fe203) and maghemite (y-Fe203). Pinawa, Man: AECL, Whiteshell Laboratories, 1997.

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Dekkers, Marinus Jacobus. Some rockmagnetic parameters for natural goethite, pyrrhotite, and fine-grained hematite =: Gesteente-magnetische parameters voor natuurlijke goethiet, pyrrhotien, en fijnkorrelige hematiet. [Utrecht]: Instituut voor Aardwetenschappen der Rijksuniversiteit te Utrecht, 1988.

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Herbert, Bartlett James, and Exposition universelle de 1885 (Antwerp, Belgium), eds. Analyses of iron ores from Pictou County, Nova Scotia, dominion of Canada: Red hematite, specular ore : brown hematite, spathose ore. [Montreal?: s.n., 1987.

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Herbert, Bartlett James, and Exposition universelle (Antwerp Belgium), eds. Analyses of iron ores from Pictou County, Nova Scotia, dominion of Canada: Red hematite, specular ore; brown hematite, spathose ore. [Montreal?: s.n., 1987.

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Dekkers, Marinus Jacobus. Some rockmagnetic parameters for natural goethite, pyrrhotite, and fine-grained hematite. Utrecht: Instituut voor Aardwetenschappen der Rijksuniversiteit te Utrecht, 1988.

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J.C. van den Berg. Direct reduction of hematite fines with coal in a fluidized bed. Randburg, South Africa: Council for Mineral Technology, 1986.

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Jobe, David James. The calculated solubilities of hematite, magnetite and lepidocrocite in steam generator feedtrains. Pinawa, Man: Whiteshell Laboratories, 1997.

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Book chapters on the topic "Hematite"

1

Pinti, Daniele L. "Hematite." In Encyclopedia of Astrobiology, 1–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_712-3.

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Pinti, Daniele L. "Hematite." In Encyclopedia of Astrobiology, 1091–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_712.

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Pinti, Daniele L. "Hematite." In Encyclopedia of Astrobiology, 743–44. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_712.

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Gooch, Jan W. "Hematite." In Encyclopedic Dictionary of Polymers, 363. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_5889.

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Pinti, Daniele L. "Hematite." In Encyclopedia of Astrobiology, 1–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2021. http://dx.doi.org/10.1007/978-3-642-27833-4_712-4.

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Pinti, Daniele L. "Hematite." In Encyclopedia of Astrobiology, 1315–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/978-3-662-65093-6_712.

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Uribe, J. D., J. Osorio, C. A. Barrero, D. Giratá, A. L. Morales, A. Devia, M. E. Gómez, J. G. Ramirez, and J. R. Gancedo. "Hematite thin films: growth and characterization." In ICAME 2005, 1355–62. Berlin, Heidelberg: Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/978-3-540-49853-7_109.

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Papangelakis, V. G., B. C. Blakey, and H. Liao. "Hematite solubility in sulphate process solutions." In Hydrometallurgy ’94, 159–75. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1214-7_9.

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Vijay, S. J., Alexandre Tugirumubano, Sun Ho Go, Lee Ku Kwac, and Hong Gun Kim. "Electrospinning of PAN–Hematite Composite Nanofiber." In Lecture Notes in Mechanical Engineering, 495–502. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-1780-4_48.

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Castroviejo, Ricardo. "Hematite (ht/red iron ore, specularite)." In A Practical Guide to Ore Microscopy—Volume 1, 349–55. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-12654-3_60.

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Conference papers on the topic "Hematite"

1

Kharakhan, M., S. Kreynin, and O. Generalov. "Hematite thermomagnetization in open air." In The 8th International Mineral Processing Symposium. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2017. http://dx.doi.org/10.4324/9780203747117-26.

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Anderson, Keith D. "Decommissioning of the Hematite Former Fuel Cycle Facility Using a Decision Flow Logic Based Work Control Process." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96345.

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The remediation and decommissioning of the Hematite Former Fuel Cycle Facility (FFCF), the Hematite Facility, is currently being carried out by Westinghouse Electric Company LLC under the Hematite Decommissioning Project (HDP). The Hematite Facility is located near the town of Hematite, Missouri, USA. The Hematite Facility consists of 228 acres of land with primary operations historically being conducted within the central portion of the property that is roughly 10 acres including Burial Pits and the Site Pond area. Decommissioning and remediation activities are being performed with the eventual objective of the release of the property. Primary contaminants include the legacy disposal and contamination of natural and enriched uranium from the nuclear fuel cycle, as well as chemicals used during the facility operations. Two major regulatory bodies, the U.S. Nuclear Regulatory Commission (NRC) and the Missouri Department of Natural Resources (MDNR), provide critical roles in the approval and oversight of the current regulatory path to remediation, decommissioning and eventual release. Further, remediation and decommissioning activities are performed under the implementing policies, plans, and procedures under the Hematite Decommissioning Plan (DP) and the Record of Decision (ROD). Remediation and decommissioning tasks at the Hematite Former Fuel Cycle Facility, referred to as the Hematite Facility, are performed against a disciplined decision logic flow that applies accumulated technical and monitoring data to determine each step of the excavation, exhumation, and removal of wastes from the Burial Pits and the remaining Areas of Concern (AOC). Decision flow logic is based upon the nuclear criticality safety controls and threshold conditions, relative level of radioactive and chemical contamination, security protocol, and final waste stream disposition. The end result is to remediate the residual radioactive and chemical contamination to approved dose-based and risk-based cleanup criteria as negotiated with U.S. Federal and State Regulators. The purpose of the paper is to provide a summary of the successful implementation of the decision flow logic to the remediation and decommissioning tasks performed to date.
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PERŠIĆ, Ana, Nina POPOV, Elza ŠTEFANOVIĆ, Stjepko KREHULA, Emi GOVORČIN BAJSIĆ, Mirela LESKOVAC, and Ljerka KRATOFIL KREHULA. "The influence of the size of hematite particles on the properties of polyethylene/hematite composites." In NANOCON 2021. TANGER Ltd., 2021. http://dx.doi.org/10.37904/nanocon.2021.4330.

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Abdelaal, Ahmed Elsayed, and Salaheldin Mahmoud Elkatatny. "High Density Geopolymers: A Step Forward Towards Low Carbon Footprint Cementing Operations." In Offshore Technology Conference. OTC, 2023. http://dx.doi.org/10.4043/32341-ms.

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Abstract The utilization of ordinary Portland cement (OPC) in well cementing is accompanied by technical and environmental problems, leading researchers to explore alternative materials that address these issues and promote eco-friendliness. Geopolymer technology, widely used in construction and other industries, has not yet been fully implemented in oil and gas well cementing. Industrial waste materials, such as Class F fly ash (FFA), can be utilized to improve cement properties or create new cement binders. Hematite is used as a weighting agent to increase cement slurry density. However, heavy particle sedimentation in cement and geopolymer slurries is a significant issue that leads to heterogenous properties along the cemented section. This study introduces a new class of geopolymers that use both hematite and Micromax as weighting materials for high-density well cementing applications. One system only used hematite, while the other used both hematite and Micromax in an effort to eliminate sedimentation issues associated with hematite in geopolymers. The effects of adding Micromax on different FFA geopolymer properties were also evaluated. The study evaluated mixability, rheology, and pumpability to determine the mix design, which was then used to examine other properties such as strength, and density variation. The results showed that adding Micromax to hematite reduced the average density variation from 12.5% to 3.9%. Micromax addition also decreased plastic viscosity by 44.5% and fluid loss by 10.5%. Both systems performed closely in terms of strength.
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Srivastava, Himanshu, Pragya Tiwari, A. K. Srivastava, S. K. Rai, S. K. Deb, Alka B. Garg, R. Mittal, and R. Mukhopadhyay. "Growth and Characterization of Hematite Nanonails." In SOLID STATE PHYSICS, PROCEEDINGS OF THE 55TH DAE SOLID STATE PHYSICS SYMPOSIUM 2010. AIP, 2011. http://dx.doi.org/10.1063/1.3605874.

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Sharma, Monika, Azeem Banday, and Sevi Murugavel. "Size dependent polaronic conduction in hematite." In DAE SOLID STATE PHYSICS SYMPOSIUM 2015. Author(s), 2016. http://dx.doi.org/10.1063/1.4948070.

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WANG, Li-Li, Hai-Bin KE, and Liang-Liang YUAN. "Application of Refractory Hematite in Pellets." In 3rd International Conference on Material Engineering and Application (ICMEA 2016). Paris, France: Atlantis Press, 2016. http://dx.doi.org/10.2991/icmea-16.2016.41.

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Cuadra, Rafael, and Akira Satoh. "Experiment on Negative Magneto-Rheological Characteristics to Verify the Theoretical Prediction Based on the Orientational Distribution Function." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65353.

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In a suspension composed of spindle-like hematite particles (α-Fe2O3), the previous theoretical study based on the orientational distribution function has shown that the viscosity due to the magnetic properties of spindle-like hematite particles exhibits negative magneto-rheological characteristics in a certain situation of the orientational distribution of the particles under a certain applied magnetic field circumstance. This is mainly because the spindle-like hematite particles have a unique characteristic in that they are magnetized in a direction normal to the particle axis direction. This weak magnetic characteristic yields an advantage to the suspension in that it is relatively straightforward to synthesize a stable dispersion of such hematite particles because the electric double layer functions well for preventing the particles from aggregating. The negative magneto-rheological effect has also energetically been investigated by a simulation approach based on the Brownian dynamics and these simulation results clearly show that the negative magneto-rheological characteristics certainly arise in a multi-particle suspension system. From this background, in the previous experimental study, we synthesized a suspension composed of spindle-like hematite particles and measured the viscosity due to the magnetic properties of the particles in a simple shear flow. This first simple experiment has succeeded in verifying that the negative magneto-rheological characteristics surely arise in an actual hematite particle suspension. The present study further advances the experimental investigation of the negative magneto-rheological effect in order to obtain the more detailed data of these negative magneto-rheological characteristics. The viscosity due to the magnetic properties was measured using a cone-plate-type rheometer, located in the uniform area of the magnetic field, under various conditions of the magnetic field strength and the shear rate of a shear flow. The viscosity of hematite-glycerol-water dispersions becomes negative, attains to a minimum value, after that starts to increase, and finally becomes positive with increasing magnetic field strength. These characteristics of the negative viscosity are in good agreement with the theoretical prediction that was obtained by the orientational distribution function.
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Alvayed, Dandi, Ahmed Abdulhamid Mahmoud, Salaheldin Elkatatny, and Saad Alafnan. "The Effect of the Heavyweight Hematite, Magnetite, and Micromax on Class G Oil Well Cement Properties." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0490.

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ABSTRACT A high-density cement slurry is required to adequately balance the high-pressure formations in deep oil wells. The slurry's density could be increased by adding a variety of heavy substances which affect cement slurry and sheath properties. This study investigated the impact of three weighing materials of hematite, magnetite, and micromax on the density fluctuation, compressive strength, and rheology test of Saudi Class G cement slurry of 18 ppg. The results of this work indicated that using a weighting material with large particles can cause vertical heterogeneity, the density variation shows that the hematite cement sample had the largest density variation, with an 8.7% difference between the top and bottom of 4 inches in length sample, led by the magnetite cement sample with a density variation of 7.3%. In the Micromax-weighted sample, the density fluctuation had a vertical variation of 4% and was far less severe than others. Compressive strength measurement shows that the magnetite-weighted cement sample exhibited the highest compressive strength of 65.1 MPa which is 28% greater than the hematite sample. The magnetite slurry had the highest plastic viscosity of 113 cP, followed by 112 cP in the hematite cement. At 56 cP, the plastic viscosity of the micromax-containing heavyweight system was the lowest (50.8 percent less than that of the hematite cement). The smallest yield point was 10 lbf/100 ft2 for the micromax-based cement. Hematite cement had a yield point of 25 lbf/100 ft2, while magnetite-based cement exhibited the highest yield point of 41 lbf/100 ft2. With a 10-sec gel of 14 lbf/100 ft2 and a 10-min gel of 21 lbf/100 ft2, the micromax cement had the lowest gel strength. To avoid problems of segregation and solid abrasion, it is recommended that the particle size of weighing materials be reduced in further investigations.
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Bandaranayake, Savini, Spencer Wallentine, Robert Baker, and Somnath Biswas. "CONTROLLING PHOTOEXCITED STATE DYNAMICS AT HEMATITE SURFACES." In 74th International Symposium on Molecular Spectroscopy. Urbana, Illinois: University of Illinois at Urbana-Champaign, 2019. http://dx.doi.org/10.15278/isms.2019.wk06.

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Reports on the topic "Hematite"

1

Gainer, G. M. Boron adsorption on hematite and clinoptilolite. Office of Scientific and Technical Information (OSTI), March 1993. http://dx.doi.org/10.2172/138776.

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2

Ivey, Wade. Letter Report for Analytical Results for Two Soil Samples Associated with the Westinghouse Hematite Decommisioning Project in Hematite Missouri. Office of Scientific and Technical Information (OSTI), October 2013. http://dx.doi.org/10.2172/1113651.

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3

Viani, B. ,. LLNL. Sorption and transport of uranium on Hematite milestone. Office of Scientific and Technical Information (OSTI), February 1998. http://dx.doi.org/10.2172/664593.

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Bargar, John R. Spectroscopic Confirmation of Uranium (VI)-Carbonato Adsorption Complexes on Hematite. Office of Scientific and Technical Information (OSTI), May 1999. http://dx.doi.org/10.2172/10076.

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5

E.N. Bailey. Final Report - Independent Confirmatory Survey Summary and Results for the Hematite Decommissioning Project. Office of Scientific and Technical Information (OSTI), March 2009. http://dx.doi.org/10.2172/959376.

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Bailey, Erika N., and Jason D. Lee. FINAL REPORT FOR INDEPENDENT CONFIRMATORY SURVEY SUMMARY AND RESULTS FOR THE HEMATITE DECOMMISSIONING PROJECT, FESTUS, MISSOURI. Office of Scientific and Technical Information (OSTI), September 2012. http://dx.doi.org/10.2172/1060181.

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Bargar, J. In-situ Grazing-Incidence EXAFS Study of Pb(II) Chemisorption on Hematite (0001) and (1-102) Surfaces (titled changed by journal: IN SITU GRAZING INCIDENCE EXTENDED X-RAY ABSORPTION FINE STRUCTURE STUDY OF PB(II) CHEMISORPTION ON HEMATITE (0001) AND (1-102) SURFACES). Office of Scientific and Technical Information (OSTI), March 2004. http://dx.doi.org/10.2172/826809.

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Goodwin, J. A., and R. G. Skirrow. Producing magnetite and hematite alteration proxies using 3D gravity and magnetic inversion: method and results for the Tennant Creek-Mount Isa Project, northern Australia. Geoscience Australia, 2019. http://dx.doi.org/10.11636/record.2019.003.

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Asenath-Smith, Emily, Emma Ambrogi, Eftihia Barnes, and Jonathon Brame. CuO enhances the photocatalytic activity of Fe₂O₃ through synergistic reactive oxygen species interactions. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42131.

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Iron oxide (α-Fe₂O₃, hematite) colloids were synthesized under hydrothermal conditions and investigated as catalysts for the photodegradation of an organic dye under broad-spectrum illumination. To enhance photocatalytic performance, Fe₂O₃ was combined with other transition-metal oxide (TMO) colloids (e.g., CuO and ZnO), which are sensitive to different regions of the solar spectrum (far visible and ultraviolet, respectively), using a ternary blending approach for compositional mixtures. For a variety of ZnO/Fe₂O₃/CuO mole ratios, the pseudo-first-order rate constant for methyl orange degradation was at least double the sum of the individual Fe₂O₃ and CuO rate constants, indicating there is an underlying synergy governing the photocatalysis reaction with these combinations of TMOs. A full compositional study was carried out to map the interactions between the three TMOs. Additional experiments probed the identity and role of reactive oxygen species and elucidated the mechanism by which CuO enhanced Fe₂O₃ photodegradation while ZnO did not. The increased photocatalytic performance of Fe2O3 in the presence of CuO was associated with hydroxyl radical ROS, consistent with heterogeneous photo-Fenton mechanisms, which are not accessible by ZnO. These results imply that low-cost photocatalytic materials can be engineered for high performance under solar illumination by selective pairing of TMOs with compatible ROS.
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Jackson, G. D. Bedrock geology, northwest part of Nuluujaak Mountain, Baffin Island, Nunavut, part of NTS 37-G/5. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/314670.

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The map area lies about 40 km northwest of Baffinland's iron mine. Dykes of unit mAnA3 within unit mAnA2 suggest that unit mAnA2 predates unit mAnA3. Unit nAMqf, basal Mary River Group unit, includes regolith material from units mAnA2 and mAnA3. Unit mAnAm may include some dykes of unit nAMb. The Mary River Group was deposited in a volcanic-arc environment, yielding zircon U-Pb ages mostly in the range of 2.88 to 2.72 Ga. Iron-formation (unit nAMi) is approximately 276 m thick locally, with oxide facies (unit nAMio) being most abundant. The quartzite triangle west of 'Iron lake' (unofficial name) may be a small horst. The main east-west-trending synclinal fold, including the area around 'Iron lake' and the no. 4 ore deposit, is upright, nearly isoclinal, and plunges mostly easterly at both ends with small scale anticlines and synclines in the middle. Magnetite constitutes about 75% of high-grade iron deposits in the north limb, whereas hematite predominates in south-limb deposits. K-Ar and Rb-Sr ages indicate middle Paleoproterozoic overprinting. Central Borden Fault Zone was active at ca. 1.27 Ga and during or after Ordovician time. Note: please be aware that the information contained in CGM 408 is based on legacy data from the 1960-1990s and that it has been superseded by regional-scale information contained in CGM 403.
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