Ilmenite Research Articles

Study of ilmenite and zero valent iron nanoparticles for persulfate activation in disinfection of wastewater

This study examines the activation of persulfate (PS) using two different iron sources, namely ilmenite (ILM) and zero valent iron nanoparticles (ZVI), under UV-A radiation, to eliminate Enterococcus sp. in simulated wastewater in a recirculating batch reactor. The best combination of PS/ILM/UV-A was found with a PS concentration of 5 mM and an ILM concentration of 5 g/L, resulting in a 2.76- log reduction of Enterococcus sp. after 120 min. Lower dosages of oxidant and catalyst were required in the PS/ZVI/UV-A system (3 mM PS and 0.1 g/L ZVI), achieving the complete inactivation of Enterococcus sp. in 60 min. ZVI was more effective at inactivating Enterococcus sp. colonies than ILM. Additionally, the treatment performed better at neutral pH than in acidic or basic conditions, which could facilitate applications on a larger scale. Furthermore, ZVI could be recovered with minimal loss of efficacy thanks to its magnetic properties. The mechanistic study indicated that SO4•- radicals are the primary radicals involved in the elimination of Enterococcus sp. through PS activation. Phytotoxicity studies showed that the process is not phytotoxic to Solanum lycopersicum (tomato) germination but is to Raphanus sativus (radish).

Construction of a novel Z-scheme FeTiO3/MOF-derived In2S3 catalyst for visible-light-driven photo-Fenton degradation of pollutants

The rapid recombination rate of photoexcited carriers for iron titanate (FeTiO3) is still limited the process performance of photo-Fenton. This article reports the successful synthesis of the highly efficient Z-scheme FeTiO3/MOF-derived In2S3 photocatalyst using the hydrothermal method, compensating for the susceptibility of FeTiO3 photo-generated carriers to complexation to a certain extent. A series of characterization have been carried out to explore the structure, morphology and composition of FeTiO3/MOF-derived In2S3 heterostructure. The 0.5 FeTiO3/MOF-derived In2S3 exhibits the excellent photo-Fenton performance for TCH, Cr6+ and OTC, the degradation rate constants (k2) are up to 0.6297 L·mg−1·min−1, 1.332 L·mg−1·min−1, and 0.427 L·mg−1·min−1, respectively. Active species capture experiments and electron paramagnetic resonance (EPR) spectra show that photo-generated holes (h+) and superoxide radicals (·O2-) are present in the photo-Fenton system. The superior photo-Fenton performance is mainly manifested in the following: the MOF-derived In2S3 micro-floral carrier extends the reaction interface of 0.5 FM-I; FeTiO3 effectively enhances the photo-absorption ability of 0.5 FM-I in visible range; the construction of Z-scheme FeTiO3/MOF-derived In2S3, forming the new carriers transport channels and enhancing the generation of ·O2- and ·OH. This experimental exploration provided a reasonable experimental basis for the preparation of efficient photocatalysts.

Enhanced solid-electrolyte interface efficiency for practically viable hydrogen-air fuel cell systems

Proton exchange membrane fuel cells (PEMFCs) provide an appealing sustainable energy system, with the solid-electrolyte membrane playing a crucial role in its overall performance. Currently, sulfonated poly(1,4-phenylene ether-ether sulfone) (SPEES), an aromatic hydrocarbon polymer, has garnered considerable attention as an alternative to Nafion polymers. However, the long-term durability and stability of SPEES present a significant challenge. In this context, we introduce a potential solution in the form of an additive, specifically a core–shell-based amine-functionalized iron titanate (A–Fe2TiO5), which holds promise for improving the lifetime, proton conductivity, and power density of SPEES in PEMFCs. The modified SPEES/A–Fe2TiO5 composite membranes exhibited notable characteristics, including high water uptake, enhanced thermomechanical stability, and oxidative stability. Notably, the SPEES membrane loaded with 1.2 wt% of A–Fe2TiO5 demonstrates a maximum proton conductivity of 155 mS cm−1, a twofold increase compared to the SPEES membrane, at 80 °C under 100% relative humidity (RH). Furthermore, the 1.2 wt% of A–Fe2TiO5/SPEES composite membranes exhibited a maximum power density of 397.37 mW cm−2 and a current density of 1148 mA cm−2 at 60 °C under 100% RH, with an open-circuit voltage decay of 0.05 mV/h during 103 h of continuous operation. This study offers significant insights into the development and understanding of innovative SPEES nanocomposite membranes for PEMFC applications.

Enhanced Photocatalytic Degradation by the Preparation of a Stable La-Doped FeTiO3 Photocatalyst: Experimental and DFT Study.

The rapid photocarrier recombination limits the photocatalytic activity of iron titanate (FeTiO3) to be further improved. Developing novel approaches to inhibit the rapid recombination rate of the FeTiO3 photocatalysts is crucial for efficiently degrading pollutants in wastewater. Rare earth ions, with unique electron dispositions and large ion radii, could effectively inhibit photocarrier recombination. Herein, novel lanthanum (La)-doped FeTiO3 photocatalysts were designed and successfully synthesized. The photocatalytic performance of the 12 mol % La/FeTiO3 photocatalyst was superior in degrading tetracycline hydrochloride (TCH), methylene blue (MB), and brilliant blue (BB). These degradation rate constants (k) were 0.12358, 0.01357, and 0.03064 L mg-1 min-1, respectively, which were 12.83, 1.61, and 7.78 times that of pure FeTiO3. The photoelectronic tests and density functional theory (DFT) calculations revealed that the La 4f orbital forms an impurity energy level in the conduction band of FeTiO3. This level narrows the bandgap and acts as an electron acceptor, capturing photoexcited electrons and inhibiting the rapid recombination of photoexcited electron-hole pairs in FeTiO3. This work enhances the potential of FeTiO3 in the photocatalysis field and provides important insights into the efficient degradation of organic pollutants in wastewater.

Sol–gel synthesis of iron titanates for the photocatalytic degradation of cyanide

Iron titanate mixed metal oxides were synthesized by the sol–gel method through four different routes. The effect of (i) the solvent of iron precursor, (ii) the addition of the chelating agent to the titanium or iron solution and (iii) the molar ratio between the chelating agent and the titanium or iron precursor over the overall percentage of obtained iron titanates was evaluated. Fourier-transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy (UV–Vis) performed on the reaction medium evidenced the formation of acetate complexes of titanium (IV) or iron (III) during the different routes. X-ray diffraction (XRD) patterns of the obtained materials showed the formation of ilmenite (FeTiO3), pseudorutile (Fe2Ti3O9) and pseudobrookite (Fe2TiO5) in different proportions, as well as hematite (Fe2O3), rutile [TiO2 (R)] and anatase [TiO2 (A)]. The materials with the highest content of iron titanates obtained in each route were characterized and evaluated in the photocatalytic degradation of cyanide using visible light irradiation. UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS) showed that the samples exhibited energy bandgap values between 2.31 and 2.90 eV, which agrees with the values reported for iron titanates and evidence the possible activation of the materials under visible light. Scanning electron microscopy (SEM) and nitrogen physisorption results showed that the synthesized materials exhibited nanometric particle size and lower surface area (36.7 ± 4.8 m2·g-1) than TiO2 Degussa P-25 (72–155 m2·g-1). The photocatalytic performance of the synthesized materials toward oxidation of CN− exceeded by 56% the activity of pure TiO2. The content of iron titanates in the synthesized materials was found to be the variable with the greatest influence on the photodegradation of cyanide. In addition, an inversely proportional relationship between the pseudorutile content of the materials and their photocatalytic activity was observed.

Improved cycle capability of Mn-doped Fe2TiO5 anode for lithium-ion batteries

Good cycling stability and high theoretical capacity are provided by Fe2TiO5 (iron titanate) as an electrode material due to its distinct crystal structure and numerous redox couples. The conventional ceramic method successfully and effectively synthesises the material. This study discloses the successful doping and replacement of Ti4+ with Mn4+ in the unit cell of Fe2TiO5 pseudobrookite, resulting in decreased band gap energy and a regular increase in unit cell volume with increased Mn-concentration. Doping improves the overall electrical conductivity due to a higher ratio of Ti3+ to Ti4+ which ultimately boosts the electrochemical performance as an anode in LIBs application. The Fe2Ti1-xMnxO5 (x = 0.2) achieves a high specific surface area of 338.6 m2 g−1 with an average pore size distribution of ∼10 nm, which is beneficial to reduce the Li-ion diffusion path and provides large contact areas between electrolyte and electrode surface. The Fe2Ti1-xMnxO5 (x = 0.2) stays ahead in its electrochemical performance compared to all counter partners delivering 765.6 mAh g−1 of initial discharge capacity and having a capacity retention of 392.3 mAh g−1 after 100 continuous charge discharge cycles at a current density of 100 mA g−1. Additionally, an excellent rate performance of 327.9 mAh g−1 is observed even at 5000 mA g−1. No further capacity fading is noted for another 45 cycles, demonstrating the structural stability of electrode material at variable current densities. The superior electrochemical results of Mn4+ doped Fe2TiO5 manifestly show the possibility of serving as an electrode material for high-performance battery applications.

Oxygen vacancy and Ce ion co-synergize to enhance the photocatalytic degradation performance of FeTiO3: An experimental and DFT study

Doping the iron titanate (FeTiO3) with rare earth element is considered as an effective method of enhancing its photocatalytic performance. In this work, the novel FeTiO3 doped with cerium (Ce) (Ce/FeTiO3) photocatalysts were designed and synthesized using the sol–gel method. The 10 mol% Ce/FeTiO3 photocatalyst displays excellent photocatalytic performance for degrading the tetracycline hydrochloride (TCH), methylene blue (MB) and brilliant blue (BB). The degradation efficiencies are 97.50 % (TCH), 95.40 % (MB), and 84.60 % (BB), respectively, and the degradation rate constants (k) are 3.68, 2.91, and 7.12 times that of pure FeTiO3. Density functional theory (DFT) calculations were used to study the photocatalytic degradation mechanism in depth. The results show that the content of oxygen vacancy is increased and the oxygen vacancy formation energy is significantly increased from 2.25 eV to 6.97 eV after doping the Ce ion, which can provide more active sites to degrade pollutants and enhance the photocatalytic performance of the FeTiO3. Furthermore, the Ce 4f orbital can narrow the bandgap and form the impurity level to capture the photoexcited electron, inhibiting the recombination rate of photocarriers in FeTiO3. This work is expected to provide a valuable insight into the Ce doped FeTiO3 photocatalyst, which is conductive to expanding the practical applications of FeTiO3-based photocatalyst.

An Emerging Trend in the Synthesis of Iron Titanate Photocatalyst Toward Water Splitting.

Hydrogen gas is a prominent focus in pursuing renewable and clean alternative energy sources. The quest for maximizing hydrogen production yield involves the exploration of an ideal photocatalyst and the development of a simple, cost-effective technique for its generation. Iron titanate has garnered attention in this context due to its photocatalytic properties, affordability, and non-toxic nature. Over the years, different synthesis routes, different morphologies, and some modifications of iron titanate have been carried out to improve its photocatalytic performance by enhancing light absorption in the visible region, boosting charge carrier transfer, and decreasing recombination of electrons and holes. The use of iron titanate photocatalyst for hydrogen evolution reaction has seen an upward trend in recent times, and based on available findings, more can be done to improve the performance. This review paper provides a comprehensive overview of the fundamental principles of photocatalysis for hydrogen generation, encompassing the synthesis, morphology, and application of iron titanate-based photocatalysts. The discussion delves into the limitations of current methodologies and present and future perspectives for advancing iron titanate photocatalysts. By addressing these limitations and contemplating future directions, the aim is to enhance the properties of materials fabricated for photocatalytic water splitting.

Hydrothermal synthesis of iron titanate hexagonal nanoplates for electrochemical detection of nitrofurazone.

Anelectrochemical sensoris established using an iron titanate (FeTiO3) modified glassy carbon electrode (GCE) to detect nitrofurazone. Various microscopic and spectroscopic analysis was performed to reveal the properties of the prepared FeTiO3 hexagonal nanoplates. The FeTiO3/GCE presents enhanced electrochemical response to nitrofurazone at the peak reduction potential of - 0.471V with a larger peak current than the bare GCE due to high electrical conductivity, enhanced specific surface area, and abundant active sites. The superior nitrofurazone detection performance includes the low limit of detection of 0.002μM and the sensitivity of 0.551 µA µM-1cm-2 in the linear concentration range of 0.01-162.2μM. The reproducibility and selectivity studies of the FeTiO3/GCE show excellent results with a relative standard deviation of < 5%. The practicability of FeTiO3/GCE is confirmed by monitoring nitrofurazone in actual samples. This work demonstrates that perovskite-type FeTiO3 has great potential in real-world sample analysis, and provides a new way to develop high-performance electrochemical sensors.

Photocatalytic Hydrogen Evolution Using Mesoporous Honeycomb Iron Titanate.

Mesoporous honeycomb iron titanate using a sol-gel, evaporation-induced self-assembly method is synthesized. A triblock copolymer, F127, serves as a structure-directing agents, with iron chloride and titanium (IV) isopropoxide as inorganic precursors. The strong intermolecular force of attraction among urea, metal precursors, and polymer led to the formation of the mesoporous honeycomb structure. The study of physicochemical properties using different techniques reveals the formation of microstructures with a remarkable degree of porosity. The amorphous iron titanate outperforms the photochemical generation of H2 due to its disorderly structural arrangement and incomplete crystal formation. The randomness on the structure provides more area for catalytic reaction by providing more contact with the reactant and superior light absorption capability. The high amount of hydrogen gas, 40.66mmolg-1h-1, is observed in the investigation over 3h of activity for the iron titanate honeycomb sample. This yield is a more significant amount compared to the obtained for the commercially available TiO2 (23.78mmolg-1h-1). The iron titanate materials synthesized with low-cost materials and methods are very effective and have the potential for hydrogen generation.

Enhanced lithium storage performance derived from Fe2Ti1-xNixO5 (0 ≤ x ≤ 0.1) as a fast charging anode

Using iron titanate (Fe2TiO5) as an electrode provides high theoretical capacity and good cycling stability because of its multiple redox couples and unique crystal structure. The synthesis of the material is successfully carried out using the conventional ceramic method. The effect of Ni2+ substitution on the overall electrochemical performance of Fe2Ti1-xNixO5 anode material is explored. When Ni2+ replaces Ti4+ in the pseudobrookite Fe2TiO5 unit cell, the volume increases smoothly with the amount of nickel and the electrical conductivity is enhanced because of the higher Ti3+/Ti4+ ratio. With pore sizes of around 10 nm and specific surface areas of 330.81 m2 g−1, Fe2Ti1-xNixO5 can provide large contact areas between the electrode and electrolyte and shorten the lithium-ion diffusion distance. With discharge capacities of 368.6 mAh g−1 at the 100th cycle, Fe2Ti1-xNixO5 negative electrode exhibits outstanding electrochemical performance. Furthermore, it demonstrates excellent rate stability, with a discharge capacity of 310.6 mAh g−1 at a current rate of 5000 mA g−1. Over another 45 cycles, a high discharge capacity of 367.1 mAh g−1 was maintained at a current density of 100 mA g−1 even after the rate performance test. The Ni2+ doping results in faster Li+ insertion/extraction kinetics due to reduced Li+ diffusion paths, which leads to performance improvement.

Nd substitution response on structural, dielectric, and electrical features of bismuth iron titanate

Nowadays, there have been much consideration to develop eco-friendly advanced materials, which have many applications in the field of multiferroics, sensors, actuators, magnetically modulated transducer devices, etc. Hence, the preparation of lead-free based multifunctional materials has now become of great interest to researchers. The present study reports the synthesis and study of structural, dielectric, and multiferroics characteristics of (Bi0.8Nd0.2)(Fe0.5Ti0.5)O3 material. The compound was synthesized using a conventional solid-state reaction method (calcination at 950 °C). The X-ray diffraction analysis of the compound confirms the single-phase formation with orthorhombic symmetry. The surface morphology of the material has been examined by the field emission scanning electron microscopy (FESEM) method, which shows uniform grain distribution in the microstructural image. Grains were to be found of different sizes with few voids. Energy dispersive X-ray (EDX) shows the purity of the sample with an equivalent amount of weight and atomic percentage. Dielectric and impedance analysis have been investigated in a wide range of frequencies and temperatures. Frequency-dependent ac-conductivity obeys Jonscher's universal power law. The P-E loop tracer was used to study the ferroelectric nature of the sample. Magnetic field-dependent magnetization is measured at room temperature by a vibrating sample magnetometer (VSM). The current study provides efficient, eco-friendly, and interesting results for further application purposes.

Strontium substituted sodium iron titanate as a possible sodium-ion conductor: Preliminary studies on preparation, crystalline transformation and conductivity

The rising interest in sodium-ion batteries is due to the widespread geographical availability of sodium and to qualify as a possible sodium-ion conductor, the proposed material should possess formidable structural stability and high ion conductivity. In the current work, therefore, the feasibility of employing strontium substituted sodium iron titanate (Sr-SIT) as a possible sodium-ion conductor was investigated. Synthesis of SIT and Sr exchange was accomplished through solution route. The crystalline transformation of Sr-SIT was elucidated through TG-DTA and XRD analyses in the temperature range of473 to 1273 K of calcination. Sodium-ion conductivity was established by EMF measurements.

Life Testing and Redox Cycling of Ni- and Ru-Doped Strontium Iron Titanate Exsolution Fuel Electrodes in Electrolyte-Supported Solid Oxide Cells

Recently perovskite materials have gained much attention as potential candidates for solid oxide cell (SOC) fuel electrodes due to their advantages of redox stability, coking resistance and sulfur resistance over their cermet counterparts. Enhanced electrochemical performance has also been observed for some of these perovskite materials resulting from exsolution, where nano-sized metal particles are formed on the material surface under reducing conditions. However, the degradation mechanism of these perovskite fuel electrodes has yet to be fully understood and the relationship between their long-term stability and operating envrionments (fuel-cell/electrolysis, fuel compositions, redox cycles, operating pressure, etc.) has not been fully investigated.Here, life tests were conducted in open-circuit and reversible operation at 850oC on electrolyte-supported symmetric and full cells with Ni and Ru-doped strontium iron titanate (Sr0.95Ti0.3Fe0.63Ni0.07O3 and Sr0.95Ti0.03Fe0.63Ru0.07O3) as fuel electrodes (SrTi0.3Fe0.6Co0.1O3 used as the air electrode in the full cells). For both materials, higher degradation rate was observed when operated with 97% H2 + 3% H2O compared with 50% H2 + 50% H2O as fuel; an increase in ohmic resistance and gas adsorption/desorption resistance contributed to most of the degradation observed. STFN also showed higher degradation rates than STFRu in both fuel compositions. Exsolution from both compositions was confirmed by scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) with both fuel compositions and in situ X-ray Diffraction (XRD) showed the simultaneous perovskite to Ruddlesden-Popper (RP) phase transformation. The faster perovskite-RP phase transformation is believed to be responsible for the higher degradation rates observed for cells using fuel electrode materials with less stable perovskite structure (STFN over STFRu) and tested in more reducing fuel compositions (97% H2 over 50% H2). Moreover, redox cycles were introduced for STFN and STFRu during life tests and partial performance recovery was observed; in situ XRD and SEM microstructural analysis suggests that the recovery resulted from a transformation from RP back to perovskite for both materials. Finally full cell reversible operation durability tests (6 hrs each in fuel cell and electrolysis modes at 0.8 A/cm2) conducted at 850oC with 50% H2 + 50% H2O as fuel at 1 atm showed reasonably good stability over 1000 h. Initial reversible life testing at 3 atm operating pressure showed higher degradation rates, and the possible reasons for this will be discussed.

Piezoelectricity ameliorates high-valent iron oxo species production in peroxymonosulfate activation for refractory atrazine remediation

Over the past few years, high-valent iron oxo species (Fe(IV)) have shown considerable promise. However, an improved solution is needed for the bottleneck of unsatisfactory electron transfer efficiency in Fe-based catalyst/PMS systems. In this study, Enteromorpha-derived biochar was pyrolyzed with iron and barium titanate (FeBCBa). Under ultrasonic treatment, it removes 94.5% of atrazine (10 mg/L) within 60 min, and is environmentally friendly. BaTiO3′s piezoelectricity enhances Fe(IV) production in FeBCBa, resulting in superior performance. In the ultrasonic condition, the apparent reaction rate was 1.42 times higher than in the non-ultrasonic condition. Using density functional theory calculations, it can be shown that due to the Fe dopant, electrons in ATZ’s LUMO are more easily transferred to the catalyst’s HOMO, which is beneficial for ATZ removal. The results of this study provide new guidance for constructing stable and efficient catalysts for environmental remediation.

Optimal Process Parameters for Direct Carbothermal Reduction of Vanadium–Titanium Magnetite in a Rotary Kiln

Direct reduction in rotary kiln plays a crucial role in the reduction and smelting of vanadium–titanium magnetite. The effect of the process parameters on the metallization rate and reaction mechanism during the reduction process in a rotary kiln is investigated. The results indicate that the optimal process parameters for direct reduction of vanadium–titanium magnetite in a rotary kiln are as follows: a reduction temperature of 1150 °C, reduction time of 4 h, carbon ratio 1.2, particle size of vanadium–titanium magnetite as 8–12 mm, and particle size of pulverized coal of &lt;8 mm. During the direct reduction of vanadium–titanium magnetite, favorable conditions such as absence of smelting phenomenon on the surface of the reduction products, high metallization rate, and high quality of direct reduction iron are achieved. Through direct reduction, the transformation process of iron oxide in vanadium–titanium magnetite is Fe3O4 → iron oxide → Fe, and the transformation process of titanium–iron oxide is Fe9TiO15 → Fe2.75Ti0.25O4 → Fe2.5Ti0.5O4 → iron titanate → Fe. In addition, vanadium and ferrochrome oxides undergo reduction to form oxides or carbides.

Preparation and Soxhlet leaching studies of strontium incorporated sodium iron titanate by ICP-OES and NAA methods

Preparation and Soxhlet leaching studies of strontium incorporated sodium iron titanate by ICP-OES and NAA methods

Photocatalytic Conversion of Lignin in the Presence of Titania and Iron Titanate Films

Photocatalytic Conversion of Lignin in the Presence of Titania and Iron Titanate Films

Kinetics study of low-grade ilmenite fusion process using sodium hydroxide: Non-isothermal condition with model-free methods

The caustic fusion process is one of the alternative processes in titanium dioxide production from low-grade ilmenite ore. The kinetics of low-grade ilmenite ore caustic fusion using sodium hydroxide (NaOH: Ti ratio = 2:1 (w/w)) under inert atmospheric conditions were studied utilizing thermogravimetric analysis (TGA) at heating ratesof 5, 10, and 15 °C/minute. In a nitrogen atmosphere, the caustic fusion kinetic parameters were calculated using the model-free isoconversion methods of Friedman, FWO, and KAS. It was observed that as conversion (α) increases, Ea and log A decrease. Because of the pre-exponential factor's high value, the order of the reactions has no effect on the process. These methods calculated activation energy profiles of conversion values with results ranging from 8.7 to 149.11 kJ/mol. They varied in a sophisticated way based on the heating rate over a wide range. The fusion product's XRD analysis revealed that the minimum temperature for the formation of a large amount of sodium iron titanate is 850 °C.

Solar-driven CO2 reduction using modified earth-abundant ilmenite catalysts

Photocatalytic CO2 reduction is an alternative technology to the depletion of highly pollutant fossil fuels through the generation of renewable solar-based fuels. This technology requires that the photocatalysts be obtained directly from nature to scale up the process. Taking that into consideration, this work proposed the fabrication of sodium iron titanate (NaFeTiO4) photocatalysts from earth-abundant ilmenite mineral. The photocatalysts exhibited full spectrum light response, good electron transfer due to its unique tunnel structure that favored the formation of rod-like morphology. These properties promoted the solar-driven CO2 reduction to generate formic acid (HCOOH) with high selectivity (157 μmol g−1 h−1). It was found that higher synthesis temperatures promoted the formation of Fe3+ species, which decreased the efficiency for CO2 reduction. Also, the possibility of reduced the CO2 molecules in the air was studied with the NaFeTiO4 samples, which resulted in an efficiency of up to 93 μmol g−1 h−1 of HCOOH under visible light. The stability of the solar-driven CO2 reduction with the NaFeTiO4 photocatalysts was confirmed after seven days of continuous evaluation.