Synthesis of iron oxide nanoparticles via sonochemical method and their characterization

Preparation of iron oxide ( -Fe 2 O 3 ) nanoparticles was carried out via a sonochemical process. The process parameters such as temperature, sonication time and power of ultrasonication play important roles in the size and morphology of the final products. The iron oxide nanoparticles were characterized by transmission electron microscopy, X-ray powder diffraction, and thermogravimetric and differential thermal analyses. From transmission electron microscopy observations, the size of the iron oxide nanopar...     

Continuous synthesis of iron oxide (Fe3O4) nanoparticles via thermal decomposition

Iron oxide nanoparticles have become of great interest in the medical field for their potential uses in areas such as biomagnetic imaging and hypothermia cancer treatment. Traditionally, particles for these applications are produced through batch-based methodologies. Herein, we demonstrate an alternative continuous flow production method for the synthesis of Fe₃O₄ iron oxide nanoparticles. Advantages of continuous flow over the batch method include consistent formation of uniformly spherical particles, thorough mixing of reactants, and capacity for high-volume particle production. In this study, a continuous flow reaction mechanism was proposed in which stoichiometric control of reactants had the potential to control final particle size. The project was conducted under the supposition that the iron oleate/ligand ratio in the precursor was the greatest size control factor, with a higher ratio resulting in smaller particles. The resulting particles produced by this continuous method were characterized by high-resolution transmission electron microscopy, X-ray diffraction, and magnetometry.     

Magnetic filtration of an iron oxide aerosol by means of magnetizable grates

The cleaning of gases with low concentrations of small ferromagnetic or paramagnetic particles is a difficult task for conventional filtration. A new alternative procedure, magnetic filtration, is used in this work. Iron oxide aerosol was generated by elutriation of iron oxide particles from a fluidized bed consisting of a mixture of Geldart-C iron oxide powder and large spherical Geldart-B sand particles. The aerosol was filtered by means of a magnetic filter which consisted of one, two or three iron grates staggered to each other. The experimental installation contained also an isokinetic sampling system and a Microtrac SRA 150 Particle Analyser. A theoretical expression for filtration efficiency was deduced from a previous model taking into account the different forces acting on the iron oxide particles. Experimental filtration efficiency matches quite well calculated theoretical efficiency. It was found that an increase in particle size, in thee number of grates or in the applied magnetic field produced higher filtration efficiencies up to 100% in some cases. In all filtration experiments pressure drop through the magnetic filter was very small.     

Thermophoresis of nanoparticles hotter/colder than the surrounding dilute gases

Aerosol particles suspended in a diluted gas with non-uniform temperature distribution are expected to experience a thermophoretic force. In theoretical treatment of thermophoresis, it is usually assumed that the particle temperature is equal to the surrounding gas temperature. However, this might not always be the case. In some particular applications, the particle temperature can significantly differ from the gas temperature. In the present paper, we theoretically investigate the effect of the particle temperature on the thermophoresis of nanoparticles in the free molecule regime. Theoretical formulas for the thermophoretic force and thermophoretic velocity are obtained based on the gas kinetic theory. As examples, a spherical Ag nanoparticle suspended in a dilute He gas is considered, and the Rudyak–Krasnolutski potential is employed to model the gas–particle interaction. It is found that the influence of the particle temperature on the thermophoresis of nanoparticles can be significant. With increasing particle size, the error due to the equal gas–particle temperature assumption can be neglected.     

Preparation and properties of magnetic iron oxide nanotubes

Magnetite (Fe3O4) nanotubes were prepared by reducing synthesized hematite (α-Fe2O3) nanotubes in 5% H2+95% Ar atmosphere,and then maghemite (γ-Fe2O3) nanotubes were obtained by re-oxidizing the Fe3O4 nanotubes.The nanotube structure was kept from collapsing or sintering throughout the high temperature reducing and re-oxidizing processes.The coercivities of the Fe3O4 and γ-Fe2O3 nanotubes synthesized were found to be 340.22 Oe and 342.23 Oe,respectively,both higher than other nanostructures with the same phase and of similar size.Both adsorbed phosphate and the nanotube structure are considered responsible for this high coercivity.     

Metallic iron nanoparticles: Flame synthesis,characterization and magnetic properties

Metallic iron (Fe) nanoparticles (NPs) with a typical core–shell structure have been prepared by a simple and continuous flame spray pyrolysis (FSP) method, which are stabilized by the corresponding Fe₃O₄ shell with a thickness of 4–6 nm. The size of metallic Fe cores is about 30–80 nm. The core–shell structured iron NPs show an air stability as long as one month as a result of the protection of oxide shell. Through the control of the residence time of materials in flame and flame atmosphere, metallic Fe and iron oxides are obtained, showing a better external magnetic field responsibility. It is concluded that the evolution of morphology and composition of flame-made magnetic NPs could be attributed to the competition mechanism between reduction and oxidation reactions of in situ flame combustion, which offers more choices and better effective design strategy for the synthesis of advanced functional materials via FSP techniques.     

Investigation on the granulation behavior of iron ore fine in a horizontal high-shear granulator

High-shear granulation is widely used in many particulate industries for its good capability to improve the size, strength and composition uniformity of powder substances. This work conducted an experimental study to investigate the granulation behavior of iron ore fine in a horizontal high-shear granulator, such as granules size distribution, granules growth rate, and permeability of the granules bed. The results show that the granule size and permeability of packed granules bed increase gradually with increasing the granulation time, and the growth of granules can be divided into three stages: the rapid growth stage, the slow growth stage and the relatively stable stage. Both the higher rotational speed and larger number of impellers increase the kinetic energy and collision frequency of the particles, which causes the increase of average granule size, growth rate and permeability of granules packed bed. On the other hand, the shear damage effect of the impellers on the granules is also enhanced with the increase of rotational speed and impeller number, resulting in significant granule size segregation.     

Growth characteristics of spherical titanium oxide nanoparticles during the rapid gaseous detonation reaction

The nanosize grain growth characteristics of spherical single-crystal titanium oxide (TiO₂) during the rapid gaseous detonation reaction are discussed. Based on the experimental conditions and the Chapman–Jouguet theory, the Kruis model was introduced to simulate the growth characteristics of spherical TiO₂ nanoparticles obtained under high pressure, high temperature and by rapid reaction. The results show that the numerical analysis can satisfactorily predict the growth characteristics of spherical TiO₂ nanoparticles with diameters of 15–300 nm at different affecting factors, such as concentration of particles, reaction temperature and time, which are in agreement with the obtained experimental results. We found that the increase of the gas-phase reaction temperature, time, and particle concentration affects the growth tendency of spherical nanocrystal TiO₂, which provides effective theoretical support for the controllable synthesis of multi-scale nanoparticles.     

Dispersion behavior of core-shell silica-polymer nanoparticles

Core-shell silica nanoparticles are superior in modifying surface wetting behavior, enhancing nucleation and growth in crystallization, improving dispersion of naked nanoparticles, and thus upgrading the overall properties of organic polymers. The dispersion behavior and morphology of monodisperse core-shell silica particles in several polymers including polyesters are reviewed and their potential applications are discussed.     

From micro-to nanosized particles:Selected characterization methods and measurable parameters

Airborne microand nanoparticles-aerosols-play an important role in many natural phenomena and in a variety of industrial processes,as well as the public health issue. They may be of natural or anthropogenic origin;their presence in an environment might be intentional or due to undesirable release. In any case,merely the particle detection and characterization,ideally in real-time,provide an insight into the potential burden allowing also controlling and abatement measures. Due to the broad size range it is ...     

Thermophoretic effects on nano-particle deposition in channel flow

In this study, deposition of particles with diameters of 3, 5, and 10 nm in a finite-length heated channel flow is numerically studied under both molecular diffusion and thermophoretic effects. Two types of thermal conditions were examined. The first condition involved various inlet temperatures with a fixed wall temperature. The second condition involved various wall temperatures and a fixed inlet temperature. For a finite channel length, higher particle deposition can be obtained for the various inlet temperature and fixed wall temperature cases. However, for the same temperature ranges, complete particle collection on the wall can only be achieved under various wall temperatures and fixed inlet temperature cases when the channel length is long enough. This is because a temperature gradient appears in these cases. The temperature gradient in the various inlet wall temperatures and fixed wall temperature cases is zero when the flow is thermally fully developed.     

Cooperative entry of nanoparticles into the cell

Interaction of nanoparticles (NPs) with cell membrane is a crucial issue in studying drug delivery, photodynamic therapy system and cytotoxicity. Single NP with relatively small size cannot be fully wrapped by the cell membrane, which prohibits its uptake. One feasible way is cooperative entry, i.e., recruiting and assembling multiple small NPs to form a larger NP cluster to enter into a cell. In this work, we present theoretical analysis about the cooperative entry of multiple NPs. Through free energy calculation we investigate how the NPs׳ size, shape, interval and NP/cell interfacial binding energy influence the feasibility of entry. Interestingly we find that the cooperative entry of oblate ellipsoidal NPs can get larger energy compensation than individual ones as well as spherical ones. We also propose that soft NPs have preference in cooperative entry of the cell. Our work can be used to actively design and transfer NPs in applications such as drug delivery as well as to understand the shape effect on toxic mechanism of ellipsoidal NPs.     

A collaboration into research on nanoparticles (ACORN)

This paper describes the operation and outcome of one of the United Kingdom's largest multi-partner research activities in nanoparticles.The research covers the discovery and development of organic and inorganic crystals/nanoparticles,nanoparticle properties towards specific product applications,The research also encompassed bespoke measurement technology for nanoparticles and structure interactions.Significant research outcomes are summarised.The paper illustrates the advantages from industrially motivated research and value of collective action between a broad group of researchers in a nation.     

Shape and size effects of ceria nanoparticles on the impact strength of ceria/epoxy resin composites

Ceria nanoparticles with various shapes (rods, cubes, and plates) and sizes were controllably synthesized and then introduced into epoxy resin. Subsequently, we investigated correlations between the shape and size of ceria nanostructures and the mechanical performance of composites. The samples were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. Compared with commercial ceria filled composites, the composites made with morphology-controlled ceria nano...     

Comparison of schemes for preparing magnetic Fe3O4 nanoparticles

Magnetic Fe3O4 nanoparticles were prepared by means of coprecipitation using NH3·H2O in water and in alcohol, and using NaOH in water. A series of instruments such as SEM, TEM, HRTEM, FT-IR, XRD and VSM were used to characterize the properties of the magnetic nanoparticles.was the longest. The process using NaOH in water was the simplest and the reaction time was the shortest, but the particle characteristics were inferior to those of the other two methods. The mean size of magnetic Fe3O4 nanoparticles prepared by coprecipitation in alcohol was the smallest among the three, but the nanoparticles aggregated severely. The magnetic Fe3O4 nanoparticles were coated with oleic acid using saturated sodium coated successfully and thoroughly.     

Progress in nanoparticles characterization: Sizing and zeta potential measurement

Characterization of various nanoparticles is on the center stage in nanotechnology development. The subjects for nanoparticles characterization are focused on particle size and particle surface charge determinations. This article summarizes the latest development in particle size analysis using dynamic light scattering and surface charge determination using electrophoretic light scattering for nano-or even sub-nanoparticles in concentrated suspensions.