γ-Fe2O3 Magnetic Nanoparticles Research Articles

A macroscopic magneto-optical response resulting from local effects in ferronematic liquid crystals.

This study investigates the magneto-optical response of liquid crystals (LCs) with planar anchoring in the presence of γ-Fe2O3 magnetic nanoparticles (MNPs). This research demonstrates the formation of novel magnetic composite chains of LCs wrapped around γ-Fe2O3 MNP chains within the LC matrix under an applied magnetic field. These composite chains exhibit a distinct magneto-optical response, characterized by changes in birefringence and dichroism as the magnetic field direction is altered. Based on experimental findings, a two-subsystem model and an effective volume fraction of composite chains are proposed to describe the magneto-optical behavior of the γ-Fe2O3 MNP-doped LCs. The first subsystem comprises the LC matrix, which retains its inherent anisotropic optical properties and does not respond to the applied magnetic field. The second subsystem consists of the magnetic composite chains, which exhibit a distinct magneto-optical response due to their rotational alignment with the magnetic field. The difference in absorbance, 2αdd, which corresponds to dichroism, decreases with increasing magnetic field angle Θ, indicating a corresponding change in dichroism. This interplay between the two subsystems leads to the macroscopic magneto-optical response observed in the γ-Fe2O3 MNP-doped LCs. Due to the stability of the composite chains, the magneto-optical response is stable and can be reversed.

Ruthenium(III) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles: A new heterogeneous nanocatalyst for efficient oxidation of hydrocarbons with tert-butyl hydroperoxide

In the present work, an unsymmetrical salen-type ruthenium(III) complex, Ru(salenac)Cl, where the unsymmetrical tetradentate Schiff base H2salenac = salicylideneiminoethyliminopentane-2-one, was synthesized and anchored on the surface of aminopropyl-functionalized silica-coated γ-Fe2O3 magnetic nanoparticles. The characterization of the resulting γ-Fe2O3@SiO2@APTES@Ru(salenac)Cl nanoparticles was performed using XRD, FT-IR, VSM, TGA, ICP, TEM, BET, SEM and EDX methods. The prepared γ-Fe2O3@SiO2@APTES@Ru(salenac)Cl magnetic nanoparticle was successfully employed as an efficient heterogeneous nanocatalyst for alkenes epoxidation and alkanes oxidation with tert-butyl hydroperoxide (tert-BuOOH, 70 % aqueous solution) as oxidant in acetonitrile at ambient temperature. In the mentioned catalytic system, the intended products were obtained with good to excellent yields along with high selectivity. The heterogeneous γ-Fe2O3@SiO2@APTES@Ru(salenac)Cl nanocatalyst can be recovered easily using an external magnet and recycled six times with no notable decrease in catalytic activity. Moreover, FT-IR, XRD, SEM and EDX techniques were used to characterize the recovered γ-Fe2O3@SiO2@APTES@Ru(salenac)Cl nanocatalyst and it was demonstrated that the catalyst maintained its structure intact following the recovery process.

A novel magnetized bio-solid phase extractor for the preconcentrations of Hg(II), Ni(II) and Zn(II) from foods

Herein, Agaricus augustus, a mushroom, loaded on γ-Fe2O3 magnetic nanoparticles was developed as a biosorbent for the simultaneous preconcentrations of trace levels of Hg(II), Ni(II), and Zn(II)) in tap water, beverages, and some food samples prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The experimental factors affecting the extraction performance were carefully examined throughout the investigation. The best experimental conditions were determined as pH 4.0, 3 mL/min of sample flow rate, 75 mg of biosorbent, 100 mg of γ-Fe2O3 magnetic nanoparticles, and 500 mL of sample volume. LOD values were determined as 0.016, 0.011, and 0.023 ng/mL, respectively for Hg(II), Ni(II), and Zn(II). The biosorption capacities were determined as 47.2 mg/g for Hg(II), 51.5 mg/g for Ni(II), and 49.0 mg/g for Zn(II). The effectiveness of the recommended method was assessed using certified reference material.

Electromagnetic Field Drives the Bioelectrocatalysis of γ-Fe2O3-Coated Shewanella putrefaciens CN32 to Boost Extracellular Electron Transfer.

The microbial hybrid system modified by magnetic nanomaterials can enhance the interfacial electron transfer and energy conversion under the stimulation of a magnetic field. However, the bioelectrocatalytic performance of a hybrid system still needs to be improved, and the mechanism of magnetic field-induced bioelectrocatalytic enhancements is still unclear. In this work, γ-Fe2O3 magnetic nanoparticles were coated on a Shewanella putrefaciens CN32 cell surface and followed by placing in an electromagnetic field. The results showed that the electromagnetic field can greatly boost the extracellular electron transfer, and the oxidation peak current of CN32@γ-Fe2O3 increased to 2.24 times under an electromagnetic field. The enhancement mechanism is mainly due to the fact that the surface modified microorganism provides an elevated contact area for the high microbial catalytic activity of the outer cell membrane's cytochrome, while the magnetic nanoparticles provide a networked interface between the cytoplasm and the outer membrane for boosting the fast multidimensional electron transport path in the magnetic field. This work sheds fresh scientific light on the rational design of magnetic-field-coupled electroactive microorganisms and the fundamentals of an optimal interfacial structure for a fast electron transfer process toward an efficient bioenergy conversion.

Microstructural insights of magnetic γ-Fe2O3/geopolymer nanocomposite for prospective green removal of heavy metals from aqueous solutions

The presented work was constructed to study the merging influence between the as-received fly ash (FA) hollow spheres (FA; 632 nm) and either nano-sized FA (18 nm) alone or combined with magnetic (40.81 emu/g) γ-Fe2O3 nanoparticles (20 nm) into the microstructural features of their resulted geopolymeric nanocomposites (nano-FA-GP and nano-MFA-GP, respectively). The neutron activation analysis proofed that the FA has a Si/Al ratio of 3.37 with a hypothesized sialate-multisiloxo structure of both nanocomposites. Batch kinetic systems were implemented to compare the capabilities of both sorbents to decontaminate simulated wastewaters containing some heavy metal (HM) ions. The percentage uptake, distribution coefficient, and decontamination factor were used as performance measures. Incorporation of the magnetic nano-γ-Fe2O3 into the nanocomposite (nano-MFA-GP) enhanced these measures especially at high temperature, with one order of magnitude where Pb2+ > Cu2+ > Cd2+ > Zn2+ >Ni2+. The transient behaviors of all systems were assessed and analyzed non-linearly revealing that all reactions were chemisorption controlled. Additionally, the intra-particle diffusion model was applied and the sorption reaction of Cu2+ and Ni2+ was exclusively onto the external surface layer of the nano-MFA-GP, at high temperature, while the other systems might be controlled by an additional diffusion mechanism into the interior pore structures.

A sustainable magnetic γ-Fe2O3@Escherichia coli (E. coli) bio-sorbent for determination trace amounts of thymol in pharmaceutical, food and cosmetic samples

Due to the need for environmentally friendly technologies, using microorganisms such as bacteria as a biosorbent for the solid phase extraction (SPE) technique has paid attention. These biosorbents have advantages, such as good performance, abundance and accessibility, operation over a wide range of environmental conditions, regeneration, and not producing secondary contaminations. This study examines a biotechnological application using Escherichia coli (E. coli), as a highly efficient adsorbent for separation, preconcentration, and determination of thymol. The E. coli was immobilized to γ-Fe2O3 magnetic nanoparticles, as a solid-phase biosorbent, for magnetic dispersive micro-solid phase extraction (MDμ-SPE) to provide an efficient and rapid recovery after the sorption process. Characterization of the prepared biosorbent was carried out using the Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscope (FE-SEM), and vibrating sample magnetometer (VSM). The MDμ-SPE as a green and sensitive method proposed for the separation and determination of trace quantities of thymol. Some experimental factors, such as sample pH, amount of sorbent, adsorption time, and temperature affecting the MDμ-SPE efficiency, were tested by the experimental design method. Under optimal conditions, linear range, detection limit, and the relative standard deviation for extraction and preconcentration of thymol were obtained; 30–500, 9.1 ng mL−1, and 1.4 %, respectively. Finally, the proposed method was successfully applied to the preconcentration and determination of target analyte in pharmaceutical, food, and cosmetic samples.

Effect of modified γ-Fe2O3 magnetic nanoparticles on the stability of heavy oil-in-water emulsions

The effects of modified γ-Fe2O3 magnetic nanoparticles having various sizes at different mass fractions on the stability of heavy oil-in-water emulsions were compared. The zeta potential, wettability, oil-water interfacial tension, apparent viscosity, and oil droplet distribution of the emulsions were measured. The optimal size of the γ-Fe2O3(-COOH) magnetic nanoparticles was 2–3 μm, and this resulted in the lowest water-separation rate (23.72% at 4 hours), greatest electrostatic repulsion, weakest hydrophilic effect, lowest interfacial tension, greatest migration resistance, and smallest and most uniform oil droplet distribution. In addition, the stability of the emulsions increased and then decreased as the mass fraction of γ-Fe2O3 (-COOH) magnetic nanoparticles increased because of the increased electrostatic repulsion and decreased migration resistance. This in-depth analysis of the effect of modified magnetic nanoparticle size on the stability of oil-in-water emulsions provides comprehensive theoretical support for achieving viscosity and resistance reduction in an environmentally friendly manner.

Design of Spherical Gel-Based Magnetic Composites: Synthesis and Characterization

The purpose of the study was the synthesis and the physicochemical characterization of spherical beads of magnetically active composite ferrogels (FGs) with diameters of 2–3 mm for further application to the needs of targeted drug delivery and/or replacement therapy. Spherical FGs based on a physical network of calcium alginate (CaAlg), a chemical network of polyacrylamide (PAAm), and a combined network of calcium alginate and polyacrylamide (PAAm/CaAlg) were analyzed. FGs were filled with γ-Fe2O3 magnetic nanoparticles (MNPs) obtained by using the electrical explosion of wire method. A comparative study of the swelling behavior and of the structural features of the polymeric network in CaAlg, PAAm/CaAlg, and PAAm spherical beads was performed. It was shown that the densest network was provided by a combination of chemical and physical networking in PAAm/CaAlg FGs. If the physical network were removed from FGs it resulted in a substantial increase in the average diameter and the swelling ratio of spherical beads and a decrease in the MNPs concentration in the swollen FGs by approximately two times. It was shown that irrespective of the gel composition, the embedding of maghemite nanoparticles led to an increase in the swelling ratio of the polymeric network. This indicated the absence of strong intermolecular interactions between the polymer and the filler. The results obtained might be useful for the design of magnetically active spherical FG beads of a given size and controlled physicochemical properties.

Nanotechnology for purifying nematic liquid crystals based on magnetic separation accompanied by phase transition

Free ions are generally unfavorable in liquid crystal (LC) displays, and LC purification technologies are critically important. The colloidal γ-Fe2O3 magnetic nanoparticles coated with oleic acid (γ-Fe2O3@OA MNPs) have a high ratio of surface to volume, which may adsorb more free ions and are uniform in the LC at room temperature. In this work, the precipitation and separation of the doped colloidal γ-Fe2O3@OA MNPs resulting from the magnetic field accompanied by an isotropic-nematic phase transition are more efficient than in the single case of the phase transition or the magnetic field. The residual ion concentrations have decreased distinctly using the low gradient magnetic field (∇ B ∼ 2 T/m) with the phase transition. In addition, when the doped colloidal γ-Fe2O3@OA MNPs are 0.4 % and 0.2 % by weight, the former concentrations of the residual ions and γ-Fe2O3@OA MNPs are lower than the latter. As a result, the commercial nematic LC can be purified by this approach based on nanotechnology in our study.

Study of the magnetic properties of Mg, Gd, and Co doped maghemite (γ-Fe2O3) nanoparticles prepared by sol–gel

The γ-Fe2O3 magnetic nanoparticles, prepared by sol gel route, were doped with Magnesium (Mg), Gadolinium (Gd), and Cobalt (Co) oxides to enhance their magnetic properties. The X-ray diffraction, of the prepared samples, show that all samples crystallized under cubic structure with P4332 space group. The morphological properties of our nanopowders were studied with TEM investigations. The average nanoparticle sizes were distributed between 15 and 23 nm for both the pure and the doped samples. The magnetization as a function of temperature and magnetic field were measured to study the effect of the doping elements on the magnetic properties. The results show that the highest magnetization (MH) of our nanoparticles increases especially with increasing Mg, Gd and Co concentration It is also observed that cobalt doping increases the magnetic coercivity by increasing the value of the coercivity field (Hc) and remanence magnetisation (Mr), which can be used in magnetic recording devices.

A fungal functionalized magnetized solid phase extractor for preconcentrations of Pb(II), Mn(II), and Co(II) from real samples

Due to increasing industrialization and overpopulation, the amount of toxic metals is increasing in the environment, including air, soil, water, and food. Solid phase extraction is an efficient and ideal technique to preconcentrate the toxic metals before their measurements by analytical instruments. Russula brevipes was immobilized on γ-Fe2O3 magnetic nanoparticles and employed as a SPE sorbent to preconcentrate the trace level of Pb(II), Mn(II), and Co(II). To investigate the extraction conditions, significant experimental parameters were examined in details. LODs were calculated as 0.022, 0.015, and 0.024 ng mL−1 for Pb(II), Mn(II), and Co(II), respectively. The biosorption capacities of R. brevipes immobilized γ-Fe2O3 were calculated as 43.1 mg g−1 for Pb(II), 54.9 mg g−1 for Mn(II), and 49.7 mg g−1 for Co(II). Pb(II), Mn(II), and Co(II) in food samples at trace levels were preconcentrated by applying the developed method.

High-performance pinecone-like MOF derivative electromagnetic wave-absorbing composite via in situ anisotropic-oriented growth

Designing multihierarchical electromagnetic wave-absorbing composite with multiphase, multieffective, and multidimensional properties is an effective way to improve absorption performance. Metal–organic frameworks (MOFs) have a high metal content and a stable carbon framework. By adjusting the metal type, organic ligand type, and precursor ratio during the preparation process, MOF materials with different morphologies can be synthesized and transferred into multihierarchical electromagnetic wave-absorbing composites via in situ pyrolysis. Herein, based on the Kirkendall diffusion effect, an in situ anisotropic-oriented growth strategy was advanced during the pyrolysis of Prussian blue, and a new magnetic carbon composite (γ-Fe2O3 @N-rGO/MWCNT) was prepared. The composite has a multihierarchical structure consisting of pinecone-like nanoflowers and a porous carbon framework. The nanoflowers are core-shell structures with γ-Fe2O3 magnetic nanoparticles as cores and nitrogen-doped reduced graphene oxides as shells interspersed in a porous carbon framework that includes intertwined multiwalled carbon nanotubes and amorphous carbon. The minimum reflection loss (RLmin) of the samples can reach up to − 59.2 dB at 5.51 GHz. The in situ anisotropic-oriented growth strategy used in this work shows great promise for the preparation of a variety of multihierarchical structure nanocomposite electromagnetic wave-absorbing materials with abundant absorption effects.

Synthesis and Characterization of a Polydioxanone-Coated Dipeptide-Functionalized Magnetic γ-Fe2O3 Nanoparticles-Modified PES Membrane and Its Biological Applications

This work is focused on the synthesis of leucyl-glycine-functionalized γ-Fe2O3 magnetic nanoparticles coated by polydioxanone (γ-Fe2O3-CA-Leu-Gly-PDX) as a polyethersulphone (PES) membrane for biotechnological applications. The physicochemical characteristics were investigated by FT-IR, SEM, XRD, a vibrating sample magnetometer (VSM), and ICP-OES. The present investigation also centered on the several biological activities of γ-Fe2O3-CA-Leu-Gly-PDX. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and metal chelating activity was studied for evaluation of its antioxidant activity potential. It exhibited 100% DPPH radical scavenging and 93.33% metal chelating activity. With applicability to antimicrobial photodynamic therapy, DNA cleavage and antimicrobial activity, the cell viability of γ-Fe2O3-CA-Leu-Gly-PDX was investigated in detail. The γ-Fe2O3-CA-Leu-Gly-PDX demonstrated the significant biofilm inhibition activity as being 81.54% and 86.34% for P. aeruginosa and S. aureus, respectively. Moreover, a novel polyethersulphone nanocomposite membrane incorporated with γ-Fe2O3-CA-Leu-Gly-PDX was prepared. The performance of the γ-Fe2O3-CA-Leu-Gly-PDX-blended polyethersulphone (PES) membrane was investigated by measuring the antifouling and E. coli rejection. The nanocomposite membranes demonstrated remarkable antifouling properties in contrast with the pristine PES when BSA (bovine serum albumin) and E. coli were filtrated. A complete rejection was obtained by the composite membrane. After an application of the membrane study, the modified polyethersulphone (PES) membrane blended with γ-Fe2O3-CA-Leu-Gly-PDX removed 100% of the E. coli.

Platelet magnetic nanocarriers as MRI sensors to delineate vascular injury network and targeted pre-protection in ischemic stroke

Accurate mapping the damaged vascular network is key to subsquent effective therapeutic strategy implementation in ischemic stroke. In this study, magnetic resonance imaging (MRI) based on a platelet membrane biomimetic magnetic nanocarrier, loaded with L-arginine and γ-Fe2O3 magnetic nanoparticles (PAMNs), has been developed for delineating the vascular injury network in acute ischemic stroke. Due to the loading of γ-Fe2O3 nanoparticles, multi-parameter MRI including T2*-weighted imaging (T2* WI) and diffusion-weighted imaging (DWI) have been used to localize the stroke lesion and evaluate the severity of damaged vasuclar network, respectively. Results demonstrated that the PAMNs can specifically target to different types of damaged blood vasculature. Based on the PAMNs accumulation in the stroke lesion, T2* imaging delineated the damaged vascular injury network, espcially for penumbra. Furthermore, with the L-arginine release in the lesion, the DWI of MRI was applied to evaluate the pre-protection effect. This showed great potential for accurate positioning and real-time monitoring of stroke ischemic lesions. Therefore, the PAMNs-based MRI technique is feasible for vascular obstruction/thrombus location, severity assessment, and real-time monitoring of lesion development in ischemic lesions in the early stage of stroke.

Biological Impact of γ-Fe2O3 Magnetic Nanoparticles Obtained by Laser Target Evaporation: Focus on Magnetic Biosensor Applications.

The biological activity of γ-Fe2O3 magnetic nanoparticles (MNPs), obtained by the laser target evaporation technique, was studied, with a focus on their possible use in biosensor applications. The biological effect of the MNPs was investigated in vitro on the primary cultures of human dermal fibroblasts. The effects of the MNPs contained in culture medium or MNPs already uptaken by cells were evaluated for the cases of the fibroblast’s proliferation and secretion of cytokines and collagen. For the tests related to the contribution of the constant magnetic field to the biological activity of MNPs, a magnetic system for the creation of the external magnetic field (having no commercial analogues) was designed, calibrated, and used. It was adapted to the size of standard 24-well cell culture plates. At low concentrations of MNPs, uptake by fibroblasts had stimulated their proliferation. Extracellular MNPs stimulated the release of pro-inflammatory cytokines (Interleukin-6 (IL-6) and Interleukin-8 (IL-8) or chemokine (C-X-C motif) ligand 8 (CXCL8)) in a concentration-dependent manner. However, the presence of MNPs did not increase the collagen secretion. The exposure to the uniform constant magnetic field (H ≈ 630 or 320 Oe), oriented in the plane of the well, did not cause considerable changes in fibroblasts proliferation and secretion, regardless of presence of MNPs. Statistically significant differences were detected only in the levels of IL-8/CXCL8 release.

Trapping and detecting nanoplastics by MXene-derived oxide microrobots

Nanoplastic pollution, the final product of plastic waste fragmentation in the environment, represents an increasing concern for the scientific community due to the easier diffusion and higher hazard associated with their small sizes. Therefore, there is a pressing demand for effective strategies to quantify and remove nanoplastics in wastewater. This work presents the “on-the-fly” capture of nanoplastics in the three-dimensional (3D) space by multifunctional MXene-derived oxide microrobots and their further detection. A thermal annealing process is used to convert Ti3C2Tx MXene into photocatalytic multi-layered TiO2, followed by the deposition of a Pt layer and the decoration with magnetic γ-Fe2O3 nanoparticles. The MXene-derived γ-Fe2O3/Pt/TiO2 microrobots show negative photogravitaxis, resulting in a powerful fuel-free motion with six degrees of freedom under light irradiation. Owing to the unique combination of self-propulsion and programmable Zeta potential, the microrobots can quickly attract and trap nanoplastics on their surface, including the slits between multi-layer stacks, allowing their magnetic collection. Utilized as self-motile preconcentration platforms, they enable nanoplastics’ electrochemical detection using low-cost and portable electrodes. This proof-of-concept study paves the way toward the “on-site” screening of nanoplastics in water and its successive remediation.

Simulating Evaluation Method on Heating Performances of Magnetic Nanoparticles with Temperature-Dependent Heating Efficiencies in Tumor Hyperthermia

The magnetic nanoparticles (MNPs) with decreasing heating efficiency (characterized by specific loss power, SLP) with temperature increase, especially around the Curie temperature (TC), are expected to realize the self-regulated temperature hyperthermia of the tumor. However, the actual decrease of the SLP is gradual, resulting in the deviation of self-regulated temperatures from the measured TC. So far, no method is available for evaluating the heating performances of those MNPs. Here, by simulating the temperature-dependent SLP, the heating performances of MNPs are evaluated from three clinically concerning aspects: the capacity for effective heating, the temperature uniformity in the tumor, and the temperature stability under environmental changes such as MNP loss or tumor progression. The developed methods were applied to ZnCoCrFeO, Fe3O4, and γ-Fe2O3 MNPs. It was found that the uniform temperature distribution relies on lowering the heating power in the inner regions of the tumor, and the stable control of temperature depends on the dynamic adaptation of the heating power to the tumor temperature change. The proposed method may be used to predict the heating ability of MNPs and help the selection of MNPs for hyperthermia.

Effect of Superparamagnetic DMSO@γ-Fe₂O₃ Combined with Carmustine on Cervical Cancer.

This study aimed to investigate the effects of DMSO@γ-Fe₂O₃ nanomagnetic fluid thermotherapy combined with the chemotherapy drug carmustine on cervical cancer cells under a certain intensity of alternating magnetic field. And the role of Mir-590-3P in the development and progression of cervical cancer. The optimal thermotherapy concentration of γ-Fe₂O₃ nanomaterials on cervical cancer cells was determined by in vitro heating. In addition, the MTT colorimetric method was used to evaluate the toxic effect of γ-Fe₂O₃ magnetic nanoparticles on cervical cancer cells, and the optimal therapeutic concentration of carbachol on cervical cancer cells was optimized (0.015 g · L-1). The cervical cancer cells were divided into control, γ-Fe₂O₃ hyperthermia, chemotherapy, and DMSO@γ-Fe₂O₃ combined chemotherapy groups. After 2 h exposure to hypothermic conditions, flow cytometry was used to assess cell apoptosis for each group. The heating effect of the γ-Fe₂O₃ magnetic nanomaterials was apparent. When the concentration of γ-Fe₂O₃ was ≥6 g· L-1, the temperature rise above 41 °C. γ-Fe₂O₃ is non-toxic to cervical cancer cells and has good biocompatibility. Taking the drug concentration of IC25 as the working concentration of this study, the working concentration of carmustine was 0.015 g · L-1. Both the 41 °C heat treatment and chemotherapy alone had a killing effect on glioma and cervical cancer cells (P < 0.05). Additionally, the combined inhibitory effect of DMSO@γ-Fe₂O₃ nanomagnetic fluid thermotherapy and drugs at this temperature was significantly stronger than that of thermotherapy and chemotherapy alone (P < 0.05). For the control, gamma-Fe₂O₃ hyperthermia, chemotherapy, and DMSO@γ-Fe₂O₃ combined chemotherapy groups, the apoptosis rates of the cervical cancer cells were 1.4%, 18.6%, 24.12%, and 38.97%, respectively. DMSO@γ-Fe₂O₃ nanomagnetic fluid thermotherapy combined with the chemotherapeutic drug carmustine exerted a noticeable toxic effect on the cervical cancer cells, and DMSO@γ-Fe₂O₃ significantly enhanced the killing effect of carmustine on cervical cancer cells.

Improved Solvothermal Synthesis of γ-Fe2O3 Magnetic Nanoparticles for SiO2 Coating.

Monodisperse magnetic γ-Fe2O3 nanoparticles (MNPs) were prepared by a simple, improved, one-pot solvothermal synthesis using SDS and PEG 6000 as double capping reagents. This double protecting layer afforded better MNP uniformity (Z average 257 ± 11.12 nm, PDI = 0.18) and colloidal stability. Materials were characterized by DLS, SEM, TEM, XPS, and XRD. The use of these MNPs in the synthesis of core–shell structures with uniform and tunable silica coatings was demonstrated, as silica coated MNPs are important for use in a range of applications, including magnetic separation and catalysis and as platforms for templated nanogel synthesis.

An optimization study on quality promotion of heavy crude oil exposed ultrasonic waves and magnetic nanoparticles addition

This study aims to investigate a new method of combining ultrasonic waves with different frequencies and magnetic nanoparticles in reducing the asphaltene content and kinematic viscosity of heavy oil. In general, the experiments included irradiation of ultrasonic waves at single-frequency mode, dual-frequency mode, temperature optimization, and the combined effects of the ultrasonic waves and magnetic nanoparticles in a constant magnetic field. The results demonstrated that, the ultrasonic irradiation at an optimum time of 10 min and a constant temperature of 20 °C with a frequency of 25 kHz and a power of 840 W decreased the asphaltene content and kinematic viscosity of the heavy oil from 13.52% and 87.2 cSt to 7.6% and 65.7cSt, respectively. In the dual-frequency mode (25 kHz and 1.7 MHz), the both parameters reduced to 7.33٪ and 62.9cSt. Subsequently the temperature of 50 °C was selected as optimum temperature for the experiments. The experimental optimizations cleared that at the concentration of γ-Fe2O3 magnetic nanoparticles (0.4 wt%) and the dual- frequency, the both parameters were significantly declined (7.1 cSt and 5.01 wt% respectively). Distillation test, FT-IR, SARA analyses and API index have verified that the ultrasonic waves and the magnetic nanoparticles have effectively lightened the studied oil.