Magnetite in Aqueous Medium : Coating Its Surface and Surface Coated with It (original) (raw)
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Synthesis and Characterization of Magnetite Nanoparticles by Chemical Co-Precipitation
A modified controlled chemical co-precipitation of alkaline aqueous ferrous and ferric salt solution at pH 8 with continuous addition of ammonia solution 25% under a degassed atmosphere was performed to synthesis magnetite (Fe3O4) nanoparticles. Formation of magnetite nanoparticles was conducted by adjusting the ferric to ferrous ions in the ratio of 1:1, 1:2 and 2:1. Further investigation on the surfactant-coated magnetite nanoparticles by using 8% surfactant sodium dodecyl sulphate (SDS) was also studied. The synthesized magnetite nanoparticles were characterized by Transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffractometer (XRD). TEM results shows that magnetite nanoparticles which were synthesized with ferric/ferrous ratio 2:1 are in sphere shape and have the smallest particle size distribution range which is about 12-17 nm. The particles size distribution range of coated magnetite was decreased to 11-15 nm after coated with 8% surfactant SDS. XPS results indicated that the produced magnetite nanoparticles consisted of elemental iron and oxygen at 72.76% and 22.27% respectively. The phase and face-centered cubic structure of magnetite nanoparticle was also confirmed by XRD. Magnetite nanoparticle synthesized with ferric to ferrous ratio of 2:1 and coated with 8% surfactant SDS shows the best crystallinity among all samples with particle distribution size range from 11-15 nm.
Surface charging, polyanionic coating and colloid stability of magnetite nanoparticles
Colloids and Surfaces A, 2009
The formation of small and large molecular polyanionic coating on the surface of magnetite (Fe 3 O 4) nanoparticles and their role in the stability enhancement of aqueous magnetic fluids are compared. Magnetite was synthesized and stabilized with citric (CA) and humic (HA) acids. The macromolecular HA, a notable fraction of the natural organic matter (NOM), contains mainly carboxylic groups similarly to the CA, and both acids are able to form surface complexes on the ≡Fe-OH sites of iron oxides. The pHdependent charge state of particles and their aggregation were quantified, and the enhanced salt tolerance of stabilized systems was studied. The dynamic light scattering (DLS) method was used to characterize colloidal stability under different conditions. The average particle size and electrophoretic mobility were measured, and the electrolyte tolerance was tested in coagulation kinetic measurements. The colloidal stability of magnetite dispersions depends sensitively on the pH and the concentration of organic acids present. The trace amount of HA neutralizes the positive charges on magnetite surface under acidic condition only in part, and so it promotes the aggregation between the particles having both positive sites and negative humate patches on the surface. Above the adsorption saturation, the surface becomes completely covered causing the reversal of charge sign and overcharging of nanoparticles. The magnetite nanoparticles become stabilized in a way of combined steric and electrostatic effects. The thicker layer of macromolecular HA provides better electrosteric stability than that of CA coating. However, in the presence of either CA or HA, the dissolution of magnetite is enhanced due to the complexation of iron ions in the aqueous medium.
Stabilization in Water of Large Hydrophobic Uniform Magnetite Cubes by Silica Coating
The Journal of Physical Chemistry C, 2011
Magnetic nanoparticles, especially magnetite and maghemite, are of great interest for a broad range of applications, due to their biocompatibility, the Food and Drug Administration (FDA) approval (as magnetic resonance imaging contrast agents), and absence of toxicity. These applications include magnetic fluids, data storage, catalysis, and bioapplications. Examples of applications in the study of biology and biomedicine are magnetic bioseparation, cell sorting, detection of biological entities, clinical diagnosis and therapy (such as magnetic resonance imaging, MRI, and magnetic fluid hyperthermia, MFH), targeted drug delivery, immunoassays, and bio-macromolecules purification. 1 In recent years, much attention has been focused on the synthesis of uniformly sized magnetite nanoparticles. 2 Although ferri-or ferromagnetic nanoparticles are desirable for many of these applications, super-paramagnetic nanoparticles of <30 nm have generally been used because nearly no preparation method was available until very recently 3 and because the synthetic routes of high-quality uniform ferrimagnetic nanoparticles larger than 30 nm involve organic solvents using hydrophobic capping reagents. Thus, the resulting magnetic nanoparticles are dispersible in hydrophobic organic solvents only.
Preparation and characterization of magnetite nanoparticles by Sol-Gel method for water treatment
Bentonite is a kind of crystalline clay mineral with the major constituent of montmorillonite. Bentonite mines should be investigated in different areas with different climatic and environmental conditions. Kerman, is a province in the southeast of Iran famous for its rich resources of bentonite mines. In the present study, the physical and chemical characteristics of the supplied bentonites from three different mines of Kerman (Kheirabad, Tang-e Quchan and Horjand) were investigated. Kheirabad sodium bentonite sample was selected as a potent adsorbent of organic and inorganic pollutants due to high swelling index. Besides, magnetite nano composites were synthesized by stabilizing Fe 3 O 4 nanoparticles on desired bentonite. The properties of nanocomposites were studied using FTIR, XRD, VSM, BET and TEM analyses.
Interfacial properties of natural magnetite particles compared with their synthetic analogue
Minerals Engineering, 2012
for flotation and agglomeration of iron ore. Model systems comprising synthetic iron oxides and pure chemical reagents are commonly applied in experimental work in order to obtain high quality data and to ease the interpretation of the empirical data. Whether the results obtained using model systems are valid for iron ore minerals and commercial reagents is a question seldom addressed in the literature. It is shown in this work that previously reported results obtained from a model system, concerning adsorption of a carboxylate surfactant and sodium metasilicate onto synthetic magnetite nanoparticles, as obtained by in-situ ATR-FTIR spectroscopy and contact angle measurements, are applicable to adsorption of flotation reagents on magnetite concentrate. Additionally, the problem of restoring magnetite wetting after flotation is addressed since good wetting of a magnetite concentrate is required to produce iron ore pellets by wet agglomeration. The results from the present work indicate that the wettability of both synthetic magnetite coated with surfactant and magnetite 1 concentrate after flotation can be improved by adsorbing a hydrophilizing agent such as silicate or polyacrylate.
Nanoparticles of Magnetite in Polymer Matrices: Synthesis and Properties
Journal of Inorganic and Organometallic Polymers and Materials, 2016
This review covers publications on magnetite nanoparticles in polymer matrix, especially in humic acids, which are very interesting, widespread natural polymers. Of special attention was the influence of synthetic conditions on the structure and physicochemical properties of magnetic nanomaterials as well as their potential in environmental applications as sorbents. Nanoparticles of Fe3O4 in polymer matrix as promising materials for environmental applications have been in the focus of a great number of studies due to their properties. The modification of magnetic nanoparticles by humic acids leads to increase the sorption properties of such composites and stabilization of magnetite nanoparticles, inhibiting their agglomeration. Thus, humic acids on the one hand, can be used as effective stabilizers for magnetoactive nanoparticles, and on the other hand, keep their protective properties towards ecotoxicants.
Surface modification of magnetite nanoparticles for biomedical applications
Journal of Magnetism and Magnetic Materials, 2009
The preparation of magnetite nanoparticles with narrow size distributions using poly(ethylene glycol) (PEG-COOH) or carboxymethyl dextran (CMDx) chains covalently attached to the particle surface using carbodiimide chemistry is described. Particles were synthesized by thermal decomposition and modified with 3-aminopropyl trimethoxysilane (APS) to render particles with reactive amine groups (-NH 2 ) on their surface. Amines were then reacted with carboxyl groups in PEG-COOH or CMDx using carbodiimide chemistry in water. The size and stability of the functionalized magnetic nanoparticles was studied as a function of pH and ionic strength using dynamic light scattering and zeta potential measurements.
New route for preparation and characterization of magnetite nanoparticles
Arabian Journal of Chemistry, 2011
We report here the synthesis of naked magnetic nanoparticles by using a facile method. Magnetic nanoparticles were prepared by mixing and stirring two equivalents of iron(II) chloride tetrahydrate with three equivalents of iron(III) chloride hexahydrate at room temperature. The mixture was treated by adding 100 ml of 28% ammonium hydroxide. Immediately, the color of the solution turned from orange to black. Magnetite nanoparticles precipitated and were washed three times with 5% NH 4 OH solution using the magnetic decantation method.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
Magnetite nanoparticles were chemically synthesized by co-precipitation method, using gelatine added in-situ and ex-situ and also using two different separation techniques for the magnetite particles (magnet or centrifuge). The product was analysed by different techniques, such as SEM, DLS, FTIR and XRD. From the comparison of the results it was concluded that the added gelatine can be preserved in the final product with a higher probability if it is added ex-situ. This is because a larger and more uncertain part of gelatine is lost during the washingseparation steps when it is added in-situ. Thus, the ex-situ addition of gelatine is more efficient to stabilize nano-magnetite particles. Also, it was concluded that particle separation by centrifuge was more efficient to separate larger and mostly paramagnetic magnetite particles, while separation by a magnet was more efficient for smaller superparamagnetic magnetite particles. This is explained by different mechanism behind these two separation techniques. Thus, for the production of suspensions with superparamagnetic nano-magnetite particles the separation method using a strong magnet is preferred vs a centrifuge. It was further shown that when sucrose was applied together with gelatine, the stabilization of magnetite particles was improved compared to the case when only gelatine was used.