Water-based Magnetic Fluid Research Articles

CMOS-compatible plasmonic magnetic field sensor: An alternative approach using ultra-compact MIM configuration

This paper introduces a novel magnetic field sensor (MFS) that utilizes a metal-insulator-metal (MIM) waveguide integrated with a resonator structure and incorporates water-based Fe3O4 magnetic fluid. The sensor uses titanium nitride (TiN) as the plasmonic material which offers numerous advantages over conventional noble plasmonic materials. The sensor takes advantage of the tunable optical properties of the magnetic fluid and TiN to detect changes in the external magnetic field and quantify the magnetic field strength which has been demonstrated using the Finite Element Method (FEM). Our proposed MFS exhibits a high sensitivity of 11.97 pm/Oe, a narrow-band full-width half maximum of 93.66 nm, and a resolution of 8.36 × 10−4 Oe. The sensor is also compatible with complementary metal oxide semiconductor (CMOS) fabrication techniques, which enables chip-scale integration and low-cost production. The sensor can be used for various applications in navigation, military, space, healthcare, and beyond.

Viscosity Anomalies of Magnetic Fluid Stabilized by a Double Layer of Surfactant in Water

Purpose to study the temperature dependence of the viscosity of a water-based magnetic fluid.Method. Consists of measuring the dynamic viscosity of a magnetic fluid based on cobalt ferrite particles stabilized in water by a double layer of surfactant. Lauric acid (first layer) and a mixture of lauric acid and sodium dodecyl sulfate (second layer) were used as a stabilizer. Measurements were performed using a Brookfield DV-II+Pro rotational viscometer equipped with a coaxial cylinder system. The measuring system of the viscometer was thermostated using a KRIO-VT-12-1 thermostat.Results. The temperature dependences of dynamic viscosity were measured for three samples of magnetic fluid based on cobalt ferrite particles of various concentrations in the temperature range 0–90C°. The obtained temperature dependences of viscosity are radically different from the temperature dependences both predicted by known theories and experimentally observed for kerosene-based magnetic fluids. According to well-known theoretical models, the ratio of the viscosity of the magnetic fluid to the viscosity of the base medium is a certain universal function of particle concentration. Different models offer different types of this feature. But it clearly follows from them that the viscosity ratio should not depend on temperature. For magnetic fluids based on kerosene, it has been experimentally established that its relative viscosity decreases with increasing temperature. However, according to the results obtained, the relative viscosity of a water-based magnetic fluid does not decrease with increasing temperature, but increases significantly. That is, the viscosity of a water-based magnetic fluid decreases more slowly with increasing temperature than the viscosity of water.Conclusion. The observed dependencies completely contradict the known patterns, both theoretical and experimentally established for kerosene-based magnetic fluids. The results obtained may be useful for the further development of the theory of aqueous colloidal solutions with particle stabilization by a double layer of surfactants.

Water Based Mn-Zn Magnetic Fluid Heat Dissipation Capacity Testing Platform

Manganese zinc magnetic fluid is a temperature sensitive magnetic fluid that can regulate its flow behavior using temperature and magnetic fields. However, there is currently no testing platform for evaluating the heat dissipation ability of this magnetic fluid working fluid by coupling temperature and magnetic fields. This article establishes two experimental testing platforms for applying magnetic fields, namely a circulating pipeline and a temperature equalization plate. Compared with deionized water, evaluate the average temperature and heat dissipation ability of water-based manganese zinc magnetic fluid. The test results show that the heat dissipation start time of the manganese zinc magnetic fluid loop pipe is better than that of deionized water. Under the action of magnetic field (500Gs), the average temperature of the circulating pipeline decreases by 7.2% (heat source power 15W); Under the action of a magnetic field (3000Gs), the thermal resistance of the homogenizing plate (filled with 48% water-based manganese zinc magnetic fluid) decreases by about 16.7% (heat source power 140W). The water-based manganese zinc magnetic fluid working fluid exhibits better heat transfer performance than the deionized water working fluid under high heat source power. The experimental results prove that the designed water-based manganese zinc magnetic fluid working fluid heat dissipation capacity testing platform has reliable experimental quantification results.

Experimental Study on Thermal Conductivity of Water-Based Magnetic Fluid Loaded with Different Nanoparticles.

Magnetic fluids, a new type of energy transfer fluid with tunable properties, have garnered significant interest from researchers worldwide. Hybrid magnetic fluids prepared by adding different types of nanoparticles exhibit superior thermophysical properties and functional characteristics. In this paper, we prepared a water-based magnetic fluid loaded with multi-walled carbon nanotubes (MCNTs), silver (Ag), and copper (Cu) to enhance thermal conductivity. Using a transient double hot-wire method, we designed and built an experimental measurement system for the thermal conductivity of magnetic fluids with an average measurement error of less than 5%. We studied the thermal conductivity of hybrid magnetic fluids under different conditions and evaluated the advantages and disadvantages of various models, including the Maxwell model, H&C model, Tim model, Y&C model, and Evans model. Our results show that MF+MCNTs, MF+Ag, and MF+Cu nanofluids can all improve the thermal conductivity of the carrier fluid, with MF+MCNTs exhibiting the best improvement effect of 10.93%. Among the five models evaluated, the Evans model had the best predictive effect with a deviation range within 5%. This work provides theoretical and practical reference for enhancing the thermal conductivity of magnetic fluids and provides a more accurate theoretical model for calculating the thermal conductivity of hybrid magnetic fluids.

Study on the Preparation and Heat Transfer Characteristics of Temperature Sensitive Magnetic Fluid

Water-based temperature sensitive magnetic fluid and kerosene-based temperature sensitive magnetic fluid are prepared by using chemical co-precipitation method. The effects of magnetic particle concentration, magnetic field strength, and temperature on its thermal conductivity and viscosity were Studied. The results show that the thermal conductivity of the fluid is greatly increased by addition of magnetic particles. The thermal conductivity of water-based magnetic fluid with a concentration of 10% is increased 27.3% compared with that of deionized water; and the thermal conductivity of kerosene-based magnetic fluid with concentration of 10% is increased 128.8% higher than that of kerosene based-liquid. An experimental platform for the cooling loop is set up to verify the starting time and heat transfer characteristics of the developed magnetic fluid.

Various rare earth particles magnetic separation using magnetic fluid and paramagnetic liquid

Rare earth elements are usually separated by solvent extraction after several separation stages. However, the separation of particles would be possible if fine rare earth and oxide particles from a mixture of rare earth materials would exhibit a relatively high degree of liberation. Here, the novel method for separating a mixture of two kinds of artificial rare earth particles was developed using a high-gradient magnetic separator. Rare earth metals and oxides have different magnetic susceptibility, and some have high magnetic susceptibility as paramagnetic materials. In conventional magnetic separation, all paramagnetic particles are captured as magnetics. However, a mixture of rare earth particles can also be separated by increasing liquid magnetization with water-based magnetic fluid and paramagnetic liquid having higher magnetization than water. As a result, the adjacent atomic number of rare earth particles can be separated. The magnetic separation efficiencies of neighboring rare earth were compared with the conventional solvent extraction results, and it was found that magnetic separation has a relatively high efficiency for separating some rare earth elements.

Rheological Tunable Magnetic Fluids with Long-Term Stability.

Magnetic fluids have advantages such as flow ability and solid-like property in strong magnetic fields, but have to suffer from the tradeoff between suspension stability and flow resistance. In this work, a thermal/photo/magnetorheological water-based magnetic fluid is fabricated by using oleic acid-coated Fe3 O4 (Fe3 O4 @OA) nanoparticles as the magnetic particles and the amphiphilic penta block copolymer (PTMC-F127-PTMC)-based aqueous solution as the carrier fluid. Due to the hydrophobic self-assembly between Fe3 O4 @OA and PTMC-F127-PTMC, the Newtonian-like magnetic fluid has outstanding long-term stability and reversible rheological changes between the low-viscosity flow state and the 3D gel structure. In the linear viscoelastic region, the viscosity exhibits an abrupt increase from below 0.10Pa s at 20°C to ≈1.3×104 Pa s at 40°C. Benefitting from the photothermal and magnetocaloric effects of the Fe3 O4 @OA nanoparticles, the rheological change process also can be controlled by near infrared light and alternating magnetic field, which endows the magnetic fluid with the applications in the fields of mobile valves, moveable switches, buffer or damping materials in sealed devices, etc.

Water-based Fe3O4 magnetic fluid-coated Aspergillus niger spores for treating liquid contaminated with Cr(VI)

The use of magnetic biosorbents for the remediation of heavy metals has attracted increasing attention due to their ease of separation and reusability. We developed a method for preparing superparamagnetic biosorbent materials using water-based magnetic fluids. Water-based magnetic fluid-spores (WMFSs) were obtained by combining water-based magnetic fluid (WMF) with Aspergillus niger spores at ratios of 0.6:1 (WMFS1), 0.8:1 (WMFS2), 1:1 (WMFS3), 1.2:1 (WMFS4), and 1.4:1 (WMFS5). A magnetic composite material was prepared from magnetic nanoparticles and spores in a ratio of 1:1 as a control. The adsorption efficiency and separation effect of WMFS3 were significantly better than those of the magnetic composite material. The morphology and structure of WMFS3 were characterized by performing transmission electron microscopy. The results showed that Fe3O4 magnetic particles were uniformly coated on the spore surface. The superparamagnetism of WMFS3 was tested using a vibrating sample magnetometer. At pH 2.0, the maximum adsorption capacity of WMFS3 for Cr(VI) was 105 mg/g; in the pH range of 2.0–3.0, the adsorption equilibrium time of WMFS3 was 60 min. Thus, the adsorption process conformed to the pseudo-second-order kinetic model and Freundlich isotherm. Thermodynamic studies showed that the process was spontaneous and endothermic. The adsorption mechanisms of WMF3 for Cr(VI) included electrostatic, reduction, and complexation adsorption. This biosorbent material showed excellent adsorption performance for Cr(VI) and is promising for wastewater resource applications.

Investigation of the surface tension of water-based Fe3O4 magnetic fluids under magnetic field: The effect of surfactants

In this work, water-based Fe3O4 magnetic fluids were prepared and the effect of surfactants on magnetic surface tension was investigated under a constant magnetic field. Different surfactants include anionic surfactants citric acid and sodium dodecyl sulfate (SDS); nonionic surfactants polyvinyl pyrrolidone (PVP K30) and polyethylene glycol(PEG-600) were employed to modify Fe3O4 nanoparticles. After the modification, the stability of Fe3O4-SDS magnetic fluid improved greatly, with the zeta potential improved to −40.5 mV compared to Fe3O4 magnetic fluid (−22 mV) without surfactants. X-ray diffraction and Fourier transform infrared spectroscopy were employed to characterize the crystalline and the surface changes. The results showed that the surfactant was successfully coated on the surface of Fe3O4 without changing the crystallinity. The surface coverage of nanoparticles by the surfactants caused a smaller saturation magnetization than uncoated Fe3O4 nanoparticles while keeping the superparamagnetic behavior. More importantly, the surface tension of the magnetic fluid was measured by the Du Noüy ring method, and an in-depth study of the magnetization time and direction on the magnetic surface tension has been carried out. Visual characterization of the cluster structure was carried out for an in-depth analysis of the influence of the external magnetic field on magnetic surface tension.

Super stable water-based magnetic fluid as a dual-mode contrast agent

Abstract Early diagnosis of cancer has become one of the effective ways to prevent and treat cancer. At present, magnetic resonance imaging (MRI) diagnosis based on nanosized iron oxide with no toxicity and excellent biocompatibility has attracted much attention. But the poor stability of magnetic fluid (MF) is becoming more and more prominent. In view of the poor stability of MF, the dodecanethiol-poly(methacrylic acid) (DDT-PMAA) as an outer shell was prepared for the MFs (Fe3O4@DDT-PMAA MF) to improve the stability. We also compared the amount of reactants, the ratio of reactants, and the reaction temperature, and finally screened out the best reaction conditions, so as to get more stable products. The stability of the system was studied by visual observation, stability index (I), and magnetic weight change. The results demonstrated that Fe3O4@DDT-PMAA can be stable for more than 60 days. The T 1 mapping image showed that the longitudinal relaxivity (r 1) value was 6.9 mM−1 s−1 (1.5 T, room temperature), which was higher than the commercial contrast agent SHU-555 (r 1 = 2.9 mM−1 s−1), but the transverse relaxivity (r 2) value accounted for 64.48% of the commercial contrast agent Feridex (r 2 = 67.8 mM−1 s−1, 1.5 T, room temperature) because the outermost layer was encapsulated by a polymer. In addition, the imaging effect was more vivid and there was almost no background interference of T 1- and T 2-weighted images in vivo, which indicated that the Fe3O4@DDT-PMAA MF exhibited excellent potential in MRI applications.

Analysis of water conveying iron(iii)oxide nanoparticles subject to a stationary magnetic field and alternating magnetic field

Present physical models describe the effects of magnetic field-dependent viscosity on unsteady water-based Fe3O4 magnetic fluid flow over a rotating and vertical moving disk. The first model represents the effect of magnetic field-dependent viscosity in the presence of a stationary magnetic field and the second model demonstrates the presence of an alternating magnetic field. However, the previous investigation of water conveying iron(iii)oxide nanoparticles flow in a rotating system is not available on the comparison of spatially variable magnetic field and alternating magnetic field on the velocity distribution in the presence of rotating and vertical moving disk. The variations in the viscosity due to the alternating magnetic field depend not only on the strength of the magnetic field but also on the frequency of the alternating magnetic field. This study might have a significant role in the improvement of the sealing of rotating shaft and study of magnetic field dependent viscosity of water conveying iron(iii)oxide nanoparticles are important for hyperthermia in the treatment of cancer disease. An alternating magnetic field generates higher friction on the disk as compared to the stationary magnetic field.

Effect of Fe3O4 concentration on 3D gel-printed Fe3O4/CaSiO3 composite scaffolds for bone engineering

In this study, porous calcium silicate (CaSiO3) scaffolds were prepared by 3D gel-printing (3DGP) method and Fe3O4 water-based magnetic fluids (WMFs) were prepared by phacoemulsification compound chemical coprecipitation method. Fe3O4 WMFs were coated on CaSiO3 scaffolds surface to prepare Fe3O4/CaSiO3 composite scaffolds. The effect of WMFs with different Fe3O4 concentrations on porous CaSiO3 scaffolds was studied. The composition and morphological characteristics of porous scaffolds were analyzed by using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis. The magnetic properties were tested by vibrating sample magnetometer (VSM). The stability of Fe3O4 WMFs coatings and the degradability of composite scaffolds were tested by immersing them in simulated body fluid (SBF). The results show that when Fe3O4 concentration was 5.4% (w/v), the composite scaffolds had the highest saturation magnetization of 69.6 emu/g and the best stability in dynamic SBF. It is obviously that Fe3O4 WMFs coatings can be used for bone tissue engineering scaffolds repairing.

Heavy metal removal with magnetic coffee grain.

The presence of heavy metals in environmental waters having an important place in the industrial waste is a major threat to viability. Heavy metals are transported to humans through the ecological cycle, damaging many tissues and organs. In recent years, agricultural and food waste can be used to remove heavy metals. At the present study, magnetically modified coffee grains which are alternative to conventional particle systems were prepared and heavy metal removal performances were investigated. The coffee grains used were magnetically modified by contact with water-based magnetic fluid. Magnetically modified coffee grains were characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis and electron spin resonance (ESR). Adsorption studies are made with four different heavy metal ions, namely Cu(II), Pb(II), Cd(II) and Zn(II). Adsorption isotherms were determined and heavy metal removal performance of magnetic coffee grains were investigated from synthetic waste water.

Temperature Dependences of the Magnetic Susceptibility of Water-Based Magnetic Fluids

This paper presents the results of a study of the temperature dependences of the magnetic susceptibility of water-based magnetic fluids (magnetic colloids) with magnetite particles stabilized by their electrostatic interaction. The average size of dispersed particles was 8 nm, and the volume concentration of particles in the selected samples under study was 1.4% and 1.6%. The investigations were carried out over a wide temperature range. The temperature dependence of the susceptibility, for the first time, was obtained in the region of the colloidal phase transition under supercooling of the dispersion medium (water). Significant differences were found between the temperature dependences of the magnetic susceptibility of such magnetic fluids, where as similar dependences have been found for the susceptibility of magnetic hydrocarbon-based fluids. The observed behavior of such dependences near the water phase transition temperature is determined by the changes in the water phase state, heat release and structuring of the colloid as a result of water crystallization. Moreover, it is suggested that a certain impact on the dependence behavior in the region of the colloidal solidification temperature can also come from the process of blocking the Brownian degrees of freedom of a small fraction of large dispersed particles. It is concluded that the observed maxima in the investigated susceptibility temperature dependences in the lower temperature region are due to magnetic transformations in the colloidal zones formed at the solidification front of the disperse medium with a dense packing of single-domain colloidal particles.

Laser Optoacoustic Method for Measurement of Light Extinction Coefficient and Investigation of Its Spatial Distribution in Colloidal Media

In the present work, the method which allows investigating the spatial distribution of light extinction coefficient in colloidal media is experimentally realized. The proposed method is based on the dependence of temporal profiles of excited OA-signals on the absorption and extinction coefficients of the studied medium. Water-based and kerosene-based magnetic fluids with volume content of magnetite particles in the range 0.35–3.5 % were studied as an example of the medium with spatially non-uniform optical properties. The capability of the reconstruction of the one-dimensional spatial distribution for the light extinction coefficient in the investigated media is demonstrated. It was shown that the relative change of the extinction coefficient with depth depends on volume concentration of magnetite particles, type of acoustical boundary and properties of carrier liquids. In the case of acoustical rigid boundary of magnetic fluid, an additional induced anisotropy occurs, which leads to increasing of the light extinction coefficient with depth in comparison with acoustical free boundary of fluid.

Research on the effect of different surfactants on fluidity of water-based magnetic fluid

In order to expand the range of applications of magnetic fluid, water-based magnetic fluid with different surfactants is synthesized and the property of fluidity has been intensively studied. Three kinds of surfactants (sodium dodecyl sulfate, oleic acid and polyethylene glycol) are used to synthesize three different magnetic fluids with the same magnetic nanoparticles and carrier liquid. Their microstructures and thermal stability of magnetic nanoparticles coated with different surfactants are characterized by transmission electron microscopy and thermogravimetric analysis. Results show that water-based magnetic fluid with sodium dodecyl sulfate agglomerates more obviously while magnetic fluid with polyethylene glycol keeps good dispersion. In addition, magnetic measurements reveal that all these magnetic fluids exhibit typical superparamagnetic behavior and the magnetic fluid using polyethylene glycol as surfactant maintains the specific saturation magnetization of ∼60 emu g−1. What is more, shear stress and viscosity of these three magnetic fluids are measured by the rotational rheometer. The shear stress increases with the increasing shear rate while the viscosity decreases with the increasing shear rate. This indicates that water-based magnetic fluid has the property of pseudo-plastic fluid. What is more, the viscosity of the magnetic fluid with polyethylene glycol as surfactant is lower than other two magnetic fluids and is prone to reach a steady state at a low shear rate in a short time.

Structural characterization of concentrated aqueous ferrofluids

Structure characterizations of concentrated water-based magnetic fluids stabilized by oleic and lauric acids were done by means of small-angle neutron scattering (SANS) and complemented by dynamic light scattering and magnetization analysis. Stability of ferrofluids with time against sedimentation was concluded despite the presence of aggregates in solutions. Differences in the average sizes of individual polydisperse magnetite nanoparticles coated with surfactants and their aggregates were revealed. Structural parameters obtained from SANS have been confirmed by magnetogranulometry data. The comparative analysis of the aggregation and its change upon dilution is made basing on the data of SANS and dynamic light scattering techniques.

Experimental study on contribution of clustering structure to surface tension change of magnetic fluid under magnetic field

When a magnetic field is applied to a magnetic fluid for long time, inner magnetic particles form clustering structure, and this clustering structure grows from time by time. The surface tension of magnetic fluid is possible to change with the influence of this growth of clustering structure. For long time use of magnetic fluid application, it is important to clarify the contribution of clustering structure to surface tension change of magnetic fluid after application of magnetic field. In this study, the surface tension of water-based and kerosene-based magnetic fluid was measured by maximum bubble pressure method, and we attempted to detect the contribution of the clustering structure to the surface tension change of the magnetic fluid after the application of magnetic field. To investigate the contribution of the clustering structure, magnetic field is applied for certain time to magnetic fluid for the growth of the clustering structure in magnetic fluid before the surface tension measurement. We defined this time as the cluster growing time in this study, and the cluster growing time was set to 2, 60 and 120 min. The magnetic field intensity was 68 mT by using permanent magnets. The result shows that we detected the contribution of the clustering structure to the surface tension change by applying magnetic field in only the case of the diluted water-based magnetic fluid. In contrast, because the clustering structure is difficult to form in kerosene-based magnetic fluid due to the difference of the surfactant structure around magnetic particle, the surface tension change by applying magnetic fluid is hardly different with the cluster growing time.

Preparation and Application of Complexes of Lignosulfonic Acids with Iron Cations

Lignosulfonates and lignosulfonic acids are the main commercial product on the world market of lignins. They are used in metallurgy, mining, concrete production, and agriculture. The review presents the results of studying the structure and properties of lignosulfonates, the synthesis and application of complexes of lignosulfonic acids with iron cations. Lignosulfonates possess unique physicochemical properties that other types of lignins do not have. They form chelate complexes when interacting with iron cations and other biogenic metals. These complexes can be used in agriculture to eliminate plant chlorosis. Chlorosis is particularly manifests itself on about 30 % of the world’s farmlands with high calcium carbonate content. It is possible to change the properties of lignosulfonic acids and lignosulfonates intentionally by theirmodification. Nitration and nitrosation enhances the complexing properties. This is due to the possibility of the formation of chelate complexes with ironcations. Iron chelates with nitrated and nitrosated lignosulfonates exhibit strong antichlorosis properties. Their use allows normalizing the content of chlorophyll in photosynthetic structures completely. In the synthesis of water-based magnetic fluids lignosulfonates modified by nitration and nitrosation exhibit the properties of a peptizing agent that promotes the formation of stable magnetic fluids of magnetite type. Lignosulfonates have a strong influence on the synthesis of magnetoactive compounds by the partial oxidation of iron (II) cations using chromate ions or silver ammonium hydroxide. In the former case, a compact magnetoactive compound is formed; and in the second – a magnetic fluid (if condensation is carried out in the presence of tetraalkylammonium hydroxides).For citation: Khabarov Yu.G., Veshnyakov V.A., Kuzyakov N.Yu. Preparation and Application of Complexes of Lignosulfonic Acids with Iron Cations. Lesnoy Zhurnal [ForestryJournal], 2019, no. 5, pp. 167–187. DOI: 10.17238/issn0536-1036.2019.5.167

Application of Amorphous Nanoparticle Fe-B Magnetic Fluid in Wastewater Treatment

Amorphous magnetic particles demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. In this report, magnetic crystalline Fe3O4 and amorphous Fe-B nanoparticles were successfully synthesized and introduced to prepare water-based magnetic fluids. The Fe3O4 and Fe-B particles are homogeneous nanoparticles with an average particle size of [Formula: see text][Formula: see text]nm. The shape of Fe-B amorphous nanoparticles is regular. The saturation magnetizations of Fe-B and Fe3O4 particles are 74 emu/g and 69 emu/g. The use of crystalline Fe3O4 magnetic fluid and amorphous Fe-B magnetic fluid in advanced treatment of high concentration organic wastewater was presented. The removal rate of chemical oxygen demand by using the amorphous Fe-B magnetic fluid reached 96%, about 16% higher than that by using the Fe3O4 magnetic fluid. Moreover, compared with Fe3O4 magnetic fluid, the treatment results demonstrate that the decolorizing effect by using the amorphous Fe-B magnetic fluid was 20% higher. It has been found that the nano-size Fe-B particles in magnetic fluid with amorphous structure led to high efficiency of wastewater treatment due to the catalytic activity.