Hematite Phase Research Articles

Fabrication of Basalt Matrix Composite Material by Pressureless Aluminum Melt Infiltration in Air Atmosphere

The microstructure of Basalt matrix composite materials produced by pressureless aluminum melt infiltration at 950 °C was investigated. It is established that uniform elements distribution is observed within the whole sample depth. Interestingly, aluminum content variation considerably matches the hardness of the sample profile that is connected with alumina phase presence. Sample color changes during temperature treatment due to phase transitions were observed. The appearance of the hematite (Fe2O3) phase makes the initial preform red. After infiltration by molten aluminum, oxygen-deficient alumosilicate phases turn the color black. The infiltration process decreases the porosity insufficiently due to a partial reduction of alumosilicates by molten Al and the hardness of infiltrated samples was only 2.2 GPa. Nevertheless, a huge thermal conductivity rise from 1.45 to 4.53 W/(m·K), along with a fracture toughness increase, makes the produced composite a prospective wear-resistant material. Moreover, the developed low-temperature production technology allows for obtaining a very cost-effective material.

Influence of Sm and Cd co-substitutions on physical, magnetic, Mössbauer, electric, and dielectric properties of Co2X hexagonal ferrites in presence of a hematite phase

X-type samarium-cadmium co-substituted hexaferrite with compositions Ba2-xSmxCo2CdyFe28-yO46 (0.00 ≤ x ≤ 0.08, and 0 ≤ y ≤ 0.4) were prepared at 1340 °C using a simple heat treatment technique. All heated samples were characterized using FTIR, XRD, SEM, VSM, Mӧssbauer, and low-frequency dielectric measurements. XRD analysis of prepared samples shows the formation of X as a major phase along with hematite. The MS value varied from 67.01 Am2/kg to 50.43 Am2/kg; whereas the Hc value changed from 2.95 kA/m to 6.17 kA/m, A high value of MS (67.01 Am2/kg) is observed in the pure sample, and a very low value of Hc (2.95 kA/m) is observed for x = 0.06, y = 0.3 compositions, but Mr/Ms < 0.5 confirm the multi-domain nature of prepared hexaferrites. Hysteresis loops of all samples are narrow, and confirmed that formed samples belong to magnetically soft. Mössbauer spectra of the three samples (S1, S3, and S5) show the existence of doublets. Significantly low values of coercivity, retentivity, and loss tangent in Sm–Cd substituted samples signified those prepared materials can be used to design electromagnets, transformer cores, electric motors, and maybe a potential candidate for lossless low-frequency applications.

Reduction behavior of hematite ore with different particle sizes in suspension roaster

High-purity hematite was divided into five size fractions, and the reduction behavior of these fractions was investigated to explore the problem of the asynchronous reaction of heterogeneous and complex refractory iron ore. The quantitative relationship between the conversion rate, roasting time, and ore particle size of different temperature systems was determined using the MATLAB software. X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) were conducted on roasted samples, and reducing the ore size was found to promote the transformation of the hematite phase into magnetite during the magnetization roasting process. Scanning electron microscopy (SEM) and specific surface area analysis demonstrated that the new magnetite had a loose porous structure, which provides a channel for CO gas to contact with the new hematite surface. The increase in the ore particle size increased the CO diffusion resistance, resulting in an asynchronous reaction.

PENGARUH DOPING MANGAN TERHADAP KOMPOSISI DAN SIFAT KRISTALINITAS PARTIKEL OKSIDA BESI PASIR ALAM SUNGAI ROKAN DIPREPARASI DENGAN METODE BALL MILLING

The composition, crystallinity and magnetic susceptibility of nanoparticles in natural sand of the Rokan River, Riau Province have been investigated. After the iron sand separator (ISS) process, the natural sand samples were separated using NdFeB magnets to separate iron oxide particles and other non-ferrous oxides. For 70 hours, the NdFeB product was prepared using the ball milling method to produce BM products. The BM products were ball milled for 30 hours with a manganese doping concentration of 0 wt.%; 5 wt.%, and 10 wt.% produced DM 0, DM 5 and DM 10 products. Magnetic susceptibility values increased based on the values of B0 and BT measured using Pasco Magnetic Probe PS-2162. The results of XRD analysis of DM products contain a hematite phase (α-Fe2O3) which has a hexagonal structure. The crystal size increased along with the increasing concentration of Manganese from 25.494 nm; 25,542 nm to 25.669 nm. The results of XRF analysis of DM products on Fe elements decreased in percentage with increasing Manganese concentration from 18.083%; 15.407% to 12.947%. Other chemical elements such as Si, Al, K, P, Ti, Ca, Ti, Cr, Zn, V and Pb also decreased.

A Facile Method for the Preparation of α-Fe2O3/Reduced Graphene Oxides Nanocomposites as Electrode Materials for High Performance Supercapacitors

In this work, a low-cost, fast, and environmental friendly microwave assisted chemical route to prepare hematite iron oxide (α-Fe2O3) nanoparticles/reduced graphene oxides (RGO) nanocomposites and their potential use as electrodes for the supercapacitors was presented. The x-ray diffraction (XRD), Raman, FESEM and high resolution transmission electron microscopy (HR-TEM) studies confirmed that the prepared nanostructures have pure rhombohedral symmetry of Fe2O3 with hematite phase and high crystallinity. Morphological features obtained from Field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analyses showed that the α-Fe2O3 nanoparticles possessed spherical shaped particles with size ranging from 10–20 nm, and the nanoparticles of α-Fe2O3 were found to be anchored on the surface of RGO sheets. Electrochemical studies were carried out using α-Fe2O3 nanoparticles and α-Fe2O3/RGO nanocomposites electrodes and their performances were compared. It was observed that that α-Fe2O3/RGO nanocomposites electrodes displayed higher specific capacitance of 356 F g−1 measured at a scan rate of 50 mV s−1, while, α-Fe2O3 nanoparticles showed a specific capacitance of 123 F g−1 at a similar scan rate. Furthermore, α-Fe2O3/RGO nanocomposites exhibited excellent cyclic stability for 2500 cycles measured at a scan rate of 50 mV s−1 with ~92% capacitance retention. The presented approach is promising for the mass production of high performance electrodes applied in energy storage device.

Visible light photocatalytic and magnetic properties of V doped α-Fe2O3 (VFO) nanoparticles synthesized by polyol assisted hydrothermal method

Vanadium-doped α-Fe2O3 nanoparticles (VFO nanoparticles) were prepared by polyol-assisted hydrothermal method. The impact on the structure, optical, magnetic and photocatalytic properties of α-Fe2O3 nanoparticles were studied by varying the vanadium concentration from 1 to 5%. XRD analysis confirms the presence of hematite phase with hexagonal structure and estimates the nanocrystals size as ∼26–38 nm. FESEM and TEM reveal the formation of 3D flower-like morphology bundled with 2D nanoflakes. The estimated band gap energy was in the range 2.01 eV–2.12 eV. XPS study shows the presence of vanadium in V4+ oxidation state in VFO nanoparticles. VSM study shows a non-saturated hysteresis loop with weak ferromagnetic behavior for all the VFO nanoparticles. 5% V doped α-Fe2O3 nanoparticles (5%VFO nanoparticles) exhibited superior visible light driven photocatalytic activity compared to other samples.

Synthesis of Ni doped iron oxide colloidal nanocrystal clusters using poly(N-isopropylacrylamide) templates for efficient recovery of cefixime and methylene blue

The synthesis of a complex hierarchical nanostructure with a definite number density and crystallite/cluster size is very challenging. Here we report a novel strategy to produce spherical magnetic colloidal nanocrystal clusters (Ni-doped iron oxide) of varying sizes using a thermosensitive polymer soft template through a hydrothermal approach. The magnetic colloidal nanocrystal clusters are nucleated in the globular spherical templates formed in the thermosensitive polymer; poly(N-isopropyl acrylamide), above lower critical solution temperature (LCST) where it acts as a nucleating agent in the initial stage and as a capping agent later. When the solution reaches super-saturation during the nucleation stage, the Ni2+, Fe2+ and Fe3+ hydroxides precipitate as ferrites of critical size and get attached to the PNIPAM globule through the coordination of oxygen and nitrogen. It was observed that, after the addition of Ni2+ ions, non-stoichiometric Ni ferrites nanocrystals were formed whereas the hematite phase was formed in the absence of Ni doping. XPS results show the presence of cation vacancies due to oxidation of Ni2+ and Fe2+. We also studied the adsorption/desorption of an anionic cefixime drug, conjugated on nanoclusters, above and below the lower critical solution temperature. The cefixime adsorption studies on the clusters showed that ~70 g/L of the sample is required to obtain a 66 sorption% at 25 °C and 52 sorption% at 45 °C. The percentage of cefixime sorption after the five cycles of regeneration was ~70%. The dye adsorption studies reveal that 15 g/L of the sample showed 99% sorption% of methylene blue at 25 °C and 87% sorption% at 45 °C This approach can be used as a new strategy to achieve controlled recovery of adsorbates (antibiotics and dyes) from aqueous solutions.

Influence of erbium doping on the structural, magnetic and optical properties of hematite (α-Fe2O3) nanorods

Pure and Er-doped hematite (α-Fe2O3) nanorods were prepared by a two-step method involving hydrothermal synthesis and calcination of pure and Er-doped goethite (α-FeOOH) nanorods. Substitution of Fe3+ by Er3+ in the crystal structure of hematite caused morpho-structural changes such as expansion of the unit cell and gradual shortening and rounding of hematite nanorods towards formation of nanoellipsoids. These changes induced modification of magnetic and optical properties suggesting the possibility of a systematic control of physical properties via rare earth substitution. A decrease in the hyperfine magnetic field, coercive field and Morin transition temperature, as well as an increase of the magnetic susceptibility and a narrowing of the optical band gap were observed by substitution. Intimate mechanisms related to the formation of more and more defect-like hematite phases with decreased temperatures for the transition to the low temperature antiferromagnetic phase at increased doping level were evidenced via temperature dependent Mössbauer spectroscopy.

Ferruginous coated grains of microbial origin from the Lower Devonian (Pragian) of the Prague Basin (Czech Republic) – Petrological and geochemical perspective

A unique occurrence of ironstone lenses represented by ferruginous oncoids is reported from the offshore Řeporyje Limestone (Lower Devonian, Pragian) from the Prague Basin (the Stydlé Vody Quarry). The oncoidal cortices show distinct arrangement of hematite/chamosite and/or iron-bearing calcite laminae, which are irregular, wavy and with a relatively high degree of inheritance of shape of the topography of the underlying laminae. Micro-domes and bulges, comparable to those observed in stromatolites and laminae overgrowing topographic irregularities represented by agglutinated foraminifers cemented to oncoid surfaces, were fairly commonly observed. The foraminifers probably represent the earliest representatives of agglutinated foraminifera encrusting surfaces of ferruginous grains. The surfaces of oncoids are wavy and often wrinkled. Although no microbial remains that could have been directly associated with oncoidal growth were recorded, we regard above mentioned features as indicators of biogenicity of the precipitates. We could only speculate the nature of the microbial consortia, but we regard the alternation of Fe2+ (chamosite, iron-bearing calcite) and Fe3+ (hematite) phases as a result of coupled oxidation - reduction processes related to passive and/or active microbial metabolic activities (precipitation of ferrihydrite – hematite precursor) and passive mineral authigenesis mediated by microorganisms (precipitation of chamosite precursor). Spatially restricted occurrence of the oncoidal lenses along with Al/Al + Fe + Mn vs. Fe/Ti, Nd vs. Ce/Ce*, Eu/Sm vs. Sm/Yb and other crossplots suggest that hydrothermal fluids were the most probable source of ferrous iron. Since most of the known oolitic or oncolitic ironstones represent rather large sedimentary bodies deposited around storm wave base to shallow subtidal environments under influence of upwelled anoxic watermasses or continental runoff, the reported oncolitic mounds represent a specific example of ironstones formation.

Alumina doped Fe2O3 foams by freeze-casting for redox cycling applications

Hydrogen is the next energy vector for a decarbonization society but industrial production is still methane-based. The Steam Iron Process (SIP) could provide a carbon-free production and safety storage option. Here, we show that a Fe2O3-3 wt% of Al2O3 foams created by freeze-casting withstand 10 redox cycles at different temperatures with no reduction in performance or pore shrinking. The use of stearic acid as a dispersant agent/binder produces the porous structure enhancement of the foam and promotes the early reduction of the hematite phase during foam sintering. The Al2O3 incorporation was detected as a solid solution in the Fe2O3 phase at the particle surface. This result is relevant as correlated the positive values of the zeta potential observed. Freeze-casted foams could improve long-term redox performances combining a unique tailored interconnected pore structure with a specific chemical composition.

Synthesis and characterization of α-Fe2O3 nanoparticles showing potential applications for sensing quaternary ammonium vapor at room temperature

P-type and n-type metal oxide semiconductors are widely used in the manufacture of gas sensing materials, due to their excellent electronic, electrical and electrocatalytic properties. Hematite (α-Fe2O3) compound has been reported as a promising material for sensing broad types of gases, due to its affordability, good stability and semiconducting properties. In the present work, the efficient and easy-to-implement sol-gel method has been used to synthesize α-Fe2O3 nanoparticles (NPs). The TGA-DSC characterizations of the precursor gel provided information about the phase transformation temperature and the mass percentage of the hematite NPs. X-ray diffraction, transmission electron microscopy and x-ray photoelectron spectroscopy data analyses indicated the formation of two iron oxide phases (hematite and magnetite) when the NPs are subjected to thermal treatment at 400 °C. Meanwhile, only the hematite phase was determined for thermal annealing above 500 °C up to 800 °C. Besides, the crystallite size shows an increasing trend with the thermal annealing and no defined morphology. A clear reduction of surface defects, associated with oxygen vacancies was also evidenced when the annealing temperature was increased, resulting in changes on the electrical properties of hematite NPs. Resistive gas-sensing tests were carried out using hematite NPs + glycerin paste, to detect quaternary ammonium compounds. Room-temperature high sensitivity values (S r ∼ 4) have been obtained during the detection of ∼1 mM quaternary ammonium compounds vapor. The dependence of the sensitivity on the particle size, the mass ratio of NPs with respect to the organic ligand, changes in the dielectric properties, and the electrical conduction mechanism of gas sensing was discussed.

Characteristics of the Properties of Absodan Plus Sorbent and Its Ability to Remove Phosphates and Chromates from Aqueous Solutions.

The aim of the research was to characterize the parameters of the diatomite sorbent Absodan Plus as well as to assess its suitability for the adsorption of chromates and phosphates from acidic aqueous solutions simulating the conditions occurring in some types of industrial wastewater. The scope of the research includes XRD, SEM, BET, and PZC analyses, and 3D observation of commercial diatomite granules and batch tests to determine the constants of kinetics and the equilibrium of chromates and phosphates adsorption. Absodan Plus is a diatomite commercial material containing an amorphous phase (33%) and is also the crystalline phase of quartz, hematite, and grossite. The material is macro- and mesoporous and its specific surface area is about 30 m2/g. Its PZC is around pH = 5.5–6.0 and in an acidic environment is able to adsorb the anions. The saturation of the adsorbent surface with molecules of the adsorbed substance occurs after 2 h for chromates and 2.5 h for phosphates. The maximum adsorption capacity of Absodan Plus in terms of phosphorus and chromium amounts to 9.46 mg P/g and 39.1 mg Cr/g, respectively. As shown by XRD analysis, Absodan Plus contains an admixture of hematite, which can support the removal of chromium and phosphorus.

Cis-9-Octadecenylamine modified ferric oxide and ferric hydroxide for catalytic viscosity reduction of heavy crude oil

Cis-9-Octadecenylamine modified α-Fe2O3 and Fe(OH)3 nanoparticles were successfully synthesized by using a one-step synthetic method. XRD results revealed that lower ratio of oleylamine to Fe3+ introduce forming hematite phase but higher ratio introduce forming Fe(OH)3 phase. FTIR, TGA, contact angle, and XPS results indicated that olelyamine were modified on the surface of α-Fe2O3 or Fe(OH)3. A larger amount of oleylamine modifier is conducive to the dispersion of the catalysts in heavy oil. Oleylamine modified Fe(OH)3 can be transformed into α-Fe2O3 in situ during the catalytic reaction and shows higher catalytic activity in the viscosity reduction of Shengli extra heavy crude oil.

Zn-Doped Iron Oxide Thin Films Prepared by Spray Pyrolysis Technique and Characterized for Use as an Efficient Photocatalyst for Methyl Green Organic Dye

Ultrasonic Spray Pyrolysis (USP) technique was used to prepare undoped and (2, 4, 6 and 10 at. %) Zn-doped iron oxide (FexOy: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.

Surface Morphology and Structural Evolution of Magnetite-Based Iron Ore Fines During the Oxidation

Abstract The use of magnetite-based iron ore fines by means of fluidized bed technology has become a promising route to produce direct reduced iron. The significant influence of a prior oxidation treatment, which occurs in the preheating stage, on the subsequent fluidization and reduction behavior was observed in our previous study. As a result, it is important to investigate the oxidation of magnetite-based iron ore fines for an optimization of the proposed route. Three magnetite-based iron ore brands were analyzed. The oxidation characteristics are investigated based on thermogravimetric analysis. The surface morphology, structural evolution, and phase transformation were studied with a scanning electron microscope, an optical light microscope, and a high-temperature-X-ray diffraction (HT-XRD), respectively. The three samples showed different oxidation capacity indexes (OCIs) but similar TG-DTG curves. The oxidation rate peaks at around 330 °C and 550 °C indicated the formation of γ-Fe2O3 and α-Fe2O3. The hematite phase shows a particular growth habit. The oxidation first occurs at the surface, forming gridlike hematite structures, and then extends to the inside, resulting in hematite needles. The specific surface area and pore volume decrease significantly due to the sintering effect during oxidation.

Structural and Magnetic Characteristics Evaluation of Iron Oxide Extracted from Printer Toner Wastes

The need to recycle and develop valuable materials from waste, and use them in various applications have become increasingly important in recent decades. Printer toner waste is one of the most polluting electronic waste due to the toxic nature of the material content in it. Despite the toxicity of the material in the toner powder, it contains iron oxide that can be extracted and recycled to make a beneficial material. Therefore, this study aims to investigate a facile and effective method to extract iron oxide from printer toner waste powder. Magnetic separation and oxidation processes were used as a method for extraction and phase conversion. The structural transformation was investigated using X-ray diffraction, microstructural observation using scanning electron microscope whereas static magnetic characteristics were investigates using vibrating sample magnetometer. The results from XRD spectra show that printer toner wastes that have been subjected to magnetic separation process and chemical treatment, even without any heat treatment process, have produced a single phase magnetite. Through the process of heat treatment on the sample, phase transformation from magnetite to hematite occurs, in which a single phase of hematite is obtained at a temperature of 1400 °C. The saturation magnetization of the sample also showed a reduction where the sample before undergoing the heat treatment process had a saturated magnetization value of 18.81 emu/g. Meanwhile, after heat treatment, the saturation magnetization value decreased to 0.42 emu/g. These results are in line with the phase transformation shown where magnetite has high ferrimagnetic characteristics, whereas hematite is basically antiferromagnetic at room temperature. However, the saturation magnetization that has been obtained in hematite shows a little difference to that of commercially sold hematite. This proves that iron oxide extracted from printer toner waste has a high potential as an alternative to existing commercial iron oxide in producing high performance magnetic materials.

Synthesis and Characterization of Zinc and Vanadium Co-Substituted CoFe2O4 Nanoparticles Synthesized by Using the Sol-Gel Auto-Combustion Method.

In recent years, cobalt ferrite has attracted considerable attention due to its unique physical properties. The present study aimed to produce cobalt ferrite magnetic nanoparticles doped with zinc and vanadium using the sol-gel auto-combustion method. For this purpose, Co1−xZnxFe2−yVyO4 (where x = 0.0, 0.1, 0.2, 0.5 and y = 0.00, 0.05, 0.15, 0.25) precursors were calcined at 800 °C for 3 h. The prepared samples were characterized with the X-ray diffraction (XRD) method in combination with Rietveld structure refinement, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometery (VSM). The XRD patterns confirmed the formation of crystalline spinel structure for all samples. However, the diffraction peaks of hematite and iron vanadium oxide phases were observed in the patterns of some doped samples. The average crystallite size for all the synthesized samples was found to be in the range of ~45–24 nm, implying that it decreased by simultaneously doping cobalt ferrite with Zn and V. The FT-IR spectrum confirmed the formation of the spinal structure of ferrite through the observed vibrational bands assigned to the tetrahedral (υ2) and octahedral (υ1) interstitial complexes in the spinel structure. The FE-SEM images showed that morphology, average grain size, and agglomeration of the synthesized powders were affected by doping, which was due to the interactions of the magnetic surface of nanoparticles. The VSM curves demonstrated that saturation magnetization and coercivity values changed in the range of 30–83 emu/g and from 27–913 Oe, respectively. These changes occurred due to the alteration in cation distribution in the spinel structure. This can be attributed to the change in superexchange interactions between magnetic ions by co-substitution of Zn and V ions in Cobalt ferrite and the changes in magnetocrystalline anisotropy.

Mineral analysis and its extraction process of ilmenite rocks in titanium-rich cumulates from Pandeglang Banten Indonesia

Pandeglang regency has a very potential mining material in the form of Ilmenite rock with high levels of Titanium content of up to 20 percent. The purpose of this study was to determine the microscopic appearance of rocks including the elements, structures, mineral compositions of the rock, and types of minerals as a first step to be able to explore titanium minerals to increase local income, especially in the Pandeglang district. In this study, the analysis of ilmenite rock minerals rich in titanium has been carried out by several testing methods. By elemental analysis using XRF and SEM-EDS, ilmenite rock contains dominant elements consisting of iron (Fe), titanium (Ti), calcium (Ca), sulfur (S), and silicon (Si), with minor elements which contains less than 1% by weight of approximately 14 elements. The results of the petrographic analysis and the phenocrysts hardness show that ilmenite rock consisted of ilmenite, calcite, quartz, and hematite. Analysis using the X-Ray Diffractometer (XRD) shows that the ilmenite rock consists of the ilmenite (FeTiO3) mineral phase of 43.78%, the calcite mineral phase (CaCO3) of 39.53%, the quartz mineral phase (SiO2) of 13.83%, and the mineral hematite phase (Fe2O3) of 2.86%. The extraction results from ilmenite rock using the hydrometallurgical method produce TiO2 Anatase phase raw material with a purity level of 99.3%. It is concluded that this study has succeeded in understanding the identification and analysis of the composition of ilmenite stones from Pandeglang, Indonesia.

Structural, elastic and magnetic properties of Ca doped copper ferrite nanoparticles

Calcium doped Copper ferrite (CaxCu1-xFe2O4, x = 0.0, 0.1, 0.2, 0.3) nanoparticles were prepared by co-precipitation method. The effect of calcium doping in structural, elastic and magnetic properties of copper ferrite were explored by X-ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transform infrared (FTIR), and Vibrating Sample magnetometer (VSM). X-ray diffraction verified the single phase cubic spinel structure and hematite phase also present in x = 0.02 with the space group Fd3m. The average crystallite size ranged in 44–58 nm and increased with increasing Ca concentration. Scanning electron microscope images showed that the ferrite particles seem in spherical shape with agglomeration. The Fourier transform infrared spectrum showed the two main absorption bands of spinel structure in the wavenumber scale of 476–576 cm−1 assigned to the stretching vibration of A and B sites. The three types of moduli of elasticity, Poisson's ratio, velocities of elastic waves and Debye temperature estimated using FTIR. Vibrating Sample magnetometer exhibited the room temperature ferromagnetic behavior and coercivity decreases with Ca concentration while saturation magnetization increases.

Immobilization of Fe2O3 on perlite for photo-Fenton degradation of methylene blue

Photo-Fenton catalysts with floating features based on the immobilization of Fe2O3 particles on the surface of perlite granules were synthesized by a simple precipitation-annealing method. The effects of annealing temperature on the crystal structure, phase composition, morphology, surface area, surface functional groups, and surface atomic composition of the prepared catalysts were investigated by powder X-ray diffraction, field emission scanning electron microscope, nitrogen adsorption-desorption, Fourier transform infrared spectroscopy, and low voltage energy-dispersive X-ray spectroscopy. The catalytic activity was evaluated via the degradation of methylene blue in the presence of oxalic acid under UVA light and visible light. Immobilization of Fe2O3 on the perlite surface resulted in photo-Fenton catalytic activity for all samples, attributable to the formation of the hematite phase and the presence of surface Fe species. Owing to the low density of perlite, all catalysts float on the surface of the solution, which allows them to be easily separated.