Iron Oxide Research Articles

Optimization of Iron Oxide (Fe2O3) Addition Parameters on the Physical Properties of Al-Si Alloys as an Advanced Material Innovation

Aluminum-silicon alloys are widely used in the industrial world, one of which is because they have high wear resistance. The aim of this research is to determine the physical and mechanical properties of the Al-Si alloy after strengthening by mixing reinforcing materials. The research method uses Taguchi optimization and analysis of the physical properties of the Al-Si alloy test results. The results showed that the highest hardness value was obtained in the 7th experiment, namely with a rotation variation of 2000 rpm, temperature of 6000C, and holding time of 60 seconds. This result is in line with the results of the tensile strength test, where the highest tensile strength was also obtained in the 7th experiment. This result is supported by the results of other researchers, which show that the higher the rotation in the casting results in higher hardness. The results of the microphotographs show that all alloy materials have an even distribution of grains, the grain size appears small, and the dendrites in the raw Al-Si alloy appear small compared to other materials. The macro photo results show that all alloy materials have fractures that appear brittle, as evidenced by the fact that these fractures provide light reflection.

Methyl esters production from Waste Cooking Oil catalysed by iron oxides supported on CaO: Cost and environmental impacts

It was the objective of this work, to assess the midpoint environmental impacts of the catalyst synthesis stage and biodiesel production from waste cooking oil (WCO) as feedstock, depending on the catalyst source, i.e. Fe2O3 or Fe(NO3)3⋅9H2O, lime or waste clam shells, to produce the applied bifunctional catalyst based on iron and CaO. The cost of biodiesel production depending on the catalyst was also established. In the catalyst synthesis stage, the use of clam shells contributed the most to the midpoint environmental categories, mainly terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity and human non-carcinogenic toxicity. In the stage of biodiesel production (esterification-transesterification reaction), the scenario contributing the lowest (20.95–22.16 %) to the midpoint environmental impacts is when using Fe(NO3)3·9H2O and CaO as iron and lime precursors, respectively. Using waste clam shells increases the environmental impacts. Regarding costs, the clam shells lead to the most expensive process ($0.08 USD/MJ). The source of energy to conduct the biodiesel production was also assessed and it was found that the use of wind turbines leads to the lowest global warming potential (GWP), 11.6 g CO2 eq·MJ-1, with the catalyst prepared with the iron salt and with the CaO from lime. The presented results were obtained with the commercial software SimaPro® version 9.6 PhD. For the inventory, experimental data obtained at laboratory scale and previously published were used.It was concluded that based on environmental impacts and costs, it is recommended to use lime instead of clam shells waste as precursor of CaO and Fe(NO3)3·9H2O as precursor of iron.

Enhanced Photocatalytic Properties and Photoinduced Crystallization of TiO2-Fe2O3 Inverse Opals Fabricated by Atomic Layer Deposition.

The use of solar energy for photocatalysis holds great potential for sustainable pollution reduction. Titanium dioxide (TiO2) is a benchmark material, effective under ultraviolet light but limited in visible light utilization, restricting its application in solar-driven photocatalysis. Previous studies have shown that semiconductor heterojunctions and nanostructuring can broaden the TiO2's photocatalytic spectral range. Semiconductor heterojunctions are interfaces formed between two different semiconductor materials that can be engineered. Especially, type II heterojunctions facilitate charge separation, and they can be obtained by combining TiO2 with, for example, iron(III) oxide (Fe2O3). Nanostructuring in the form of 3D inverse opals (IOs) demonstrated increased TiO2 light absorption efficiency of the material, by tailoring light-matter interactions through their photonic crystal structure and specifically their photonic stopband, which can give rise to a slow photon effect. Such effect is hypothesized to enhance the generation of free charges. This work focuses on the above-described effects simultaneously, through the synthesis of TiO2-Fe2O3 IOs via multilayer atomic layer deposition (ALD) and the characterization of their photocatalytic activities. Our results reveal that the complete functionalization of TiO2 IOs with Fe2O3 increases the photocatalytic activity through the slow photon effect and semiconductor heterojunction formation. We systematically explore the influence of Fe2O3 thickness on photocatalytic performance, and a maximum photocatalytic rate constant of 1.38 ± 0.09 h-1 is observed for a 252 nm template TiO2-Fe2O3 bilayer IO consisting of 16 nm TiO2 and 2 nm Fe2O3. Further tailoring the performance by overcoating with additional TiO2 layers enhances photoinduced crystallization and tunes photocatalytic properties. These findings highlight the potential of TiO2-Fe2O3 IOs for efficient water pollutant removal and the importance of precise nanostructuring and heterojunction engineering in advancing photocatalytic technologies.

Cracking of Used Engine Oil to Gasoline-Like Fuel Using Iron Oxide Nanoparticles Supported on HZSM-5

Cracking of Used Engine Oil to Gasoline-Like Fuel Using Iron Oxide Nanoparticles Supported on HZSM-5

Recent Advancement of Indocyanine Green Based Nanotheranostics for Imaging and Therapy of Coronary Atherosclerosis.

Atherosclerosis is a vascular intima condition in which any part of the circulatory system is affected, including the aorta and coronary arteries. Indocyanine green (ICG), a theranostic compound approved by the FDA, has shown promise in the treatment of coronary atherosclerosis after incorporation into nanoplatforms. By integration of ICG with targeting agents such as peptides or antibodies, it is feasible to increase its concentration in damaged arteries, hence increasing atherosclerosis detection. Nanotheranostics offers cutting-edge techniques for the clinical diagnosis and therapy of atherosclerotic plaques. Combining the optical properties of ICG with those of nanocarriers enables the improved imaging of atherosclerotic plaques and targeted therapeutic interventions. Several ICG-based nanotheranostics platforms have been developed such as polymeric nanoparticles, iron oxide nanoparticles, biomimetic systems, liposomes, peptide-based systems, etc. Theranostics for atherosclerosis diagnosis use magnetic resonance imaging (MRI), computed tomography (CT), near-infrared fluorescence (NIRF) imaging, photoacoustic/ultrasound imaging, positron emission tomography (PET), and single photon emission computed tomography (SPECT) imaging techniques. In addition to imaging, there is growing interest in employing ICG to treat atherosclerosis. In this review, we provide a conceptual explanation of ICG-based nanotheranostics for the imaging and therapy of coronary atherosclerosis. Moreover, advancements in imaging modalities such as MRI, CT, PET, SPECT, and ultrasound/photoacoustic have been discussed. Furthermore, we highlight the applications of ICG for coronary atherosclerosis.

Experimental and process simulation on solid fuel chemical looping cascade utilization conversion technology aiming hydrogen generation

In this work, a novel chemical looping process towards hydrogen generation based on the cascade utilization of components in solid fuels (like biomass and coal) with different reactivity (pyrolysis gas and char) was proposed, aiming for energy conversion from carbon-intensive fuels to carbon-free renewable hydrogen via the material migration of iron oxides. Biomass, represented by sawdust, is an important part among various renewable energy sources and a typical solid fuel with great potential. Therefore, in the most concerned reduction stage, experiments were conducted mainly using sawdust to investigate the effects of various parameters (temperature, oxygen/fuel ratio, residence time) on the carbon conversion involved in char in the primary reduction stage, gas/solid spatiotemporal distribution in the deep reduction stage and subsequent H2 generation performance, and kinetic parameters were fitted for different reduction stages. Process simulation was further conducted based on the actual experimental results. The proposed process demonstrated satisfactory applicability to solid fuels with different characteristics, and biomass was more suitable for hydrogen production. Compared with chemical looping combustion process, a significant improvement of sawdust-fueled energy conversion efficiency from 33.26 % to 51.76 % and a decrease of OCs theoretical circulation rate (27.77 %) were achieved under the chemical looping process aiming hydrogen generation.

Applicability of energy-theta mapping in resonant soft X-ray reflectometry to probe depth dependence of oxidation state and crystallographic environment in iron oxide multilayers

In the present paper we discuss applicability of the synchrotron method of resonant x-ray reflectometry to non-destructive depth profiling of multilayer heterostructures with low optical contrast between the sublayers. The two-dimensional mapping approach comprising evaluation and measurement of reflectance as a function of photon energy and grazing angle is shown to provide a convenient way to effectively utilize the enhancement of optical contrast between the sublayers that exists at the absorption edges of chemical elements due to particular spectral shape peculiarities related to oxidation state, crystallographic environment and magnetization. In the present study the evaluation of the resonant X-ray reflectivity maps is performed using a specially developed modeling and fitting software. Estimation of the photon energy / grazing angle combinations at which the reflectance is most sensitive to the minor changes in the physical properties of the sublayers is illustrated by the example of ferroic-on-semiconductor nanoscale heterostructures composed of nanoscale film of metallic iron oxidized from either top or bottom side. The subtle differences in resonant soft x-ray reflectance caused by variation of the oxide film thickness, oxidation state and crystallographic environment are discussed. The presented approach is applicable to a large class of heterostructures composed of sublayers that can be distinguished only by the differences in their near edge X-ray absorption fine structure.

The Sustainable Remediation of Antimony(III)-Contaminated Water Using Iron and Manganese-Modified Graphene Oxide–Chitosan Composites: A Comparative Study of Kinetic and Isotherm Models

This study introduces a series of Fe/Mn-GOCS composites using high-temperature impregnation with graphene oxide and chitosan as substrates, modified by diverse manganese salts, including MnCl2∙4H2O, KMnO4, and MnSO4. Among these, FeCl2/MnSO4-GOCS demonstrated the highest adsorption capacity for Sb(III), peaking at 57.69 mg/g. The adsorption performance was extensively evaluated under various conditions, such as different initial concentrations, pH levels, solid–liquid ratios, and adsorption durations. It was observed that when the Fe/Mn molar ratio exceeded 4:1, there was a notable decrease in both the adsorption capacity and removal rate. Kinetic analyses using the pseudo-second-order model revealed a better fit (R2 > 0.99) compared to the pseudo-first-order model, indicating that chemisorption dominated the adsorption process. Additionally, isothermal modeling highlighted the efficiency of Fe/Mn-GOCS, particularly in high-concentration environments, with the Sips model demonstrating the best fit, integrating characteristics of both Langmuir and Freundlich models. These results not only offer a robust theoretical and practical basis for efficient Sb(III) removal but also underscore the potential of multi-metal-modified adsorbents as sustainable solutions for environmental remediation.

Nano Fe3O4 improved the electron donating capacity of dissolved organic matter during sludge composting

The effect of Fe3O4 nanoparticles (Fe3O4 NPs) on the electron transfer process in aerobic composting systems remains unexplored. In this study, we compared the electron transfer characteristics of DOM in sludge composting without additives (group CK) and with the addition of 50 mg/kg Fe3O4 NPs additive (group Fe). It was demonstrated that the electron transfer capacity (ETC) and electron donating capacity (EDC) of compost-derived DOM increased by 13%–29% and 40%–47%, respectively, with the addition of Fe3O4 NPs during sludge composting. Analyzing the composition and structure of DOM revealed that Fe3O4 NPs promoted the formation of humic acid-like substances and enhanced the aromatic condensation degree of DOM. Correlation analysis indicated that the increase in EDC of DOM was closely associated with the phenolic group in DOM and influenced by quinone groups and the degree of aromatization of DOM. The higher EDC and the structural evolution of DOM in group Fe reduced the bioaccessibility of Cu, Cr, Ni, Zn. This study contributes to a deeper understanding of the redox evolutionary mechanism of DOM in sludge composting and broadens the application of iron oxides additives.

Ultrasound Control of Pickering Emulsion-Based Capsule Preparation.

Capsules with microparticle shells became of great interest due to their potential in many fields. Those capsules can be fabricated at high temperatures from particle-stabilized emulsions (Pickering emulsions) by sintering together particles that cover droplets. One of the problems with such an approach is accurately controlling whether particles are already sintered and creating the rigid capsule shell of a capsule. Here, we propose using a non-destructive ultrasound method for monitoring Pickering emulsion-based capsules prepared using heating under an alternating magnetic field. The polyethylene microparticles that were responsive to temperatures higher than 112 °C were used as droplet stabilizers together with iron oxide nanoparticles. During the coalescence of the droplets, facilitated by an external electric field, the ultrasonic attenuation increased, giving evidence that the ultrasound method detects structural changes in Pickering emulsions. The main change was the difference in the droplets' size, which was also observed via optical microscopy. The attenuation of ultrasound increased even more when measured after magnetic heating for the same concentration of particle stabilizers. Simultaneously, the values of ultrasonic velocity did not exhibit similar variety. The results show that the values of the attenuation coefficient can be used for a quantitative evaluation of the capsule formation process.

Extent of As(III) versus As(V) adsorption on iron (oxyhydr) oxides depends on the presence of vacancy cluster-like micropore sites: Insights into a seesaw effect

Iron (oxyhydr)oxides are ubiquitous in terrestrial environments and play a crucial role in controling the fate of arsenic in sediments and groundwater. Although there is evidence that different iron (oxyhydr)oxides have different affinities towards As(III) and As(V), it is still unclear why As(V) adsorption on some iron (oxyhydr)oxides is larger than As(III) adsorption, while it is opposite for other ones. In this study, six typical iron (oxyhydr)oxides are selected to evaluate their adsorption capacities for As(III) and As(V). The characteristics of these iron minerals such as morphology, arsenic adsorption species, and pore size distribution are carefully examined using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), positron annihilation lifetime (PAL) spectroscopy, and X-ray absorption spectroscopy (XAS). We confirm a seesaw effect occurred in different iron minerals for As(III) and As(V) immobilization, i.e., at pH 6.0, adsorption of As(V) on hematite (0.73 μmol m−2) and magnetite (0.33 μmol m−2) is higher than for As(III) (0.61 μmol m−2 and 0.27 μmol m−2, respectively), for goethite and lepidocrocite it is almost equal, while As(III) sorption on ferrihydrite (5.77 μmol m−2) and schwertmannite (28.41 μmol m−2) showed higher sorption than As(V) (1.53 μmol m−2 and 12.99 μmol m−2, respectively). PAL analysis demonstrates that ferrihydrite and schwertmannite have a large concentration of vacancy cluster-like micropores, significantly more than goethite and lepidocrocite, followed by hematite and magnetite. The difference of adsorption of As(III) and As(V) to different iron (oxyhydr)oxides is due to differences in the abundance of vacancy cluster-like micropore sites, which are conducive for smaller size As(III) immobilization but not for larger size of As(V). The findings of this study provide novel insights into a seesaw effect for As(III) and As(V) immobilization on naturally occurring iron mineral.

Recent Developments in the Catalytic Heterocycles Synthesis and Applications of Iron Oxide Nanomaterials

The synthesis of heterocyclic compounds has made extensive use of magnetic iron oxide (Fe2O3 and Fe3O4) nanoparticles as a heterogeneous catalyst. They are cheap, readily available, environmentally benign, and comparatively nontoxic catalysts. Crucially, these nanoparticles’ surface modification allows reactivity to be tailored enabling catalysts to be designed for specific uses. Important performance for economically viable industrial processes include the easy recovery and reuse of the magnetic nanoparticles from the reaction mixture by magnetic separation. In recent literature on catalytic applications of magnetic iron oxide NPs numerous reactions are reported viz. selective hydrogenation of nitro-heterocyclic compounds, synthesis of functionalized [1,3]-oxazoles, synthesis of benzothiazepine, spirobenzothiazine chroman derivatives and many more. We have collected various reports from the past twelve years and compiled this review on recent trends in catalytic heterocycles synthesis and other applications of iron oxide nanomaterials.

Sunscreens prescribed to patients with skin of color and/or with melasma: A survey of 221 dermatologists and dermatology residents in Spain.

Dark-skinned individuals (DSI) present high rates of melasma and post-inflammatory hyperpigmentation. The use of sunscreens with mineral filters is essential for prevention and treatment. Our objective was to determine the preferences of dermatologists and dermatology residents in the prescription of sunscreens for DSI. An anonymous survey of attendees at an online photoprotection event held on March 31, 2022, in Spain. The survey was answered by 66.6% (221/332) of the attendees: 159 dermatologists (71.9%) and 62 dermatology residents (28.1%). Respondents reported recommending the use of sunscreen to a median of 80% of DSI [interquartile range (IQR), 50-90]. Physicians reported prescribing tinted sunscreens to a median percentage of 60% (IQR, 25-90) of DSI with acne; and to a median percentage of 90% (IQR, 58-99) of DSI with melasma. The most prescribed photoprotectors to DSI with melasma were organic broad-spectrum sunscreens with antioxidants: 102/220 (46.4%) and mineral broad-spectrum sunscreens (with iron oxides): 45/220 (20.4%). In DSI with melasma or other pigmentary disorders, the most preferred features of sunscreens were as follows: sun protection factor ≥ 30: 217/221 (98.2%), UVA protection: 214/221 (96.8%), color for camouflage: 150/220 (68.2%) and mineral filters such as titanium dioxide and zinc oxide: 151/220 (68.6%) or iron oxides: 131/220 (59.5%). Online survey, potential inclusion bias. Respondents reported to prescribe sunscreens to the majority of DSI, and tinted sunscreens for the majority of DSI with pigmentary disorders. However, the most frequently recommended sunscreens for DSI were organic broad-spectrum sunscreens with antioxidants.

Pyrometallurgical processing of manganese ore

Manganese ore contains valuable oxides, such as manganese oxide (MnO2/Mn2O3/Mn3O4), iron oxide (Fe2O3) and silica (SiO2). In the present study, an attempt has been made to separate these oxides through pyrometallurgical processing routes for the extraction of ferromanganese and silicomanganese. Lean manganese ores were subjected to ball milling followed by carbothermic reduction at a temperature of 1200 °C for 2 h. The reduced ores were then subjected to wet magnetic separation to obtain the magnetic constituents in the reduced ores. It was observed that it is not possible to remove the silica content from the ore. It appeared that the reduced sample had oxides of iron, silicon and manganese after its wet magnetic separation. The magnetic constituents were subjected to metallothermic reduction through pure aluminium powders to recover valuable metals/alloys.

Surface complexation of rare earth elements on goethite in sea-floor hydrothermal environment: Insight from first principles simulations

Deep-sea mud shows tremendous resource potential for rare earth elements (REEs) and its formation is closely associated with sea-floor hydrothermal activities. Iron (oxyhydr)oxides link the sources and sinks of REEs in sea-floor hydrothermal systems. However, the complexation mechanisms of REEs on iron (oxyhydr)oxides have not been well understood yet. In this study, by using the first principles molecular dynamics technique, we first calculated the pKa’s of surface groups on goethite (110) surface at elevated temperatures relevant to sea-floor hydrothermal systems and then evaluated the complexation structures and free energies of REEs on goethite (110) and (010) surfaces using the method of constraint by taking Sc3+, Y3+, and La3+ as model REE cations. The results show that REE complexation occurs in mildly acidic to neutral conditions. The most thermodynamically stable complexes of REEs are bidentate complexes on two neighboring FeOH sites on goethite (110) surface and tridentate complexes on two neighboring FeOH sites plus one Fe2OH site on goethite (010) surface. Sc3+ complexes match the goethite lattice and can be incorporated into the lattice. The stabilities of REE complexes increase with the distance from hydrothermal vents. Complexation of Y3+ is less favored on goethite compared to other REEs whereas Sc3+ prefers complexation on goethite (010) surface and La3+ exhibits similar stabilities on both (010) and (110) surfaces. The derived atomic level complexation mechanisms would be helpful for the interpretation of experimental data and the prediction of REEs’ behavior in the sea-floor. The findings presented here provide valuable insights into REEs fractionation and enrichment in deep-sea muds.

The Origin and Nature of Magnetic Particles From Soils and Sediments Constrained by Hydrodynamics and Geochemistry Around a Tropical Lagoon System

AbstractMagnetic iron oxides are commonly enriched in soils and sediments on Earth's surface. Magnetic properties are widely employed in soil taxonomy, sediment tracing and paleoclimate reconstruction as indicators of associated pedogenic and depositional processes. However, in coastal regions, frequent shifts in pedogenesis and diagenesis accompanied by changes in hydrodynamic and geochemical conditions from land to sea can influence the formation and preservation of magnetic particles in sediment sequences. To discern the origin and nature of magnetic particles driven by these processes, we systematically examined soils and sediments around a tropical lagoon that has been closing for two hundred years. We found that the finest superparamagnetic particles are enriched along with hematite from inland soils with high‐Fe and high‐Al backgrounds, which was driven by pedogenesis. Single‐domain ferrimagnetic particles are enriched along with amorphous iron oxides in the lagoon with high‐Mg and high‐Mn backgrounds, which was driven by early diagenesis in quiet and reducing depositional environments. Coarse titanomagnetite particles are strongly enriched in inshore sediments with high‐Si and high‐Ti backgrounds, which was driven by seawater elutriation. However, magnetic particles in barrier bar soils have mixed features depending on the neighboring environment. Identifying magnetic particles derived from different soils and sediments in tropical coastal regions can assist in tropical coastal paleoclimate and paleoenvironment reconstruction on the basis of magnetic properties along coastal sediment sequences.

Tuning the toughness, strength, and biological properties of functionally graded alumina/titania-based composites for use in bone repair applications

In this study, functionally graded composite (FGC) was prepared using a high-energy ball mill by fabricating five layers of alumina (Al2O3), titania (TiO2), hydroxyapatite (HA), and iron oxide (Fe3O4), which were sintered at 1100 °C to create an FGC sample. Scanning electron microscopy (SEM), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and weight loss measurements were used to assess bioactivity and biodegradation after immersing samples in simulated body fluid (SBF). Also, the antimicrobial activity and biocompatibility of these layers were evaluated. Furthermore, their electrical, dielectric, and mechanical properties were examined. The results revealed that all sintered layers were bioactive, and adding HA and Fe3O4 enhanced this desired property. Also, S. aureus bacterial growth was inhibited by TiO2 and Fe3O4. Fortunately, the sintered layers showed no cytotoxic effect, validating the ICP findings that demonstrated acceptable biodegradation. Adding HA and Fe3O4 enhanced fracture toughness in another hopeful outcome, which is crucial for biomaterial efficacy and long-term therapeutic success. Moreover, the compressive strength of all the layers and the FGC sample was 191.7, 182.2, 171.18, 159.8, 142.5, and 171.1 MPa. Layers 3, 4, and 5 notably had a compressive strength similar to cortical bone. This means that implanting these layers into human bone will protect the bone around them from stress-shielding action. Finally, the successive increase in HA/Fe3O4 contents increased the electrical conductivity. Accordingly, the prepared FGC sample and its layers are attractive bone substitute materials.

Lithium isotope systematics in an endorheic saline lacustrine system: Insights from Qinghai Lake, China

The study of lithium isotopic (δ7Li) signatures in sedimentary deposits has become a powerful tool to infer past silicate weathering regimes, thus informing our knowledge of the geological carbon cycle and paleoclimate evolution. Sediments from Qinghai Lake, the largest saltwater lake in China (4625 km2), offer an unparalleled archive for investigating the climatic history of the Qinghai-Tibet Plateau. However, prior to leveraging the δ7Li proxy in this context, it is imperative to unravel the mechanisms of lithium (Li) isotope fractionation and elemental cycling within the lake's aqueous and sedimentary systems. In this study, we collected and analyzed samples of Qinghai Lake's water, sediments, and recharge waters (rivers, groundwater, and rainfall) to investigate the processes controlling the δ7Li value recorded in Qinghai Lake sediments.Our data reveal subtle variances in Qinghai Lake water Li concentration ([Li]), ranging from 652 to 873 ng/g, suggesting interactions with iron oxides or suspended matter. The δ7Li signature, however, exhibits remarkable uniformity across the lake at 32.1‰ (±0.4‰). Near the estuary of the Buha River, there is a swift homogenization of [Li] and δ7Li, stabilizing within just 3 km of the inflow. Lake sediments exhibit δ7Li values ranging from 1.5‰ to 6.6‰, exceeding those of the upper continental crust (∼0‰ ± 4‰), yet approximately 30‰ lower than those in lake waters. This significant discrepancy between the δ7Li of lake water and sediments is likely due to the preferential incorporation of 6Li over 7Li during the neoformation of clay minerals.Lithium mass balance modeling for Qinghai Lake, incorporating inputs from river and groundwater (∼46.5 t/a with δ7Li ∼18.3‰) and outputs via clay mineral uptake (∼44 t/a with δ7Li ∼5.1‰), indicates that the lake's Li system is currently out of steady state. The model predicts a gradual rise in the lake's Li inventory, estimated to achieve steady state within 1.2 ka and the δ7Li value of lake water will increase until reaching ∼45‰ assuming constant climate conditions.

Dynamics of localized accelerated corrosion in reinforced concrete: Voids, corrosion products, and crack formation

A comprehensive 3D imaging analysis was conducted to investigate the corrosion process in reinforced concrete (RC) samples at various stages of the accelerated galvanostatic corrosion process. A state-of-the-art X-ray computed tomography (CT) scan technology was utilized to collect high-resolution 3D images of the specimen. The CT imaging was complemented and validated using a multi-faceted approach utilizing Scanning electron microscopy (SEM) and Raman spectrometry techniques. The distribution and evolution of voids, corrosion products, and cracks were investigated. A localized corrosion was observed that has some similarity to pitted corrosion but not as wide spread along the bar. The micro-scale imaging investigations revealed a gradual increase in the diameter of voids as the time of corrosion increased, especially after 8 days of accelerated corrosion process at which a significant decrease in small-sized voids (≤0.11 mm) accompanied by an increase in other void sizes was observed. At 10 and 12 days of accelerated corrosion process, the volume of larger-sized voids (≥0.35 mm) continued to increase, indicating a rapid corrosion progress and the formation of corrosion-induced cracks. In addition, a thorough X-ray CT analysis allowed us to differentiate between various categories of corrosion products. Notably, iron oxides and iron hydroxides were found to dominate the corrosion products. Understanding the composition and distribution of these corrosion products is essential as they play a significant role in the degradation and deterioration of the concrete structure. The coexistence of iron oxides and iron hydroxides in the region of corrosion products were confirmed using Raman spectroscopy analysis. The CT scan images captured the evolution of cracks at different time intervals, revealing a strong correlation between the initiation of cracks and the presence of corrosion products. Subsequently, during the cracking in the matrix, while the propagation of corrosion products within the matrix contributed to the expansion of cracks. SEM images and elemental analysis confirmed that these cracks were filled with corrosion products.

Harnessing the power of ternary nanocomposites: Iron oxide, multiwalled carbon nanotubes, and bentonite for superior ciprofloxacin adsorption

Water contamination from antibiotics can have detrimental effects on one’s health. Consequently, treating the polluted water is required to fix this issue. Fe3O4-multiwalled Carbon Nanotubes (MWCNTs)-Bentonite nanocomposite has been successfully prepared using a customized co-precipitation process. The synthesized nanocomposite was used as an adsorbent to extract the ciprofloxacin from aqueous solutions. The synthesized nanocomposite was examined using several characterization methods. Scanning electron microscopy demonstrates that the Fe3O4 nanoparticles and bentonite are well-decorated on MWCNTs. The nanocomposite exhibits a high BET surface area of 221.577 m2/g and a pore volume of 0.411 cm3/g. According to the analysis, the average pore diameter was found to be 3.717 nm. Additionally, the adsorption model agreed with the Jovanovic model, which had a 137.35 mg/g adsorption capacity, with a χ2 of 2.161, and a good nonlinear R2 value of 0.999. Moreover, adsorbent was found to be highly stable even after 4 cycles. The ΔS and ΔH values were found to be positive, which suggested an endothermic process. The synthesized nanocomposite proved to be a viable option for water treatment applications, and there is no literature available on CIP antibiotic adsorption using Fe3O4-MWCNT-Bentonite nanocomposite.