Ferric Oxide Research Articles

Cooperation of ferrous ions and hydrated ferric oxide for advanced phosphate removal over a wide pH range: Mechanism and kinetics

Excessive phosphate loading leads to eutrophication problems in rivers or lakes and causes serious environmental and economic damages, urging new technologies to reduce effluent phosphate at ultra-low levels. As a promising candidate, adsorption over metal oxides is restricted by the released hydroxide anions (OH−) through ligand exchange, which elevates pH and suppresses further adsorption. In this contribution, we found ferrous ions (Fe2+) significantly enhance phosphate removal over hydrated ferric oxide (HFO) in a wide pH range via a cooperation of adsorption and precipitation, and clarified the synergistic mechanism by a series of characterizations and the modified models of adsorption isotherms and pseudo second-order kinetics. The combination of Fe2+and HFO removed up to 51.7 mg/g of phosphate at pH 4.0, with 43.6 and 8.1 mg/g attributing to adsorption and precipitation, respectively. In comparison to HFO alone, HFO/Fe2+ system achieved 2.2-fold increase in phosphate removal, 1.9-fold increase in phosphate adsorption capacity, and 3.4-fold increase in phosphate removal rate. The enhancement is understood by that hydroxide anions released from ligand exchange over HFO are neutralized by protons produced from the oxidative precipitation of ferrous ions. The HFO/Fe2+ combining system is promising to realize advanced removal of low concentration phosphate containing wastewater, and these findings bring new insights for the development of novel phosphate removal technologies through a rational design of a combination process.

Effect of miR-21 Inhibitor Coated with Ferric Oxide on Ovarian Cancer Cells Through Mitogen-Activated Protein Kinase Signaling Pathway

Ovarian cancer (OC) incidence has in recent years been on the rise among common gynecological cancers. Iron oxide nanoparticles (IONPs), as emerging nanomedicines, have been widely used in research on cancer therapy. However, with in-depth research on microRNA (miRNA), the effect of combining miRNA with nanoparticles on ovarian cancer is not yet clear. We deeply explored the mechanism of IONPs loading miRNA to regulate ovarian cancer cells. In this study, novelmiR-21 inhibitor-IONPs nanoparticles were prepared by loading miR-21 inhibitor into IONPs. Electron microscopy was used to observe nano-encapsulation and miR-21 expression was measured along with analysis of cell proliferation, apoptosis by flow cytometry, and phosphorylation of apoptotic proteins and mitogen-activated protein kinase (MAPK) signaling pathways by Western blot. Our results showed that miR-21 inhibitor-IONPs reduced miR-21 expression, thereby inhibiting ovarian cancer cells activities and promoting apoptosis. miR-21 inhibitor-IONPs also inhibited p-p38MAPK and p-ERK levels, which were increased after addition of MAPK agonist (U-46619). Moreover, ovarian cancer cell proliferation increased and apoptosis decreased. miR-21 inhibitor-IONPs can thus inhibit MAPK signaling, thereby reducing the activities of ovarian cancer cells. This study provides theoretical support for application of miR-21 inhibitor-IONPs as novel nanoparticles for the treatment of ovarian cancer.

Multisource Information Fusion for Autoformer: Soft Sensor Modeling of FeO Content in Iron Ore Sintering Process

As a key thermal-state indicator of the iron ore sintering process, the content of ferrous oxide (FeO) in the finished sinter is directly related to product quality. Based on the massive data of sintering process, the data-driven soft sensor model provides a good choice for real-time FeO content detection. However, the complex characteristics of the data, including dynamics, nonlinearity, and multi-source heterogeneity, are still the main obstacles to improving the modeling accuracy. To solve this problem, a multi-source information fusion Autoformer (MIF-Autoformer) model is introduced in this paper. Firstly, feature-level information fusion and data-level information fusion are implemented based on the MIF strategy. Then, the comprehensive information of the sintering process is fed to the downstream Autoformer model in a serial manner, which not only improves the information capacity, but also provides additional prior information about the FeO content grade. This is helpful for Autoformer to capture the complex temporal distributions in the sintering process. Finally, the proposed model is applied to a real sintering plant. Experimental results show that the hybrid image features provided by the MIF strategy have a general optimization effect on different competitive models, and MIF-Autoformer exhibits the lowest prediction error on the test set.

Growing pigs’ diets with increased phytase activity and reduced available phosphorus resulted in similar performance and environmental impacts

The objective of this study was to evaluate, through a life cycle assessment, the environmental impacts of the postweaning growth of pigs fed with diets with reduced levels of available phosphorus and increased phytases. In Trial I (nitrogen and phosphorus balance), 25 crossbreed barrow pigs (BP 400 × BM 500 Biriba’s®), with an average weight of 23.05 ± 3.24 kg and average starting age of 60.75 ± 4.73 days, were assigned to five dietary treatments using a randomized block design, with five replications and each animal as an experimental unit. Five experimental diets were evaluated: each increasing phytase activity units (FTU) (control [0], 250, 500, 750 and 1 000 FTU) and decreasing levels of available phosphorus (0.435, 0.375, 0.315, 0.255 and 0.195%), respectively. Due to phytase supplementation, all diets meet the requirements for available phosphorus. The pigs received two daily meals. Total collection of feces was performed, adding 2 g of ferric oxide as a fecal marker. Feces were collected daily, stored in plastic bags and frozen. All excreted urine was collected in plastic buckets containing 20 mL of HCl (1:1), and a 20% aliquot was frozen for further analysis. In Trial II (performance), 40 crossbreed barrow pigs (BP 400 × BM 500 Biriba’s®) with an initial average weight of 15.11 ± 0.67 kg, average starting age of 50.63 ± 0.81 and finishing age of 72.43 ± 2.07 days were assigned using a randomized block design to five dietary treatments, with eight replications and each animal as an experimental unit. The pigs were weighed at the beginning and at the end of the trial, as were the feed supplies and refusals. These data were used to calculate the feed conversion ratio, average daily gain and average daily feed intake. The life cycle analysis was based on the CML 2001 (baseline) method V3.02, as implemented in the Simapro software, version 8.05 (PRé Consultant, 2014). These data may further serve as a reference for the study of the impact of phytase supplementation during other breeding phases, or even in other animals whose environmental impacts are being studied.

Application of a Multifractal Model for Identification of Lithology and Hydrothermal Alteration in the Dasuji Porphyry Mo Deposit in Inner Mongolia, China

The Dasuji giant porphyry molybdenum deposit is one of the largest ore deposits recently discovered along the Yinshan–Yanshan–Liaoning molybdenum belt in China. Using this deposit along the Yinshan–Yanshan–Liaoning molybdenum belt as the study area, the present study proposed a two-stage approach aimed at marking out the hydrothermally altered anomalies in the study area for the guidance of future prospecting in other regions. First of all, the Principal Component Analysis (PCA) and specific Band Ratio methods were applied to the ASTER images from different acquisition dates to extract ferric oxides and hydroxyl alterations related to the porphyry molybdenum deposit. Then, the Fractal-Aided Anomaly-Overlaying Selection model was adopted to recognize two ferric and hydroxyl alteration layers for separating anomalies from the interferences caused by geology and random noise from the data. Furthermore, for lithological differentiation in the previously marked off area, the Random Forest Classifier (RFC) was applied to the composite data obtained via the ASTER, ETM, and DEM, and it is demonstrated that the DEM can significantly improve lithological mapping in areas with complex vegetation cover and topography. Based on field verification and comparison with geological maps, the research revealed that the suggested two-stage approach may effectively reduce erroneously recognized anomalies produced during the first stage while retaining ore-related anomalies for gigantic porphyry molybdenum deposit prospecting in the Dasuji area, which showed the good application potential of the proposed model to extract actual hydrothermally altered anomalies adopted for lithological discrimination and mapping.

Rational Design of High-Performance Electrodes Based on Ferric Oxide Nanosheets Deposited on Reduced Graphene Oxide for Advanced Hybrid Supercapacitors.

The core strategy for constructing ultra-high-performance hybrid supercapacitors is the design of reasonable and effective electrode materials. Herein, a facile solvothermal-calcination strategy is developed to deposit the phosphate-functionalized Fe2O3 (P-Fe2O3) nanosheets on the reduced graphene oxide (rGO) framework. Benefiting from the superior conductivity of rGO and the high conductivity and fast charge storage dynamics of phosphate ions, the synthesized P-Fe2O3/rGO anode exhibits remarkable electrochemical performance with a high capacitance of 586.6Fg-1 at 1Ag-1 and only 4.0% capacitance loss within 10000 cycles. In addition, the FeMoO4/Fe2O3/rGO nanosheets are fabricated by utilizing Fe2O3/rGO as the precursor. The introduction of molybdates successfully constructs open ion channels between rGO layers and provides abundant active sites, enabling the excellent electrochemical features of FeMoO4/Fe2O3/rGO cathode with a splendid capacity of 475.4C g-1 at 1Ag-1. By matching P-Fe2O3/rGO with FeMoO4/Fe2O3/rGO, the constructed hybrid supercapacitor presents an admirable energy density of 82.0Whkg-1 and an extremely long working life of 95.0% after 20000 cycles. Furthermore, the continuous operation of the red light-emitting diode for up to 30min demonstrates the excellent energy storage properties of FeMoO4/Fe2O3/rGO//P-Fe2O3/rGO, which provides multiple possibilities for the follow-up energy storage applications of the iron-based composites.

Two-stage method recovery of metals from copper slag: Realize the resource utilization of all components

The recovery of metal from copper slag is of great significance to the resource utilization of copper slag and the sustainable development of copper smelting industry. Currently, hydrometallurgy is the traditional method used to recover mineral metals. However, as copper slag is a silicate mineral, the traditional acid-leaching process of metal results in the leaching of Si, resulting in the formation of silica gel. The silica gel can inhibit the recovery of metal while making metal difficult to separate from Si and causing filtration problems. This study proposed a two-stage method (evaporation + water washing) to selectively recover Fe and Zn from copper slag. Under the optimal conditions (evaporation: H2SO4 = 3 M; time = 60 min; temperature = 120℃; and liquid–solid ratio = 4; water washing: liquid–solid ratio = 5), the leaching efficiency of Fe, Zn, and Si reached 99.94 %, 97.40 %, and 0.15 % respectively. The separation mechanism was determined through mineral characterization (XRD, SEM, HRTEM-EDS, SAED, AFM, etc.) and the application of DLVO theory. It was found that H+ destroyed the Fe2SiO4 structure in copper slag during the evaporation stage, which promoted the release of Fe and Zn, forming soluble sulfate crystals. Simultaneously, evaporation increased the ion concentration, reducing the repulsive force between colloids, resulting in the aggregation and precipitation of silica gel into stable amorphous silica. After washing, soluble sulfate is dissolved in water. The recovered Fe can be processed to get red iron oxide (96.32 % purity), the Zn-containing solution can be recycled for electrolytic Zn, and the residue can be used to prepare geopolymer (52.47 MPa, 28 days). The two-stage method for recovering metals from copper slag is highly efficient and provides valuable insights into resource utilization of metals and Si in silicon-containing solid wastes.

Synthesis of nano Fe2O3 cement compositions for concrete shielding

The world's most popular building material, concrete, is in constant demand. Because concrete is so widely used, the research trend to improve its sustainability and reduce its adverse effects during its production has gradually expanded. The future of contemporary concrete technology will be the addition of nanoparticles to concrete. Nanomaterials are now used to create inventive, resilient, and cutting-edge concrete constructions since they require less cement to be poured, have reduced overall project costs, and are environmentally conscious. Due to their distinctive features, titanium dioxide and nanocrystalline silica are among the best prospective nanomaterials for a variety of applications. Over the past ten years, there has been a significant rise in interest in nanotechnology as it relates to building materials. The workability of specimens containing 3% nano ferric oxide improves by up to 13.25% compared to control concrete. For concrete elements made with nano-Fe2O3, the values for flexural, split tensile, and compressive strength are respectively 7.90%, 7.4%, and 6.07% higher than for conventional concrete. Hydrophobic properties are produced when nano ferric oxide is used to substitute cement in concrete mixtures up to a particular amount. They aid in improving the self-sensing properties of concrete. Anti-iron oxide nanopowder has been employed in many products, such as corrosion coatings, plastics, silicones, rubber, alloys, lithium batteries, magnetic seals and certain drug delivery. Temperatures of around 450 degrees Celsius can be withstood by Fe2O3. Once they reach this temperature, the particles lose their magnetic characteristics. Because of their high aspect ratio, those particles cannot exist in nanoform without surface treatment.

Iron doped nickel oxide nanoparticle modified carbon paste electrode sensor for paracetamol in presence of ascorbic acid: A voltammetric study

This manuscript reveals the synthesis of ferric doped nickel oxide (Fe–NiO) nanoparticle via a co-precipitation method and is depicted by XRD, SEM and EDS analysis. It is utilized as modifier at bare CPE with analysis of ascorbic acid (AA). AA (vitamin-C) found in citrus fruits and vegetables, it is acts as essential nutrients involved in tissue repair, making of collagen and enzymatic constructions of certain neuro transmitters. The Fe–NiO/MCPE brings the excellent selectivity and sensitivity towards AA in existence of Paracetamol (PA) by using cyclic voltammetry and differential pulse voltammetry. The experimental parameters like pH, sweep rate and concentration studied at 0.2 M PBS solution for the investigation of AA and PA. The Fe–NiO/MCPE is used for the illustration of AA and PA, The limit of detection for both AA and PA is 4.47 μM and 1.84 μM respectively. The prepared sensor can be used for the resolve of AA in real sample investigation.

Chemical looping gasification of biomass using rare earth oxides doped ferric oxide oxygen carrier for hydrogen‐rich syngas production

AbstractAn efficient oxygen carrier (OC) is in great demand in the biomass chemical looping gasification (BCLG) process. In the present study, an innovative rare earth oxide doped ferric oxide OC (Fe2O3−REaOb) derived from the Nd‐Fe‐B sintered magnet waste scraps was employed for the BCLG process for hydrogen‐rich syngas production. The critical variables, including the temperature of gasification, the mass ratio of OC/biomass, the mass ratio of steam/biomass, and the cycle performance of the novel OC, were investigated regarding syngas yield and carbon conversion efficiency. Results found that the optimum conditions were achieved at 900°C, with a mass ratio of OC to biomass of 3:1 and a mass ratio of steam to biomass of 0.4, and a syngas yield of 1.19 Nm3/kg with an H2/CO mole ratio of 2.45, and a carbon conversion efficiency of 76.80% was reached. Additionally, a comparison between Fe2O3−REaOb OC, Fe2O3−Al2O3 OC, and Fe2O3−CeO2 OC was also conducted, with Fe2O3−REaOb OC demonstrating a superior performance. The synergistic effects between REaOb and Fe2O3, particularly the generation of perovskite oxide NdFeO3, contributed to the excellent performance of the Fe2O3−REaOb OC during the BCLG process. The outward diffusion of Fe and sintering of the OC reduced the syngas yield and carbon conversion efficiency by about 16.00% and 25.00% over the 20 redox cycles of the BCLG process. In summary, Fe2O3−REaOb can be an efficient and promising OC for hydrogen‐rich syngas production in the BCLG process.

Direct reduction of pellets through hydrogen: Experimental and model behaviour

This paper presents the hydrogen reduction behaviour of industrial pellets designed for the efficient hydrogen based direct reduction. The pellets were provided with very low non ferrous oxides percentage (0.52 of basicity index) and with the absence on TiO2 oxides. The pellets measured diameters in the range 1.14–1.72 cm and were characterized in terms of porosity, pores size, tortuosity and compression strength. The pellets were reduced in hydrogen atmosphere in a laboratory shaft furnace in the temperature ranges of 600–1200 °C at the pressures of 1 and 5 bar. The pellets' reduction behaviour was analysed in terms of time to reduction, rate of reduction and kinetics constant. All the obtained results were analysed through the employment of a commercial multi-objective optimization tool (modeFrontier) in order to precisely define the effect of each single parameter on the pellets’ reduction. It was also defined the effect of the ongoing reduction rate of the final metallization of the starting iron oxides.

Kinetic constraints for the formation of microniches for microaerophilic Fe(II) oxidation

Oxidation of Fe(II) by oxygen (O2) at circumneutral pH occurs abiotically or is mediated by microaerophilic Fe(II)-oxidizing bacteria. Abiotic Fe(II) oxidation(s) compete with microbial processes and the relative contribution of abiotic reactions depend on the chemical conditions, e.g. PO2, pH and the presence and identity of ferric (oxyhydr)oxide mineral surfaces, catalyzing the heterogeneous reaction. At circumneutral pH, abiotic Fe(II) oxidation proceeds rapidly, which raises the question how and to which extent neutrophilic microaerophilic Fe(II)-oxidizing bacteria can compete with chemical reactions and gain metabolic energy from microbial Fe(II) oxidation. In this study, we have investigated the environmental constraints for microaerophilic Fe(II) oxidation in a film layer characterized by diffusive supply of both atmospheric O2 (from the top) and dissolved Fe(II) (from the bottom) by use of a numerical model. A coupled diffusion–reaction model was tested at different chemical (pH and alkalinity gradients) and physical (film layer thickness) parameters to investigate their effects on the relative contributions of different reactions (abiotic homogeneous, heterogeneous and biological Fe(II) oxidation) to the overall (net) Fe(II) oxidation. A first order rate constant for biological oxidation was derived from experimental data from simplifcation of a Monod rate law to be 0.06 h−1. The simulations demonstrate distinct spatial oxidation rate patterns for all of the considered reactions. Microaerophilic Fe(II) oxidation is predominant at a uniform pH 6 and a film thickness z of 1 mm with minor importance at pH 7. Maximum biological rates were on the order of 7∙10-10 mol L−1 s−1 and are in the range of experimentally observed values. Minimum rates were close to the thermodynamic limit. In the presence of a pH gradient and z ≤ 1 mm, two distinct zones were observed: an upper zone dominated by abiotic Fe(II) oxidation (pH ∼ 7) and a lower zone dominated by microaerophilic Fe(II) oxidation (pH < 6.3), while the position and extent of the zones depend on the alkalinity. Such separation is strongly amplified for thinner films (z = 0.2 mm). The importance of heterogenous oxidation depends both on the pH and the amount of ferric (oxyhydr)oxides formed which increases with decreasing diffusive O2 supply at z > 1 mm. In combination with high resolution imaging of pH values in a biofilm, our simulations underpin the importance of pH gradients in allowing for the formation of microniches. The conditions suitable for microaerophilic Fe(II) oxidation can be predicted based on reaction time scales and three factors were identified to be especially important: i) a pH low enough (<6.3) to outcompete abiotic processes; ii) sufficiently fast diffusive supply of Fe(II) (e.g. by Fe(III)-reducing bacteria or chemical processes) with O2 concentrations below 150 μmol L−1; iii) sufficient energy gain from Fe(II) oxidation reaction considering the thermodynamic factor FT. We end by discussing strategies that Fe(II)-oxidizing microorganisms can employ to enhance their competitiveness against abiotic reactions.

Ferric Oxide Nanocrystals-Embedded Co/Fe-MOF with Self-Tuned d-Band Centers for Boosting Urea-Assisted Overall Water Splitting.

A novel semiconductive Co/Fe-MOF embedded with Fe2 O3 nanocrystals (Fe2 O3 @CoFe-MOF) is developed as a trifunctional electrocatalyst for the urea oxidation reaction (UOR), oxygen evolution reaction (OER), and hydrogen evolution reaction for enhancing the efficiency of the hydrogen production via the urea-assisted overall water splitting. Fe2 O3 @CoFe-TPyP-MOF comprises unsaturated metal-nitrogen coordination sites, affording enriched defects, self-tuned d-band centers, and efficient π-π interaction between different layers. Density functional theory calculation confirms that the adsorption of urea can be optimized at Fe2 O3 @CoFe-TPyP-MOF, realizing the efficient adsorption of intermediates and desorption of the final product of CO2 and N2 characterized by the in situ Fourier transform infrared spectroscopy. The two-electrode urea-assisted water splitting device-assembled with Fe2 O3 @CoFe-TPyP-MOF illustrates a low cell voltage of 1.41V versus the reversible hydrogen electrode at the current density of 10mA cm-2 , attaining the hydrogen production rate of 13.13µmol min-1 in 1m KOH with 0.33m urea. The in situ electrochemical Raman spectra and other basic characterizations of the used electrocatalyst uncover that Fe2 O3 @CoFe-TPyP-MOF undergoes the reversible structural reconstruction after the UOR test, while it demonstrates the irreversible reconstruction after the OER measurement. This work redounds the progress of urea-assisted water spitting for hydrogen production.

Preparation of SiO2/Fe2O3 composite aerogels for thermal insulation enhancement

Silica aerogel, with a unique nano-network structure, serves as a high-performance thermal insulation material. However, silica aerogel possesses a high infrared wave transmission ratio above 300 °C, whose thermal conductivity increases and thermal insulation performance further decreases with the increasing temperature. Introducing opacifiers to silica aerogel is a crucial strategy for addressing this issue. In this work, the ferric oxide exerted as an opacifier was incorporated into the main-phase silica aerogel to improve its thermal insulation at high temperatures. The SiO2/Fe2O3 composite aerogels were created via the two-step sol-gel process followed by supercritical drying, which involved doping ferric nitrate nonahydrate as a Fe2O3 precursor into the silica sol generated with tetraethoxysilane. In this way, SiO2/Fe2O3 composite aerogels with low density (0.04 g/cm3), high specific surface area (705 cm2/g), and low thermal conductivity (0.026 W/(m K)) were obtained by structural adjustment. The incorporation of Fe2O3 improves the thermal insulating properties of silica aerogels. After heat treatment at 1100 °C, the thermal conductivity of the SiO2/Fe2O3 composite aerogel was 0.167 W/(m K), lower than that of the pure silica aerogel (0.249 W/(m K)). Furthermore, the SiO2/Fe2O3 composite aerogel maintained its amorphous structure and exhibited a specific surface area of approximately 94.56 cm2/g, which was three times that of the pure silica aerogel. When subjected to 5-min heating at 1000 °C, the maximum surface temperature of the heat delivery surface of the SiO2/Fe2O3 composite aerogel reached 280.8 °C, whereas the pure silica aerogel reached 353.8 °C.

Synthesis of AgFeO2 delafossite catalyst and its application for photo-degradation of dye present in solution

The present work highlights the physicochemical properties of a series of novel silver ferric oxide (AgFeO2) delafossite nanoparticles while employing them as photocatalysts under visible light irradiation. The first sample was synthesized by a facile co-precipitation route (AFO-0) while the second and third samples were prepared at a constant hydrothermal temperature (180 °C) with varying reaction time of 2 h (AFO-2) and 8 h (AFO-8) and all three samples were subjected to visible light irradiation to photo-degrade Malachite Green (MG) dye. The crystalline structure, morphology, functional groups, elemental analysis, and optical property was conducted by their respective characterization techniques. The size of nanocrystals increased with the hydrothermal time and the average particle size of AFO-0, AFO-2 and AFO-8 were 87.7 nm, 154 nm, and 209.3 nm respectively, with AFO-8 exhibiting prominent hexagonal flake-like morphology. The direct band gap of AFO-0, AFO-2 and AFO-8 were 2.74 eV, 2.53 eV and 2.11 eV respectively and the Urbach energy was 0.20 eV, 0.217 eV and 0.254 eV respectively. The photo generated charge isolation efficiency of the samples was conducted where charge recombination sequence was of the order: AFO-8<AFO-2<AFO-0. The sample AFO-8 exhibited the optimum performance which resulted in excellent degradation of MG under visible light irradiation based on all the batch study experiments using solution pH, comparative analysis, catalyst dose, initial pollutant concentration as parameters. Finally, the optimum conditions at which AFO-8 degraded 97 % of MG were: 80 mg catalyst dose, pH 8, 20 mg L−1 (100 mL) MG, 90 min reaction time, 30 °C temperature and 130 rpm agitation speed. As per the quenching tests, the OH° and O2°− radicals were the governing reactive species that were responsible for degrading MG.

A numerical study on the thermal response of biodegradable ferrous oxide/aluminium oxide nanofluid flow past an unsteady contracting permeable cylinder: A comparative analysis

Esters that are considered natural come from renewable sources like vegetable or animal oils or other bio-based materials. Due to natural esters' great biodegradability, lack of toxicity, and high flash point, their use in industrial applications has been expanding quickly in recent years. The current study, thus numerically investigates an unsteady laminar flow and heat transfer of biodegradable nanofluids past over a shrinking cylinder of time dependent radius. Natural Ester (NE) is used as the base fluids, and two nanoparticles such as Fe3O4 (ferrous oxide) and Al2O3 (aluminium oxide) are used to create different combinations of nanofluids. The unsteady Navier-Stokes equations are used to model it, and similarity solutions are introduced to solve the problem. A MATLAB built-in package BVP4c has been employed to tackle the problem. The physical behavior of the solution has been explored in terms of parametric analysis and graphical demonstration and the validation of present solutions is reported by the comparative benchmark with already available results in a limiting sense. Our findings demonstrate that Fe3O4 biodegradable nanofluids are capable of carrying and dispersing thermal energy more effectively, resulting in improved heat transfer rates compared to Al2O3 biodegradable nanofluids.

Selective extraction of zinc from high iron-bearing zinc calcine by reduction and magnetization roasting

A novel process that combined reduction roasting with magnetization roasting was developed to intensify the decomposition of zinc ferrite for the selective extraction of zinc from high iron-bearing zinc calcine. The decomposition mechanism of zinc ferritewas investigated in detail by thermodynamics analysis and roasting experiments. The results indicated that 94.65% of the zinc ferrite was decomposed into zinc oxide and ferrous oxide under the optimal reduction roasting conditions of 8 vol.% CO, 750 °C, 50 vol.% CO/(CO+CO2), and 90 min. The generated ferrous oxide was further converted to ferriferrous oxide by magnetization roasting under an air atmosphere at 450 °C for 30 min. After that, 93.62% of zinc contained in the calcine could be selectively extracted by low acid leaching, whereas more than 90% of iron was concentrated in the leaching slag in the form of magnetite, which could be recovered by the subsequent magnetic separation.

Influence of ferric oxides with varying crystallinity on the enrichment of halophilic exoelectrogens: An application for power generation in microbial fuel cells

Pre-enriching electroactive microbes (EAM) capable of respiration using solid terminal electron acceptors (TEA) is a prospective strategy that promotes faster start-up of bioanodes in microbial fuel cells (MFC) for energy-efficient treatment of saline wastewater. Previous studies demonstrated a reduction in the start-up times of bioanodes with ferric oxides as TEA, though the enriched EAM generated a wide range of current densities as opposed to those using graphene oxide (GO) as TEA. Additionally, the influence of ferric oxides with varying crystallinity on the anode-respiring activity of halophilic EAM is understudied. This study elaborates a systematic investigation into the influence of inoculum sources, different crystallinity of ferric oxides and their redox potentials on the selective enrichment of GO-respiring EAM for developing bioanodes with high current-generating capacity at shorter start-up times. A holistic assessment of the bioanodes, including analysis of their electrochemical performance and generated power densities, revealed that enrichment of GO-respiring EAM with amorphous ferrihydrite as TEA fostered the growth of high-performing biofilms at shorter start-up times (48–72 h) compared to crystalline goethite used as TEA (∼96 h). These biofilms produced power densities ranging from 142 ± 10 mW/m2 to 276 ± 76 mW/m2 with corresponding Coulombic efficiencies of 16 ± 6 % to 30 ± 6 %. Finally, the implications of promising halophilic EAM consortia were explored for saline MFC as a prospective energy-neutral wastewater treatment technology.

Effect of carbonation on the corrosion behavior of steel rebar embedded in magnesium phosphate cement

Magnesium Potassium Phosphate Cement (MKPC) as a protective binder for steel rebars has been well-established. However, corrosion performance of steel rebars in MKPC subjected to carbonation is still unknown. This investigation aimed at revealing the impact and mechanism of carbonation on corrosion performance of steel rebars in MKPC using electrochemical techniques and surface analyses. The findings indicate that, unlike Portland cement (PC) system, carbonation positively influences corrosion performance of steel rebars when embedded in MKPC, as demonstrated by comparable (M/P = 7) or even higher (M/P = 12) corrosion resistance values. Under carbonation, the ingressive CO2 reacts with Mg-bearing phases in MKPC to form nesquehonite with a higher pH, while the MgO still keep supersaturated. The resultant increase in pH facilitates formation of ferrous oxide and iron phosphate/borate within oxide film developed on steel surface, which enhances protective capability of oxide film and consequently improves the corrosion resistance of the steel rebars.

Natural convection of hybrid nanofluid with magnetic and thermal effects over an inclined needle

Hybrid nanofluids have several potential applications in various industries, including electronics cooling, automotive cooling systems, aerospace engineering, and biomedical applications. The primary goal of the study is to provide more information about the characteristics of a steady and incompressible stream of a hybrid nanofluid flowing over a thin, inclined needle. This fluid consists of two types of nanoparticles: non-magnetic nanoparticles (aluminium oxide) and magnetic nanoparticles (ferrous oxide). The base fluid for this nanofluid is a mixture of water and ethylene glycol in a 50:50 ratio. The effects of inclined magnetic fields and joule heating on the hybrid nanofluid flow are considered. The Runge-Kutta fourth-order method is used to numerically solve the partial differential equations and governing equations, which are then converted into ordinary differential equations using similarity transformations. Natural convection refers to the fluid flow that arises due to buoyancy forces caused by temperature differences in a fluid. In the context of an inclined needle, the shape and orientation of the needle have significantly affected the flow patterns and heat transfer characteristics of the nanofluid. These analyses protest that raising the magnetic parameter results in an increase in the hybrid nanofluid thermal profile under slip circumstances. Utilizing the potential of hybrid nanofluids in a variety of technical applications, such as energy systems, biomedicine, and thermal management, requires an understanding of and ability to manipulate these effects.