Magnetic Hybrid Research Articles

Baffles’ size impact on the heat transfer and second law features of magnetic hybrid nanofluid within a hexagonal-shaped porous domain

In this study, entropy production (EnG) and natural convection (NC) of magnetic Cu-TiO2-water hybrid nanoliquid in a hexagonal-shaped porous enclosure equipped with two straight hot baffles placed at two sides have been scrutinized. The 4 side walls are considered as adiabatic walls and top and bottom ones are considered as cold walls. The behaviour of hybrid nanofluid (HN) arising from temperature difference between hot baffles (TH) and cold walls (TC) at various Rayleigh and Darcy numbers, porosity of porous medium and different baffles’ length is perused by a numerical simulation method. Governing equations and their related boundary conditions formulated in non-dimensional type with exchangeable baffles’ length using Forchheimer-Brinkman extended Darcy pattern for permeable blocks are solved numerically via FEM. The results reveal that if porosity increases from 0.5 to 0.8, the Nuavg will decrease by 13%. Besides, if the fin length increases from L/16 to L/4, the Nuavg increases up to 86%. This investigation is important for the cases in which the heat transfer enhancement is the main concern.

Improving the thermal efficiency of parabolic trough collector equipped with combined turbulator containing two-phase magnetic hybrid nanofluid

A parabolic trough collector (PTC) is a beneficial device for collecting heat from the sun. Increasing the efficiency of these devices in recent years has attracted the attention of researchers to a significant extent. The present study has been carried out to increase the thermal efficiency in the PTC by using a new geometric form of compound turbulator and magnetic hybrid nanofluid. In this study, MWCNT-Fe3O4-Cu/Water magnetic hybrid nanofluid is prepared using a two-step method. Then its thermophysical properties are used as a working fluid in the present study. The absorber tube of the studied PTC is equipped with three different geometric shapes of the compound turbulator (Case A, B, and C). Case A and B geometric shapes differ in their vertical or horizontal position. Therefore, a circular coil is wrapped around the compound turbulator in Case C. Magnetic hybrid nanofluid is simulated in the Reynolds range of 18,000 to 42,000 and volume fraction 1.25 and 2.25% of nanoparticles considering the two-step method. The results show that using a magnetic hybrid nanofluid with three MWCNT, Fe3O4, and Cu nanoparticles in the PTC always causes the heat transfer rate to be higher than the water. Adding the compound turbulator has caused, unlike the laminar flow in which the movement of fluid particles is in the form of layers, the fluid particles in the direction perpendicular to the movement path are also mixed and create a random movement. The analyzed results of the thermal–hydraulic performance evaluation criteria describe that in this study, using the compound turbulator in the absorber tube of the PTC always has a favorable role. Finally, the maximum exergy efficiency and energy efficiency are related to the absorber tube equipped with a combination of a compound turbulator and circular coil.

New approach for hybrid electromagnetic phase of hybrid optical fibers

In this article, we construct optical hybrid magnetic surfaces of -magnetic optical fibers by using hybrid tangent electromagnetic flow -density with a hybrid frame. Also, we obtain new optical hybrid conditions of the hybrid tangent electromagnetic -phase with hybrid optical fields by the Landau Lifshitz model. We illustrate hybrid tangent electromagnetic Lorentz -flux for hybrid fields with a hybrid Landau Lifshitz approach by the axial optical density of hybrid frame. Finally, we also analyzed optical density and the magnetic hybrid density lines for different angular velocities in hybrid frame.

Synthesis and Characterization of Hydrogel Droplets Containing Magnetic Nano Particles, in a Microfluidic Flow-Focusing Chip.

Magnetic hybrid hydrogels have exhibited remarkable efficacy in various areas, particularly in the biomedical sciences, where these inventive substances exhibit intriguing prospects for controlled drug delivery, tissue engineering, magnetic separation, MRI contrast agents, hyperthermia, and thermal ablation. Additionally, droplet-based microfluidic technology enables the fabrication of microgels possessing monodisperse characteristics and controlled morphological shapes. Here, alginate microgels containing citrated magnetic nanoparticles (MNPs) were produced by a microfluidic flow-focusing system. Superparamagnetic magnetite nanoparticles with an average size of 29.1 ± 2.5 nm and saturation magnetization of 66.92 emu/g were synthesized via the co-precipitation method. The hydrodynamic size of MNPs was changed from 142 nm to 826.7 nm after the citrate group's attachment led to an increase in dispersion and the stability of the aqueous phase. A microfluidic flow-focusing chip was designed, and the mold was 3D printed by stereo lithographic technology. Depending on inlet fluid rates, monodisperse and polydisperse microgels in the range of 20-120 μm were produced. Different conditions of droplet generation in the microfluidic device (break-up) were discussed considering the model of rate-of-flow-controlled-breakup (squeezing). Practically, this study indicates guidelines for generating droplets with a predetermined size and polydispersity from liquids with well-defined macroscopic properties, utilizing a microfluidic flow-focusing device (MFFD). Fourier transform infrared spectrometer (FT-IR) results indicated a chemical attachment of citrate groups on MNPs and the existence of MNPs in the hydrogels. Magnetic hydrogel proliferation assay after 72 h showed a better rate of cell growth in comparison to the control group (p = 0.042).

An explorative study of biotin functionalized magnetic hybrid particles

In the field of biomedicine, magnetic particles have a significant role, owing to their low production cost and the possibility to control their characteristics, like size, shape and ability to tailor the cellular interactions, in order to promote their involvement in the development of novel therapies. Biofunctionalisation is by far, the most studied aspect, since it provides multifunctionality (e.g. increased biocompatibility and biodistribution, or cytotoxicity and toxic selectivity mechanisms). In this framework, this explorative study is devoted to development and characterization of the biotin functionalized magnetic hybrid particles, comprised of a hydrophilic magnetite, synthesized by co-precipitation, in the presence of Pluronic F-127, and a biotinylated N-palmitoyl chitosan matrix. Microscopy images, corroborated with FT-IR spectroscopy results and thermal analysis data confirmed the hybrid structure - multiple magnetite crystallites entrapped in the biofunctionalized polymer matrix, whilst the magnetic assays indicated adequate magnetic properties for biomedical applications. In vitro investigations highlighted that biotin functionalized magnetic hybrid particles are biodegradable and biocompatible, whilst hemocompatibility assessment revealed no significant modifications of blood coagulation times. To conclude, biotin functionalized magnetic hybrid particles exhibited promising assets for future biomedical applications as drug delivery systems or theranostic agents.

Amine Functionalized Magnetite GO‐MWCNT as an Efficient 3D Hybrid Aerogel for the Remediation of Copper(II) from Wastewater: Box‐Behnken Design Optimization

AbstractThis work focuses on the sequestration of Cu(II) from aqueous environment owing to the risks posed to human health. A magnetic hybrid aerogel (mGO‐TETA‐MWCNT) was synthesized by one‐pot self‐assembly of magnetic graphene oxide (mGO) and multiwalled carbon‐nanotubes (MWCNT) post functionalization with triethylenetetramine (TETA) through hydrothermal reduction. The prepared adsorbent was characterized and employed for efficient removal of Cu(II). The aerogel, mGO‐TETA‐MWCNT presented maximum adsorption capacity (Qmax) of 232.22 mg g−1 at Box‐Behnken design optimized conditions: pH 5.6, time 36.7 min, and concentration 999.7 mg L−1. The Brouers‐Sotolongo (BS) isotherm and Fractal‐like pseudo‐second‐order (FLPSO) kinetic model fitted best representing heterogeneity of the hybrid adsorbent. The presence of interferent metal ions(Ni(II), Pb(II), Cd(II), Zn(II)) showed negligible effect on the selective sorption of Cu(II). The prepared adsorbent could be regenerated upto five cycles (>95 % removal) when eluted using 0.5 m HCl. The aerogel was successfully utilized to remove Cu(II) from wastewater, river‐water, and groundwater.

MOF-derived La–ZnFe2O4@Fe3O4@carbon magnetic hybrid composite as a highly efficient and recyclable photocatalyst for mycotoxins degradation

During the planting, storage, or feeding stages, foodstuffs can be easily polluted by mycotoxins such as aflatoxin B1, patulin and zearalenone, which are produced by pathogenic microorganisms. Therefore, the removal of these mycotoxins constitutes an active area of research. Herein, we used an Fe/Zn metal–organic framework (MOF) as a precursor to fabricate a novel La–ZnFe2O4@Fe3O4@carbon magnetic hybrid composite via a simple absorption–pyrolysis method and explored its photocatalytic performance in the degradation of aflatoxin B1, patulin, and zearalenone. La–ZnFe2O4@Fe3O4@carbon can effectively degrade 98.37% of aflatoxin B1, outperforming Fe3O4@carbon (69.57%) and ZnFe2O4@Fe3O4@carbon (91.39%). Moreover, La–ZnFe2O4@Fe3O4@carbon exhibits superior stability and excellent photocatalytic activity for the degradation of patulin (97.35%) and zearalenone (98.52%). Transient photocurrent response measurements reveal that the La doping and the combination with ZnFe2O4 highly promote the separation of photoinduced electron–hole pairs on Fe3O4@carbon. An electron spin resonance analysis suggests that ·OH and ·O2− are the main active radicals during the photodegradation process. Thus, a plausible photodegradation pathway for the degradation of mycotoxins produced by pathogenic microorganisms is proposed.

Adsorption mechanism and removal efficiency of magnetic graphene oxide-chitosan hybrid on aqueous Zn(II)

Magnetic architecture incorporating graphene-chitosan has demonstrated encouraging application in wastewater purification. Herein, a ternary hybrid based on Fe3O4-graphene oxide-chitosan (MGOCS) was fabricated and employed as adsorbent to remove aqueous Zn(II). The adsorption mechanism was intensively inspected based on the hard and soft acid base (HSAB) theory. Results present, MGOCS removes 96.73 % of Zn(II) in 38 min, with adsorption quantity 386.92 mg·g−1. Electron transfer and energy lowering determined by the HSAB theory illuminate the plausible adsorption sites in each component of MGOCS: O2− in Fe3O4, -C(=O)NH-, -NH2 in chitosan and -OH in graphene oxide. The exploration was upheld by spectroscopic analyses. Thereby, following adsorption mechanism was proposed. (1) ZnO bond was formed featured by electron donation. (2) The -C(=O)NH- group formed via amidation between graphene oxide and chitosan contributes to Zn(Π) uptake. This work may inspire the development of efficient adsorbent based on magnetic graphene-chitosan for wastewater remediation.

Synthesis of green magnetic hybrid adsorbents and their application for reactive red methyl 4 BL dye removal

Synthesis of green magnetic hybrid adsorbents and their application for reactive red methyl 4 BL dye removal

Dynamic tuning of phase change interfacial thermal energy transport in hybrid nano-enhanced phase change materials by a non-uniform magnetic field

The present study aims to explore the synergistic enhanced phase change heat transfer behavior between magnetic field and hybrid nanoparticles under the consideration of non-Newtonian effects. The visualized experiments are conducted using thermochromic liquid crystal technology to extract the interconnection between dynamic phase change interface evolution and temperature change of hybrid nano-enhanced phase change material (HNEPCM), and thermocouples to measure temperature data inside the latent heat thermal energy storage unit. The magnetic field and hybrid nanoparticles synergistic mechanism is then further revealed based on the analysis of liquid phase fraction, Nusselt number, energy storage and energy storage efficiency. The results show that under magnetic field, the magnetic nanoparticles form a “thermal conductivity layer” at the solid-liquid interface, while the non-magnetic nanoparticles in the liquid phase region drive the phase change heat transfer to proceed. The non-Newtonian effect induced by high concentration of HNEPCM can weaken the convection intensity. The competition between natural convection and magnetic viscous effect under magnetic field is induced at different hybrid ratios of magnetic and non-magnetic nanoparticles. High hybrid ratios (R = 1.0, 1.5 and 2.0) will be more favorable to satisfy the high thermal conductivity requirement in the liquid phase region and the dynamic adjustment condition at the phase change interface. Under a non-uniform magnetic field, 1 wt.% HNEPCM with R = 1.0 is considered as the optimum strategy with better energy storage performance and higher magnetic field effect.

Fe3O4@MOF hybrid for supercilious recovery of Au(III) and Pd(II) from e-waste and spent as catalysts for cyclohexane oxidation

Improving the economic viability of the most successful precious metal catalysts is one of the significant challenges in renewable energy production. We designed a magnetic hybrid material based on Cu-pPDA MOF and Fe3O4 nanosphere for selective recovery of Au(III) and Pd(II) from e-waste. Owing to its superior maximum adsorption capacities of 1450 and 1236 mg/g for Au (III) and Pd(II), respectively, at 45 °C with the pH of 3 and 1, the sorbed samples were converted into catalysts through an annealing process to obtain carbon supported FeAu and FePd nanoparticles catalysts (FeAu/C and FePd/C). Furthermore, these catalysts were applied for the oxidation of cyclohexane and resulted that FeAu/C catalyst exhibited higher conversion rate of cyclohexane (93.2%) than FePd/C catalyst (88.3%). Mechanistic investigations suggested that synergetic effect of Fe and Au on the supported carbon promoted better bond cleavage of the O–O bond in cyclohexyl hydroperoxide, a crucial intermediate species in the oxidation of cyclohexane. This study provides an alternate approach for the sustainable preparation of highly desired catalytic materials.

Rational design of stimuli‐responsive magnetic polymer hybrid (nano)materials

AbstractCombining organic and inorganic materials is a fascinating strategy to produce hybrid materials that combine the advantages of both polymeric and inorganic materials. Among the various types of organic–inorganic hybrids, stimuli‐responsive magnetic polymer hybrids (RMPHs) are particularly promising materials for a wide variety of applications. While the magnetic properties are generally provided by the presence of magnetic nanoparticles, such as iron oxide nanoparticles, the polymeric compound brings the stimuli‐responsiveness, e.g. responsiveness to pH, temperature, redox reaction or irradiation. Furthermore, as the chemical structure and architecture of the polymeric materials are diverse and easily tunable, stimuli‐RMPHs have found applications in various domains, including catalysis, biotechnology, (bio)imaging and cancer therapy. Given the importance of the hybrids' shape and morphology for the targeted application, this review presents the possible synthetic strategies to rationally design stimuli‐RMPHs of various morphologies ranging from nanometric core–shell structures to nanogels, microgels and membranes. © 2023 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.

Thermosolutal hydromagnetic mixed convective hybrid nanofluid flow in a wavy walled enclosure

This paper deals with the effects of an inclined magnetic field and hybrid nanoliquid on thermosolutal mixed convection in a partially heated wavy walled enclosure. Two distinct flow features are considered by performing a variant of heating and concentrating locations in both the vertical walls. The upper border is in motion with the same speed in the right direction. The governing Navier–Stokes equations are modeled to describe thermosolutal phenomena. These equations are solved by reconstructing a recently developed compact scheme. Results are displayed in terms of streamlines, isotherms, iso-concentrations, average Nusselt and Sherwood numbers to evoke the thermosolutal phenomena for various physical parameters. Furthermore, the significance of well-defined parameters influencing the fluid rotation and thermosolutal transfer, namely Richardson number (0.1≤Ri≤10), Lewis number (1≤Le≤5), thermal Grashof number (GrT=104), Buoyancy ratio (−1≤N≤1), Hartmann number (0≤Ha≤40), orientation angle of magnetic field (00≤γ≤900) and solid volume fraction (0.0≤ϕhnp≤0.04) of the hybrid nanofluid are performed generously. Results reveal that the heating areas and the angle γ play a vital role in flow topology, thermal and solutal transport inside the wavy enclosure. In addition, thermal and solutal transfer enhancement are noted with increasing values of γ while thermal and solutal transfer reduction are noted with the increasing Hartmann number. We have noticed that for the change in the concentration of Cu-Al2O3/water hybrid nanofluid (ϕhnp) from 1% to 4%, average Nusselt number is enhanced by 7.46% in Case-I and 5.09% in Case-II whereas average Sherwood number is decreased by 2.42% and 1.58% for Case-I and Case-II respectively. It is also concluded that the single nanofluid is more effective than the hybrid nanofluid in the case of thermosolutal transport phenomena.

Modeling of Uneven Air Gap Magnetic Field for Disc Planetary Permanent Magnet Machine With Segmented Gap Halbach Array

A new analytical magnetic circuit hybrid model (AMCHM) is proposed to predict uneven air gap magnetic field for disc planetary permanent magnet machine (DP-PM machine) with segmented gap Halbach array. The 3-D model is transformed into 2-D model by using radial sectors-of-rings division method and coordinate transformation. The 2-D magnetic field model is obtained by analytical method, and the magnetic equivalent circuit (MEC) model is used to consider the leakage flux loops with and without magnetic coupling. Finally, the analytical models of uneven air gap magnetic field and torque are obtained. The results obtained from proposed model are in good agreement with those of 3-D finite element method (FEM), which verifies the validity of AMCHM. Compared with 3-D FEM model, the AMCHM is convenient for the analysis and optimization of structure parameters, and it improves the calculation efficiency. The research results can be utilized for the research on structural optimization and power analysis.

A Brillouin light scattering study of the spin-wave magnetic field dependence in a magnetic hybrid system made of an artificial spin-ice structure and a film underlayer

We present a combined Brillouin light scattering (BLS) and micromagnetic simulation investigation of the magnetic-field-dependent spin-wave spectra in a hybrid structure made of permalloy (NiFe) artificial spin-ice (ASI) systems, composed of stadium-shaped nanoislands, deposited on the top of an unpatterned permalloy film with a nonmagnetic spacer layer. The thermal spin-wave spectra were recorded by BLS as a function of the magnetic field applied along the symmetry direction of the ASI sample. Magneto-optic Kerr effect magnetometry was used to measure the hysteresis loops in the same orientation as the BLS measurements. The frequency and the intensity of several spin-wave modes detected by BLS were measured as a function of the applied magnetic field. Micromagnetic simulations enabled us to identify the modes in terms of their frequency and spatial symmetry and to extract information about the existence and strength of the dynamic coupling, relevant only to a few modes of a given hybrid system. Using this approach, we suggest a way to understand if the dynamic coupling between ASI and film modes is present or not, with interesting implications for the development of future three-dimensional magnonic applications and devices.

Investigation into the effect of twisted tape on the thermo-hydraulic performance and entropy generation of turbulent flow of mono and hybrid magnetic nanofluids inside a parabolic solar collector absorber tube by applying two-phase analysis

This research study examines the impact of applying a twisted tape on thermo-hydraulic performance as well as entropy generation related to the turbulent flow of mono and hybrid magnetic nanofluids inside a parabolic solar collector (PSC) absorber tube. In this study, two-phase water/multi-walled carbon nanotubes (MWCNTs) nanofluid and two-phase water/MWCNT-iron oxide nanofluid having the 1% volume fraction (VF) are applied as the working fluid. To model two-phase flow, the mixture model standard k-ε turbulence model and QUICK algorithm are utilized. This research study is implemented for diverse Reynolds numbers of 6000 to 24000 and some twisted tape's pitch ratios including 0.25, 0.50, and 0.75. In addition, the standard k-ε turbulence model is then applied for modeling the turbulent flow. The obtained results obtained by the numerical study demonstrate that using the twisted tape in solar collectors could improve thermo-hydraulic performance in comparison to the solar collector with no particular twisted tape. Also, the considered HT related to the collector having twisted tape is more than that without twisted tape in all cases, i.e., thermo-hydraulic performance coefficient is always greater than 1. The results reveal that using magnetic hybrid nanofluid leads to better thermal performance than mono nanofluid. Finally, the entropy generation is reduced with the Reynolds number as well as the pitch ratio of the twisted tape. The highest value in PEC surge was about 27% owing to using of magnetic hybrid nanofluid, while for simple nanofluid, it was 22%. According to this case, the use of magnetic hybrid nanofluid is recommended.

Heat energy performance for radiated wall jet stream of magnetic hybrid nanofluid under strong suction

The traditional Merkin and Needham wall jet issue was investigated for a copper-titanium dioxide incorporating magnetic field and heat production or heat absorption implications. Further, suction/injection and radiation effects are also considered. Employing correspondent alterations, the central equations were modified as non-linear ordinary differential equations which resolved quantitatively in favour of the hybrid nanofluid circulation and heat allocation that use the shooting approach. Consequently, we discover equations for the decreased layer resistance coefficient along with a lower Nusselt number. The analysis presented that the velocity of fluid enhances with increment in moving stricture, while it can be lowered via higher estimation of velocity slip stricture. The layer resistance coefficient is lowered via the velocity slip factor, whereas it increased for Cu-nanoparticle volume fraction. When there is a magnetic polarity and heat flux present, nanofluid transfers heat more slowly than hybrid nanofluid.

Seebeck-driven transverse thermoelectric generation in magnetic hybrid bulk materials

Seebeck-driven transverse thermoelectric generation in magnetic/thermoelectric hybrid materials (STTG) has been investigated in all-bulk hybrid materials. Transverse thermopower in a ferromagnetic Co2MnGa/thermoelectric n-type Si hybrid bulk material with adjusted dimensions reaches 16.0 μV/K at room temperature with the aid of the STTG contribution, which is much larger than the anomalous Nernst coefficient of the Co2MnGa slab (6.8 μV/K). Although this transverse thermopower is smaller than the value for previously reported thin-film-based hybrid materials, hybrid bulk materials exhibit much larger electrical power owing to their small internal resistance. This demonstration confirms the validity of STTG in bulk materials and clarifies its potential as a thermal energy harvester.

Multiple Solutions and Stability Analysis of Magnetic Hybrid Nanofluid Flow Over a Rotating Disk with Heat Generation

This study highlights the hybrid Fe3O4-CoFe2O4/H2O ferrofluid flow and heat transfer with the effects of linear heat generation, magnetic field and suction on a rotating disk. Using the similarity transformation, the mathematical model is simplified and reduced to a similarity set of equations. The bvp4c solver is used for computational analysis as well as the stability analysis procedure. The present model is successfully validated with previous results, and also verified with the fulfillment of the asymptote profiles. Triple solutions are observed within a limited range of testing parameters. The flow progress of Fe3O4-CoFe2O4/H2O is reduced when some changes made by varying the magnetic and suction parameters while a reverse result is obtained for the third solution. Only the suction parameter boosts the thermal progress of Fe3O4-CoFe2O4/H2O. The stability analysis surprisingly shows that two of the solutions have positive smallest eigenvalues and align with the physical results.

Synergism of adsorption and ROS-dominated catalytic oxidation in activating peroxymonosulfate by magnetic hybrid MOFs for selective removal of organophosphorus pesticides

Selective removal organic pollutants using heterogeneous catalytic system via peroxymonosulfate (PMS) activation has drawn intensive interest in water purification. Herein, a core–shell magnetic composite (MZU) having a double-layer of two kinds of MOFs (ZIF-67 and UiO-66) was prepared with Fe3O4 as the core. To present the selective removal of organophosphorus pesticides (OPPs), phenylphosphonic acid (PPOA) was selected as the target pollutant and its removal rate by MZU/PMS system achieved near 100 % within 30 min. The resultant MZU exhibited robust activation of PMS with reactive oxygen species (ROS) including SO4−, OH and 1O2, and efficient adsorption performance for produced phosphate during the degradation process. Attractively, the degradation rate constant of PPOA was significantly higher than that of the other five OPPs in a mixed solution, depending on the strong interaction between PPOA and MZU. This study constructs a fascinating strategy with efficient synergy adsorption and PMS-activation for selective removal of target pollutants in a complex water system.