Papers by Keyword: Magnetite

Abstract: Spinel ferrite nanoparticles are potential candidates for multiple biomedical applications. Spinel ferrite nanoparticles have been studied extensively for understanding physical, chemical, electro-optical as well as magnetic properties which are fascinating due to cationic distributions corresponding to tetrahedral sites and octahedral sites in a cubic phase. Biocompatibility and large magnetic moment are basic requirements in spinel ferrite nanoparticles for efficient functioning in specific application purpose. Fe₃O₄ (magnetite) is an important member of spinel ferrite group with high chemical stability and ferrimagetic material property at nanodimension. Superparamagnetic state and biocompatibility of magnetite (Fe₃O₄) spinel ferrite nanoparticle has already been proven. Spinel ferrite magnetite nanoparticles have been developed based on precipitation of iron oxide using ferric and ferrous ions at the ratio 2:1 in alkaline media at and above 100°C. The experimental parameters have been set to synthesize pure and uniformly sized magnetite nanoparticles. No other phases of iron oxides were detected other than magnetite spinel phase in the XRD result. The average crystal size has been determined from XRD peak broadening. Absorption spectra were investigated using UV-Vis Spectrometer and FTIR. Thermal and magnetic measurements were carried out Digital Scanning Calorimeter and SQUID Magnetometer. One sample of the prepared nanoparticles with polymer coating of polyvinyl alcohol has been studied for superparamagnetic nature. Superparamagnetic particles show saturation value of magnetization 51.26 emu/g at 100 K. ZFC-FC curves for two samples with polymer coating of polyvinyl alcohol and hydroxy-propyl methyl cellulose have also been studied. Keywords: Spinel Ferrite, Magnetite, Ferrimagnetism, Transition metal oxide, Superparamagnetism. Statements and declarations Competing Interests: The authors declare that there is no competing financial interest that are related directly or indirectly to the reported work in this paper. Conflict of interest: There is no conflict of interest. Acknowledgements The Authors are grateful to IISER Bhopal, CRF facility for providing instrumentation facility to characterize magnetic properties. We acknowledge thanks to Lovely Professional University for providing us necessary characterization technique for the XRD analysis and thermal analysis.

Abstract: In this research, a homemade autoclave reactor was used for preparing iron oxide nanoparticles by hydrothermal technique at different reaction times by using ferric chloride, ferrous sulfate, and ammonium hydroxide as raw materials. The XRD characterization showed that the nanoparticles of the samples have high crystallinity with the crystal phase of magnetite, furthermore, the crystal phase of hematite appears clearly as the reaction time increased. The SEM results showed when the time of reaction increased the average particle size increased too from 28.1 to 49.2 nm. That means the reaction time is an effective parameter for the nanoparticle's growth, The EDX spectrum verified the confirmation of iron oxide nanoparticles by the appearance of Iron and Oxygen peaks. The FT-IR results showed that all samples have an absorption peak at about 578 cm^-1 corresponding to the Fe-O bond stretching modes of the in magnetite and the peak of hematite appeared as the reaction time increased above 2 hours which was confirmed with XRD results. Finally, the reaction time is a powerful tool for controlling in size and phase of nanoparticle preparation. Keywords: Hydrothermal, Iron Oxide, Reaction time, magnetite, and hematite.

Abstract: In this research, iron oxide nanoparticles were prepared by a new hydrothermal pyrolysis technique at different reaction times. X-ray diffractometer (XRD) characterization showed that the nanoparticles have high crystallinity with a combination of two crystal phases maghemite and magnetite, as the reaction time increase the ratio of magnetite phase to maghemite phase increased. The morphological properties of the samples showed an increase in the particle size from 58 to 108 nm due to the single domain–multidomain transition as showed by scanning electron microscope (SEM). Electron Dispersive X-ray (EDX) spectra showed only peaks of oxygen and iron that verified the formation of iron oxide nanoparticles. The Fourier transform infrared spectroscopy (FT-IR) showed that the absorption peaks at about 578 cm^-1 and 630 cm^-1 correspond to the stretching modes of the Fe-O in magnetite, as the reaction time increased the peak around 630 cm^-1 decreased due to the magnetite phase only. Finally, all the results showed the formation of iron oxide nanoparticles by this new technique that merges spray pyrolysis and hydrothermal techniques with many advantages such as spraying successive parameters in a short time, high-speed, good homogeneity, and pure material with small particle size.

Abstract: Adsorbents from green and sustainable source are highly desirable for practical applications. In this study, humic acid-like substance extracted from dry horse dung powder and carboxymethyl cellulose (CMC) were adopted to fabricate a composite immobilized on magnetic precipitates of magnetite. The as-prepared adsorbent, denoted as CMC-MHDHA, was analyzed by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission and scanning electron microscopy equipped with energy dispersive X-ray (TEM and SEM-EDX), thermo gravimetric analysis (TGA), and vibration sample magnometer (VSM). Application to the synthetic wastewater of Pb (II) and Rhodamine B (RhB), a high Langmuir monolayer adsorption capacity of 63.38 and 42.78 mg/g was achieved over CMC-MHDHA, respectively. The fabricated adsorbent was also demonstrating quick and easy retraction of pollutant-loaded adsorbent by an external magnet with the magnetic strength of 40.7 emu/g. Based on the estimated free adsorption energy of Dubinin-Radusckevich (D-R) isotherm model, the adsorption interaction of both Pb (II) (9.76 kJ/mol) and RhB (12.39 kJ/mol) with CMC-MHDHA was mainly occurred by ion exchange mechanism. Adsorption rate analysis at the initial adsorbate concentration ranged from 50 to 400 mg/L of both Pb (II) and RhB showed that the rapid adsorption generally occurs in early 20 minutes then slow down and reaches equilibrium after 180 minutes. The Ho (pseudo second order) kinetics model represent appropriately the adsorption of both Pb (II) and RhB onto the adsorbent. The developed adsorbent is also reusable with 72.3% of stability in pH 11. Therefore, the adsorbent of CMC-MHDHA is suggested to be a promising candidate for adsorption applications.

Abstract: Ultrasonic Spray Pyrolysis (USP) technique was used to prepare undoped and (2, 4, 6 and 10 at. %) Zn-doped iron oxide (Fe_xO_y:Zn) thin films for use in photocatalytic applications. The effect of Zn ion substitution on structural, optical, and electrical properties was studied. The X-ray diffraction patterns showed that there are two different phases of iron oxide, a hematite phase (α‑Fe₂O₃) and a magnetite phase (Fe₃O₄) that crystallized in the prepared samples. The nominal fractions of α‑Fe₂O₃ and Fe₃O₄ phases changed from 74 % to 42 % for the hematite phase and from 26 % to 58 % for the magnetite phase and this confirmed that the Zn doping favored the growth of Fe₃O₄ phase. The crystallite size decreased from 15.43 nm to 8.99 nm, while the micro-strain changed from 0.0056 to 0.0215 and the dislocation density from 0.0099 nm^‑2 to 0.0639 nm^‑2. The unit cell parameters were also improved when the doping rate was changed. Optical measurements showed that the energy gap decreased from 2.26 eV to 2.16 eV, the film thickness changed from 569 nm to 479 nm while the refractive index increased from 2.99 to 3.51 and the Urbach energy from 544 meV to 558 meV. Electrical measurements performed by the two-point probe method showed that the electrical conductivity increased directly with increasing Zn concentration reaching 18.5 10^‑15 (Ω.cm)^‑1 with 10 at. % Zn concentration. The variation of the electrical conductivity curves versus the sample heating temperature as well as the activation energy showed a semiconductor behavior of the films. Zinc doped iron oxide thin films exhibit 51.85 % photocatalytic degradation efficiency for methyl green organic dye.

Abstract: In this paper, the magnetic properties of Aceh iron sand was studied. The iron sand was collected from the Syiah Kuala coastal area, Banda Aceh and obtained by mechanical alloying method using planetary ball milling. The mineral compositions were investigated by XRD and XRF analysis tests. The XRF test showed that the sand mostly contain magnetite, Fe₃O₄ (85.80%) in association with other impurities of SiO₂, TiO₂, Al₂O₃ and some others minor minerals. Compare to XRD results, the phase compositions were mainly magnetite (Fe₃O₄). So, it is consistent with the XRF data. The electron microscopy observation (SEM) showed the fine crystalline structure and the main morphology was micro-crystalline in agglomerate forms. Furthermore, the magnetic properties after 20 hours milling showed the increasing in the coercivity (Hc) and remanent (Br), while the magnetic saturation (Ms) was decreased. This behavior can be explained that nano-Fe₃O₄ phase after the milling process plays an important role in the magnetic properties of iron sand.

Abstract: In this study, iron removal was carried out by the adsorption process as a well-known method of removing heavy metal. Natural bentonite with magnetic properties in a monolithic form or Magnetite-Bentonite-based Monolith (MBM) adsorbent was used as an adsorbent to remove Iron (II) ion from the aqueous solution. The magnetic properties of adsorbents are obtained by adding magnetite (Fe₃O₄), which is synthesized by the coprecipitation process. The characterization of magnetic properties was performed using the Vibrating Sample Magnetometer (VSM). VSM results showed that the magnetic particles were ferromagnetic. Adsorption efficiency, isotherm model, and adsorption kinetics were investigated in a batch system with iron solution concentration varied from 2 to 10 mg/L and magnetite loading at 2% and 5% w/w. The highest removal efficiency obtained reached 89% with a 5% magnetite loading. The best fit to the data was obtained with the Langmuir isotherm (non-linear) with maximum monolayer adsorption capacity (Q_o) at 5% magnetic loading MBM adsorbent is 0.203 mg/g with Langmuir constants K_L and a_L are 2.055 L/g and 10.122 L/mg respectively. The pseudo-first-order (non-linear) kinetic model provides the best correlation of the experimental data with the rate of adsorption (k₁) with magnetite loading 2% and 5%, respectively are 0.024 min^-1 and 0.022 min^-1.

Abstract: The Fe₃O₄/ZnO/Ag nanocomposite has been successfully synthesized, and the material was applied as a photocatalyst to degrade titan yellow. The Fe₃O₄ was synthesized through sono-coprecipitation method using NH₄OH as a precipitating agent. The synthesized ZnO/Ag was performed via coprecipitation method using ethylene glycol, zinc acetate, and silver nitrate as a reagent. This study investigated several parameters, such as the effect of time reaction, equilibrium state, and material responsiveness under visible light irradiation. The XRD measurement indicated the presence of ZnO, Ag, and Fe₃O_4, whereas the TEM image displayed the photocatalyst had a nanosized particle with approximately 17 nm. The photocatalyst activity has shown the equilibrium process at 60 minutes. The highest degradation (up to 90%) of titan yellow was achieved by Fe₃O₄/ZnO/Ag nanocomposite. The reusability test showed that Fe₃O₄/ZnO/Ag nanocomposite had high stability and could be used up to three times.

Abstract: We reported simple processing of local iron sand in order to increase the purity of magnetic phase. The refining process of iron sand is carried out in two stages, namely the iron sand extract using a permanent magnet and the purification process. The purification process was carried out by co-precipitation method in varying of the dissolving temperatures and volume of HCl. The iron salt solution formed is then precipitated using NH₄OH solution and then sintered at 100 °C and 1000 °C, respectively. All samples are characterized by X-ray fluorescence (XRF) and X-ray diffraction (XRD) to identify the elemental content and the crystal structure. From the XRF measurements, it was found that the Fe content before purification process was 32.68 %, increasing to 33.12 % after purification process with HCL volume of 75 ml and sintered at 100 °C. From XRD measurement, it was found that the crystal structure of iron sand before purification process was dominated by magnesioferrite (33.2 %), and magnetite (20.2 %). After purification process at 1000 °C, the magnesioferrite phase increased to 80.2 % and 50.2 % for HCl volume of 50 ml and 75 ml, respectively, while the magnetite phase increase to become 34.5 % for 100 ml of HCl.

Abstract: References on microwave energy use were reviewed and it demonstrated wide use of this kind of energy in various sectors of national economy. However in ferrous metallurgy this type of energy practically is not used despite the fact that it holds much promise and offers a number of advantages over other kinds of energy. In this work an attempt was made to use microwave energy in ferrous metallurgy and it was implemented in terms of concentration process development for limonite ores of the Lisakskoye deposit with hydro-goethite being a base iron-bearing mineral. Qualitative and quantitative characteristics of the subsequent magnetic separation process were determined. The developed concentration process of the Lisakovskoye deposit ores with the microwave energy used for baking and magnetizing of intermediate concentration products was compared with the current deep concentration process of the Lisakovskiy Mining and Processing Works and its advantages were demonstrated. Technical and economic calculation showed that the concentration process with microwave energy used is more efficient than deep concentration process without the product baking; it allows a significant increase of iron recovery into the concentrate and provides additional profit to the Company.