Water-based Magnetic Fluid Research Articles

Obtaining and Characterizing a Water-Based Magnetic Fluid

A way of obtaining a biocompatible magnetic fluid and its parameters are described. It is proposed that depolarized dynamic light scattering be used to determine the size of nanoparticles in the fluid phase, and to estimate the aggregative and sedimentation stability of a magnetic fluid upon dilution. It is established that upon the dilution of the magnetic fluid, ellipsoidal aggregates consisting of 20 or more single nanoparticles form in it.

Frequency Dependence of an Electromagnetic Absorption Coefficient in Magnetic Fluid

The samples of water-based magnetic fluid, which contain Fe3O4–SiO2 particles with a spherical shape and sizes less than 100 nm, have been obtained. The method based on using a transmission line has been applied to measure the electromagnetic absorption coefficient in the frequency range from 0.1 to 18.0 GHz using a measuring setup based on horn antennas and the cell based on a coplanar transmission line. It has been found that magnetic fluids can be used to produce electromagnetic shields and electromagnetic wave absorbers as well as means to carry out local hyperthermia at electromagnetic radiation frequencies higher than 7 GHz.

Using Nitrated Lignosulfonates for the Synthesis of a Water-Based Magnetic Fluid

Nitrated lignosulfonates were used to synthesize a water-based magnetic fluid. Lignosulfonates were nitrated by nitric acid under mild conditions and without further purification were used to synthesize a magnetic fluid. Part of the iron(II) were oxidized with an excess of nitric acid, so that the magnetoactive phase under the condensation by action of sodium hydroxide was formed. Optimum conditions for nitration of lignosulfonates and synthesis of a magnetic fluid were experimentally established. The optimum consumption of iron(II) was 1.3–1.5[Formula: see text]g per 1[Formula: see text]g of sodium lignosulfonate. Unlike the initial lignosulfonates, nitrated lignosulfonates have peptizing properties, due to which the precipitate formed during condensation was dispersed to nanoparticles (15–30[Formula: see text]nm). The resulting magnetic fluid had a high magnetic activity and was stable for a long time.

Multifunctional amphiphilic ionic liquid pathway to create water-based magnetic fluids and magnetically-driven mesoporous silica.

Amphiphilic ionic liquids, 1-alkyl-3-methylimidazolium chloride (CnmimCl with n = 10, 12, 14, 16) were firstly used as modifiers to construct a self-assembly bilayer on the surface of iron oxide nanoparticles for generation of highly stable, water-based magnetic fluids. Subsequently, a magnet-driven mesoporous silica was synthesized by in situ self-assembly in the bilayer CnmimCl-stabilized magnetic fluid using the C16mimCl as template and tetraethylorthosilicate (TEOS) as silicon source via a hydrothermal synthesis and following calcination procedure. A systematic study was carried out addressing the influence of the alkyl chain length of CnmimCl in the primary and secondary layers on the stability of magnetic fluids. The characterization of TEM, XRD, VSM, electrophoresis experiments, TGA and DTA showed that stable water-based magnetic fluids can be synthesized based on the assembly of the well-defined bilayer-CnmimCl structure with long-chain C16mimCl as secondary layer on the magnetite (Fe3O4) nanoparticles. The results of small and wide-angle XRD, TEM, VSM, and N2 absorption experiments indicated that the nano-scale magnetic Fe3O4 particles were inlayed into hexagonal p6mm mesoporous silica (MCM-41 type) framework. Importantly, it was found that the obtained Fe3O4/MCM-41 was an appropriate adsorbent for the adsorption of rhodamine B and methylene blue from their aqueous solution. In addition, the adsorbent could be separated and reclaimed fleetly from the solution under external magnetic field.

Частотная зависимость коэффициента поглощения электромагнитного излучения в магнитной жидкости

AbstractThe samples of water-based magnetic fluid, which contain Fe_3O_4–SiO_2 particles with a spherical shape and sizes less than 100 nm, have been obtained. The method based on using a transmission line has been applied to measure the electromagnetic absorption coefficient in the frequency range from 0.1 to 18.0 GHz using a measuring setup based on horn antennas and the cell based on a coplanar transmission line. It has been found that magnetic fluids can be used to produce electromagnetic shields and electromagnetic wave absorbers as well as means to carry out local hyperthermia at electromagnetic radiation frequencies higher than 7 GHz.

Comparative experiment of enhanced heat transfer performance between water-based magnetic fluid heat pipe and ordinary water heat pipe under magnetic field

Comparative experiment of enhanced heat transfer performance between water-based magnetic fluid heat pipe and ordinary water heat pipe under magnetic field

MHD natural convection in a square porous cavity filled with a water-based magnetic fluid in the presence of geothermal viscosity

PurposeThe purpose of this paper is a numerical analysis of natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity under the effect of inclined uniform magnetic field.Design/methodology/approachThe domain of interest includes the square porous cavity filled with a water-based magnetic fluid (W40). Horizontal walls are supposed to be adiabatic, while right vertical wall is kept at constant low temperature and left vertical wall is kept at constant high temperature. An inclined uniform magnetic field affects the fluid flow and heat transfer inside the cavity. The viscosity of the working fluid is proportional to the linearly decreasing function of depth (vertical coordinate) and inversely proportional to the linear function of temperature. It is assumed in the analysis that the flow is laminar. The fluid is Newtonian and the Boussinesq approximation is valid. The governing equations have been discretized using the finite difference method with the uniform grid. Simulations have been carried out for different values of the Rayleigh number, Hartmann number, Darcy number, magnetic field inclination angle and viscosity variation parameters.FindingsIt has been revealed that an increase in the viscosity parameters leads to the heat transfer enhancement and convective flow intensification. At the same time, this intensification is more essential for high values of the Rayleigh number.Originality/valueThe originality of this work is to analyze MHD natural convection in a square porous cavity filled with a water-based magnetic fluid of geothermal viscosity. The results would benefit scientists and engineers to become familiar with the analysis of convective heat and mass transfer in nanofluids, and the way to predict the properties of nanofluid convective flow in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors and electronics.

Investigation on Magnetoviscous Effects of Water-Based Magnetic Fluid

Magnetic fluid or called ferro-fluid is such kind of magnetic nanomaterials, which is stable of solid-liquid two phase colloidal solution composited by magnetic nanoparticles coated by surfactant and highly disperse in a carrier liquid. The basis of magnetic fluid widely applied mainly is due to their unique magnetic properties and rheological properties, which enable its action as intelligent control materials in the magnetic field so as to achieve the goal of magnetic liquid dynamic seal, magnetic damping vibration and so on. In our recent research, the water-based magnetic fluid was synthesized using a co-precipitation method and its magnetorheological properties were studied. During the process, the magnetorheological properties of stable water-based magnetic fluids were determined by magnetic rheometer. The results show that the shear-thinning behavior of magnetic fluids was observed both in the absence and presence of magnetic field. However, there was a remarkable magnetoviscous effect with magnetic field function and the unexpected variation of shear stress was related to the chain aggregation. Furthermore, the constitutive equation of water-based magnetic fluid at a low magnetic field was discussed.

Water Electrolysis Process in Water-Based Magnetic Fluids Under Non-uniform Magnetic Field

Water Electrolysis Process in Water-Based Magnetic Fluids Under Non-uniform Magnetic Field

Preparation and Biological Applications of Graphene Oxide Functionalized Water-Based Magnetic Fluids.

Magnetic fluids (MFs) with good dispersion were prepared by speed-controlled co-precipitation method, using polyethylene glycol (PEG-4000) as dispersing agent. To functionalize the MFs with graphene oxide (GO), highly dispersed nano-magnetic particles (NMPs) were firstly prepared by low-temperature freeze-drying technique. 3-aminopropyltriethoxysilane (APTES) was then attached on the surface of NMPs to form amino functionalized NMPs. GO was finally assembled with amino functionalized NMPs, to prepare GO functionalized MFs (GO-NMPs) by electrostatic adsorption. The obtained GO-NMPs were then characterized by FTIR, XRD, TEM, SEM and VSM. Meanwhile, mice were in vivo used as animal model to study biological application of 99Tcm labeled GO-NMPs, suggesting that the targeted functionalized magnetic particles had higher magnetic response effect under pulsed magnetic gradient field.

The concept of ferrofluid preheating in the treatment of cancer by magnetic hyperthermia of tissues

The frequency dependence of the complex magnetic susceptibility, χ(ω) = χ′(ω) − i χ″(ω), of a water-based magnetic fluid with magnetite particles, over the frequency range 500 kHz to 2 MHz and at three different temperatures of 30 °C, 40 °C and 50 °C are presented. Based on these experimental measurements, the dependence on frequency, f = (ω/2π) Hz, of the heating rate, ΔT/Δt, of the ferrofluid has been evaluated at these stated temperatures and alternating magnetic field of different amplitudes, Ho = 200 A/m, 400 A/m, 600 A/m, 800 A/m and 1 kA/m.The results show that the preheating of the ferrofluid sample at the desired operating temperature has the advantage of using lower levels of H0 during over a shorter time period, as opposed to the case of an unheated sample. This concept of preheating a sample, has major significance for the treatment of cancer by magnetic hyperthermia in that the patient is subjected to lower values of H0, over the time period of the treatment.

Barium Hexaferrite Magnetic Fluid: Preparation, Characterization and the In Vitro Identification of Cytotoxicity and Antibacterial Activity

As an alternative way to encounter antibiotic-resistant strains of bacteria, we report here a harmless magnetic fluid, which can be targeted to infections using external magnetic field and destroy the target. Ultrafine BaFe12O19 nanoparticles were synthesized using the hydrothermal approach; for the first time, the nanoparticles were coated with citric acid to form a stable aqueous suspension. Characterization of the prepared (coated) oxide was performed on Furrier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDS) analysis and vibrating sample magnetometry (VSM). In vitro cytotoxicity, as well as the antibacterial activity of the surface modified nano-oxide, was measured against eukaryotic cells and samples from both Grams of bacterial strains, respectively. The results showed that the superparamagnetic crystals of barium hexaferrite were successfully surface modified to form a water-based stable magnetic fluid. The magnetic fluid measured to be extremely bio compatible by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) test. Disc diffusion and minimum inhibitory concentration (MIC) methods revealed that the surface modified nano-oxide is fetal for both the Gram-negative Escherichia coli (E. coli) and the Gram-positive Staphylococcus aureus (S. aureus). However, the fatality of the nanoparticles is lower for the Staphylococci strain.

Soft magnetic nanocomposite microgels by in-situ crosslinking of poly acrylic acid onto superparamagnetic magnetite nanoparticles and their applications for the removal of Pb(II) ion

FeCl3·6H2O and FeCl2·4H2O is used to produce a water-based nanometer Fe3O4 magnetic fluid, which is in-situ modified in liquid paraffin with silane in the form of water-in-oil emulsion. The emulsion of the resulting multi-functionalized Fe3O4 magnetite nanoparticles is then used as the only crosslinker and in-situ grafted with acrylic acid to produce beaklike soft magnetic nanocomposites microgels. This “one-pot” process has a number of advantages over the traditional methods: it is a simpler process; it avoids aggregation of nanometer Fe3O4; and it shows a much improved mechanical strength credited to the covalent crosslinking between the rigid Fe3O4 skeleton and the soft PAA blocks. The obtained microgels have showed selective adsorption to Pb(II), and the adsorbed Pb(II) can be easily desorbed, suggesting good reusability. Also, the microgels exhibit certain magnetic properties, therefore providing a convenient approach for stirring or separation by applying external magnetic field.

Defected-core photonic crystal fiber magnetic field sensor based on Sagnac interferometer

A high-sensitivity magnetic field sensor based on photonic crystal fiber (PCF) Sagnac interferometer is proposed by finite element method (FEM). The elliptical-hole PCF is injected with water-based magnetic fluid. The fiber core is introduced in an elliptical hole to act as a defected core. The sensitivities are 13.25 and −14.32 nm/Oe at the wavelength of 1750 and 1780 nm, respectively, as the magnetic field H is 100 Oe. The simulation result shows that the sensitivity is extremely high near the wavelength of 1765 nm, because the group birefringence Bg is about zero at that wavelength. The above theory is examined in a different configuration by the transmission mode. The average sensitivities are 0.265, 1.63 and −1.915 nm/Oe, respectively, for the dip wavelength A, B and C as the fiber length is 5 cm. The detecting window is 60Oe. We also demonstrate that the sensitivity can be greatly enhanced by 1–2 orders of magnitude by introducing a defected core.

Theoretical Research on the Thermal-Lens Effect of Magnetic Fluid by Using Brownian Dynamics Method

Magnetic fluid has not only rich optical properties, but also interesting thermal-lens effect. The thermal-lens effect of magnetic fluid was studied by using the Brownian dynamics method. The Theoretical simulation and analysis were taken to research the whole generation process of thermal-lens effect. The thermal-lens effect generation of water-based magnetic fluid irradiated by the laser of different optical powers was studied in microscopic view. Based on the model of the thermal-lens effect, Monte Carlo method and Kirchhoff diffraction theory were adopted to simulate and analyze the far-field diffraction ring pattern generated by a Gauss light beam passing through the magnetic fluid. Then, the influences of different central temperatures of the magnetic fluid to the ring numbers, width, and intensity distribution of far-field diffraction ring pattern were obtained. The results were verified with the published experimental results.

Superparamagnetic Composites Based on Ionic Resin Beads/CaCO3 /Magnetite.

The preparation of superparamagnetic composites obtained by CaCO3 mineralization from supersaturate aqueous solutions is presented. The preparation was conducted in the presence of oleic acid stabilized magnetite nanoparticles as a water-based magnetic fluid and insoluble templates as gel-like cross-linked polymeric beads. The presence of the magnetic particles in the composites provides a facile way for external manipulation using a permanent magnet, thus allowing the separation and extraction of magnetically modified materials. Two ion exchangers based on divinylbenzene/ethyl acrylate/acrylonitrile cross-linked copolymer-a cation ion exchanger (CIE) and an amphoteric ion exchanger (AIE)-were used, as well as different addition orders of magnetite and CaCO3 crystals growth precursors. The morphology of the composites was investigated by SEM, the polymorphs content by X-ray diffraction, and the thermal stability by thermogravimetric analysis. Polymer, CaCO3 , and magnetite in the composite particles were shown to be present by energy dispersive X-ray (EDX), XPS, and TEM. The sorption capacity for CuII ions was tested, as compared to samples prepared without magnetite.

Ultrasensitive magnetic field sensor based on an in-fiber Mach–Zehnder interferometer with a magnetic fluid component

An ultrasensitive magnetic field sensor based on a compact in-fiber Mach–Zehnder interferometer (MZI) created in twin-core fiber (TCF) is proposed, and its performance is experimentally demonstrated. A section of TCF was spliced between two sections of standard single-mode fibers, and then a microchannel was drilled through one core of the TCF by means of femtosecond laser micromachining. The TCF with one microchannel was then immersed in a water-based Fe3O4 magnetic fluid (MF), forming a direct component of the light propagation path, and then sealed in a capillary tube, achieving a magnetic sensing element, which merges the advantages of an MZI with an MF. Experiments were conducted to investigate the magnetic response of the proposed sensor. The developed magnetic field sensor exhibits a linear response within a measurement range from 5 to 9.5 mT and an ultrahigh sensitivity of 20.8 nm/mT, which, to our best knowledge, is 2 orders of magnitude greater than other previously reported magnetic sensors. The proposed sensor is expected to offer significant potential for detecting weak magnetic fields.

Synthesis and properties of magnetic fluids produced on the basis of magnetite particles

Magnetic fluids based on magnetite synthesized by the chemical condensation method at temperatures of 25, 40, 60, and 80°C were obtained and studied. Magnetite particles were examined by X-ray phase and X-ray fluorescence analyses and electron microscopy. The average size of the coherent scattering region of magnetite particles was 13–17 nm, depending on the synthesis temperature. Magnetic fluids were synthesized from magnetite particles obtained at 25 and 80°C, with water and octane serving as carrier fluids. The NMR method was used to determine the saturation magnetization and average magnetic moment of the particles: for water-based magnetic fluids, 2100 A m–1 and 5.7 × 10–19 A m2 at magnetite particle synthesis temperature of 25°C and 3670 A m–1 and 4.6 × 10–19 A m2 at magnetite particle synthesis temperature of 80°C; for octane-based magnetic fluids, 2250 A m–1 and 4.1 × 10–19 A m2 at magnetite particle synthesis temperature of 25°C.

Preparation and Characterization of Water-based Magnetic Fluids

Water-based magnetic fluids (Fe 3 O 4 ) with good dispersion were synthesized by co-precipitation method in this study. The synthesis conditions for the product were studied and results showed that the particle sizes were between 10-20 nm, and the nanoparticles proved to be Nano Fe 3 O 4 . Stability tests for the water-based magnetic fluids showed that the product had better dispersion both in ethanol and water, using the PEG-4000 as the surfactant. The nanoparticles can be placed in the air for a long time, which is good for preparation of core-shell composite materials when needed.

High sensitivity side-hole fiber magnetic field sensor based on surface plasmon resonance

A high sensitivity magnetic fluid (MF) filled side-hole fiber magnetic field sensor based on surface plasmon resonance (SPR) is designed and investigated. Within the side-hole fiber, the water-based MF is injected into the two side holes, and both of the holes are coated with gold to realize the measurement of the magnetic field by using the SPR effect. The refractive index of the MF changes with different external magnetic fields, resulting in the resonant wavelength moving to other wavelengths. Furthermore, when the external magnetic field increases from 30 to 210.9 Oe, the magnetic field sensitivity can reach to 1.063 nm/Oe.