Coated Fe3O4 Magnetic Nanoparticles Research Articles

Green preparation of Fe3O4/HA/CS magnetic nanoparticles for oil–water separation

AbstractBACKGROUNDDemulsification using chitosan (CS)‐coated magnetic nanomaterials has garnered significant attention. However, traditional methods for synthesizing chitosan (CS)‐coated magnetic nanomaterials are often contaminated, laborious, and time‐consuming. Moreover, they showed poor demulsification efficiency due to the occupation of free amino groups in CS by crosslinking agents.RESULTSCS‐coated Fe3O4 magnetic nanoparticles (MNPs) were synthesized using humic acid (HA) as a bridge. The Fe3O4/HA/CS MNPs are recyclable demulsifiers for hexadecane‐water microemulsions. The impacts of MNP dosage, separation time, and pH on demulsification efficiency were studied comprehensively. Compared with Fe3O4/HA and Fe3O4/CS MNPs, the demulsification efficiency of the Fe3O4/HA/CS MNPs was superior. The pseudo‐second‐order kinetic model and the Sips isotherm best describe the demulsification process. Combined with the influence factors of demulsification efficiency, the demulsification mechanism involves electrostatic interactions between MNPs and oil microparticles. The maximum adsorption capacity for oil by the Fe3O4/HA/CS MNPs was 91.73 mg g−1.CONCLUSIONThis research presents a new method for connecting CS to MNPs with a high surface positive charge. As synthesized Fe3O4/HA/CS MNPs is expected to serve as highly efficient and recyclable demulsifiers for emulsified oil wastewater. © 2024 Society of Chemical Industry (SCI).

Viscoelastic and microwave resonant absorption studies of NixFe3−xO4 (0 ≤ x ≤ 0.7) mixed ferrite nanoparticle based magnetic fluid

We investigated the effect of Ni substitution on oleic acid coated Fe3O4 magnetic nanoparticles of 10–13 nm size dispersed in kerosene medium with enhanced colloidal stability. Study of molecular dynamics and coating of oleic acid to ferrite NixFe3−xO4 (0 ≤ x ≤ 0.7) nanoparticles was confirmed by Fourier transform infrared spectroscopy (FTIR) measurements. The increase of Zeta potential (ζ) up on Ni concentration confirms the stability of Ni substituted Fe3O4 magnetic nano fluid. Magnetization measurements (M-vs-H) reveals the substitution of Ni2+ suppresses the magnetic moment thereby decrease of saturation magnetization while increase in Ni concentration from x = 0–0.7 of Fe3O4 nano magnetic fluid. Moreover, field dependent elastic (G′) and viscous (G′′) modulus recorded at varying strain rate confirms a cross-over from viscoelastic-to-viscous behavior of Ni substituted Fe3O4 nanofluid. Further, the induced spin-disorder upon Ni concentration in corroboration with microwave resonant absorption (EPR) measurements through the increase of resonance field and narrowing of peak-to-peak linewidth indicating the suppression of magnetic dipole interactions and enhancement of super-exchange-interactions (Fe3+-O-Ni2+/Fe2+-O-Ni2+) . Moreover, the dominance of spin-spin interactions over the spin-lattice interactions was determined by EPR relaxation-time-scales: spin-spin relaxation (τ2) increases and spin-lattice relaxation (τ1) decreases, which is in conjunction with lande-g-factor while increasing Ni concentration. The present results are useful for knowing the effect of Ni concentration on magnetic and viscoelastic properties of NixFe3−xO4 (0 ≤ x ≤ 0.7) magnetic nanoparticles. Also, it offers a chance to create such types of stable nano magnetic fluids that may be actively controlled by outside magnetic fields, which results in heat sink damping materials in sealed devices and biomedical applications, etc.

Evaluation of the Cytotoxic Effect of Thymol Loaded Chitosan Coated Fe3O4 Magnetic Nanoparticles on MDA-MB-231 Cell Line and Expression of Autophagic MAP1LC3A Gene

Evaluation of the Cytotoxic Effect of Thymol Loaded Chitosan Coated Fe3O4 Magnetic Nanoparticles on MDA-MB-231 Cell Line and Expression of Autophagic MAP1LC3A Gene

Recyclable magnetic Fe3O4 supported photocatalyst for the metal-free ATRP

Silica layer coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) were used to support an photocatalyst rhodamine B (RB) (Fe3O4@SiO2-RB) for the metal-free atom transfer radical polymerization (metal-free ATRP) of methyl methacrylate (MMA) for easy separation and recycling of the catalysts. The metal-free ATRP of MMA was carried out under 365 nm UV light using Fe3O4@SiO2-RB as photocatalyst, and ethyl 2-bromoisobutyrate (EBIB) as initiator. The structure of Fe3O4@SiO2-RB was demonstrated by FT-IR, XPS, XRD and TG. The changes of morphology and specific surface area of Fe3O4 before and after modification were observed by SEM and BET. For the metal-free ATRP reaction, the polymerization process was controllable, the molecular weight was uniform and end of the molecular chain was active. The Fe3O4@SiO2-RB catalyst can be recycled through simple magnetic separation to catalyze polymerization in a controlled manner for three times, and the catalytic activity of the three polymerization reactions decreased slightly in turn. The implementation of this strategy demonstrates that the photoinitiated catalysts can be recovered and reused for subsequent light-induced ATRP.

Multifunctional biosensor constructed by Ag-coating magnetic-assisted unique urchin core porous shell structure for dual SERS enhancement, enrichment, and quantitative detection of multi-components inflammatory markers

The simultaneous, precise, and quantitative detection of multi-components inflammatory markers (IMs) in sepsis serum by surface-enhanced Raman scattering (SERS) remains a challenging problem. A novel, multifunctional biosensor with dual enrichment and enhancement was designed for the ultrasensitive and quantitative analysis of multi-components IMs. The biosensor contains SERS tags-unique urchin core/porous shell (CPS) structure modified with Raman reporters (RaRs), magnetic assist-Ag coated Fe3O4 magnetic nanoparticles (Ag MNPs) modified with internal standard (IS), and then aptamer (Apt) modification to form the sandwich structure (Ag MNPs/IMs/CPS). This multifunctional sensor used for IMS detection has the following innovations: The intensity ratio IRaRs/IIS with Lg CIMs present a good and wide linear relationship to achieve the simultaneous, precise, and quantitative detection of IMS in serum; The detection results display ultrasensitivity, and the limit of detection (LOD) for CRP, IL-6, and PCT is 100 fg/mL, 0.1 fg/mL, and 1.0 fg/mL, which is lower than other detection techniques; The calculated data of clinical blood samples of sepsis by this SERS method is consistent with the hospital results, and can provide more compositional data of IMs. Thus, this combined approach developed a sensing platform for rapid screening, accurate evaluation, early warning, and diagnosis of sepsis.

Release of 5-FU loaded pectin/Fe3O4 from porous PBSA matrix under magnetic and electric fields

In this work, the porous poly(butylene succinate co adipate) (PBSA) was used as the drug matrix for transdermal drug delivery system (TDDS). The porous PBSA matrices were fabricated via solvent casting and particulate leaching method using Tween20 as a pore generator, and the matrices were capable of absorbing the drug solution within 3 s prior to the release. The Fe3O4 magnetic nanoparticles were successfully synthesized via co-precipitation method and successfully coated with pectin through the electrostatic attraction. The 5-fluorouracil, the model drug, was successfully loaded onto the pectin coated Fe3O4 magnetic nanoparticles through the hydrogen bonding. Under magnetic fields, the drug diffusion coefficient increased by the factors of 2 and 5 by the 157 and 247 mT permanent magnets, respectively, whereas the drug release duration was reduced. This was due to the magnetic attraction between the magnetic particles and the magnets. Under the combined electric voltage of 3 V and the magnetic flux of 157 mT, the drug diffusion coefficient increased and the release duration was reduced further, due to the combined driving forces between the magnetic attraction, the electrostatic repulsion of the negative charged pectin layer, and the electro-osmosis. The present work demonstrates the potentials and benefits of the porous matrices along with the combined magnetic and electric fields in the transdermal drug delivery.

A Ferrofluid with High Specific Absorption Rate Prepared in a Single Step Using a Biopolymer.

An exhaustive characterization of the physicochemical properties of gum arabic (GA)-coated Fe3O4 magnetic nanoparticles was conducted in this work. These nanoparticles were obtained via the in-situ coprecipitation method (a fast single-step method) in two GA:Fe ratios, 10:1 and 20:1, respectively. Several experimental techniques were applied in the characterization process, all of them described below. Using Transmission Electron Microcopy images, they were shown to have spherical-like morphology with 11 nm diameter. The Fourier Transform Infrared spectra confirmed the attachment of the GA on the surface of the magnetic nanoparticles (MNPs), providing good colloidal stability from pH 7 to 8. The thickness of the coatings (1.7 nm and 1.1 nm) was determined using thermogravimetric measurements. A high specific absorption rate and superparamagnetic properties were determined using alternant and static magnetic fields, respectively. The GA-coated MNPs were non-cytotoxic, according to tests on HT-29 human intestine cells. Additionally, HT-29 cells were exposed to magnetic fluid hyperthermia at 530 kHz, and the induction of cell death by the magnetic field, due to the heating of GA-coated MNP, was observed.

Black Mesoporous TiO2 Nanoparticles for Enhancing Surface Assisted Laser Desorption and Ionization in Mass Spectrum Analysis

AbstractSurface assisted laser desorption ionization mass spectrometry (SALDI‐MS) is a powerful analytical technology for the high‐throughput detection of metabolites, drugs, and other bioactive molecules. The performance of SALDI‐MS in enhancing molecules desorption and ionization mainly depends on the surface properties of matrix utilized. Here, black titanium dioxide (B‐TiO2) nanoparticle is used for the first time as a novel matrix for enhancing laser desorption and ionization (LDI) and demonstrates significant advantages over white titanium dioxide (W‐TiO2). Further, the black mesoporous TiO2 coated Fe3O4 magnetic nanoparticles (B‐mTiO2 MNPs) are designed and prepared, which possess a high molar absorption coefficient, strong magnetic response, higher specific surface area, and ample phosphorylation binding sites. The B‐mTiO2 MNPs exhibit a superior ionization efficiency, low background signal, and good reproducibility (RSD < 10%) in the analysis of compounds with different molecular weights and practical bio‐sample. Salt tolerance of B‐mTiO2 MNPs up to 10 mm PBS, meanwhile, B‐mTiO2 MNPs also provides excellent enrichment efficiency for phosphopeptides (the detection limit low to 5 × 10−10 M).

Transmittance Measurements in Non-alternating Magnetic Field as Reliable Method for Determining of Heating Properties of Phosphate and Phosphonate Coated Fe3O4 Magnetic Nanoparticles

Different phosphates and phosphonates have shown excellent coating ability toward magnetic nanoparticles, improving their stability and biocompatibility which enables their biomedical application. The magnetic hyperthermia efficiency of phosphates (IDP and IHP) and phosphonates (MDP and HEDP) coated Fe3O4 magnetic nanoparticles (MNPs) were evaluated in an alternating magnetic field. For a deeper understanding of hyperthermia, the behavior of investigated MNPs in the non-alternating magnetic field was monitored by measuring the transparency of the sample. To investigate their theranostic potential coated Fe3O4-MNPs were radiolabeled with radionuclide 177Lu. Phosphate coated MNPs were radiolabeled in high radiolabeling yield (> 99%) while phosphonate coated MNPs reached maximum radiolabeling yield of 78%. Regardless lower radiolabeling yield both radiolabeled phosphonate MNPs may be further purified reaching radiochemical purity of more than 95%. In vitro stabile radiolabeled nanoparticles in saline and HSA were obtained. The high heating ability of phosphates and phosphonates coated MNPs as sine qua non for efficient in vivo hyperthermia treatment and satisfactory radiolabeling yield justifies their further research in order to develop new theranostic agents.

Highly selective enrichment of aflatoxin B1 from edible oil using polydopamine-modified magnetic nanomaterials

Abstract Aflatoxin B1 (AFB1) is a highly toxic mycotoxin that enters the human body through the food chain and poses a serious threat to human health. In this paper, polydopamine (PDA)-coated Fe3O4 magnetic nanoparticles (Fe3O4@PDA MNPs) were prepared by the co-precipitation method to enrich aflatoxin from edible oil. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and vibrating sample magnetometer were used to characterize the Fe3O4@PDA MNPs. Using the obtained Fe3O4@PDA MNPs as an adsorbent, a simple method for enriching AFB1 from samples by magnetic solid phase extraction (MSPE) combined with fluorescence rapid detection was developed. The effects of the ratio of Fe3O4 MNPs to PDA, adsorption dosage, sample volume, adsorption time, and elution time on enrichment of AFB1 were investigated to determine the optimal experimental conditions. This method has good intraday and daytime precision.

Development of recoverable and recyclable Fe3O4‐supported organocatalysts for ring‐opening polymerization

AbstractAn iminotris(dimethylamino)phosphorane (HMP1) phosphazene superbase has been anchored onto poly(hexachlorocyclotriphosphazene‐co‐4,4′‐sulfonyldiphenol) (PZS)‐coated Fe3O4 magnetic nanoparticles (MNPs) through efficient phosphorous‐chloride (from PZS surface) and imino (from HMP1) reaction. Subsequently, these novel heterogeneous Fe3O4@PZS@HMP1 catalysts have been successfully utilized in the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and δ‐valerolactone (δ‐VL). Notably, such catalysts can be easily removed from the reaction mixture and reused 3 times without obvious activity loss.

Polyethylenimine-graft-poly (maleic anhydride-alt-1-octadecene) coated Fe3O4 magnetic nanoparticles: promising targeted pH-sensitive system for curcumin delivery and MR imaging

A theranostic amphiphilic nanocarrier based on iron oxide core with polyethyleneimine and poly(maleic anhydride-alt-1-octadecene) shell was synthesized, labeled with folic acid and loaded with Curcumin. Fe3O4@PIMF nanoparticles displayed a size of 20–30 nm with a shell thickness of 2–5 nm. Fe3O4@PIMF-CUR MNPs exhibited pH-responsive release behavior matched with Michaelis–Menten model. The MNPs showed more toxicity than free CUR against MCF-7 and Hela cells, while the drug-free carrier was safe against both cell lines. Hemolytic activity less than 1.5% in concentrations of <500 µg/mL indicated excellent blood compatibility. Appropriate negative signal enhancement in MRI confirmed the efficiency of the system for cancer theranostics.

Preparation of reduced graphene oxide modified magnetic phase change microcapsules and their application in direct absorption solar collector

Development of latent functionally thermal fluid (LFTF) with excellent optical absorption and controllable heat transfer properties for direct absorption solar collector (DASC) is crucial in solar thermal utilization. In this study, the microcapsule, with melamine-formaldehyde (MF) resin shell and octadecane core, was prepared via in situ polymerization, as its shell was modified by reduced graphene oxide (rGO) and its core was doped with oleic acid coated Fe3O4 magnetic nanoparticles (OA-MNs). The microstructure, optical, thermal and magnetic properties of rGO modified magnetic phase change microcapsules (rGO-MPCMs) were investigated by means of various characterizations. The experimental results revealed that adding rGO substantially enhanced the thermal conductivity of magnetic phase change microcapsules (MPCMs) and only had tiny impact on the phase change behavior of MPCMs. Meanwhile, the thermal stability of octadecane in rGO-MPCMs was remarkably improved due to MF resin shell served as protective barrier. Furthermore, the rGO-MPCMs slurry exhibited better optical absorption and thermal storage capacities compared with MPCMs slurry and deionized water, thus enhancing photo-thermal conversion performance. Under an external magnetic field, the rGO-MPCMs in slurry presented excellent controllability and recyclability. Our research demonstrated that the rGO-MPCMs slurry, as a desirable working fluid, showed spacious application prospect for DASC.

Effect of surfactant coating of Fe3O4 nanoparticles on magnetic dispersive micro-solid phase extraction of tetracyclines from human serum

A procedure for separation and preconcentration of tetracyclines from human serum samples involving magnetic dispersive micro-solid phase extraction was proposed. The extraction efficiency of different tetracyclines was improved with the use of the surfactant coated Fe3O4 magnetic nanoparticles. Sorption mechanism was presented, and the potential use of magnetic Fe3O4 nanoparticles coated with different surfactants for tetracyclines adsorption was demonstrated for the first time. The procedure involved nanoparticle floating in a liquid sample phase for analyte extraction followed by elution and determination by high performance liquid chromatography with diode array detection. Influence of the main involved parameters was studied, the system was dimensioned accordingly. The analytical curves were linear in the ranges of 0.25–10 mg L−1 for tetracycline and 0.10–10 mg L−1 for oxytetracycline or doxycycline. Limits of detection were estimated (IUPAC, 3 concept) as 0.08 mg L−1 for tetracycline, and 0.03 mg L−1 for oxytetracycline or doxycycline. The proposed procedure proved to be fast (10 min), simple (two stages), inexpensive (10 mg of nanoparticles) and was applied to human serum samples. Unlike previously synthesized nanoparticles for tetracyclines separation, the surfactant-coated Fe3O4 nanoparticles can be easily prepared with widely available and low-cost reagents. Moreover, elution of the analytes was accomplished in absence of organic solvents by an aqueous chelating agent solution.

Enhanced degradation of Acid Red 73 by using cellulose-based hydrogel coated Fe3O4 nanocomposite as a Fenton-like catalyst

Carboxymethyl cellulose-based hydrogel coated Fe3O4 magnetic nanoparticles were prepared using a coprecipitation combining graft copolymerization method, and characterized by various techniques to study their structure-property relationships. The nanocomposite was used as a heterogeneous Fenton-like catalyst for Acid Red 73 degradation. The effects of several key parameters, solution pH, H2O2 concentration, catalyst dosage, and temperature of the reaction medium on the pseudo-first-order kinetics of dye degradation was evaluated. The results showed that the nanocomposite catalyst were highly effective in activating H2O2 to produce reactive radicals for dye degradation, achieving complete decomposition under optimal conditions of 300 min at 25 °C and pH 3.5 with 100 mM H2O2 and 200 mg·L−1 catalyst. The complexing hydrogel-Fe2+/Fe3+ were the key factors that speed up the redox cycling between Fe2+ and Fe3+ species, thus accelerate the fast degradation rate of target pollutants. Scavenging experiments and electron paramagnetic resonance analyses revealed that Acid Red 73 was decomposed mainly by the attack of •OH radicals. Besides, reusability of the prepared nanocatalyst was also tested.

Removal of Emulsified Oil from Aqueous Environment by Using Polyvinylpyrrolidone-Coated Magnetic Nanoparticles

In recent years, a large amount of emulsified oily wastewaters were produced from petroleum and food industries, resulting in severe environmental problems. In this study, a series of polyvinylpyrrolidone (PVP)-coated Fe3O4 magnetic nanoparticles (MNPs) were prepared via one-step solvothermal method by introducing various amounts or types of PVP. The synthesized MNPs were characterized by multiple techniques, and their demulsification performances were evaluated in petrochemical and vegetable oil wastewaters, respectively. Results showed that the introduction of PVP in solvothermal process could significantly enhance the demulsification efficiency of MNPs, although excessive addition of PVP could not further increase its efficiency. Moreover, the effects of pH, surfactant concentration of wastewater, and the recycle number of MNPs on the demulsification performance were investigated in detail. It was found that the demulsification efficiency decreased with the increase of pH and surfactant concentration, and the synthetic MNPs were still effective after being reused for 5 cycles under acidic and neutral conditions. It is expected that the development of the PVP-coated MNPs can provide a simple and powerful route for the oily wastewater treatment.

In vitro inhibition of tumor growth by low-dose iron oxide nanoparticles activating macrophages.

Macrophages as immunocyte are attracting more and more attention in cancer therapy. Our previous study observed that dimercaptosuccinic acid (DMSA)-coated Fe3O4 magnetic nanoparticles triggered comprehensive immune responses of mouse macrophages (RAW264.7 cells) and induced production of many kinds of cytokines. This study investigated the effects of Fe3O4 magnetic nanoparticles on RAW264.7 cells proliferation, migration, and inhibition of tumor growth in vitro. Fe3O4 magnetic nanoparticles had an average size of about 11 nm with good dispersibility and uniformity. Fe3O4 magnetic nanoparticles internalized efficiently into RAW264.7 cells. Through Cell Counting Kit-8 (CCK-8) detection, the proliferation of RAW264.7 cells significantly increased by the low-dose Fe3O4 magnetic nanoparticles (50 µg/mL) treatment. The results of wound-healing and Transwell assays both displayed a significant promotion of the RAW264.7 cells migratory capability compared with control group ( P<0.01). It is interesting to find that a large number of proliferated RAW264.7 cells were activated to surround quickly and attack mouse liver cancer cell (Hepa1-6) cells by Fe3O4 magnetic nanoparticles. The growth of Hepa1-6 cells was effectively inhibited according to microscope imaging and flow cytometry analysis. The inhibition may be cooperative effects of RAW264.7 cells proliferation, migration, and immune activation. The results suggest potential clinical value of low-dose iron oxide nanomaterials in cancer therapy.

One-step synthesis of versatile magnetic nanoparticles for efficiently removing emulsified oil droplets and cationic and anionic heavy metal ions from the aqueous environment.

Versatile polyethyleneimine (PEI)-coated Fe3O4 magnetic nanoparticles (MNPs) have been synthesized by a one-step solvothermal method. The morphologies, structures, and properties of MNPs prepared for different reaction times have been characterized through various techniques. The synthesized MNPs were then used to separate emulsified oil and cationic and anionic heavy metal ions from the aqueous environment; moreover, the effects of the temperature, pH, and ionic strength of aqueous media, the solvothermal reaction time, and the number of reuse cycles on the removal efficiency have been investigated in detail. The results showed that pseudo-second-order kinetics and the Langmuir isotherm well described the adsorption processes of Cu(II) and Cr(VI). The Langmuir model yielded maximum adsorption capacities of 66.6mgg-1 for Cu(II) and 54.5mgg-1 for Cr(VI) at pH5.0 and 25°C. The synthetic MNPs could also efficiently separate diesel oil or olive oil droplets stabilized by sodium dodecyl sulfate from aqueous media. Moreover, these MNPs could be recycled five times without showing significant loss in separation efficiency. Notably, the synthesized PEI-coated MNPs could simultaneously separate emulsified oil and cationic and anionic heavy metal ions from multicomponent wastewater. Such versatile PEI-coated MNPs displayed good affinity towards emulsified oil and cationic and anionic heavy metal ions, showing great potential for practical applications in the treatment of complicated industrial wastewater matrices. Graphical abstract Simultaneous separation of emulsified oil and cationic and anionic heavy metal ions from aqueous media by using polyethyleneimine-coated Fe3O4 magnetic nanoparticles.

Preparation and characterization of magnetic theranostic nanoparticles for curcumin delivery and evaluation as MRI contrast agent

In this study we described the production of curcumin (CUR) loaded L‐tyrosine (Tyr coated Fe3O4 magnetic nanoparticles. CUR loaded Tyr modified Fe3O4 nanoparticles (F@Tyr@CUR NPs) were analyzed by transmission electron microscopy, fourier transform infrared spectroscopy, thermo gravimetric analysis, vibrating sample magnetometer, X‐ray diffraction and dynamic light scattering techniques. The dynamic light scattering results showed that the ζ‐potential of F@Tyr@CUR NPs was about −15.4 mV. Also, the internal average size was about 25.81 ± 3.31 (mean ± SD (n = 30)) nm. The drug loading and encapsulation efficiency were 8.87 ± 0.09% and 35.21 ± 0.41%, respectively. In addition, hemolysis test on human red blood cells were conducted to determine the hemocompatibility of F@Tyr@CUR NPs. Next, MTT assays on HEK‐293 were conducted to determine the toxicity of F@Tyr@CUR NPs. Lastly, the potential anticancer effect of F@Tyr@CUR NPs was considered on MCF‐7 cancer cell line. The outcomes indicated that these F@Tyr@CUR NPs are appropriate for delivery of CUR anticancer drug. Also, the MRI training established the effectiveness of Fe3O4 magnetic nanoparticles as contrast agent for the revealing of tumor as evidenced from the phantom images as well as higher T2 relaxivity.

One-Step Synthesis of Polyethylenimine-Coated Magnetic Nanoparticles and its Demulsification Performance in Surfactant-Stabilized Oil-in-Water Emulsion

In this study, polyethylenimine (PEI)-coated Fe3O4 magnetic nanoparticles (MNPs) were successfully synthesized via a one-step, solvo-thermal method. The synthetic PEI-coated MNPs were characterized by using multiple techniques and their demulsification efficiencies were evaluated in surfactant-stabilized, oil-in-water emulsions. The results showed that the synthesized MNPs successfully adsorbed to the emulsion’s O/W interfaces and, consequently, the oil droplets could be rapidly destabilized under an applied magnetic field. It was found that the demulsification efficiency was enhanced with the increased particle dosage. The opposite effect was found with the increase in pH value and surfactant concentration. The presence of electrolytes facilitated oil removal, presumably by reduction of the electrostatic repulsion or by altering the hydrophobicity of the MNPs. Recovery experiments at various pH levels indicated that the PEI-coated MNPs could be reused for up to ten times without significant reduction in demulsification efficiency. Altogether, the results suggested that the PEI-coated MNPs could provide a simple but powerful tool to remove emulsified oil from aqueous systems.