Hematite Phase Research Articles

Influence of annealing temperature on Fe₂O₃ nanoparticles: Synthesis optimization and structural, optical, morphological, and magnetic properties characterization for advanced technological applications

In this study, Iron oxide nanoparticles (Fe₂O₃ NPs) were synthesized using iron chloride hexahydrate (FeCl3·6H2O) and ammonia solution through a straightforward co-precipitation method. The nanoparticles were annealed at temperatures of 100 °C, 300 °C, 500 °C, 700 °C, and 900 °C, with one sample left unannealed. Comprehensive analyses were performed using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Zeta potential, Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and UV–Vis Spectrophotometry. The XRD patterns confirmed the presence of both Maghemite (γ-Fe2O3) and Hematite (α-Fe2O3) phases, with a phase transition observed between 100 °C and 300 °C, and the most pronounced transition occurring at 500 °C. At this optimal temperature, the crystallite size was 19.14 nm, the average particle size was 37.36 nm, and the band gap energy was measured at 1.76 eV. SEM images revealed that nanoparticles formed clusters as the annealing temperature increased. The zeta potential measurements showed a range from 6.12 mV at 100 °C to −1.9 mV at 900 °C, indicating changes in particle stability. DLS analysis indicated a size increase from 86.81 nm at 300 °C to 1577 nm at 900 °C, reflecting aggregation trends. The reduction in band gap energy with higher temperatures is attributed to enhanced crystallinity and increased particle size. The magnetic properties of Fe₂O₃ NPs were evaluated using a Physical Property Measurement System (PPMS), revealing an increase in magnetic response with rising annealing temperatures. The transition from superparamagnetic γ-Fe₂O₃ to weakly ferromagnetic α-Fe₂O₃ was confirmed through changes in the hysteresis loop area and shape. These findings suggest that 500 °C is the optimal annealing temperature for producing Fe₂O₃ NPs with desirable properties for applications in targeted drug delivery, MRI contrast enhancement, and environmental remediation. This research advances the engineering of Fe₂O₃ NPs, paving the way for their use in various technological applications.

Phase Evolution, Mechanical, and Electrical Properties of Lightweight Ceramic Prepared Using Scoria at Low Temperature

This study aimed to produce lightweight, eco-friendly ceramic materials with superior properties using natural raw materials and low processing temperatures. Five ceramic samples were fabricated using red clay and varying contents of volcanic scoria (10%, 20%, 30%, 40%, and 50%) through sintering at 950 °C for 4 h. The crystalline phases, electrical properties, porosity, and mechanical strength of all the ceramic specimens were comprehensively evaluated. It was determined that the chemical composition of the raw materials and the resulting phases significantly influenced these various attributes. The XRD analysis revealed that the ceramic samples primarily consisted of the crystalline phases gehlenite, low quartz, and anorthite, along with the minor wollastonite and hematite phases. As the scoria content was increased, the MgO and Fe2O3 concentrations also increased, leading to a reduction in dielectric constant, dielectric loss, and electric conductivity. Moreover, the porosity of samples decreases from S10 to S50 due to the increase in the percentage of scoria and this reduction in porosity led to increased bending strength. The findings of this study suggest that volcanic scoria can serve as a viable eco-friendly raw material to produce lightweight ceramics with excellent electrical and mechanical properties, presenting cost-effective and energy-efficient solutions for various applications.

Controllable mechanism of hazardous jarosite transformation into recyclable hematite in the leaching solution of secondary zinc oxide powder

The controlled synthesis of recyclable hematite in the leaching solution of secondary zinc oxide powder is an urgent problem in the chemical industry and metallurgy fields. In this paper, the effects of the temperature, agitation speed, and seed addition on the contents of iron, sulfur, potassium, sodium, and zinc in the iron removal residues, as well as the iron concentration in the supernatant after iron removal were systematically studied. In addition to the temperature control already reported, we found that the agitation speed can also control the transformation between jarosite and hematite phases. The content of jarosite in the residues can be effectively controlled by adjusting the agitation speed, thereby significantly improving the quality of hematite product, as indicated by SEM-EDS and XRD results. Under temperature of 185 °C, an agitation speed of 500 rpm, and a seed addition of 15 g/L, the iron, sulfur and zinc contents in the filter residues and the iron concentration in the supernatant were 59%, 3.22%, 0.92%, and 4.182 g/L, respectively. Kinetic studies show that the rapid oxidation kinetics is not conducive to the formation of high-quality hematite products. These results can directly guide the process of transformation of harmful jarosite into recyclable hematite from the leaching solution of secondary zinc oxide powder, which is of great practical significance for the controlled and waste-free removal of iron from aqueous solutions in the chemical industry and metallurgy fields.

Antibacterial and antifungal activities of Platycladus orientalis leaf extract-mediated Fe2O3 and Ce-doped Fe2O3 nanoparticles

Green synthesis of nanomaterials harnesses naturally occurring materials, including plant extracts, to offer environmentally friendly alternatives to conventional biomedicine, agriculture, and other field applications. This study explores the green route to Fe2O3 and cerium-doped Fe2O3 (Ce-doped Fe2O3) nanoparticles synthesized for the first time using the leaf extract of Platycladus orientalis. The synthesized nanoparticles were characterized for their structural, morphological, chemical, and optical properties. The hematite phase of Fe2O3 nanoparticles with spherical morphology was obtained. The introduction of Ce as a dopant into Fe2O3 increased the lattice strain of Ce-doped Fe2O3 nanoparticles (0.51%) compared to pristine Fe2O3 (0.46%) even though the size of both nanomaterials was similar. Compared to pristine Fe2O3 nanoparticles, Ce-doped Fe2O3 nanoparticles also demonstrated enhanced antimicrobial and antifungal activities against Escherichia coli, Enterococcus faecalis, Listeria monocytogenes, Penicillium chrysogenum, Aspergillus niger, and Mucor mucedo. The green-synthesized Ce-doped Fe2O3 nanoparticles possess potential for application in biomedical and environmental fields based on their relevance to human health and food safety, diversity in microbial characteristics, and potential for resistance to conventional treatments.

Pristine and Nature‐Inspired Hematite (α‐Fe2O3) Nanoparticles and Search for their Photocatalytic Application

AbstractThe article describes synthesis of green‐mediated hematite nanoparticles (20–30 nm) using Polianthes tuberosa flower extract. Structural, microscopic, and magnetic studies confirm the synthesis of iron oxide nanoparticles of pure hematite phase. Spectroscopic techniques are employed to identify different electronic transitions and defect levels as well as to estimate the energy bandgap and Urbach energy. A correlation among the particle size, bandgap energy, and Urbach energy is noticed. These hematite nanoparticles act as visible light photocatalyst which degrade dye in aqueous medium without the addition of any additives. The catalyst particle size, catalyst quantity, pH of dye solution, and solution temperature have significant impact on the photodegradation process of dye molecules in aq. solution. All observations advocate that green synthesis of hematite nanoparticles with Polianthes tuberosa flower extract can significantly modulate their optical and photocatalytic properties. These materials may find potential uses in water splitting for hydrogen production and purification of water by removing organic pollutants. The study highlights that using commercially cheap starting materials and extract made from naturally available plant parts, materials having huge application potentials can be synthesized at low cost by the simple green synthesis approach.

Synthesis and optimization of chitosan-incorporated semisynthetic polymer/α-Fe2O3 nanoparticle hybrid polymer to explore optimal efficacy of fluorescence resonance energy transfer/charge transfer for Co(II) and Ni(II) sensing

Initially, four synthetic fluorescent polymers (SFPs) are synthesized from α-methacrylic acid and methanolacrylamide monomers carrying –C(=O)OH and –C(=O)NH subfluorophores, respectively. Among SFPs, ∼1:1 incorporation of subfluorophores in the optimum SFP3 is explored by spectroscopic analyses. Subsequently, chitosan is incorporated in SFP3 to produce five semi-synthetic fluorescent polymers (SSFPs). The maximum incorporation of chitosan in SSFP4 is supported by different spectroscopies. In SSFP4, strong electrostatic interactions among polar functionalities of chitosan and synthetic polymer favor resonance-associated charge transfer (RCT) from SSFP4-(amide) to SSFP4-(canonical). Finally, three hybrid fluorescent polymers (HFPs) are fabricated encapsulating iron-oxide nanoparticle within SSFP4. The maximum proportion of hematite (α-Fe2O3) phase in HFPs is explored by spectroscopic, magnetometric, microscopic, and light scattering studies. HFP2 shows local/RCT/fluorescence resonance energy transfer (FRET) emission at 393/460/570 nm. In HFP2, FRET, RCT, and ratiometric pH-sensing within 3.0–6.5 phenomena are explored by solvent polarity effects, time-correlated single photon counting, quantum yield measurements, alongside I431/I460 vs pH plots. RCT and FRET emissions of HFP2 are utilized for selective sensing of Co(II)/Ni(II) with limits of detection of 4.990 ppb (460 nm)/4.353 ppb (570 nm) and 45.041 ppb (428 nm)/29.617 ppb (527 nm) in organic and aqueous solutions, respectively.

Charge-dependent CALPHAD analysis of defect chemistry and carrier concentration for space charge layers

The development of conductive materials plays a crucial role in improving the efficiency of electrochemical processes. In polycrystalline materials, space charge layers (SCLs) adjacent to grain boundaries (GBs) often dictate charge transport behavior. This study explores relaxing the charge neutrality constraint in the CALculation of PHAse Diagrams (CALPHAD) approach as a new method to model the electrical conductivity effects of SCLs. A new charge-dependent defect chemistry analysis is applied to the wustite, magnetite, and hematite phases in the Fe–O binary system. Using pycalphad, charge-dependent results for the molar Gibbs energies, Brouwer diagrams, and charge carrier concentrations were determined for each phase at 1273K within the oxygen partial pressure stability ranges. With a negative charge of 0.16 × 10−19 C, the hematite and magnetite phases exhibit an increased charge carrier concentration. The opposite trend was observed for wustite. While further work is needed to quantify the electrical conductivity effects of the SCLs and GBs with this approach, it provides a robust thermodynamic foundation to rapidly develop and optimize conductive materials.

Effect of Fe2O3 on CeO2 films in the photocatalytic evaluation towards the degradation of brilliant green and oxytetracycline

This paper presents a photochemical synthesis method for producing pure CeO2 deposits and CeO2 deposits loaded with varying proportions of Fe2O3. The deposits were calcined at 950 °C and characterized structurally, compositionally, and morphologically using XRD, XPS, SEM, FT-IR, and Raman spectroscopy techniques. Cerianite and hematite phases were identified in CeO2/Fe2O3 samples, indicating heterogeneous surface deposits. Photocatalytic testing under UV–Vis illumination for 5 h demonstrated promising results. For the degradation of bright green dye, efficiencies of 78.9 % and 90.1 % were achieved for pure CeO2 and CeO2 samples loaded with 1.0 mol% Fe2O3, respectively. Similarly, for oxytetracycline drug degradation, performance rates of 35.3 % and 67.0 % were observed for CeO2 and CeO2 samples loaded with 1.0 mol% Fe2O3, respectively. Recyclability tests showed a gradual decline in photocatalytic performance over successive cycles due to by-product accumulation contaminating the catalyst.

Effects of Temperature and Precursor Concentration on the Morphological and Optical Properties of Iron Oxide Nanoparticles

Iron oxide nanoparticles are inexpensive materials that are environmentally friendly and have properties that render them suitable for wide range of applications. A facile and time-effective coprecipitation method was used to prepare iron oxide nanoparticles in a 1:1 molar ratio of Fe2+ and Fe3+ ions in solution. Iron oxide nanoparticles obtained at 18 and 60 °C yielded spherical magnetite nanoparticles with particle sizes of 7.63 and 8.5 nm respectively while comprising a mixture of magnetite and hematite nanorods, with a mean width of 9.5 nm and a mean length of 75 nm were obtained at 90 °C. Iron oxide nanoparticles synthesized at 18 °C have energy band gap of 4.16 eV while those synthesized at 60 and 90 °C have the same band gap of 4.66 eV. Precursor concentrations of 0.042, 0.08 and 0.0126 M yielded spherical magnetite nanoparticles with particle sizes of 7.94, 8.5 and 8.5 nm respectively and the particle size range increased with increasing concentration. Magnetite nanoparticles synthesized with concentrations of 0.042, 0.08 and 0.126 M have optical band gaps of 4.65, 4.88 and 5.19 eV respectively. The magnetite crystalline phase was produced regardless of concentration at temperatures of 18 and 60 °C while a temperature of 90 °C yielded a mixture of magnetite and hematite phases. The band optical band gap showed direct proportionality with temperature and concentration in an inert environment.

Analyzing the Impact of Annealed Steel Sludge Doses on the Physicochemical Properties of Biochar Obtained from Waste Date Palm Frond

Large quantities of date palm frond waste generated from the pruning process are accumulated or burned in burn barrels, harming the environment and having very little economic value. However, because of the lack of data revealing the characteristic magnetic properties of biochar derived from date palm fronds, further research on low-cost and sustainable strategies could offer a new composite material and serve to extend the way for novel applications. In this study, we prepared biochar derived from palm fronds via pyrolysis under a limited-oxygen atmosphere at a lower temperature of 300 °C for 2 h. We introduced a facile strategy for the production of magnetic biochar with various doses of annealed steel sludge material via ball milling. Various amounts of annealed steel sludge material (5%, 15%, and 25% w) were added to date palm frond biochar, and the obtained product was fabricated by ball milling. The physicochemical characteristics of the magnetic biochar composite were subsequently analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and UV-vis spectroscopy. Our findings showed that the ball milling method is a successful step for producing date palm fronds with magnetic biochar material possessing rough and packed pores, as shown by SEM. XRD patterns assumed the existence of magnetic phases of iron oxide (magnetite (Fe3O4), hematite (α-Fe2O3), and maghemite (γ-Fe2O3) at different generated peaks. FTIR outputs exhibited the abundant presence of various oxygen-containing functional groups (- COOH and -OH) on the surface of magnetic biochar material, which help to create chemically reactive sites to adsorb potential surrounding species. The UV spectra showed a noticeable enhancement of the optical properties of the magnetic biochar with an increase in the sludge dose for light absorption in the visible region from wavelengths of 400 – 700 nm . This result signifies the synthetic optimization and potential application of magnetic biochar materials for composites that could be employed in targeted uses including soil amendment, water remediation and energy applications.

Synthesis and Characterization of Hematite (α-Fe<sub>2</sub>O<sub>3</sub>) from Iron Sand Using Coprecipitation Method

Hematite (α-Fe2O3) has been synthesized from iron sand using the coprecipitation method. This study aims to determine the morphology and mineral content using SEM-EDX, crystal structure and phases formed using XRD, and magnetic properties using VSM on iron sand before and after synthesis. SEM-EDX results show that the average particle size of iron sand before and after synthesizing is 356.23nm and 12.40 µm, respectively. XRD results show that iron sand before synthesizing has multipahase including Hematite, magnetic, and ilmenite and after synthesizing produces Single Phase hematite. VSM results show that iron sand before synthesizing has saturation, remanence, and coercivity of 47.56 emu/g, 5.97emu/g, and 121.03 Oe respectively, and after synthesizing has saturation, remanence, and coercivity of 9.47 emu/g, 1.53 emu/g and 102.97 Oe respectively.

Polyethylene glycol-assisted hydro-solvothermal growth of anisotropic magnetic iron oxides: The role of mixed environment conditions

In this study, an alternative mixed hydro-solvothermal route has been investigated for the synthesis of magnetic iron oxide nanoparticles with anisotropic shape. The synthesis was performed at mild conditions (150 °C) in a water/2-propanol environment, using poly(ethylene glycol) (PEG400) as structure directing agent, sodium thiosulfate as reducing agent, and NaOH as precipitating agent. The resulting systems were characterized by combining morphological, structural, and magnetic techniques. Experimental results clearly demonstrate that magnetite/maghemite nanorods are preferentially obtained in water/PEG400 environment, whereas 2-propanol/PEG400 environment promotes the growth of magnetite/maghemite polyhedral systems. Interestingly, synthesis performed in a mixed hydro-solvothermal (i.e., water/2-propanol) environment favors the preferential growth of hematite phase.

Biodiesel photoelectrocatalytic synthesis employing α-Fe2O3 film decorated with Pt nanoparticles as photoanode

In this work, photoelectrochemical route for biodiesel production using an electrochemical cell configured with platinum and α-Fe2O3 modified with Pt nanoparticles as electrodes was investigated. XRD patterns registered for film prepared by modified hydrothermal method revealed a trigonal structure of the hematite (α-Fe2O3) phase. The α-Fe2O3 film surface was decorated by metallic Pt nanoparticles (PtNP) in order to reduce the charge recombination and improve the photocatalytic efficiency. The band gap energy (EBG) of the α-Fe2O3 and PtNP/α-Fe2O3 films was estimated by UV-Vis spectroscopy at approximately 2.1 eV. Electrochemical measurements showed that the oxide is an n-type semiconductor adequate to be used as a photoanode in biodiesel synthesis. Under polarization conditions, the electrochemical cell changed the pH from 7 to 14 when the system was polarized at 5.0 V. In the synthesis of biodiesel by esterification reaction, oleic acid, 300 µL of 0.1 mol L−1 aqueous KCl solution and methanol were used as precursor reagents. The reaction was carried out free of strong base, such as KOH or NaOH, as a supporting electrolyte. In this route, the reduction of the water molecule occurred on the cathode, with the formation of hydroxyl (OH-) species, methoxy, and consequently fatty acid methyl esters (FAMEs). Thermogravimetric analysis (TGA) and Gas chromatography coupled to mass spectrometry (CG-MS) were performed to evaluate the catalysis products. GC-MS analyzes show that the reaction has a yield of about 7 % with the formation of FAMEs, such as methyl 9-octadecenoate, methyl hexadecanoate and methyl hexadecanoate.

Tailoring the Lithium Concentration in Thin Lithium Ferrite Films Obtained by Dual Ion Beam Sputtering.

Thin films of lithium spinel ferrite, LiFe5O8, have attracted much scientific attention because of their potential for efficient excitation, the manipulation and propagation of spin currents due to their insulating character, high-saturation magnetization, and Curie temperature, as well as their ultra-low damping value. In addition, LiFe5O8 is currently one of the most interesting materials in terms of developing spintronic devices based on the ionic control of magnetism, for which it is crucial to control the lithium's atomic content. In this work, we demonstrate that dual ion beam sputtering is a suitable technique to tailor the lithium content of thin films of lithium ferrite (LFO) by using the different energies of the assisting ion beam formed by Ar+ and O2+ ions during the growth process. Without assistance, a disordered rock-salt LFO phase (i.e., LiFeO2) can be identified as the principal phase. Under beam assistance, highly out-of-plane-oriented (111) thin LFO films have been obtained on (0001) Al2O3 substrates with a disordered spinel structure as the main phase and with lithium concentrations higher and lower than the stoichiometric spinel phase, i.e., LiFe5O8. After post-annealing of the films at 1025 K, a highly ordered ferromagnetic spinel LFO phase was found when the lithium concentration was higher than the stoichiometric value. With lower lithium contents, the antiferromagnetic hematite (α-Fe2O3) phase emerged and coexisted in films with the ferromagnetic LixFe6-xO8. These results open up the possibility of controlling the properties of thin lithium ferrite-based films to enable their use in advanced spintronic devices.

An experimental investigation on freeze-thaw resistance of fiber-reinforced red mud-slag based geopolymer

This study aims to investigate the influence of different fiber types, lengths, and contents on their performance in freeze-thaw environments. Indoor freeze-thaw tests were conducted to evaluate the flexural strength, compressive strength, and mass loss of fiber-reinforced geopolymer materials. Additionally, SEM and XRD analyses were performed to examine the internal structure of the geopolymer composites. The results demonstrated that the incorporation of different fibers significantly improved various properties, particularly the flexural strength of the specimens. With an increasing number of freeze-thaw cycles, surface cracks became more prominent in the geopolymer specimens, leading to a gradual decrease in frost resistance. However, the addition of an appropriate amount of fiber effectively enhanced frost resistance. Following freeze-thaw exposure, an increase in fiber content initially resulted in a decrease and subsequently an increase in relative flexural strength, compressive strength, and mass loss. Notably, studies revealed that polypropylene fibers with a length of 9 mm and a content of 0.9 % exhibited minimal mass and strength loss. SEM analysis indicated uniform distribution of fibers within the geopolymer matrix, contributing to improved flexural strength and enhanced frost resistance in fiber-reinforced structures. XRD results indicate that red mud-slag based geopolymers produce high-strength hydrated calcium (aluminosilicate) silicate and hematite phases, which enhances the mechanical properties and durability of the specimens. In conclusion, this study highlights that incorporating suitable fibers can enhance the durability and performance of red mud-slag based geopolymers under freeze-thaw conditions. The findings provide valuable insights for optimizing fiber type, length, and content to achieve superior mechanical properties and frost resistance in geopolymer composites.

The Temperature of Pretreatment on Microstructure Change of Lump Ore and Improvement of Metallurgical Properties

Goethite is one of the most common minerals in iron ore, and is the main source of internal crystal water generated during the heating process of lump ore. To address this challenge, three measures are proposed: first, minimizing the decomposition of crystalline water upon the introduction of lump ores into the furnace; second, reducing the heat absorption of water vapor within the furnace; and third, increasing the proportion of lump ores being introduced into the furnace. With this in mind, the lump ore preheating treatment technology is introduced. By preheating the lumps at different temperatures, the influence of pretreatment on the reduction and soft melting of the lumps is studied. The results show that at different preheating temperatures, due to the transformation of FeOOH to Fe2O3, the natural goethite gradually changes from natural granular to spherical at higher preheating temperatures. When the preheating temperature is 400–700 °C, the coexisting phase of goethite and hematite in the pores changes obviously. The metallurgical properties of lump ore change dramatically. When the temperature is lower than 400 °C or higher than 700 °C, almost all goethite in lump ore is transformed into hematite, and the morphology does not change.

OPTIMIZING VANADIUM CONVERTER SLAG UTILIZATION: TARGETED ENRICHMENT AND STABILIZATION OF VANADIUM THROUGH NON-EQUILIBRIUM SOLIDIFICATION

The objective of this research was to optimize the comprehensive utilization of vanadium converter slag through targeted enrichment and stabilization of heavy metal vanadium. Employing the non-equilibrium solidification theory and FactSage software, we investigated the potential of modifying vanadium converter slag. When the original slag failed to generate vanadium-rich spinel with usable V elements, introducing modifying agents Fe and Al proved effective. Fe facilitated the enrichment of Cr within spinel, while Al significantly promoted the V enrichment. Expanding on this, we systematically examined the influence of Fe2O3, Al2O3 and MgO contents on spinel phase precipitation during vanadium slag solidification. The addition of Al resulted in the precipitation of corundum, hematite, spinel, olivine and diopside phases. With an increase in the Fe2O3 content, the precipitation of FeV2O4 and MgV2O4 initially increased, peaking at 9.67 % before subsequently decreasing. Maintaining the Fe2O3 content within a range of 25–30 % proved optimal for enhancing vanadium precipitation and enrichment. In contrast, variations in the Al2O3 content had minor impacts on SP-V phase precipitation, with slight effects on FeV2O4 reaching 10.34 %. Furthermore, the incorporation of MgO facilitated the precipitation of MgV2O4 while concurrently suppressing the FeV2O4 precipitation. By judiciously controlling the MgO content at approximately 20 %, vanadium enrichment in the form of FeV2O4 and MgV2O4 spinel phases reached a remarkable 94.46 %.

The dual role of manganese oxide simultaneously in enhancing bioactivity and magnetic properties of glass ceramics used in cancer treatment

Replacing conventional cancer treatment methods like chemotherapy, which has many adverse effects, with new methods such as magnetic fluid hyperthermia, is one of the significant challenges. In this study, the effect of adding different MnO2 wt% to 20SiO2‐50FeO‐15CaO‐15Na2O glass-ceramic was studied. Maghemite, hematite, jacobsite and sodium calcium silicate phases were crystallized in the glass ceramics. Absorption bands of maghemite with a completely regular crystal structure were observed in the range of 472 and 560 cm−1 wavenumbers. The investigation of the magnetic properties also showed that the saturation magnetization of the samples increased from 21.5 emu/g to 30.80 emu/g by increasing the MnO2 from 0 to 15 wt%. The highest amount of heat loss under alternating magnetic field was also measured for the same sample and its value was 18 °C. Hydroxyapatite with cauliflower morphology was also observed in the phase and structural investigations of the samples immersed in the simulated body fluid.

Development of red mud based sintered artificial aggregates with various industrial wastes

Red mud (RM) has drawn a lot of attention in the search for potential uses in the production of sintered artificial aggregate from industrial waste products. The main objective of the study is to produce an RM-based sintered artificial aggregate (SAA), with several blends (binary, ternary, and quaternary) using various industrial wastes. This study includes assessing the mechanical and physical properties of SAA as well as the sintering parameters in order to determine the appropriate material mix ratio. To achieve these objectives, a comprehensive experimental approach was adopted. A total of 35 different mixtures were formulated by incorporating various industrial wastes as binders and sintering additives. The green pellets were preheated at 105 °C for 24 h, and consecutively sintered at different temperatures, namely 700 °C, 900 °C, 1100 °C, and 1150 °C with a duration of 30 min. A compressive strength test was performed in order to find the mechanical property of SAA similarly water absorption and bulk density tests were conducted to find the physical properties of SAA. To characterize the SAA, scanning electron microscope analysis (SEM), X-ray diffraction (XRD) and energy dispersive x-ray analysis were conducted, and also data analysis was performed using Artificial Neural Network (ANN) tools, yielding accurate predictions. Successfully best compressive strength low water absorption SAA was produced. The best material weight mix ratio for the production of SAA was identified as (A18) RM: Fly Ash: Waste Glass Powder; 78:10:12. Out of all blends the ternary blend (A18) SAA exhibited impressive properties after 30 min of sintering at 1150 °C: high compressive strength of 22.92 MPa, water absorption of 4.26%, and bulk density of 1296.12 kg m−13. This was made possible by the high amount of Al2O3, SiO2, in the combination of fly ash, and waste glass powder with RM. SEM and XRD analysis also confirmed that the (A18) SAA achieved the best compressive strength, and low water absorption due to turning the surface and core area into a solid, reduced internal pores and formed quartz, and hematite phases. The findings of this study serve as a foundation for future work and pave the way for the development of sustainable construction materials.

Hydroxyapatite-magnetite nanocomposites: Synthesis and superior adsorption properties for lead ion removal, with insights into intraparticle diffusion, kinetic modeling, and phase dependency

Multifunctional superparamagnetic magnetite/hydroxyapatite (Fe3O4/Ca10(PO4)6(OH)2 or MHAp) nano-composites were synthesized via a facile two-step co-precipitation method at room temperature. These magnetic nano-composites underwent heat treatment at various temperatures ranging (400°, 600°, and 900 °C), which were subsequently utilized as nanosorbents for removing Pb2+ ions. The XRD data revealed that both the magnetite and hydroxyapatite synthesized were in a pure phase. In the Fe3O4/HAp composites, there was an augmentation in the intensity peak of hydroxyapatite observed up to 600 °C. However, at 900 °C, a calcium iron phosphate phase emerged, and magnetite (Fe3O4) transitioned into the hematite (Fe2O3) phase. Elevating the heat treatment enhanced the crystallinity of the developed Fe3O4/HAp composites while diminishing the surface area. The prepared nanocomposites exhibited high adsorption efficiency across a wide pH range, with an optimal pH of 5.5. Notably, the adsorption rate of Pb2+ reached 94 % within the first 5 min, with complete metal adsorption progressively at 60 min. The kinetic and isotherm analysis of the adsorption process revealed that pseudo-second-order model and Langmuir model agreed well with the adsorption process. Also, FAH0 demonstrated the highest adsorption capacity (263.2 mg/g) for Pb2+ ions. Furthermore, the Fe3O4/HAp composite NPs exhibited remarkable recyclability even after five cycles of reuse; retaining an efficiency of over 96 %, and allowing for easy separation without a significant loss of adsorption efficiency. The results of the current desorption study underscore the promising practical applications of these nano-composites in decontaminating aqueous media.