Fe Nitrates Research Articles

A simple route to synthesize nickel ferrite (NiFe 2O 4) nanoparticles using egg white

NiFe2O4 nanoparticles were synthesized by a simple and cost-effective method using Ni and Fe nitrates and freshly extracted egg white (ovalbumin) in an aqueous medium. The X-ray diffraction and selected-area electron diffraction results indicated that the synthesized nanoparticles have only the inverse spinel structure without the presence of any other phase impurities. Room temperature magnetization results showed a ferromagnetic behavior of the NiFe2O4 nanoparticles, with saturation-specific magnetization values in the range of 26.4–42.5 emu/g at 10 kOe.

Pyrolysis of metal impregnated biomass: An innovative catalytic way to produce gas fuel

An innovative way of catalysis was investigated for its potential to reduce the amount of condensable hydrocarbons produced during the pyrolysis of oak wood. The experiments were carried out in a horizontal tubular reactor, fed with a controlled flow rate of nitrogen and equipped with accessories to collect char, liquid and gaseous products. Pyrolysis was performed at 700 °C with different wood sample series impregnated with either Ni or Fe nitrates (in aqueous solution) and by varying the metal concentration in the wood. In the blank run the biomass was acid-washed to determine the impact of demineralization. The influence of the metal type and content introduced into the wood to reduce the fraction of condensable organic compounds produced during pyrolysis was determined. Depending on the experimental conditions, the gas yield increases from 20.0 to 33.1%. Condensable hydrocarbons are cracked into gaseous components and the concentration of H 2 is significantly increased, by 260% compared to the reference sample. In particular, the Ni-loaded wood samples give much higher H 2 yields than the Fe-loaded ones under similar conditions but less toxic products are formed with the latter. These results show that biomass impregnation with either nickel or iron salts is a promising way to reduce the fraction of condensable organic compounds produced during pyrolysis.

Catalytic properties of stoichiometric and non-stoichiometric LaFeO 3 perovskite for total oxidation of methane

Perovskite LaFeO 3 and derived materials La (1− ϵ) FeO (3−1.5 ϵ) with ϵ=0.1, 0.2, 0.3 have been prepared as polycrystalline powders by thermal low-temperature decomposition of La and Fe nitrates, a method which ensures a high surface area. They have been used in catalytic methane combustion in the range 300–450 °C, showing a 100% selectivity to carbon dioxide. The reaction is indeed characterised by two ranges with different dependence of the reaction rate on temperature, as shown by the Arrhenius plot, whose slope decreases markedly above about 375 °C. Temperature programmed desorption experiments of oxygen allowed us to ascertain the presence of two surface oxygen species, whose desorption occurs, respectively before and after the above indicated temperature on this basis, we propose here an hypothesis on the way of working of the catalysts. The characterisation of the catalysts has been then completed by means of temperature programmed reduction, whose results contribute to strengthen the hypothesis that the catalyst reduction operated by methane involves a smaller number of lattice planes than reduction of hydrogen.

Synthesis and characterization of non-stoichiometric LaFeO 3 perovskite

La (1− ε) FeO (3−1.5 ε) perovskite catalysts ( ε=0, 0.1, 0.2, 0.3) are synthetized by low-temperature thermal decomposition of La and Fe nitrates and further heating to 873 K in air. They are characterized by DTA, XRD, BET, SEM, Mössbauer spectroscopy and tested for the catalytic combustion of methane. All oxides are monophasic; for ε=0 the structure is orthorhombic, whereas for 0< ε≤0.3 a pseudocubic symmetry is evident. The Mössbauer spectra are characterized by antiferromagnetic sextuplets; for ε=0.3 a doublet is also present. The catalytic activity toward CH 4 oxidation appears to be strongly enhanced in the samples with ε>0; the most active composition corresponds to ε=0.1, while for ε=0.2 and 0.3 the catalytic activity is slightly decreased. The results are explained assuming that the excess of iron oxide in the ε>0 samples corresponds to the presence of surface of layers of FeO 5 polyhedra, coordinatively unsaturated, according to proposed structural model.

Extraction of Americium(III) from Nitric Acid Solutions with Neat Diphenyl(dibutylcarbamoylmethyl)phosphine Oxide in the Presence of Metal Salts

Extraction of Am(III) from nitric acid solutions with a liquid complex of diphenyl(dibutylcarbamoylmethyl)phosphine oxide (Ph2Bu2) with nitric acid as influenced by concentration of Al, Ca, Na, Ni, Co, Cr, Fe, Zr, and Mo nitrates was studied. Nonextractable (Al, Ca, Na) and poorly extractable (Ni, Co, Cr) nitrates at their widely varied concentration do not interfere with the exhaustive extraction of americium from 3 M HNO3. These salts facilitate both formation of the extraction-active liquid phase on contact of Ph2Bu2 with 1 M HNO3 and exhaustive extraction of americium from the acid. Extraction of Fe(III) at its widely varied concentration insignificantly interferes with extraction of americium, but this effect increases with increasing acidity and phase contact time. Americium is extracted with a powdered reagent from 0.1 M HNO3 when liquid extractant is not formed in the visible amounts. In extraction of americium from weakly acidic solutions in the presence of salts the solid reagent, apparently, partially transforms into the liquid extractant, and two different extraction mechanisms are operative. It was shown that the neat liquid complex of Ph2Bu2 with HNO3 can be used for exhaustive extraction of americium from high-level saline wastes from plants for processing nuclear fuel.

Point of Use HF Purification for Silicon Surface Preparation by Ion Exchange

The point of use (POU) HF purification performance of an ion exchange membrane (IEM) is evaluated in this paper. First, no cationic extractable (i.e., Cu, Fe, and Ni) from two IEMs was detected in HF 0.5% which makes these membranes compatible with sub‐ppb grade HF. The IEM purification performance was evaluated with 0.5% HF spiked with 10 ppb of Fe, Ni, and Cu nitrates. The results show that after less than five turnovers through an IEM, the impurity concentration drops below 1 ppb. The decrease rate can be fitted to a model assuming the experimental tanks to be continuously stirred tank reactors and that the impurity concentration after the membrane is a function of the single‐pass purification efficiency of the IEM, the concentration before purification, and the metals desorbed from the IEM. The concentration after purification was investigated up to a cumulative Fe loading of 300 ppb in the 23 liter recirculated loop. It increases linearly vs. cumulative loading and can be explained by the Langmuir theory resulting in a purification efficiency at the equilibrium of close to 99.5% in this loading regime. This suggests that the capacity of the membrane is high enough to ensure an adequate lifetime. Finally, a POU IEM can reduce the Cu concentration in the bath resulting in less Cu outplating. No impact was noticed on particle and organic deposition, on surface roughness, and on 5 nm gate oxide integrity.

Magnetic viscosity and microstructure: Particle size dependence of the activation volume

Ba hexaferrite samples having average particle sizes in the range from the tens up to the thousands of nm have been prepared by using conventional ceramic techniques and the exothermic reaction between Ba and Fe nitrates and oxalic dihydrized acid. The magnetic characterization of these samples included the measurement of the temperature dependence of the high field magnetization, the coercive force, and the evaluation, from thermally activated demagnetization measurements, of the activation volume at different temperatures. From the results of this characterization it was possible to reach conclusions about the occurrence of remarkable differences between the average particle size dependence of the coercive force and that corresponding to the activation volume: whereas the coercive force value increased monotonically with the decrease of the particle size, an activation volume minimum was observed for particle diameters of the order of hundreds of nm. We suggest that this minimum reflects a change of the mechanism ruling the magnetization reversal of the particles forming our samples.

Preparation of NiFe2O4 powder by spray pyrolysis of nitrate aerosols in NH3

To avoid the formation of hollow spheres during spray pyrolysis, NH3 was employed to change the mechanism of forming NiFe2O4 from aerosols, containing Ni(II) and Fe(III) nitrates in the required stoichiometric ratio. Nearly spherical, solid submicron NiFe2O4 particles with narrow size distribution were produced in one step using a dilute aqueous solution at pyrolysis temperatures as low as 823 K. However, higher pyrolysis temperatures (≥1023 K) reduced the oxides to metallic alloy of Ni and Fe due to dissociation of NH3. The forming steps and possible reaction mechanisms for aerosol droplets involved in the process were discussed.

Preparation of fine, hollow, spherical NiFe2O4 powders

Aerosol droplets of a dilute aqueous solution of Ni(II) and Fe(III) nitrates were used to synthesize fine nickel ferrite powders by pyrolysis at temperatures ranging from 450 °C to 810 °C. The aerosol product was characterized by thermal analysis, x-ray diffraction, scanning electron microscopy, and BET surface area determination. At low temperature (480 °C), very active fine, hollow, noncrystalline spheres were formed. As the pyrolysis temperature increased, sintering occurred, larger particles with broader size distribution were obtained, and a higher degree of crystallinity of nickel ferrite was produced. The products at pyrolysis temperatures of 660 °C and above exhibited magnetic properties. The powders prepared from the aerosolization process at low temperatures had high reactivity and crystallized rapidly. The effect of the initial solution concentration was also studied, and dilute solutions produced spheres with fine size and narrow size distribution.

Homogeneous fine-grained Mn-Zn ferrites by sintering of colloidally precipitated powders

Colloidally precipitated powders were investigated for the synthesis of chemically homogeneous, uniformly fine-grained Mn-Zn ferrites. The process consists of the atomized dispersion of an aqueous solution of Mn, Zn, and Fe nitrates in an agitated solution of 1M ammonium hydroxide. This results in the coprecipitation of a fine colloidal mixture of Mn, Zn, and Fe hydroxides. The mixture is filtered, washed, dried, and heat treated to form agglomerated powders. The agglomerated powders are reduced in size and sintered after cold compaction. Sintering was performed at temperatures of 1100–1250 °C with oxygen partial pressures from 0 to 500 ppm in argon. Magnetic permeability and disaccommodation were measured on selected samples after an initial 0.5–5.0 Oe decaying sinusoidal field was applied to the specimens to excite time varying permeability. The permeability variation depended strongly on the magnitude of this excitation; both disaccommodation and accommodation were observed. The duplex structure typically associated with severe discontinuous grain growth was not observed for either of the two compositions examined over the range of sintering temperatures studied. Low levels of porosity were seen in samples sintered at 1150 and 1250 °C.

Effects of Reaction Conditions on the Properties of Products in Flame-spraying Technique-Zn-ferrite Powder

Formation of Zn-ferrite powder by flame-spraying technique from the ethanol solution of Zn and Fe nitrates was investigated to elucidate the effects of reaction conditions on the properties of products. The reaction was carried out by spraying the solution into a reactor heated by an electric furnace.The formation of Zn-ferrite by the present method took place to completion at reaction temperatures higher than about 800°C. Among the reaction conditions which affect the particle size of powder produced, the concentration of spraying solution is most important and one can obtain Zn-ferrite powder finer than 0.5μ by its control.

Studies on the Utilization of Metal Chelates. X.

Some EDTA-bis (N-alkylimides) were synthesized by the reaction of ethylenediaminetetraacetic acid (EDTA) with hexyl, octyl, nonyl, decyl, undecyl and dodecyl amines. The hydrolysis of the imides gave the corresponding EDTA-bis (N-alkylamides). Some metal chelates were obtained by the reaction of these amides with Fe (III), Cu (II), Zn (II), Ni (II), Co (II) and Al (III) nitrates. The presumed formulas of the chelates are as follows : [Fe (OH) A (H2O)2], [CuA], [ZnA], [NiA], [CoA (H2O)2], [Al (OH) A (H2O)], where A is a ligand anion formed from EDTA-bis (N-alkylamides) by the elimination of 2H+. These chelates were soluble in some organic solvents, but did not dissolve in water.Some metal chelates had superior dispersing power for TiO2 pigment in organic solvent. For instance, the 0.025% toluene-butanol (20 : 1) solution (about 30 ml) of EDTA-bis (N-dodecylamide) nickel chelate needed 128 h for complete sedimentation of dispersed 0.3 g TiO2 (Rutile type, having no treated surface), while the solvent (containing no chelate) needed only 0.5h for the same sedimentation experiment.