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The purpose of this paper is to focus on the removal of copper(II) ions from aqueous model salt solution by using chitosan-coated magnetite nanoparticles.

The chitosan-coated magnetite nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric differential thermal analysis. The adsorption of Cu(II) by using magnetite nanoparticles as an adsorbent was investigated under different adsorption conditions. The parameters studied were contact time, adsorbent dose and initial concentrations.

The sorption capacities of prepared samples were studied for the removal of Cu²⁺ ions from aqueous model solutions with varying experimental conditions of the initial metal concentration, contact time and dosage. It is found that the removal percent of Cu²⁺ ions increases with an increase in initial metal concentration, contact time and amount of dosage.

Based on the obtained results, this study recommends that chitosan-coated magnetite nanoparticles can also be applied for removal of some heavy metal ions and/or organic compounds in aqueous solution. It is recommended that this study be shared with the polymer-based nanomaterial researchers, especially material science.

The purpose of this paper is to synthesize anticorrosion pigments ZnFe₂O₄ from diverse raw materials of various shapes and size of primary particles.

Anticorrosion pigments were synthesized through a high‐temperature process during a solid phase. Zinc ferrites were prepared from hematite (α‐Fe₂O₃), goethite (α‐FeO.OH), magnetite (Fe₃O₄), and specularite (Fe₂O₃) entering into reaction with zinc oxide at temperatures ranging from 600 up to 1,100°C. The nature of the initial raw material, primarily the shape of its particles, affects the shape of the particles of the synthesized zinc ferrite. The formulated zinc ferrites had a rod‐shape, lamellar, and/or isometric shape. The shape of the particles of synthesized zinc ferrites was studied with regard to its effects on the mechanical and corrosion resistance of organic coatings. The obtained pigments were characterized by means of X‐ray diffraction analysis and scanning electron microscopy. The synthesized anticorrosion pigments were used to prepare epoxy coatings and water‐borne styrene‐acrylate coatings that were subjected to post‐application tests for physical‐mechanical properties and anticorrosion properties.

The shape of the particles was identified in the synthesized pigments. X‐ray diffraction analysis revealed the degree of precipitation and lattice parameters. All of the synthesized pigments had good anticorrosion efficiency in an epoxy and in styrene‐acrylate coatings. Compared with a commercially used anticorrosion pigment, their protective power in coatings was demonstrably stronger.

The synthesized pigments can be used conveniently in coatings protecting metal bases against corrosion.

The synthesis of zinc ferrites with different particle shapes for applications in anticorrosion coatings provides a new way of protecting metals against corrosion. Of benefit is the fact that the synthesized pigments do not contain any environmentally harmful substances.

The study aims to determine an efficiency of external magnetic field on the bacteria surrounded by thousands of magnetic magnetite nanoparticles. The interstitial nanoliquid in which an artificial bacteria swims in biological cell is utilized with variable thermal conductivity. Two dimensions unsteady motion of second grade fluid are considered. The stretching wall is taken as a curved surface pattern.

The mathematical results have been obtained by Chebyshev pseudospectral method.

The impact of the various governing parameters is described by numerical tables and diagrams. It is proven that the pure blood velocity curves are higher when compared with the magnetite/blood. It is demonstrated from clinical disease that dangerous tumors show diminished blood flow. This study concludes that the blood velocity profile increases by increasing the values of fluid parameters. This implies that the medication conveyance therapy lessens the tumor volume and helps in annihilating malignancy cells. The blood temperature distribution raises as the magnetite nanoparticles concentration increases. Consequently, the physical properties of the blood can be enhanced by immersing the magnetite nanoparticles. Further, the present outcomes cleared the thermal conductivity as, a variable function of the temperature, has an important role to enhance the heat transfer rate.

To the best of authors’ knowledge, this study is reported for the first time.

The application of hydrogen plasma on corroded steel and excavated iron artefacts has been studied. Transformations of the corrosion layer due to the plasma effect were investigated by means of X‐ray diffraction analysis. The reduction of iron oxides to the stable iron oxide, magnetite, was observed for all the samples. In the case of excavated objects, the reduction to magnetite did not occur throughout the whole of the bulk of the oxides, as it does (for example) in the case of steel corroded in the laboratory. Nevertheless, excavated objects, in which a metallic core remained, were stabilised against subsequent corrosion. However, objects that are completely oxidised must be treated carefully, because treatment may result in the formation of a brittle outer layer, and there is a risk of disintegration of such items, if treated using the plasma conditioning and restoration procedure.

The work described in this paper is part of a current programme that has two objects: (1) to investigate further the reasons for the different scaling behaviour of steel in steam and carbon dioxide, although these gases have similar oxygen potentials; (2) to provide background information for an investigation into the effect of variations in re‐heating furnace atmospheres upon scaling and scale adhesion.

One of the problems in the production of narrow hot‐rolled mild steel strip is the formation, at the edges of the strip, of scale that can be extremely resistant to pickling; This extreme resistance to pickling of ‘hard edge scale’ sometimes requires repickling of a considerable percentage of coils with consequent loss of production and deterioration of surface finish. The paper considers in detail the correlation between the microstructure of scale on the strip and its pickling behaviour. It is shown that certain characteristics of the microstructure, peculiar to ‘hard edge scale’, i.e. increased thickness, the presence of a primary magnetite layer, greater degree of wüstite transformation and the nature and presence of haematite, can be suppressed to a greater or lesser degree by variations in the cooling cycle. It is considered that no single one of these structural differences between hard edge scale and that which is removed readily from the centre of the strip would, by itself, interfere with pickling, but when these characteristics occur together repickling is made necessary. The above observations and conclusions are supported by results obtained from pickling tests carried out in the laboratory on samples taken from a wide range of coils.

The purpose of this study is to use thermodynamic data to estimate the pressure exerted by the crystallization of iron oxyhydroxides following the equation proposed by Correns and Steinborn.

Standard free energy and molar volume data have been considered for goethite, lepidocrocite, magnetite and hematite, which are described in the literature as the most commonly found mineral phase rust constituents.

The studied mineral phases generate higher to lower crystallization pressure values in the following order: goethite > lepidocrocite > hematite > magnetite. The crystallization pressures calculated for these phases are in the 32-350 MPa range, which is higher than the tensile strength of concrete (of the order of 0.2-10 MPa) and thus leads to failure of the cover concrete.

The aim of this paper is to shed light on this issue by calculating the stresses generated by the crystallization of iron oxide from a supersaturated solution using thermodynamic data. A deliberately simplistic method was proposed, taking as reference the Correns–Steinborn model (Correns and Steinborn, 1939; Correns, 1949). The crystalline phases considered in this paper are those most commonly found in the literature as rust constituents, that is, goethite (α-FeOOH), lepidocrocite (γ-FeOOH), magnetite (Fe₃O₄) and hematite (α-Fe₂O₃). The FeO synthetic phase was also included as a reference.

Due to the extensive industrial applications of stagnation flow problems, the present work aims to investigate the magnetohydrodynamics (MHD) flow and heat transfer of a magnetite nanofluid (here Fe₃O₄–water nanofluid) impinging a flat porous plate under the effects of a non-uniform magnetic field and chemical reaction with variable reaction rate.

Similarity transformations are applied to reduce the governing partial differential equations with boundary conditions into a system of ordinary differential equations over a semi-infinite domain. The modified fourth-order Runge–Kutta method with the shooting technique which is developed for unbounded domains is conducted to give approximate solutions of the problem, which are then verified by results of other researchers, showing very good agreements.

The effects of the volume fraction of nanoparticles, permeability, magnetic field, chemical reaction and Schmidt number on velocity, temperature and concentration fields are examined and graphically illustrated. It was found that fluid velocity and temperature fields are affected strongly by the types of nanoparticles. Moreover, magnetic field and radiation have strong effects on velocity and temperature fields, fluid velocity increases and thickness of the velocity boundary layer decreases as magnetic parameter M increases. The results also showed that the thickness of the concentration boundary layer decreases with an increase in the Schmidt number, as well as an increase in the chemical reaction coefficient.

The thermophysical properties of the magnetite nanofluid (Fe₃O₄–water nanofluid) in different conditions should be checked.

Stagnation flow of viscous fluid is important due to its vast industrial applications, such as the flows over the tips of rockets, aircrafts, submarines and oil ships. Moreover, nanofluid, a liquid containing a dispersion of sub-micronic solid particles (nanoparticles) with typical length of the order of 1-50 nm, showed abnormal convective heat transfer enhancement, which is remarkable.

The major novelty of the present work corresponds to utilization of a magnetite nanofluid (Fe₃O₄–water nanofluid) in a stagnation flow influenced by chemical reaction and magnetic field. It should be noted that in addition to a variable chemical reaction, the permeability is non-uniform, while the imposed magnetic field also varies along the sheet. These, all, make the present work rather original.

This paper aims to traitted the combined effects of ferromagnetic particles and magnetic field on mixed convection in the Falkner Skan equation using analytical solution by the Duan–Rach method.

Visualization and grouping of effects of various physical parameters such as electrical conductivity of ferro-particles (electrical conductivity calculated using Maxwell model), ferro fluid volume fraction for Magnetite-Fe₃O₄-water and magnetic field represented by the Hartmann number in a set of third- and second-order nonlinear coupled ordinary differential equations. This set of equations is analytically processed using the Duan–Rach Approach (DRA).

Obtained DRA results are validated using a numerical solution (Runge–Kutta–Fehlberg-based shooting method). The main objective of this research is to analyze the influence of physical parameters, in particular electrical conductivity, Ferrofluid volume fraction in the case of Magnetite-Fe₃O₄-water, in addition to the types of solid nanoparticles and Hartmann number on dynamic and thermal distributions (velocity/temperature). Results of the comparison between the numerical solution (Runge–Kutta–Fehlberg-based shooting method) and the analytical solution (DRA) show that the DRA data are in good agreement with numerical data and available literature.

The study uses Runge–Kutta–Fehlberg-based shooting method) and the analytical solution (DRA) to investigate the effect of mixed convection, in the presence of Ferro particles (Magnetite-Fe₃O₄) in a basic fluid (water for example) and subjected to an external magnetic field on the Falkner–Skan system.

The purpose of this study is to investigate the aesthetic blackening coating formed by a hydrothermal process, focusing on the formation of magnetite and the oxide adhesion for improving the corrosion resistance of the steel.

The aesthetic black coating was applied on AISI 4140 steel using a hydrothermal process with a non-toxic solution consisted of ferrous sulphate hydrate (FeSO4·7H₂O), sodium hydroxide (NaOH) and hydrazine hydrate (N2H4·H₂O). Upon process parameters temperature and time, the morphology of the coatings and oxidation kinetics were investigated by using scanning electron microscopy and X-ray diffraction (XRD) analysis. Furthermore, the samples with coatings were subjected to the adhesion test using a tensile testing machine equipped with a charge-coupled device (CCD) camera.

From the formation parameters due to temperature and time for the conversion coatings, it was found that the oxidation kinetics had special characteristics which were in accordance with a linear rate law and Arrhenius relation. For the samples blackened, the XRD analysis results revealed that the magnetite was successfully formed on the surface of the steel. On the other hand, increasing the blackening temperature worsened the scale adhesion as observed by the lower strain provoking the first spallation and the higher sensitivity of the oxide to spall out with the imposed strain.

The effects of parameters of the formation of conversion coatings were investigated to understand the kinetics of the coatings. Furthermore, a tensile adhesion test using a CCD camera was applied to evaluate the adhesion between the native oxide formed by conversion coating.