Magnetic MgFe2O4 Research Articles

Development of immobilized peroxidase on amino-functionalized magnetic MgFe2O4 nanoparticles for antioxidant activity and decolorization

This investigation aims to immobilize peroxidase onto 3-aminopropyltriethoxysilane (APTES)-functionalized MgFe2O4 magnetic nanoparticles to increase enzyme stability, efficiency, and recyclability. The synthesized samples were analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, Thermogravimetric analysis, Vibrating sample magnetometer, and Scanning electron microscopy. The free and immobilized peroxidase were examined against different pH and temperatures as well as storage time and reuse. The immobilized peroxidase maintained 52 % of its initial activity after 10 consecutive measurements thanks to easy magnetic separation. In addition, antioxidant activity was increased by immobilizing the peroxidase to the MgFe2O4 magnetic nanoparticles. Congo red dye removal for peroxidase immobilized MgFe2O4-APTES was found to be 98.6 % for 240 min. Also, it showed approximately two times more dye decolorization efficiency compared to MgFe2O4 and APTES modified MgFe2O4. Finally, the immobilized peroxidase was studied by a decolorization study of congo red. So, we believe that the immobilized peroxidase on magnetic nanoparticles reported in this study may be utilized in diverse biotechnology, industrial, and environmental practices.

Photocatalysis and adsorption coupling in S-scheme K and P doped g-C3N4/GO/MgFe2O4 photocatalyst for enhanced degradation of Congo red dye

Abstract Photocatalysis is an environmentally friendly approach for harnessing solar light to degrade pollutants. This study investigates the degradation of Congo red (COR) dye by a visible light-active photocatalyst, with a primary focus on the efficiency and reusability of the photocatalytic material. We synthesized phosphorus- and potassium-doped graphitic carbon nitride photocatalysts attached to graphene oxide and MgFe2O4 (KPCN/GO/MgFe2O4). Doping graphitic carbon nitride enhanced light absorption, while graphene oxide improved the adsorption properties. The addition of magnetic MgFe2O4 enhanced charge separation and reusability. The KPCN/GO/MgFe2O4 composite was analyzed using a range of techniques. The activity of the synthesized materials for Congo red (COR) dye degradation was analyzed under visible light. The photocatalytic activities of bare, binary, and ternary photocatalysts were compared, and KPCN/GO/MgFe2O4 exhibited the highest photoactivity among all. The KPCN/GO/MgFe2O4 photocatalyst (60 mg) showed a 76% removal efficiency for 5 x 10-6 M Congo red within 60 minutes, which was 2.5 times higher than that of pure graphitic carbon nitride. The •OH and •O2- were the major reactive species during COR photodegradation. The photocatalyst also displayed good reusability after five cycles, enhancing its overall effectiveness.

Cu(II) tagged magnetic MgFe2O4: starch based surface imprinted polymer for selective copper targeting from aqueous media

Cu(II) tagged magnetic MgFe2O4: starch based surface imprinted polymer for selective copper targeting from aqueous media

Extraction of Iron and Alumina from Red Mud with a Non-Harmful Magnetization Sintering Process

Red mud, which could cause numerous problems to the environment, is a hazardous waste generated from the alumina smelting industry. In general, the storage and harmless utilization of red mud are hard to implement due to its fine particle size and high alkalinity. This study put forward a novel process to separate iron (MgFe2O4) and alumina (Al2O3) in red mud by a magnetization sintering method. The magnesium oxide was added to transform the nonmagnetic Fe2O3 into magnetic MgFe2O4 to achieve physical separation of iron-bearing minerals, and the alumina-bearing minerals were converted into dissoluble NaAlO2 minerals in a one-step reaction. The atmospheric pressure leaching process was adopted in this study for alumina resource recovery. To achieve clean alumina production, the silicate in the leaching solution was removed by adding the slightly soluble CaSO4, and the entire process becomes clean and harmless. The feasibility of the process was verified by thermodynamic analysis, and a series of experiments were performed to detect the optimum MgO/(Fe2O3 + MgO) ratio and the calcining and leaching conditions. The morphological and mineralogical characteristics of modified red mud, leaching red mud, and magnetic separation product were studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS). It was observed that under the optimal conditions with MgO/(Fe2O3 + MgO) of 14.89% to recover iron and aluminum, the corresponding recovery rates were 67.54% and 73.01% respectively, and the iron grade was 30.46%. The EDS results showed that the obtained Mg/Fe ratio of the magnetic separation product was 0.4677–0.528, which is slightly different from that of the standard MgFe2O4 at 0.5. This new method can promote the development of comprehensive utilization of red mud and iron production.

Fabricating Dual-Functional Plasmonic-Magnetic Au@MgFe2O4 Nanohybrids for Photothermal Therapy and Magnetic Resonance Imaging.

Bifunctional nanohybrids possessing both plasmonic and magnetic functionalities are of great interest for biomedical applications owing to their capability for simultaneous therapy and diagnostics. Herein, we fabricate a core–shell structured plasmonic–magnetic nanocomposite system that can serve as a dual-functional agent due to its combined photothermal therapeutic and magnetic resonance imaging (MRI) functions. The photothermal activity of the hybrid is attributed to its plasmonic Au core, which is capable of absorbing near-infrared (NIR) light and converting it into heat. Meanwhile, the magnetic MgFe2O4 shell exerts its ability to act as a MRI contrast agent. Our in vivo studies using tumor-bearing mice demonstrated the nanohybrids’ excellent photothermal and MRI properties. As a photothermal therapeutic agent, the nanohybrids were able to dramatically shrink solid tumors in mice through NIR-induced hyperthermia. As T2-weighted MRI contrast agents, the nanohybrids were found capable of substantially reducing the MRI signal intensity of the tumor region at 10 min postinjection. With their dual plasmonic–magnetic functionality, these Au@MgFe2O4 nanohybrids hold great promise not only in the biomedical field but also in the areas of catalysis and optical sensing.

Study on Oxidation Behavior of Industrial Basic Oxygen Furnace Slag and Recovery of Magnetic Iron‐Containing Phase

The BOF slag contains a lot of iron‐containing species and its efficient recovery is a difficult problem in metallurgy. Herein, the oxidation behavior of industrial BOF slag under air atmosphere is investigated to explore the optimal oxidation conditions for transforming nonmagnetic FeO into magnetic MgFe2O4, including oxidation temperature, oxidation time, and airflow rate. The raw slag and oxidized slags are analyzed using chemical analysis, X‐ray diffraction (XRD) analysis, scanning electron microscope (SEM)‐energy dispersive spectroscopy (EDS) analysis, and Factsage thermodynamic simulation. The results show that the formation of MgFe2O4 phase is closely related to the oxidation temperature, oxidation time, and airflow rate. With the increase in temperature, the conversion rate of MgFe2O4 increases, and reaches the maximum at 1050 °C. However, the conversion rate of MgFe2O4 decreases and part of β‐C2S is converted to α‐C2S above 1050 °C. When the oxidation time and airflow rate increase, the conversion rate of MgFe2O4 increases and reaches the maximum value at 100 min and 1.25 L min−1, respectively. Correspondingly, the grade increased from 16.3% of the raw slag to 27.86% of the magnetic slag, an increase of 11.5%. This is a more convenient and effective method, which can not only bring economic benefits for relevant enterprises but also reduce environmental pollution.

Controllable synthesis of cubic magnetic MgFe2O4 derived from MgFe-LDHs for efficient removal of methyl orange

A novel cubic magnetic MgFe2O4 derived from MgFe-layered double hydroxides (MgFe-LDHs) has been constructed by a combination of facile urea hydrothermal method and calcinations method and applied for the efficient removal of methyl orange (MO) with a maximum adsorption capacity of 535 mg g−1. The studies of formation mechanism of cubic MgFe-LDHs demonstrate the type of ferric salt and reaction time are two most important parameters influencing their cubic structures. Besides, calcinations temperature can not only decide magnetic performance of MgFe2O4, but also not change its cubic structure. Then the structural and surface properties of cubic magnetic MgFe2O4 were investigated by various characterization techniques. In addition, batch adsorption experiments were carried out to investigate the effects of different parameters such as the initial concentration of MO, pH, temperature and time on the adsorption behavior of MO on MgFe2O4. The kinetics, isotherm and thermodynamics of the adsorption of MO by MgFe2O4 were studied in detail. Moreover, adsorption mechanism of MO by MgFe2O4 was studied deeply. At last, MO could be desorbed from MgFe2O4 by 0.1 M NaOH solution and reused at least three times, indicating cubic magnetic MgFe2O4 is an effective and promising adsorbent for the removal of dye pollutants.

Boosted sono-oxidative catalytic degradation of Brilliant green dye by magnetic MgFe2O4 catalyst: Degradation mechanism, assessment of bio-toxicity and cost analysis

The magnetic MgFe2O4 nanoparticles (NPs) were fabricated via a facile co-precipitation technique and was comprehensively characterized by XRD, FTIR, SEM, EDX and VSM. The prepared NPs were used as catalyst in presence of ultrasound (US) irradiation to activate persulfate (PS) for generation of sulfate radicals (SO4·-) for boosted degradation of toxic Brilliant Green (BG) dye. Preliminary experiments revealed that highest BG dye degradation efficiency of 91.63% was achieved at MgFe2O4 catalyst dose of 1.0 g/L, PS dose of 300 mg/L, and initial dye concentration of 70 ppm within 15 min of US irradiation. However, only US, US in presence of PS oxidation and US in presence of MgFe2O4 catalyst have shown 20.2%, 83.6% and 45.0% of BG dye removal, respectively. Furthermore, response surface methodology (RSM) based central composite design (CCD) was executed to investigate the effect of interaction between independent variables such as MgFe2O4 catalyst dose (0.5–1.5 g/L), PS dose (150–350 mg/L), initial BG dye concentration (50–150 ppm) and US irradiation time (4–12 min). The RSM based quadratic model was used to predict the experimental data, and the prediction accuracy was confirmed by analysis of variance (R2 = 0.98). The established RSM model has predicted the optimum experimental conditions as MgFe2O4 catalyst dose of 0.75 g/L, PS dose of 300 mg/L, initial dye concentration of 75 ppm and sonication time of 10 min. Subsequently, the treatment cost analysis was performed for all thirty experimental runs of CCD, and the RSM predicted response was found to be evidently optimum as this has delivered best economic condition (140 $/kg of BG removed) with respect to relative dye removal (%). COD removal and residual sulfate analysis have demonstrated satisfactory reduction of COD (90.31%) as well as sulfate ions (42.87 ppm) in the dye solution after treatment. Results of degradation pathway analysis portrayed the transformation of BG molecule (M/Z ratio 385) into simpler fractions with M/Z ratio of 193, 161, 73, and 61. Moreover, the toxicity analysis revealed that sono-catalytically activated PS system has efficiently reduced the toxicity level of BG dye from 93.9% to 5.13%.

Magnetic MgFe2O4–CaFe2O4 S-scheme photocatalyst prepared from recycling of electric arc furnace dust

In this research, magnetic MgFe2O4–CaFe2O4 photocatalyst powder was prepared from recycling of electric arc furnace (EAF) dust as a secondary source through a two-step leaching process followed by co-precipitation method. To maximize the total Fe to Ca recovery ratio (F/C) and evaluate the effective parameters of sulfuric acid concentration and temperature, response surface methodology (RSM) as a design of experiment was used. The best temperature and acid concentration were obtained as 85 °C and 1 M, respectively for the second step of the leaching process. X-ray diffraction (XRD) results indicated that the synthesized nanocomposite sample contains MgFe2O4 and CaFe2O4 phases together with a small amount of Ca2Fe2O5. The saturation magnetization and optical band gap of the synthesized composite powder were 24 emu/g and 2.17 eV, respectively. X-Ray photoelectron spectroscopy (XPS) result revealed the oxidation states as Fe3+, Ca2+, Mg2+ and O2−. Energy dispersive X-ray spectroscopy (EDS) showed that the elements were uniformly distributed within the nanostructured particles. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) results indicated the presence of CaFe2O4 and MgFe2O4 nanoparticles with good contact between them. The nanocomposite sample showed the capability of 45% for degrading methylene blue (MB) dye under 240 min visible light irradiation. The reusability tests showed that the photocatalytic activity of the nanocomposite was not considerably changed after three cycles.

Fabrication of Magnesium Ferrites for Enormous Adsorbance of Neutral Red and Their Electrochemical Properties.

Magnetic magnesium ferrite nanoparticles were fabricated via the ethanol-assisted solution combustion and gel calcination route. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometer, Brunauer-Emmett-Teller (BET) surface area measurement, vibrating sample magnetometer (VSM) and X-ray diffraction (XRD) were applied to characterize magnetic magnesium ferrite nanoparticles which were prepared under the condition of 20 mL absolute alcohol and calcined at 600 °C for two hours. The results showed that the nanoparticles were spinel structure with the saturation magnetization of 183 emu·g-1, the average grain size of 52 nm, the specific surface area of 33.2 m² · g-1. In addition, the electrochemical property and adsorption mechanism of neutral red (NR) onto the magnetic MgFe₂O₄ nanoparticles were investigated. The adsorption results were conformed to the pseudo-second-order adsorption kinetic and Temkin model, which implied that the multimolecular layer chemical adsorption had occurred. Moreover, the pH had little effect on the process of the adsorption, and the value of the magnetic magnesium ferrite nanoparticles for NR adsorption was up to 555 mg · g-1.

Microstructure and properties of YIG/bismuth-based composite glass/YIG joints with growth of in situ MgFe2O4 whiskers

Bismuth-based glasses doped with MgO nanoparticles were designed to realize the in situ growth of MgFe2O4 whiskers with the aim of improving the mechanical and magnetic properties of YIG/YIG joints. The microstructure of the joints and the formation mechanism of MgFe2O4 whiskers were systematically investigated, as well as the mechanical and magnetic properties. The MgFe2O4 nuclei grew along the [001] orientation to form MgFe2O4 whiskers. The shear strength of YIG/YIG joints increased with an increase in doping of MgO nanoparticles, reaching a maximum of 67.5 MPa for the joint brazed with Bi25-21MgO. It indicated that MgFe2O4 whiskers play an important role in strengthening the joints. The magnetic force microscopy (MFM) and vibrating sample magnetometer (VSM) results indicated that the magnetic properties of the brazing seam improved with the growth of in situ magnetic MgFe2O4 whiskers. The magnetism of YIG/YIG joints could be intensified by brazing with Bi25-21MgO composite glass.

Adsorption characteristics and electrochemical performance of reactive red onto magnetic MgFe2O4 nanoparticles prepared via a facile alcohol combustion process

Magnetic MgFe2O4 nanoparticles were prepared successfully via a facile alcohol combustion process and applied to remove the reactive red (RR) from aqueous solution. Characterizations of the as-prepared MgFe2O4 nanoparticles were performed by the scanning electron microscopy (SEM), the transmission electron microscope (TEM), the X-ray diffraction (XRD), the vibrating sample magnetometer (VSM), and the Brunauer–Emmett–Teller (BET) measurement. The adsorption characteristics of RR onto MgFe2O4 nanoparticles at room temperature were investigated. Compared with the pseudo-first-order and intraparticle diffusion model, the pseudo-second-order kinetic model could be applied to evaluate the adsorption performance of RR onto MgFe2O4 nanoparticles in a range of initial concentration of 100–400 mg/L. Based on the values of the correlation coefficients, the equilibrium experimental data related to the adsorption of RR showed that the adsorption performance followed the Langmuir isotherm model with maximum adsorption capacity of 119.07 mg/g. The obtained results implied that the adsorption mechanism of RR onto MgFe2O4 nanoparticles at room temperature was the monolayer adsorption.

A novel magnetic MgFe2O4–MgTiO3 perovskite nanocomposite: Rapid photo-degradation of toxic dyes under visible irradiation

In this research, we report a simple and inexpensive path for synthesis of magnesium titanate (MgTiO3) and magnesium ferrite (MgFe2O4) nanostructures. MgFe2O4 were synthesized using a microwave-assisted method. The impact of time and microwave radiation power on the morphology of magnetic nanoparticles was studied. Magnesium ferrite-magnesium titanate (MgFe2O4–MgTiO3) nanocomposite was prepared by sol-gel method. The morphology and particles size of samples were studied by scanning electron microscopy (SEM). The crystallinity and purity of products were checked using X-ray diffraction technique. The magnetic property of the produced material was obtained by vibrating sample magnetometry (VSM). The photocatalytic activity of products for degradation of different organic dyes, such as acid black and acid brown under visible light was investigated. The results show a good photo-degradation for organic dyes under the radiation of visible light. Our results indicate that, MgFe2O4–MgTiO3 nanocomposite can be employed for effective charge separation, and lifetime increase of the charge carriers. This product exhibits photocatalytic activity higher than which is reported for MgTiO3 nanostructures.

Structural, Magnetic and Mossbauer Studies of Magnesium Ferrite Nanoparticles Prepared by Hydrothermal Method

Magnesium ferrite (MgFe2O[Formula: see text] being a soft magnetic material with fast frequency response, high a.c. heat power generation and high biocompatibility, is widely used in biomedical fields such as targeted drug delivery, magnetic hyperthermia, etc. This paper reports the synthesis of magnetic MgFe2O4nanoparticles by hydrothermal method using chloride salts of metal ions. The effect of calcination on the structural and magnetic properties is studied by XRD, FTIR, VSM and Mossbauer spectrum analysis. Fine particles in the size range 3–24[Formula: see text]nm are obtained. On calcination, crystallite size increases and lattice parameter decreases. From the magnetic characterization, it is seen that the magnetic properties mainly depend on crystallite size and cation distribution. The mixed spinel states of the prepared materials are confirmed from the FTIR and Mossbauer spectrum analysis. The doublet spectrum obtained in the Mossbauer studies indicates the superparamagnetic relaxation at room temperature.

Fabrication and functionalization of magnesium nanoparticle for lipase immobilization in n-propyl gallate synthesis

An extracellular lipase partially purified from Bacillus thermoamylovorans BHK67 was effectively immobilized onto modified magnetic MgFe2O4 nanoparticles (NPs). NPs were prepared by the sol-gel auto-combustion method and characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Ultra-Violet–Visible Spectroscopy (UV–vis) and atomic force microscopy (AFM). Protein loading reached a saturated amount of about 0.20mg lipase per milligram of MgFe2O4 NPs with 78.9% binding efficiency. The NPs-bound lipase also showed stability following exposure to n-propanol and iso-propanol or FeCl2 and MgCl2 metal ions at (1mM) at 55°C. NPs-bound lipase also retained 50% of its original hydrolytic activity even after 8th cycle, as well as after 12h of incubation at 55°C. NPs-bound lipase in an esterification reaction of n-propanol and gallic acid (25mM) performed for 12h at 55°C produced n-propyl gallate with a conversion rate of 82%. Synthesized n-propyl gallate possessed strong antioxidant activity, which was confirmed by DPPH assay, and in addition has anticancerous activity which was tested on a human L132 cell line.

Removal Performance of Methyl Blue Onto Magnetic MgFe2O4 Nanoparticles Prepared via the Rapid Combustion Process

A rapid combustion process for the preparation of magnetic MgFe2O4 nanoparticles was introduced; the structure and properties of the as-prepared product were investigated by XRD, SEM, TEM and VSM techniques. The experimental results revealed that the volume of absolute alcohol and the calcination temperature were two key parameters for the preparation of MgFe2O4 nanoparticles. With the volume of absolute alcohol increasing from 10 mL to 25 mL, the particle size of MgFe2O4 nanoparticles decreased from 70 nm to 52 nm; while with the calcination temperature increasing from 400 °C to 800 °C, the particle size was increased from 52 nm to 123 nm. The magnetic MgFe2O4 nanoparticles calcined at 400 °C for 2 h were characterized with the average particle size of around 50 nm and the specific magnetization of 247.2 Am2/kg. The magnetic MgFe2O4 nanoparticles were employed to remove methyl blue (MB) from aqueous solution, the adsorption kinetics and adsorption isotherm of MB onto MgFe2O4 nanoparticles at room temperature were investigated, and the regression equation was found in good agreement with the pseudo-second-order model in the initial MB concentrations of 100–400 mg/L; the adsorption equilibrium data of MB onto MgFe2O4 nanoparticles at room temperature were analyzed with Langmuir, Freundlich and Temkin models, and the adsorption isotherm was more effectively described by the Temkin model based on the value of the correlation coefficient (0.9981).

Efficient Fenton Oxidation of Congo Red Dye by Magnetic MgFe<SUB>2</SUB>O<SUB>4</SUB> Nanorods

We reported a highly active magnetic MgFe2O4 nanorods catalyst by annealing Mg(OH)2 deposited α-FeOOH nanorods. The catalyst was fully characterized by X-ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), and Vibrating Sample Magnetometer (VSM), and the results showed that the magnetic MgFe2O4 nanorods were a diameter of 50 nm. The as-prepared MgFe2O4 nanorods were used to catalyze Fenton oxidation of Congo red (CR) solution, and the degradation rate of CR reached 95% after 2 h. The catalytic activity remained high after five cycles. The magnetic MgFe2O4 nanorods could be easily separated from organic solvent. The effects of parameters such as temperature, dosage of catalyst, and H2O2 were also analyzed. This opens new perspectives for the synthesis of one-dimensional magnetic catalyst based on a template method and effective treatment of aqueous hazardous dye.

Comparative Studies of Removal of Methyl Green and Basic Fuchsin from Wastewater by a Novel Magnetic Nanoparticles Mg-Ferrites

Adsorptions of methyl green (MG) and basic fuchsin (BF) by magnetic MgFe2O4 were compared in this study. Adsorption mechanism studies indicated that electrostatic interaction may play a main role for MG, but for BF, hydrogen-bond interaction may be more predominant. Kinetics data of both dyes conformed to the pseudo-second order model. The overall rate process was mainly governed by intraparticle diffusion. Comparative isotherm studies indicated that MG followed the Langmuir isotherm and BF followed the Freundlich isotherm. Thermodynamic parameters revealed that the adsorption process was endothermic (ΔH 0 > 0) for MG, but it was exothermic (ΔH 0 < 0) for BF.

Preparation of high saturation magnetic MgFe2O4 nanoparticles by microwave-assisted ball milling

In this present paper, well-ordered magnesium ferrite nanoparticles with high saturation magnetization were directly synthesized at low temperature with microwave‐assisted ball milling. The as-milled products were characterized by X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results showed that the mean size and the saturation magnetization of the magnesium ferrite nanoparticles are about 30nm and 43.40emu/g, respectively. Compared with conventional milling process, the microwave‐assisted ball milling is a simple and environment‐friendly approach and which could be considered as a promising ball milling approach for the synthesis of high performance ferrite nanoparticles in the future.