Presence Of Hematite Research Articles

Hematite facet confined ferrous ions as high efficient Fenton catalysts to degrade organic contaminants by lowering H2O2 decomposition energetic span

In this study, we demonstrate that ferrous ions confined on the hematite facets can significantly promote the H2O2 decomposition to produce •OH for more efficient organic contaminants degradation than the unconfined counterparts, while hematite nanorods with exposed {001} and {110} facets exhibit better confining effect than nanoplates with exposed {001} facets. Experimental results revealed that the H2O2 decomposition efficiency of hematite facet confined ferrous ions was affected by the amount of surface confined ferrous ions, and also governed by the binding mode of ferrous ions on the hematite facets. We interestingly found that the polar {110} facets could confine ferrous ions of higher density with a five-coordination binding mode and thus lower the H2O2 decomposition energetic span more efficiently than the nonpolar {001} facets, which confined ferrous ions with a six-coordination binding mode. The specific surface area normalized •OH formation rate constants were, respectively, 5.50×10−3 and 1.04×10−2s−1 for hematite nanoplates and nanorods confined ferrous ions, which were 1.2 and 2.2 times that (4.75×10−3s−1) of the unconfined counterpart. Moreover, rhodamine B could be efficiently degraded in the presence of hematite (0.4gL−1), Fe2+ (5.0×10−5molL−1) and H2O2 (5.0×10−5molL−1) at pH 4.7, along with 23.6% and 72.5% of H2O2 consumption efficiencies for hematite nanoplates and nanorods, respectively. Meanwhile, 6.6% and 11.8% of nitrogen in rhodamine B were converted to NO3− in the hematite nanoplates and nanorods confined ferrous ions Fenton systems, respectively. It was found that N-deethylation, destruction of chromophores, opening-ring and mineralization occurred during the confined ferrous Fenton rhodamine B oxidation process. This study can deepen our understanding on the enhanced reactivity of ferrous ions bound on the surface of iron oxides, and also shed light on the design of high efficient heterogeneous Fenton catalysts.

Iron-containing pigment from an archaeological rupestrian painting of the Planalto Tradition in Minas Gerais, Brazil

Archaeological rupestrian arts of the Planalto Tradition are of relatively widespread occurrence all over the land area of the state of Minas Gerais (MG), Brazil. They are typically composed by monochromic zoomorphic figures, especially of cervids, mainly in red or orange color. A fragment of a rock wall containing an archaeological painting was collected at the Itangua site, in the municipality of Senador Modestino Goncalves (geographical coordinates, 17° 56′ 51″ S 43° 13′ 22″ W), MG. The rock piece was covered with an archaeological painting with pigments of two different hues of red. The X-ray fluorescence (XRF) analysis revealed only a slight difference in Fe and P content for the two different color zones. The pigment materials on this small fragment of rock were analyzed by X-ray diffraction on the conventional incidence mode (XRD) and on grazing incidence X-ray mode (GIXRD), scanning electron microscopy with energy dispersive x-ray detector (SEM/EDS) and conversion electron Mossbauer spectroscopy (CEMS) at room temperature. Results indicated the occurrence of mainly hematite but also of diopside in the pigment. CEMS at RT reveal the presence of hematite and (super)paramagnetic ferric components. In order to confirm these results a small amount of powder from the painting pigments was also analyzed by transmission Mossbauer spectroscopy at 20 K.

Conductive iron oxide minerals accelerate syntrophic cooperation in methanogenic benzoate degradation

Recent studies have suggested that conductive iron oxide minerals can facilitate syntrophic metabolism of the methanogenic degradation of organic matter, such as ethanol, propionate and butyrate, in natural and engineered microbial ecosystems. This enhanced syntrophy involves direct interspecies electron transfer (DIET) powered by microorganisms exchanging metabolic electrons through electrically conductive minerals. Here, we evaluated the possibility that conductive iron oxides (hematite and magnetite) can stimulate the methanogenic degradation of benzoate, which is a common intermediate in the anaerobic metabolism of aromatic compounds. The results showed that 89–94% of the electrons released from benzoate oxidation were recovered in CH4 production, and acetate was identified as the only carbon-bearing intermediate during benzoate degradation. Compared with the iron-free controls, the rates of methanogenic benzoate degradation were enhanced by 25% and 53% in the presence of hematite and magnetite, respectively. This stimulatory effect probably resulted from DIET-mediated methanogenesis in which electrons transfer between syntrophic partners via conductive iron minerals. Phylogenetic analyses revealed that Bacillaceae, Peptococcaceae, and Methanobacterium are potentially involved in the functioning of syntrophic DIET. Considering the ubiquitous presence of iron minerals within soils and sediments, the findings of this study will increase the current understanding of the natural biological attenuation of aromatic hydrocarbons in anaerobic environments.

Downhole Upgrading of Orinoco Basin Extra-Heavy Crude Oil Using Hydrogen Donors under Steam Injection Conditions. Effect of the Presence of Iron Nanocatalysts

An extra-heavy crude oil underground upgrading concept and laboratory experiments are presented which involve the addition of a hydrogen donor (tetralin) to an Orinoco Basin extra-heavy crude oil under steam injection conditions (280–315 °C and residence times of at least 24-h). Three iron-containing nanocatalysts (20 nm, 60 nm and 90 nm) were used and the results showed increases of up to 8° in API gravity, 26% desulfurization and 27% reduction in the asphaltene content of the upgraded product in comparison to the control reaction using inert sand. The iron nanocatalysts were characterized by SEM, XPS, EDAX, and Mössbauer spectroscopy before and after the upgrading reactions. The results indicated the presence of hematite (Fe2O3) as the predominant iron phase. The data showed that the catalysts were deactivating by particle sintering (~20% increase in particle size) and also by carbon deposition. Probable mechanisms of reactions are proposed.

A study on initiation of ash agglomeration in fluidized bed gasification systems

Agglomeration in fluidized beds begins locally by the sticking of slag–liquid-covered particles. Analysis of the composite fuel is not adequate in predicting agglomeration problems. Separation of the high rank Pittsburgh seam coal into particle classes based on specific gravity (SG1: <1.3g/cm3; SG2: 1.3–1.6g/cm3; SG3: 1.6–2.6g/cm3 and SG4: >2.6g/cm3) and particle size (PS1 through PS7) helped to identify important particle-level slag–liquid formation tendencies. Slag–liquid formation tendencies under fluidized bed operating temperatures were determined both computationally and experimentally. Particles rich in certain iron and calcium phases melt at very low temperatures that are well within fluidized bed operating conditions. The iron rich particle classes (SG3 and SG4) showed the presence of several phases containing iron in different oxidation states. The presence of these iron phases was not detected in the composite bulk fuel. The possibilities of equilibrium liquid phase formation in the presence of different ratios of these iron and calcium oxides to alumino-silicates were determined. Presence of hematite was found to delay slag–liquid formation. Each of the particle classes showed distinct slag–liquid formation tendencies that indicate initiation of agglomeration around SG3 and SG4 particles. The study revealed the importance of particle class-level differences in mineral matter composition for the prediction of agglomeration during fluidized bed gasification.A novel integrated ash agglomeration model that accounts for particle hydrodynamics as well as particle class level ash chemistry has been outlined to predict agglomeration kinetics.

Primary hematite in Neoarchean to Paleoproterozoic oceans

Banded iron formations (BIFs) are ironand silica-rich chemical sedimentary rocks formed throughout the Archean and Paleoproterozoic Eras. The presence of hematite (Fe2O3) and magnetite (Fe3O4) in BIFs has led to the widespread assumption that Fe(II) oxidation must have occurred in the ancient oceans via either a biological or chemical mechanism. However, it is unclear whether the ferric iron now present in BIF represents the original ferric oxyhydroxide [e.g., ferrihydrite, Fe(OH)3] precipitated in the water column, or if it is the result of later-stage circulation of oxidizing fl uids through the sediment pile. In this study, we conducted high-resolution microscopic investigations on BIF from the 2728 Ma Abitibi greenstone belt located in the Superior Province of the Canadian Shield and the 2460 Ma Kuruman Iron Formation in South Africa to ascertain the timing and paragenesis of the hematite. Three types of hematite are identifi ed by high-resolution electron microscopic characterization and selected area electron diffraction: (1) 3–5 nm ultrafi ne hematite particles in the iron oxide–rich bands (H1); (2) submicrometer subhedral to euhedral hema tite crystals randomly distributed in the chert matrix of transitional zones between iron oxide– and chert-rich bands (H2); and (3) needle-like, radial and fi brous hematite that replaced stilpnomelane or carbonates and is distributed along fractures or layer boundaries (H3). We interpret the fi rst two types as primary minerals dehydrated from precursor ferric oxyhydroxides. H1 remains ultrafi ne in size, while H2 has undergone an Ostwald coarsening process facilitated by internal fl uids produced during amorphous silica to quartz transformation. H3 is a later-stage mineral formed by external fl uid-mediated replacement of iron silicates or carbonates. These results indicate that a signifi cant fraction of the hematite in the BIF originated from ferric oxyhydroxide precursors. Importantly, this implies that photosynthetic Fe(II) oxidation, by either a direct or indirect biological mechanism, did exist in seawaters from which some BIF material was deposited.

Mössbauer spectroscopy studies of the magnetic properties of ferrite nanoparticles

Studies of the ferrite nanoparticles prepared by the chemical decomposition of iron chlorides with a various ratio ξ = Fe3+/Fe2+ are herein presented. The microstructure and the magnetic properties have been studied by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Mössbauer spectroscopy (MS). The TEM studies show that the nanoparticles have almost a spherical shape with the diameter of (12 ± 2) nm for all samples. The measured XRD pattern was mainly composed of lines which were indexed with a cubic spinel structure. The analysis of the Mössbauer data shows that the microstructure of the nanoparticles consists of the core formed by nonstoichiometric magnetite and maghemite shell. A small amount of hematite, probably on the surface of the nanoparticles with ξ = 1.75, 2.0, was detected. At temperatures T ≤ 150 K the spin canting of surface maghemite with ξ = 2.25 was observed while for the samples with ξ = 1.75, 2.0 such effect was suppressed by the presence of hematite on the surface of the nanoparticles. Infield Mössbauer spectra with ξ = 1.75, 2.0 show that magnetic moments of the magnetite/maghemite core are parallel while magnetic moments of the surface hematite are perpendicular to the direction of the external magnetic field.

Influence of surface mechanical attrition treatment on the oxidation behavior of 316L stainless steel at 750°C

In this paper, the effects of Surface Mechanical Attrition Treatment on the high- temperature oxidation of AISI 316L austenitic stainless steel are investigated. Samples treated with different conditions were oxidized at 750°C in order to study the effect of this type of nanocrystallisation on the oxidation resistance of the alloy concerned. X-ray diffraction and in- situ Raman spectroscopy were used to identify the oxides formed at the surface. The results indicate the presence of hematite, magnetite and chromium oxides. Experimental results obtained by Raman spectroscopy were also used to study the stress evolution in Cr2O3 films during isothermal conditions.

Influence of Surface Mechanical Attrition Treatment (SMAT) on Oxidation Behavior of 316L Stainless Steel at 650°C

In this paper, the effects of Surface Mechanical Attrition Treatment on the high-temperature oxidation of AISI 316L austenitic stainless steel are investigated. Samples treated with different conditions were oxidized at 650°C in order to study the effect of this type of nanocrystallisation on the oxidation resistance of the alloy concerned. X-ray diffraction and in-situ Raman spectroscopy were used to identify the oxides formed at the surface. The results indicate the presence of hematite and chromium oxides. Experimental results obtained by Raman spectroscopy were also used to study the stress evolution in Cr2O3films during isothermal conditions.

Hematite-bearing materials surrounding Candor Mensa in Candor Chasma, Mars: Implications for hematite origin and post-emplacement modification

The Valles Marineris canyon system on Mars is of enduring scientific interest in part due to the presence of interior mounds that contain extensive layering and water-altered minerals, such as crystalline gray hematite and hydrated sulfates. The presence of hematite and hydrated sulfate minerals is important because their host rock lithologies provide information about past environments that may have supported liquid water and may have been habitable. This work further defines the association and relationship between hematite-bearing materials and low albedo (presumably aeolian) deposits and layered materials, identifies physical characteristics that are strongly correlated with the presence of hematite, and refines hypotheses for the origin and post-emplacement modification (including transport) of these hematite-bearing and associated materials. There are only three regions surrounding Candor Mensa where hematite has been identified, even though morphologic properties are similar throughout the entire mensa. Three possible explanations for why hematite is only exposed in these regions include: (1) the topographic structure of the mensa walls concentrates hematite at the base of the layered deposits, influencing the ability to detect hematite from orbit; (2) the presence of differing amounts of “dark mantling material” and hematite-free erosional sediment; (3) the potential fracturing of the mensa and the influence of these structures on fluid flow and subsequent digenesis. The observations of hematite-bearing materials in this work support the hypothesis that hematite is eroding from a unit in the Candor Mensa interior layered deposits (ILD) and is being concentrated as a lag deposit adjacent to the lower layers of Candor Mensa and at the base in the form of dark aeolian material. Due to the similar geologic context associated with hematite-bearing and ILD materials throughout the Valles Marineris canyon system, the insight gained from studying these materials surrounding Candor Mensa can likely be applicable to similar layered deposits throughout Valles Marineris.

Isotope Geochemistry of the Northeast Zone, Mount Polley Alkalic Cu-Au-Ag Porphyry Deposit, British Columbia: A Case for Carbonate Assimilation

Mount Polley is a Late Triassic (~205 Ma) alkalic porphyry Cu-Au-Ag deposit (226.3 thousand tonnes (t) Cu, 21.5 t Au, and 65.1 t Ag), hosted by silica-undersaturated to silica-saturated monzonitic intrusions of the Mount Polley Complex, located in British Columbia, Canada. The Northeast ore zone at Mount Polley is hosted by magmatic-hydrothermal breccia. Copper and precious metals occur in sulfide minerals primarily as coarse- to fine-grained breccia cement. Local wall rocks include equigranular to porphyritic diorite, monzodiorite, and monzonite. Alteration, breccia cement, and veins of the Northeast ore zone formed in five paragenetic stages: prebreccia (stage 1), brecciation and main-stage mineralization (stage 2), late-stage mineralization (stage 3), unmineralized postbreccia dikes and veins (stage 4), and epithermal-style veins (stage 5). Intense pervasive K and Fe metasomatism ± calcite and calc-silicate alteration occurred prior to brecciation caused by the intrusion of megacrystic K-feldspar-phyric monzonite. Stage 2 fluids were silica undersaturated, high temperature (>350°C), CO2 enriched, and of near-neutral to alkaline pH. Potassic, sodic, and calc-potassic assemblages precipitated with mineralization during stage 2 with moderate temperatures at the deposit periphery and in stages 3 and 4. Evidence for more acidic and lower-temperature conditions is preserved in stage 5 veins. The δ 34Ssulfide isotope compositions of stages 2 and 3 chalcopyrite, pyrite, and bornite range from −7.1 to +1.4‰. Sulfur isotope compositions of anhydrite and gypsum are mostly between 6.2 and 9.8‰. These values, together with the presence of hematite, are consistent with deposition from an oxidized, sulfate-dominant, high-temperature magmatic-hydrothermal fluid. Limited sulfur isotope geothermometry indicates that Cu sulfides precipitated at temperatures from ~480° to ~250°C. Hydrothermal calcite occurs in all paragenetic stages at Mount Polley. Calcite δ 13C values range from −0.2 to −10.5‰, and δ 18O values from 4.0 to 20.9‰. The enriched C-O isotope values are not consistent with simple precipitation from an entirely magmatic source of hydrothermal fluid. Interaction of the fluid and/or magma with limestone is considered a likely process to explain the C and O isotope signature. Lead isotope data suggest mixing of mantle and crustal sources during mineralization. Main-stage chalcopyrite and pyrite as well as late-stage galena have 206/204Pb values of 18.77 to 18.92, 207/204Pb of 15.56 to 15.59, and 208/204Pb of 38.22 to 38.32. Strontium isotope data (0.70331–0.70371) provide evidence of a strongly depleted mantle source of Sr with minor crustal input. Epsilon Nd values for main-stage apatite range between 5.9 and 6.5, also indicating a depleted mantle source. Stage 5 carbonate 206/204Pb values of 18.96 to 19.04, 207/204Pb of 15.57 to 15.59, and 208/204Pb of 38.26 to 38.36 suggest superposition of an epithermal system onto the Northeast ore zone, potentially as late as ~100 m.y. after breccia formation. The data presented are consistent with the hypothesis that the silica-undersaturated alkalic Mount Polley Complex formed due to carbonate assimilation prior to mineralization. This process can explain the δ 13C- δ 18O isotope data, calcite precipitation concurrent with Cu-Au mineralization, and silica undersaturation of the magma. The CO2 released during assimilation of carbonate also could have promoted magmatic-hydrothermal brecciation. Silica-undersaturated alkalic porphyry systems may preferentially form in arc terranes built on a carbonate-bearing substrate.

Solid solution between potassic alkali amphiboles from the silica-rich Kvaløya lamproite, West Troms Basement Complex, northern Norway

Alkali amphibole of rare compositions occurs as a rock-forming mineral in a high-Si phlogopite lamproite from Kvaloya, northern Norway. The amphibole typically occurs as small grains forming irregular and rosette-shaped aggregates in a matrix dominated by Fe-rich K-feldspar and quartz. Amphibole shows compositions ranging between the three limiting compositions: A : A,B ( K 1.01 Na 1.99 ) C ( Na 0.26 Mg 1.58 Mn 0.03 Fe 2 + 0.91 Fe 3 + 1.6 Ti 0.47 □ 0.13 ) T Si 8 O 22 W [ F 0.97 O 1.03 ] B : A,B ( KNa 2 ) C ( Na 0.04 Mg 1.04 Mn 0.22 Fe 2 + 0.65 Fe 3 + 2.07 Ti 0.25 □ 0.7 ) T Si 8 O 22 W [ F 0.68 Cl 0.01 O 0.13 ( OH ) 1.18 ] C : A,B ( K 0.9 Na 2.1 ) C ( Na 0.04 Mg 3.54 Mn 0.02 Fe 2 + 0.28 Fe 3 + 1.04 Ti 0.03 □ 0.02 ) T Si 8 O 22 W [ F 1.34 O 0.06 ( OH ) 0.6 ] Composition C shows significant content of fluoro-potassic-magnesio-arfvedsonite, while composition A is a Fe 2+ , Fe 3+ and C Na rich variety of potassic-obertiite. Composition B is characterized by an exceptional high value of C □. It is emphasized that the presence of C □ and C Na in amphibole needs to be confirmed by other methods. The relationship between W O 2− , C □,Ti 4+ and Fe 3+ of amphibole can be expressed by the following exchange operators, choosing potassic-magnesio-arfvedsonite [KNa 2 (Mg 4 Fe 3+ )Si 8 O 22 (OH) 2 ] as the additive component: Ti 4 + Mg 2 + − 1 H + − 2 Fe 3 + Mg 2 + − 1 H + − 1 Ti 4 + □ Mg 2 + − 2 Fe 3 + 2 □ Mg 2 + − 3 The two first exchange operators result in deprotonation of OH, while the two others result in the formation of vacancies on the C sites. The presence of amphibole both in the lamproite and in the adjacent fenitized granite suggests that the mineral formed during reactions between rock and fluids derived from the volatile-rich lamproite magma. Possibly, amphibole core (composition A and B), formed in equilibrium with the fluid phase during crystallization of the melt, while amphibole rim (composition C) formed during subsequent mineral-fluid reactions. Presence of hematite in the lamproite matrix in addition to oxo-amphibole indicates that the rock formed during highly oxidizing conditions.

Tribological and tribochemical properties of magnetite nanoflakes as additives in oil lubricants

This detailed the tribological and tribochemical properties of magnetite (Fe3O4) nanoflakes used as additives in #40 base oil in a four-ball tribo-tester. The average friction coefficient of the friction pair for lubricant containing the Fe3O4 nanoflakes of 1.5wt% as a lubricant additive in the base oil is decreased by 18.06% compared to that of solely base oil. The chemical composition of base oil with the Fe3O4 nanoflake additives did not change during the 48-h friction assessment. The decreased saturation magnetization and increased coercivity of magnetite nanoflakes occurred due to the distortion of the basal planes and the presence of hematite (α-Fe2O3) generated by the tribochemical reactions during the friction process. The multi-layer low-shear-stress tribochemical lubrication films on the surface of the friction pair could form because the nanoflake particles arrange and adhere onto the surface of the friction pair in an orderly manner, and the tribochemical reactions of the friction pair in the presence of the nanoflakes occur as Fe→FeO→Fe3O4→γ-FeOOH→γ-Fe2O3→α-Fe2O3. The formation of the films can improve the tribological properties.

Flocculation behaviour of hematite–kaolinite suspensions in presence of extracellular bacterial proteins and polysaccharides

Cells of Bacillus subtilis exhibited higher affinity towards hematite than to kaolinite. Bacterial cells were grown and adapted in the presence of hematite and kaolinite. Higher amounts of mineral-specific proteinaceous compounds were secreted in the presence of kaolinite while hematite-grown cells produced higher amounts of exopolysaccharides. Extracellular proteins (EP) exhibited higher adsorption density on kaolinite which was rendered more hydrophobic. Hematite surfaces were rendered more hydrophilic due to increased adsorption of extracellular polysaccharides (ECP). Significant surface chemical changes were produced due to interaction between minerals and extracellular proteins and polysaccharides. Iron oxides such as hematite could be effectively removed from kaolinite clays using selective bioflocculation of hematite after interaction with EP and ECP extracted from mineral-grown cells.

Heterogeneous reduction of 239PuO2 by aqueous Fe(II) in the presence of hematite

Abstract The reduction of PuO2(am) by Fe(II) in the presence and absence of hematite was studied over a range of pH values and oxidation/reduction potentials. In contrast to thermodynamic predictions, the presence of hematite did not have a major effect on the overall reduction of PuO2(am) to aqueous Pu(III). Instead the aqueous Pu(III) concentrations at longer time frames were accurately predicted using the measured Fe(II) concentration and existing thermodynamic data for the reaction: H2O + H++ Fe2++ PuO2(am) ⇌ Pu3++ Fe(OH)3(am) with log K =− 0.6. The accuracy of this approach in all solutions containing aqueous Fe(II), coupled with the apparent lack of oxidation of Fe(II) by O2(g), suggests that the Fe(OH)3(am) is formed by the oxidation of Fe(II) to Fe(III) by radiolysis. The continued generation of reactive amorphous iron hydroxide by radiolysis prevents thermodynamic equilibrium from being reached with more stable ferric oxide compounds, except possibly under acidic conditions where amorphous ferric hydroxide is soluble. The use of measured pe values, instead of aqueous Fe(II) measurements, also yields reasonable predictions of the final Pu(III) concentrations although the predictions are more uncertain.

Magnetization of three Nubia Sandstone formations from Central Western Desert of Egypt

A total of 198 oriented cores (from 16 sites) have been sampled from three Cretaceous Nubia sandstone formations distributed around the Kharga–Dakhla and Dakhla–Uwainat roads in the Western Desert for paleomagnetic studies. Two of these formations are of the Early Cretaceous (the Six Hills, Abu Ballas formations) and the third one is of the Late Cretaceous (Maghrabi formation). The studied rocks are subjected to rock magnetic measurements as well as demagnetization treatment.Rock magnetic experiments reveal that the presence of hematite is the main magnetic mineral in the three formations. Therefore, present study relies mostly on thermal demagnetization.Two magnetic components have been isolated from the studied rocks. The first component has been isolated from the Six Hills and Abu Ballas formations and is carried by hematite with D=347.1°, I=41.6° with α95=7.8° and the corresponding pole lies at lat.=78.2° N and long.=294.1° E. The second component has been isolated from the Maghrabi formation and is carried also by hematite with D=22.7°, I=28.4° with α95=9.9° and pole position lies at lat.=66.3° N and long.=140.6° E.The first magnetic component obtained from the two older formations is considered primary, as the corresponding pole reflects the age when compared with the previously obtained Cretaceous poles for North Africa. On other hand, the second pole obtained from the Maghrabi formation (the younger) is inconsistent with the Cretaceous pole positions for North Africa, but falls closer to the Eocene pole indicating that the rocks of this formation could have suffered remagnetization during the late Eocene time.

LiFe5O8 prepared by sol–gel synthesis: microstructural and morphological effects by organic and inorganic templates

Lithium ferrite was prepared using a sol–gel growth process using different fuels and inorganic templates. The aim of this study is to evaluate the influence of inorganic template agent like KCl, KBr and KI as well as the effect of different fuels like urea, glycine and citric acid on the morphology change of lithium ferrite. The structure, morphology and magnetic properties of the ferrite were investigated using powder X-ray diffraction (XRD), Infrared red spectroscopy and vibrating sample magnetometer. Thermal decomposition studies reveal the formation of lithium ferrite at a low temperature ~440 °C. Powder XRD pattern has shown the formation of a single α-phase lithium ferrite except the sample with inorganic template KBr, in which the presence of hematite as a secondary phase was observed. Scanning electron microscopy studies show that the structural morphology is highly sensitive to the inorganic template as well as on the fuel. The rod shaped nanoparticles are observed with the inorganic template KCl and KBr. The decrease in grain size is observed for LiFe5O8/glycine as compared to LiFe5O8/citric acid and flake shaped dense particles are observed for LiFe5O8/urea. The magnetic properties of the ferrite have also been investigated.

Fe2O3 particles enwrapped by graphene with excellent cyclability and rate capability as anode materials for lithium ion batteries

A facile hydrothermal method is employed to prepare Fe2O3/graphene composites with different contents of graphene which is determined by thermogravimetric analysis (TG). While the X-ray diffraction (XRD) indicates the presence of hematite, the graphene and Fe2O3 are demonstrated to be existed via Fourier transform infrared spectra (FI-IR) and Raman spectroscopic analysis. Furthermore, the scanning electron microscopy (SEM) and transmission electron microscope (TEM) also illustrate the good combination of graphene and Fe2O3, especially for the composite with graphene mass content of 30%. After performed as anode for lithium ion battery, Fe2O3/graphene composite with graphene mass content of 30% exhibits outstanding cyclability with highly reversible charge capacity of 1069mAhg−1 after 50 cycles, at current density of 50mAg−1. And when the current density is increased to 1000mAg−1, it could still retain charge capacity of 534mAhg−1. Meanwhile, the critical role of graphene to the electrochemical performance of composites has also been proven.

Biobeneficiation of Iron Ores

Utilization of aerobic and anaerobic microorganisms in iron ore beneficiation is discussed. Microorganisms such as Paenibacillus polymyxa, Bacillus subtilis, Saccharomyces cerevisiae (yeast) and Desulfovibrio desulfuricans (SRB) are capable of significantly altering the surface chemical behavior of iron ore minerals such as hematite, corundum, calcite, quartz and apatite. Differing mineral surface affinities of microbial cells and metabolic products such as proteins and polysaccharides can be utilized to induce their flotation or flocculation. Mineral-specific bioreagents such as proteins are generated when bacteria and yeast were grown in the presence of hematite, corundum, calcite, quartz and apatite. This study has demonstrated the utility and amenability of microbially-induced mineral beneficiation of iron ores through bacterial and yeast cells and their metabolic byproducts.

Synthesis of Inorganic Pigments from Glass-Ceramics of System Li&lt;sub&gt;2&lt;/sub&gt;O-ZrO&lt;sub&gt;2&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; and Waste from Metallurgical Industry

In the ceramic coating industry, color and its stability influence the visual appearance of the product. These features account for the growing interest in obtaining pigments that are stable and may optimize the process. There are different synthesis routes to obtain pigments. Obtaining glass and its subsequent crystallization is an alternative proposed in the literature. This study focuses on the possible use the glass of the Li2O-ZrO2-SiO2 system as base glass and hematite as chromophore source. Different contents of hematite (1%, 2%, 3%), from the beneficiation process of metal sheets were used. The choice of composition aimed at facilitating the devitrification process for the formation of zirconia, which is often used as an encapsulating matrix in inorganic pigments. Results showed that glass synthesis is feasible and the effect of crystallization in the presence of hematite is favored, so an effective pigmenting effect is expected.