Magnetic Properties Of Iron Oxides Research Articles

Efficient synthesis of magnetic activated carbon from oak pericarp for enhanced dye adsorption: A one-step approach

This study presents a one-step synthetic method utilizing oak pericarp treated with FeCl3 and ZnCl2 as a precursor for the production of magnetic activated carbon (MAC). Characterization techniques including FTIR, SEM-EDX, TGA, XRD, VSM, BET, and pHpzc confirm the integration of biochar characteristics and magnetic properties of iron oxides in the MAC composite. Batch adsorption tests investigate the adsorption capacity of Rhodamine B (RhB) and Rose Bengal (RB) dyes by MAC under varied conditions, including adsorbent dose, contact time, solution pH, ionic strength, temperature, and initial dye concentration. Optimal adsorption conditions for RhB and RB are identified at pH 2 and 7, with adsorbent doses of 0.75 g/L and 1 g/L, and equilibrium times of 180 min and 120 min, respectively. Adsorption isotherm models (Langmuir, Freundlich, and Temkin) are employed, with the Freundlich model providing the best fit. MAC demonstrates a maximum monolayer adsorption capacity of 198.529 mg.g−1 for RhB and 42.551 mg.g−1 for RB at 20 °C. Kinetic data align with the pseudo-second-order model, and thermodynamic parameters confirm the spontaneous and endothermic nature of the adsorption process. In conclusion, this study successfully synthesizes magnetic biochar with enhanced efficacy in dye adsorption. The one-step method proves efficient for treating industrial dye effluents, as evidenced by batch desorption studies over four cycles, establishing the reusability of the MAC.

In vitro and Bioimaging Studies of Mesoporous Silica Nanocomposites Encapsulated Iron-oxide and Loaded Doxorubicin Drug (DOX/IO@Silica) as Magnetically Guided Drug Delivery System.

In recent years, the delivery of drugs by nanocomposites has emerged as an exciting field of research for bio-imaging tools and targeted cancer treatment. The large surface area and porous volume of mesoporous silica nanocomposites (MSN's) have gained a lot of interest for their application in the delivery of drugs and the magnetic properties of iron oxide (IO) nanocomposites play a key role in the targeted delivery system. In this study, mesoporous silica encapsulated IO nanocomposites loaded with doxorubicin (DOX) were synthesized for the magnetically guided delivery of anticancer drugs. The synthesis of IO nanocomposites was done through the precipitation method, and then silica encapsulation and drug loading were done by the StÖber method. The magnetically driven delivery of the drug is produced by the encapsulation of magnetically active IO in the mesoporous silica shell. The controlled release of DOX is possible because of the MSN's. TEM images show that the nanocomposites have a spherical morphology and average diameter in the range of 120 nm. Power-XRD data confirm the crystalline nature of nanocomposites. The strong absorption peak was observed in UV-Visible spectroscopy at 490 nm and quenching in fluorescence spectra confirms the encapsulation of DOX in the mesoporous silica shell. VSM data showed the magnetic nature of nanocomposites, with large magnetic susceptibility (74.88 emu/g). The use of DOX/IO@Silica nanocomposites as a sustainable drug release and targeted drug delivery vehicle has been reported here. The pH dependent release of DOX was studied and significant release was observed at lower pH. In-vitro cell viability assay and fluorescence imaging assay have demonstrated that these nanocomposites show significant dose-dependent toxicity to cancer cells in the presence of a magnetic field. In-vitro studies via the MTT assay showed that these synthesized nanocomposites in culture are non-toxic to healthy cells compared to DOX-induced cytotoxicity due its controlled release and can be further strengthened by magnetic guidance. Therefore, due to its optical properties and potential for guided delivery of drug to the targeted site, these nanocomposites are ideal as an anticancer agent and bio-imaging prob.

Impact of the pulling rate on the redox state and magnetic domains of Fe-Si-O glass ceramic processed by LFZ method

This work studies the effect of the pulling rate, varying from 100 to 400 mm/h, on the redox state, structure and magnetic properties of iron oxide bearing silica glasses processed by laser floating zone (LFZ) method.XRD analysis revealed that the maximum crystallinity is obtained in the fibre grown at the lowest pulling rate. A detailed Raman analysis demonstrated that the global content of Fe2+ increases with pulling rate, while the growth under a lower pulling rate promotes the α-Fe2O3 crystallization. Atomic/magnetic force microscopy provided further evidence of phase-separated iron oxide crystallites formation with a high Fe2+/Ftotal ratio as the pulling rate increases.The magnetic measurements performed over a wide temperature range showed that the highest magnetization is found in the fibre grown at the highest pulling rate. A strong correlation between structural-topographical features and the magnetic characteristics of the glass fibres is substantiated.

Effects of Additives on Structural and Magnetic Properties of Iron Oxide

This paper analyzes the effects of additives on the properties of Iron oxide. The Iron oxide was synthesized using the co-precipitation method. The X-ray diffraction (XRD) peaks of resultant Iron oxide perfectly matched with JCPDS #860550 ([Formula: see text] phase of Iron oxide / Hematite). The additives like Cobalt oxide, Nickel metal, Indium oxide and Tin metal with diverse properties procured in readymade forms were mechanically mixed with Iron oxide in 1:99, 3:97, 5:95 and 7:93 weight ratios, respectively. The XRD peaks for additives were prominent for 7:93 (Additive: Base Material) weight % ratio samples. Therefore, for further studies, only these samples were used. In this study, variations in XRD intensity, lattice parameters, unit cell volume, grain size, micro-strains (W-H analysis), dislocation density and stacking fault probability were analyzed. The specific surface area of particles was calculated by scanning electron microscope analysis. The presence of additives was also confirmed by energy dispersive spectra (EDS). The M-H loops (Vibrating Sample Magnetometer analysis) for samples under investigation showed rare vertical shifts. The weak magnetic behavior of bare Hematite (1.0 emu/gm) sample improved to antiferromagnetic behavior due to the addition of Cobalt oxide (7.89 emu/gm) and Nickel metal (2.76 emu/gm). The addition of Indium oxide (0.65 emu/gm) and Tin metal (0.73 emu/gm) samples showed a decreased magnetic saturation.

The Influence of Synthesis Parameters on Structural and Magnetic Properties of Iron Oxide Nanomaterials.

Magnetic iron oxides have been used in biomedical applications, such as contrast agents for magnetic resonance imaging, carriers for controlled drug delivery and immunoassays, or magnetic hyperthermia for the past 40 years. Our aim is to investigate the effect of pressure and temperature on the structural, thermal, and magnetic properties of iron oxides prepared by hydrothermal synthesis at temperatures of 100–200 °C and pressures of 20–1000 bar. It has been found that pressure influences the type of iron oxide crystalline phase. Thus, the results obtained by Mössbauer characterization are in excellent agreement with X-ray diffraction and optical microscopy characterization, showing that, for lower pressure values (<100 bar), hematite is formed, while, at pressures >100 bar, the major crystalline phase is goethite. In addition, thermal analysis results are consistent with particle size analysis by X-ray diffraction, confirming the crystallization of the synthesized iron oxides. One order of magnitude higher magnetization has been obtained for sample synthesized at 1000 bar. The same sample provides after annealing treatment, the highest amount of good quality magnetite leading to a magnetization at saturation of 30 emu/g and a coercive field of 1000 Oe at 10 K and 450 Oe at 300 K, convenient for various applications.

Preparation of magnetic biochar obtained from one-step pyrolysis of salix mongolica and investigation into adsorption behavior of sulfadimidine sodium and norfloxacin in aqueous solution

In this work, salix mongolica, pretreated by FeCl3 and ZnCl2, was applied as a precursor to prepare the magnetic biochar (MBC, containing γ-Fe2O3) with the method of one-step pyrolysis. According to the characterization results of MBC (SEM, XPS, XRD, FTIR, VSM, BET), the features of biochar and the magnetic properties of iron oxides were combined in a composite of MBC. The magnetic biochar can be used as adsorbent for sulfadimidine sodium (SMS) and norfloxacin (NOR) removal from aqueous solution and subsequently removed from the medium by a simple magnetic process. The adsorption characteristics of SMS and NOR from aqueous solution by MBC have been investigated. The adsorption kinetics was best described by Elovich model. The equilibrium data was best fitted by the Freundlich isotherm and Koble-Corrigan model implying the adsorption process mainly was multilayer adsorption on heterogeneous surfaces. The maximum adsorption capacity for SMS and NOR was 251 mg/g and 210 mg/g at 308 K, respectively. The values of thermodynamic parameters were calculated indicating the process of adsorption was an endothermic and spontaneous process. The adsorption mechanism may be attributed to the π–π dispersion, the hydrophobic interaction, hydrogen bonding or the electrostatic interaction between the MBC and the molecule of NOR or SMS.

Synthesis, photoluminescence and Magnetic properties of iron oxide (α-Fe2O3) nanoparticles through precipitation or hydrothermal methods

In this work the iron oxide (α-Fe2O3) nanoparticles are synthesized using two different methods: precipitation and hydrothermal. Size, structural, optical and magnetic properties were determined and compared using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA), Ultraviolet–Visible (UV–Vis) analysis, Superconducting QUantum Interference Device (SQUID) magnetometer and Photoluminescence (PL). XRD data further revealed a rhombohedral (hexagonal) structure with the space group (R-3c) and showed an average size of 21 nm for hydrothermal samples and 33 nm for precipitation samples which concorded with TEM and SEM images. FT-IR confirms the phase purity of the nanoparticles synthesized. The Raman spectroscopy was used not only to prove that we have synthesized pure α-Fe2O3 but also to identify their phonon modes. The TGA showed three mass losses, whereas DTA resulted in three endothermic peaks. The decrease in the particle size of hematite of 33 nm for precipitation samples to 21 nm for hydrothermal samples is responsible for increasing the optical band gap of 1.94–2.10 eV where, the relation between them is inverse relationship. The products exhibited the attractive magnetic properties with good saturation magnetization, which were examined by a SQUID magnetometer. Photoluminescence measurements showed a strong emission band at 450 nm. Pure hematite prepared by hydrothermal method has smallest size, best crystallinity, highest band gap and best value of saturation magnetization compared to the hematite elaborated by the precipitation method.

A Mineral Magnetic Approach to Determine Paleo‐Firing Temperatures in the Neolithic Settlement Site of Mursalevo‐Deveboaz (SW Bulgaria)

AbstractArcheological remains from the Neolithic period in SE Europe are characterized by the presence of massive burnt daub relics sintered at high temperatures. These findings raised the hypothesis of deliberate house burning as a strategy for ensuring the survival of place and the development of social memory in Neolithic society. Although highly discussed in the archeological community, analytical data on the ancient firing temperatures achieved during burning Neolithic houses are missing except an empirical study determining firing temperatures according to the color of burned clay. The Neolithic site Mursalevo‐Deveboaz (Bulgaria) is one of the largest known settlements consisting of more than 70 houses. Rock‐magnetic analyses are applied for characterization of iron oxides produced during firing, and the firing temperatures were estimated using the magnetic susceptibility method. Results on a collection of 445 samples show the presence of very fine grained magnetite/maghemite and hematite. Magnetic data are supported by elemental analysis, reflectance spectroscopy, and scanning electron microscopy. The data suggest an increase in the magnetic grain size from superparamagnetic toward single domain with increasing firing temperature. Firing temperature estimates for 148 samples of different color vary between 680 and 1,140°C. Comparing the magnetic properties of iron oxides identified and literature data on solution‐combustion synthesis of iron oxides allowed a mechanism behind the extreme firing of Neolithic houses to be suggested. Our study proposes for the first time that combustion synthesis of iron oxides could explain the extreme house burning in many Neolithic settlements achieved through intentional addition of wood, dung and urine.

Multifunctional gold coated iron oxide core-shell nanoparticles stabilized using thiolated sodium alginate for biomedical applications

In this paper we report synthesis of aqueous based gold coated iron oxide nanoparticles to integrate the localized surface plasma resonance (SPR) properties of gold and magnetic properties of iron oxide in a single system. Iron oxide-gold core shell nanoparticles were stabilized by attachment of thiolated sodium alginate to the surface of nanoparticles. Transmission electron microscope (TEM) micrograph presents an average elementary particle size of 8.1±2.1nm. High resolution TEM (HR-TEM) and X-ray photon spectroscopy further confirms the presence of gold shell around iron oxide core. Gold coating is responsible for reducing saturation magnetization (Ms) value from ~41emu/g to ~24emu/g – in thiolated sodium alginate stabilized gold coated iron oxide core-shell nanoparticles. The drug (curcumin) loading efficiency for the prepared nanocomposites was estimated to be around 7.2wt% (72μgdrug/mg nanoparticles) with encapsulation efficiency of 72.8%. Gold-coated iron oxide core-shell nanoparticles could be of immense importance in the field of targeted drug delivery along with capability to be used as contrast agent for MRI & CT.

The Effects and Role of Polyvinylpyrrolidone on the Size and Phase Composition of Iron Oxide Nanoparticles Prepared by a Modified Sol-Gel Method

Fe2O3 nanoparticles (as maghemite and hematite mixtures) were prepared using adapted sol-gel method from a polyvinylpyrrolidone (PVP) aqueous solution in various Fe3+ : PVP monomer ratios. Analysis of X-ray diffraction was obtained to evaluate the crystalline state, average crystallite size, and composition of iron oxide phases. The morphology and average nanoparticles size were evaluated by electronic transmission microscopy. Magnetic properties of iron oxide were analyzed at low and room temperatures. Optical characteristics were evaluated by UV-Vis photoacoustic spectroscopy and the Mössbauer spectrum was obtained in order to evaluate subtle changes in the nuclear environment of the iron atoms.

A simple route to diverse noble metal-decorated iron oxide nanoparticles for catalysis.

Developing facile synthetic routes to multifunctional nanoparticles combining the magnetic properties of iron oxides with the optical and catalytic utility of noble metal particles remains an important goal in realizing the potential of hybrid nanomaterials. To this end, we have developed a single route to noble metal-decorated magnetic nanoparticles (Fe3O4@SiO2-M; M = Au, Pd, Ag, and PtAg) and characterized them by HRTEM and STEM/EDX imaging to reveal their nanometer size (16 nm Fe3O4 and 1-5 nm M seeds) and uniformity. This represents one of the few examples of genuine multifunctional particles on the nanoscale. We show that these hybrid structures have excellent catalytic activity for the reduction of 4-nitrophenol (knorm = 2 × 10(7) s(-1) mol(Pd)(-1); 5 × 10(6) s(-1) mol(Au)(-1); 5 × 10(5) s(-1) mol(PtAg)(-1); 7 × 10(5) s(-1) mol(Ag)(-1)). These rates are the highest reported for nano-sized comparables, and are competitive with mesoparticles of similar composition. Due to their magnetic response, the particles are also suitable for magnetic recovery and maintain >99% conversion for at least four cycles. Using this synthetic route, Fe3O4@SiO2-M particles show great promise for further development as a precursor to complicated anisotropic materials or for applications ranging from nanocatalysis to biomedical sensing.

Influence of silica coating process on fine structure and magnetic properties of iron oxide nanoparticles

We present influences of silica coating process on the nanostructure and magnetic properties of superparamagnetic iron-oxide (SPIO) nanoparticles (NPs). The silica coating on SPIO NPs is done to render the composite particles suitable for biomedical applications. SPIO NPs synthesized using iron oleate in the present study are composed of an antiferromagnetic FeO core and a ferromagnetic Fe3O4 shell except NPs of 7nm in diameter, which are a single crystal of Fe3O4. The conversion of FeO phase to Fe3O4 phase at their interface resulting from silica coating is confirmed using X-ray diffraction and magnetic measurements. The magnetic properties of SPIO NPs change with the increase in volume fraction of Fe3O4 due to the conversion from FeO by the silica coating. In addition, a temperature-dependent magnetization reveals that the magnetic interaction between the antiferromagnetic FeO and the ferromagnetic Fe3O4 influences the magnetic properties. These results suggest the strategy to obtain optimum magnetic properties of iron oxide/silica composite particles for biomedical applications.

Synthesis of α-Fe2O3 Sphere/Rod-Like Nanostructure via Simple Surfactant-Free Precipitation Route: Optical Properties and Formation Mechanism.

Sphere/rod-like α-Fe2O3 nanostructure were successfully synthesized by simple surfactant-free precipitation route. The as-prepared samples were characterized by X-ray powder diffraction (XRD) to determine the phase purity and the crystal structure. The lattice parameter and crystallite size of the samples have been calculated from the Rietveld analysis. The crystallite size has been compared by Scherrer's formula and Rietveld method and both method showed increase of the grain size with the increase of the calcined temperature. The crystallite size was in the range of 5-30 nm. The high resolution scanning electron microscopy (HR-SEM) analysis of the samples shows that the morphology of the nanostructures changed from nanospheres into nanorods and it was confirmed by high resolution transmission electron microscopy (HR-TEM). Energy dispersive X-ray (EDX) analysis reveals the presence of O and Fe elements only. The optical properties of the as-prepared nanostructures were determined by photoluminescence (PL) spectra. The band gap energy was investigated by UV-Visible diffuse reflectance spectra (DRS) and calculated by means of the Kubelka-Munk method. The band gap values are decreased from 2.26 eV to 2.17 eV as the temperature increased from 300 degrees C to 400 degrees C with increasing the crystallite size. A Vibrating Sample Magnetometer (VSM) was used to study the magnetic properties of iron oxide (α-Fe2O3) nanostructures. Magnetic hysteresis (M-H) loops revealed that the as-prepared α-Fe2O3 samples displayed ferromagnetic behavior.

Preparation of alumina-iron oxide compounds by coprecipitation and gel evaporation methods and their characterization

Fe2O3-Al2O3 compounds were synthesized by coprecipitation(CP) and gel evaporation (GE) method with different Fe/Al compositions andcalcined at high temperatures (300oC-1000oC). Thecrystalline phases in the samples were determined by XRD, the latticeparameters of the resulting crystalline phases were calculated by aleast-square method. The properties were also characterized by magnetizationmeasurements. The formation of crystalline phases (e.g., maghemite, hematite),transformation temperature, magnetic properties of iron oxide were all affectedby the component ratio and thermal treatment.

XPS and FTIR spectroscopic study on microwave treated high phosphorus iron ore

A growing interest in microwave heating has emerged recently. Several potential microwave applications regarding minerals’ processing have been investigated. This paper investigates the effect of microwave radiation on Egyptian high phosphorus iron ore. Three different iron ore samples have varying Fe2O3 and P2O5 contents and mineralogical textures were studied. A comparative study has been carried out between untreated and microwave treated iron ore. XRD and FTIR analyses showed that after microwave radiation the crystallinity of iron bearing minerals (hematite) increased, while the functional chemical groups of phosphorus bearing minerals (fluorapatite) and other gangues dissociated. High resolution XPS analyses of Fe 2p peaks showed that after microwave radiation a portion of Fe(+III) was reduced to Fe(+II). This means that after microwave radiation iron oxide (hematite, Fe3+) transformed into more magnetic phase. The results indicated that microwave radiation had a positive effect on the magnetic properties of iron oxide, through formation of ferromagnetic phases.

Arsenic removal from aqueous solutions by adsorption onto iron oxide/activated carbon magnetic composite

In this work the adsorption features of activated carbon and the magnetic properties of iron oxides were combined in a composite to produce magnetic adsorbent. Batch experiments were conducted to study the adsorption behavior of arsenate onto the synthetic magnetic adsorbent. The effects of initial solution pH, contact time, adsorbent dosage and co-existing anionic component on the adsorption of arsenate were investigated. The results showed that the removal percentage of arsenate could be over 95% in the conditions of adsorbent dosage 5.0 g/L, initial solution pH 3.0-8.0, and contact time 1 h. Under the experimental conditions, phosphate and silicate caused greater decrease in arsenate removal percentage among the anions, and sulfate had almost no effect on the adsorption of arsenate. Kinetics study showed that the overall adsorption rate of arsenate was illustrated by the pseudo-second-order kinetic model. The applicability of the Langmuir and Freundlich models for the arsenate adsorption data was tested. Both the models adequately describe the experimental data. Moreover, the magnetic composite adsorbent could be easily recovered from the medium by an external magnetic field. It can therefore be potentially applied for the treatment of water contaminated by arsenate.

Influence of Au addition on magnetic properties of iron oxide in a silica–phosphate glass matrix

The influence of gold particle addition on structural and magnetic ordering of iron oxide in a glass matrix was studied. The silica–phosphate glasses containing iron oxide and Au were prepared by the melt quench technique. Evolution of crystalline phases was studied by X-ray diffraction (XRD). Magnetic properties were investigated by means of a Superconducting Quantum Interference Device (SQUID) magnetometer and room temperature Mössbauer spectroscopy. The microstructure exhibited the formation of 30–40nm size particles. The samples showed the formation of magnetite and hematite as major crystalline phases. Magnetic studies revealed the relaxation of magnetic particles. Blocking temperature of investigated sample increased with an increase of Au content implying an increase in the strength of magnetic interactions. Mössbauer spectroscopy has shown the presence of both doublets and magnetic sextets. The magnetization value increased as Au content was increased, which is attributed to the increase in magnetic and structural ordering.

Preparation of Alumina-Iron Oxide Compounds by Coprecipitation Method and Its Characterization

Fe2O3-Al2O3 compounds with different Fe/Al compositions were synthesized by coprecipitation (CP) method and calcined at 300°-1000°C. The formation of crystalline phases (e.g., maghemite, hematite), transformation temperature, specific surface area, lattice parameter, crystallite size, magnetic properties of iron oxide were all affected by the component ratio and thermal treatment.

Remoção de cromo (VI) de soluções aquosas utilizando o compósito magnético calcinado hidrotalcita-óxido de ferro: estudo cinético e de equilíbrio termodinâmico

In this work, hydrotalcite, a layered double hydroxide, had its ion exchange properties combined with the magnetic properties of iron oxide to produce a magnetic adsorbent, HT-Fe 500. These magnetic composites can be used as adsorbents for anionic contaminants in water and subsequently removed from the medium by a simple magnetic process. Removal of chromium (VI) from aqueous solutions using HT-Fe 500 was achieved using batch adsorption experiments. The adsorption capacity, calculated with the Langmuir-Freundlich model showed to be dependent on temperature, reaching values of 25.93 and 48.31 mg g-1, respectively, for temperatures of 25 and 30 oC.

Alumina/Iron Oxide Nano Composite for Cadmium Ions Removal from Aqueous Solutions

Magnetic alumina nano composite (MANC) was prepared for combination of the adsorption features of nano activated alumina with the magnetic properties of iron oxides to produce a nano magnetic adsorbent, which can be separated from the medium by a simple magnetic process after adsorption. MANC was characterized using XRD, SEM, TEM, EDX and surface area (BET). Quantum design SQUID magnetometer was used to study the magnetic measurement. The present study was conducted to evaluate the feasibility of MANC for the removal of cadmium ions from aqueous solutions through batch adsorption technique. The effects of pH, adsorbent dose, temperature, contact time and initial Cd2+ concentration on cadmium ions adsorption were studied. Equilibrium data were fitted to Langmuir, Freundlich and Temkin isotherms. The equilibrium data were best represented by the Langmuir isotherm. The kinetic data were fitted to pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models, and it was found to follow closely the pseudo-second-order model. Thermodynamic parameters were calculated for the Cd2+ ion-MANC system and the positive value of ΔH° showed that the adsorption was endothermic in nature. Furthermore, a single-stage batch adsorber was designed for the removal of Cd2+ ions by MANC based on the equilibrium data obtained.