Activity of Ferric Oxide in Steelmaking Slag

Refining reactions in steelmaking primarily involve oxidation of impurity element(s). The oxidation potential of the slag and the activity of oxygen in the metal (h(O)) are the major factors controlling these chemical reactions. In turn, the oxidation potential of the slag is influenced strongly by the equilibrium distribution of oxygen between ferrous and ferric oxides. We recently investigated the activity coefficient of FeO in steelmaking slag and the effect of chemical composition thereon. This work is focused on estimation of theactivity coefficient of Fe2O3.

Magnetic behavior of basic iron(III) compounds. I. Magnetic behavior of the basic iron sulphates and basic iron chromate. II. Magnetic behavior of delta ferric oxide hydroxide

I. The thermomagnetic behavior and infrared spectroscopic features of KFe₃(SO₄)₂(OH)₆ (jarosite), (H₃O)Fe₃(SO₄)₂ (OH)₆ (hydronium jarosite), KFe₃(CrO₄)₂ (OH)₆, Fe(OH)SO₄ (basic iron sulfate), and Fe(OH)CrO₄ (basic iron chromate) are reported. Fe(OH)CrO₄ and KFe₃(CrO₄)₂ (OH)₆ are shown to be weak ferro magnets with Curie temperatures of 73 and 71 °K, respectively. This unusual magnetic behavior is rationalized in terms of the ionic spin configurations of the phases. Exchange coupling through chromate bridging groups is shown to be weak.

II. The magnetic behavior and the influence of preparative history on the magnetic behavior of δFeO(OH) is reported. δFeO(OH) is shown to be a fine-particulate, uniaxial, magnetic species. Magnetization data for this species are shown to be consistent with the existence of magnetically inactive layers surrounding magnetic particles.

An organic-inorganic hybrid ultrathin film: preparation and characterization of copper phthalocyanine derivative-ferric oxide nanoparticles

A nanoparticulate ferric oxide-copper tris(2,4-di-tert-amylphenoxy)-8-quinolinolylphthalocyanine hybrid ultrathin film was constructed from alternate layers by the Langmuir-Blodgett technique. The composition, morphology and structure of the film were studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, atomic force microscopy, small-angle X-ray diffraction, visible spectroscopy and polarized UV-Vis spectroscopy. All the above analyses suggest that the thin film is a kind of one-dimensional superlattice, composed of organic and inorganic components. The XPS data reveal that the nanoparticulate ferric oxide exists as an alpha-Fe2O3 phase in the films. Gas-sensing measurements show that the hybrid LB film has very fast response-recovery characteristics towards 2 ppm C2H5OH vapor.

Alternating LB film of ferric oxide nanoparticles-copper phthalocyanine derivative and its gas sensitivity

Nanoparticulate ferric oxide - tris - (2,4-di-t-amylphenoxy) - (8-quinolinolyl) copper phthalocyanine Langmuir-Blodgett Z-type multilayers were obtained by using monodisperse nanoparticle ferric oxide hydrosol as the subphase. XPS data reveal that the nanoparticle ferric oxide exist as alpha -Fe2O3 phase in the films. Transition electron microscopic (TEM) image of the alternating monolayer shows that the film was highly covered by the copper phthalocyanine derivative and the nanoparticles were arranged rather closely. IR and visible spectra all give the results that the nanoparticles were deposited onto the substrate with the copper phthalocyanine derivative. The gas-sensing measurements show that the alternating LB film had very fast response-recovery characteristic to 2 ppm C2H5OH gas, and also sensitive to larger than 200 ppm NH3.

Study of ferric oxide nanoparticles-tris-(2,4-di-t-amylphenoxy)-(8-quinolinolyl) copper phthalocyanine composite LB film

The ferric oxide nanoparticles-tris-(2,4-di-t-amylphenoxy)-(8-quinolinolyl) copper phthalocyanine (CuPcA(2)) composite ultrathin film was obtained by LB (Langmuir-Blodgett) technique. Structure of the composite LB film was characterized by X-ray photoelectron spectra, transmission electron microscopy, infrared spectra and visible spectra. Gas sensitivity measurements indicate that the composite LB film is sensitive to 100-200 ppm C2H5OH at room temperature. (C) 2000 Elsevier Science S.A. All rights reserved.

Application of citrate-stabilized gold-coated ferric oxide composite nanoparticles for biological separations

Gold-coated magnetic nanoparticles were synthesized with size ranging from 15 to 40 nm using sodium citrates as the reducing agent. Oxidized magnetites (Fe3O4) fabricated by co-precipitation of Fe2+ and Fe3+ in strong alkaline solution were used as magnetic cores. The structures of gold (Au) shell and magnetic core (Au–Fe) were studied by transmission electron microscopy (TEM) image and energy dispersive spectroscopy (EDS) spectrum. Results from high-resolution X-ray diffraction (HR XRD) show that the Au–Fe oxide nanoparticles have a face-centered cubic shape with the crystalline faces of {1 1 1}. The Au-coated magnetic nanoparticles exhibited a surface plasmon resonance peak at 528 nm. The nanoparticles are well dispersed in distilled water. A 3000 G permanent magnet was successfully used for the separation of the functionalized nanoparticles. Magnetic properties of the nanoparticles were determined by magnetic force microscope (MFM) in nanometric resolution and vibrating sample magnetometer (VSM). Magnetic separation of biological molecules using Au-coated magnetic oxide composite nanoparticles was examined after attachment of protein immunoglobulin G (IgG) through electrostatic interactions. Using this method, separation was achieved with a maximum yield of 35% at an IgG concentration of 400 ng/ml.

Development of pure and doped gamma ferric oxide

Optimum conditions and experimental details for the formation of v-Fe203 from goethite have been worked out. In another method, a cheap complexing medium of starch was employed for precipitating acicular ferrous oxalate, which on decomposition in nitrogen and subsequent oxidation yielded acicular y-Fe203. On the basis of thermal decomposition in dry and moist nitrogen, DTA, XRD, GC and thermodynamic arguments, the mechanism of decomposition was elucidated. New materials obtained by doping ~'-Fe203 with 1-16 atomic percent magnesium, cobalt, nickel and copper, were synthesised and characterized

Thermodynamic study of Fe2O3 Fe2(SO4)3 equilibrium using an oxyanionic electrolyte (Na2SO4 I)

The emf of the cell, Pt, Ar + O2 + SO2 + SO3/Na2SO4-I/Fe2O2 + Fe2(SO4)3, Pt, has been measured in the temperature range 800 to 1000 K, using a gas mixture of known input composition as the reference electrode. The equilibrium composition of the reference gas at the measuring temperatures was computed using the thermodynamic data on the gaseous species reported in the literature. A mixture of ferric oxide and sulfate was kept in a closed system to ensure establishment of equilibrium partial pressure at the electrode. The cell was designed to avoid physical contact between Fe2(SO4)3 and Na2SO4 electrolyte. Uncertainties arising from the formation of sulfate solid solution were thus eliminated. The Gibbs’ energy of formation of ferric sulfate calculated from the emf is discussed in comparison with data reported in the literature. There is no evidence for the formation of oxysulfates in the Fe-S-0 system. Based on the results obtained in the present study for Fe2(SO4)3 and literature data for other phases, chemical potential diagrams have been constructed for the Fe-S-O system at 900 and 1100 K.

Dielectric Barrier Discharge Cascaded with Red Mud Waste to Enhance NOX Removal from Diesel Engine Exhaust

Red mud is a waste by-product generated during the processing of bauxite, the most common ore of aluminium. With the presence of ferric oxide, high surface area, resistance to poisoning and low cost, red mud made itself a good alternative to the existing commercial automobile catalyst. The cascading of dielectric barrier discharge plasma with red mud improved the NOX removal from diesel engine exhaust significantly. The DeNO(X) efficiency with discharge plasma was 74% and that with red mud was 31%. The efficiency increased to 92% when plasma was cascaded with red mud catalyst operating at a temperature of 400 degrees C. The NOX removal was dominated by NO2 removal. The studies were conducted at different temperatures and the results were discussed.

Gas sensitivity of composite Langmuir-Blodgett films of Fe2O3 nanoparticle-copper phthalocyanine

The Langmuir-Blodgett (LB) composite films, ferric oxide nanoparticle composite with tris-(2,3-di-t-amylphenoxy)-(8-quinolinolinolyl) copper phthalocyanine (CuPcA(2)), were obtained by capped type and alternated type and characterized by X-ray photoelectron spectroscopy (XPS) and visible spectra. The gas sensitivity of the composite films and the pure ferric oxide and pure CuPcA(2) LB films to ammonia and ethanol were measured at room temperature. The composite films could be used as the C2H5OH sensors in the range of 2-8 or 100-200 ppm. The XPS data suggested that the adduct complex NH3-CuPcA(2) was formed after the capped film was exposed to the detected gas of ammonia. (C) 2000 Elsevier Science B.V. All rights reserved.

Low cost synthesis of cathode and anode materials for lithium-ion batteries

Dans cette thèse, nous démontrons des travaux sur la synthèse à faible coût des matériaux de cathode et l'anode pour les piles lithium-ion. Pour les cathodes, nous avons utilisé des précurseurs à faible coût pour préparer LiFePO4 et LiFe0.3Mn0.7PO4 en utilisant une méthode hydrothermale. Tout d'abord, des matériaux composites (LiFePO4/C) ont été synthétisés à partir d'un précurseur de Fe2O3 par une procédé hydrothermique pour faire LiFePO4(OH) dans une première étape suivie d'une calcination rapide pour le revêtement de carbone. Deuxièmement, LiFePO4 avec une bonne cristallinité et une grande pureté a été synthétisé en une seule étape, avec Fe2O3 par voie hydrothermale. Troisièmement, LiFe0.3Mn0.7PO4 a été préparé en utilisant Fe2O3 et MnO comme des précurseurs de bas coûts au sein d'une méthode hydrothermale synthétique. Pour les matériaux d'anode, nous avons nos efforts concentré sur un matériau d'anode à faible coût α-Fe2O3 avec deux types de synthèse hydrothermales, une a base de micro-ondes (MAH) l’autre plus conventionnelles (CH). La nouveauté de cette thèse est que pour la première fois le LiFePO4 a été préparé par une méthode hydrothermale en utilisant un précurseur Fe3+ (Fe2O3). Le Fe2O3 est un précurseur à faible coût et en combinant ses coûts avec les conditions de synthèse à basse température nous avons réalisé une réduction considérable des coûts de production pour le LiFePO4, menant ainsi à une meilleure commercialisation du LiFePO4 comme matériaux de cathode dans les piles lithium-ion. Par cette méthode de préparation, le LiFePO4/C procure une capacité de décharge et une stabilité de cycle accrue par rapport une synthétisation par la méthode à l'état solide pour les mêmes précurseurs Les résultats sont résumés dans deux articles qui ont été récemment soumis dans des revues scientifiques.

Magnetic, Dielectric and Physicomechanical Properties of Rubber Ferrite Nanocomposites

In the present study the preparation and characterisation of rubber ferrite composites containing nickel ferrite and gamma ferric oxide have been dealt with.Synthetic rubbers viz. ethylene propylene diene rubber and neoprene rubber were used for the incorporation of nickel ferrite and gamma ferric oxide for the synthesis of RFCs. Incorporation of ferrites were carried out according to a specific recipe for various loadings of the magnetic fillers. The ferrites used for the preparation of RFCs were synthesised using sol-gel method and structural characterisation was carried out. Experimental techniques like X-ray diffraction, Transmission electron microscopy and other analytical techniques were used for this. Precharaterised ferrites were then incorporated at different loading into rubber according to conventional mixing methods. The cure characteristics, mechanical, dielectric, magnetic and microwave properties of these composites were evaluated. The effect of carbon black on these properties of RFCs were carried out.

A new inexpensive method for the preparation of acicular precursors for magnetic recording media

Magnetic materials meant for audio/video recording applications necessitate that polycrystalline materials be in acicular shape. So preparation of acicular precursors for magnetic storage materials assumes significance. The employment of aqueous solutions do not produce needle shape crystallites. Glycerol is one of the complexing media used for the precipitation of ferrous oxalate dihydrate. An inexpensive method using starch for preparation of acicular particles is described. The influence of an additive namely Gd on acicularity is also investigated

Níveis de prebiótico em substituição ao antibiótico em dietas para leitões recém - desmamados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)