Nano-sized Oxide Research Articles

Converting Prussian blue to porous cubic Fe3O4/nitrogen-doped carbon nanocomposite through a space-confined calcination strategy for high lithium storage anodes

Prussian blue is usually used to be precursor to prepare nanosized cubic iron oxides due to its well-defined cube morphology, but the as-prepared iron oxides need to be extral coated with carbon otherwise their lithium storage performance is not satisfactory. Moreover, during preparation of the iron oxides not only the carbon-rich CN– group of the Prussian blue is wasted, but also the resulting gas derived from the decomposition of the CN– is bad for environment. Therefore, it will be significant if the CN– can be converted into N-doped carbon directly. Herein, we develop a novel space-confined calcination strategy to directly convert Prussian blue to Fe3O4/nitrogen-doped carbon (N-C) nanocube composite, in which the interconnected Fe3O4 nanoparticles are in-situ embedded within a porous cubic N-C matrix. The as-prepared composite, therefore, integrates the structural advantages of Fe3O4 nanoparticles, porous cubic nanostructure, and N-doped carbon, which guarantee its excellent structure stability and enhanced electrochemical kinetics during cycling process. As a result, this composite exhibits outstanding performance, including high capacity, long life and good rate, with 785 mA h g−1 at 200 mA g−1 after 350 cycles and 705 mA h g−1 at 1000 mA g−1 after 600 cycles.

The Potential of Graphene Oxide and Reduced Graphene Oxide in Diagnosis and Treatment of Cancer.

Nanotechnology is a pioneer field of study for engineering smart nanosystems in targeted diagnosis and treatment in cancer therapy. Effective treatment for various types of solid tumors should ideally target malignant cells and tissue while having no effect on healthy cells in the body. Nano-sized graphene oxide (GO) and reduced graphene oxide (rGO) have phenomenal chemical versatility, high surface area ratio, and supernatural physical properties. The synergistic effects caused by the well-defined assembly of GO and rGO surface generate not only essential optical, mechanical, but also electronic behaviors. In multimodal cancer therapy, developing innovative multifunctional hybrid nanoparticles with significant potential is extensively considered. GO and rGO are programmable targeted delivery systems infused with photonic energy that may be used in photothermal treatment. Its remarkable properties indicated its applications as a biosensor, bio-imaging for cancer diagnosis. In this current review, we show a remarkable highlight about GO, rGO, and discuss the notable applications for cancer diagnosis and treatment, and provide an overview of possible cellular signaling pathways that are affected by GO, rGO in cancer treatment.

Ethanol gas sensing with lower temperature and higher response based on three-dimensional multilevel materials composed of micron hollow carbon spheres@SnO2 nanoparticles

Metal oxide semiconductor gas sensors (MOS) based on tin oxide have excellent performance in ethanol gas detection and have been widely used in industrial production, environmental protection, and road safety detection. However, conventional tin oxide sensors can only show excellent detection performance for ethanol gas above 250 °C. In this work, nano-size tin oxide particles were grown on the micron hollow carbon spheres derived from the biomaterial chlorella by a gel method. This three-dimensional hierarchical porous structure can enrich ethanol gas at a certain temperature. Ethanol gas sensor fabricated with this material has better sensing performance at low temperature (168–200 °C).

High-temperature creep properties of 9Cr-ODS tempered martensitic steel and quantitative correlation with its nanometer-scale structure

ABSTRACT The Japan Atomic Energy Agency (JAEA) has been developing 9Cr-oxide dispersion strengthened (ODS) tempered martensitic steel (TMS) as a candidate material for use in the fuel cladding tubes of sodium-cooled fast reactors (SFRs). The creep property is essential for the fuel cladding tube of SFR; the reliable prediction of in-reactor creep-rupture strength is critical for implementing the 9Cr-ODS TMS cladding tube in the SFR. This study investigated the quantitative correlation between the creep properties of 9Cr-ODS TMS at 700°C and the dispersions of nanosized oxides by analyzing the creep data and the material’s nanostructure. The possibility of deriving a formula for estimating the in-reactor creep properties of 9Cr-ODS TMSs based on an analysis of the nanostructure of neutron-irradiated 9Cr-ODS TMSs was also discussed. The creep properties of 9Cr-ODS TMS at 700°C closely correlated with the dispersion of nanosized oxide particles. The correlation between creep-rupture lives and nanosized oxide particle dispersion in 9Cr-ODS TMS was determined using existing creep models. The elucidation of correlation between the stress exponent of secondary creep rate and the nanostructure is essential to enhance future modeling reliability and formulation.

Palliative Effect of Resveratrol against Nanosized Iron Oxide-Induced Oxidative Stress and Steroidogenesis-Related Genes Dysregulation in Testicular Tissue of Adult Male Rats

The nano-sized iron oxide (Fe2O3-NPs) is one of the most used engineered nanomaterials worldwide. This study investigated the efficacy of natural polyphenol resveratrol (RSV) (20 mg/kg b.wt, orally once daily) to alleviate the impaired sperm quality and testicular injury resulting from Fe2O3-NPs exposure (3.5 or 7 mg/kg b.wt, intraperitoneally once a week) for eight weeks. Spermiograms, sexual hormonal levels, oxidative stress indicators, and lipid peroxidation biomarker were assessed. Moreover, the steroidogenesis-related genes mRNA expressions were evaluated. The results showed that RSV substantially rescued Fe2O3-NPs-mediated sperm defects. Additionally, the Fe2O3-NPs-induced depressing effects on sperm motility and viability were markedly counteracted by RSV. Moreover, RSV significantly restored Fe2O3-NPs-induced depletion of testosterone, follicle-stimulated hormone, luteinizing hormone, and testicular antioxidant enzymes but reduced malondialdehyde content. Furthermore, the Fe2O3-NPs-induced downregulation of steroidogenesis-related genes (3 β-HSD, 17 β-HSD, and Nr5A1) was significantly counteracted in the testicular tissue of RSV-treated rats. These findings concluded that RSV could limit the Fe2O3-NPs-induced reduced sperm quality and testicular injury most likely via their antioxidant activity and steroidogenesis-related gene expression modulation.

Recent progress and challenges on the removal of per- and poly-fluoroalkyl substances (PFAS) from contaminated soil and water.

Currently, due to an increase in urbanization and industrialization around the world, a large volume of per- and poly-fluoroalkyl substances (PFAS) containing materials such as aqueous film-forming foam (AFFF), protective coatings, landfill leachates, and wastewater are produced. Most of the polluted wastewaters are left untreated and discharged into the environment, which causes high environmental risks, a threat to human beings, and hampered socioeconomic growth. Developing sustainable alternatives for removing PFAS from contaminated soil and water has attracted more attention from policymakers and scientists worldwide under various conditions. This paper reviews the recent emerging technologies for the degradation or sorption of PFAS to treat contaminated soil and water. It highlights the mechanisms involved in removing these persistent contaminants at a molecular level. Recent advances in developing nanostructured and advanced reduction remediation materials, challenges, and perspectives in the future are also discussed. Among the variety of nanomaterials, modified nano-sized iron oxides are the best sorbents materials due to their specific surface area and photogenerated holes and appear extremely promising in the remediation of PFAS from contaminated soil and water.

Synthesis of nano-sized magnetic iron oxide by a simple and facile o-precipitation method

Magnetic iron oxide (Fe3O4) in nano form has been synthesized by a simple wet chemical method involving co-precipitation using iron salt and ammonium hydroxide as precipitating agents. Characterization of the synthesized nanoparticles were carried out by using XRD, FTIR, FESEM and VSM techniques. Crystallite sizes determined from XRD data were found to be between 6.8 and 12.6 nm with face center cubic crystal structures. The lattice parameter was determined to be 8.34 Å. FESEM microstructure revealed a spherical like nanoparticles with average particle size of. The saturation magnetization of the synthesized magnetite nanoparticles was measured to be 49.88 emu/gm. The Fe3O4 nanoparticles synthesized by co-precipitation method is considered to be potentiality good magnetic material with diverse applications.
 Bangladesh J. Sci. Ind. Res. 57(2), 67-76, 2022

Multi-scale modified nitramine crystals with conjugated structure intercalation and thin-layer catalyst coating for well-controlled energy release rate

High-energy solid propellants with lower pressure exponent, lower burn rate but with high combustion efficiency are usually desired. The use of catalysts in less amount but maintained high efficiency is essential for high-energy content and better combustion performances. The fine combination of catalyst with energetic fillers as oxidizer has been found to be a promising strategy to achieve this goal. In this paper, a widely used nitramine oxidizer, cyclotrimethylenetrinitramine (RDX) has been selected as a typical example, which was first intercalated for lower sensitivity and lower burn rate, and then it was coated with in-situ synthesized nanosized metal oxides as catalysts for lower pressure exponent using polydopamine as the interfacial binding layer. Two types of catalyst-coated hybrid RDX crystals (named as qy-RDX@Fe2O3 and qy-RDX@CuO) have been prepared and characterized. It is found that the in-situ grafted nano-Fe2O3 and CuO crystals have significant catalytic effect on qy-RDX, which increased the heat release of qy-RDX@Fe2O3 and qy-RDX@CuO from 1747 J·g−1 to 2159 J·g−1 and 2133 J·g−1, respectively. The results show that both qy-RDX@Fe2O3 and qy-RDX@CuO could reduce the ignition delay time and largely improve the burn rate of corresponding propellants at lower pressure (e.g. increased from 3.14 mm·s−1 to 5.50 mm·s−1 at 1 MPa) by coating only 0.13 wt% Fe2O3 and 0.15 wt% CuO catalysts, resulting in much lower pressure exponent (from 0.32 to 0.15). In particular, the decomposition heat of propellant containing only 10 wt% of qy-RDX@CuO is 1.5 times higher than the reference blank sample, so that its flame temperature was increased from 1800 °C to 2400 °C due to higher combustion efficiency with more energy release.

Nanostructured Superhydrophobic Titanium-Based Materials: A Novel Preparation Pathway to Attain Superhydrophobicity on TC4 Alloy.

This study develops the nanostructured superhydrophobic titanium-based materials using a combined preparation method of laser marking step and the subsequent anodizing step. The structural properties were determined using an X-ray diffractometer (XRD) and scanning electron microscope (SEM), while the performance was explored by wear and corrosion tests. The laser marking caused a rough surface with paralleled grooves and protrusions, revealing surface superhydrophobicity after organic modification. The anodizing process further created a titanium oxide (TiO2) nanotube film. Both phase constituent characterization and surface elemental analysis prove the uniform nanofilm. The inert nanosized oxide film offers improved stability and superhydrophobicity. Compared to those samples only with the laser marking process, the TiO2 nanotube film enhances the corrosion resistance and mechanical stability of surface superhydrophobicity. The proposed preparation pathway serves as a novel surface engineering technique to attain a nanostructured superhydrophobic surface with other desirable performance on titanium alloys, contributing to their scale-up applications in diverse fields.

Iron dust explosion characteristics with small amount of nano-sized Fe2O3 and Fe3O4 particles

Iron powder, as one of the most abundant metal fuels that can be used as recyclable carriers of clean energy, is a promising alternative to fossil fuels in a future low-carbon economy. It may pose a potential explosion hazard during the process of processing, storage, transport, and reduction/oxidation (redox). The explosion characteristics of iron dust in air were undertaken via a 20 L spherical explosion chamber with an emphasis on minimum explosion concentration (MEC) of iron dust. The alternative method of combustion duration time (tc) was used to determine MEC and compared with the standardized over pressure method. Two kinds of nano-sized iron oxides (Fe2O3 and Fe3O4) were used as inertants to determine the inhibition effect of different oxidation products. The iron dust explosion products with various shapes and sizes were found to be able to grow up 4–6 times of the iron dust for the first time. Adding small amount of Fe2O3 or Fe3O4 could reduce the explosion severity and sensitivity of iron dust. The MEC data determined by both methods were comparable. The addition of 5 % oxide has obvious inhibition effect under 1500 g/m3 concentration. With the increase of oxide concentration to 10 %, the inerting effect increases, and the MEC of iron dust increases more than 3 times. The increase of dust concentration will weaken the inerting effect. When the concentration increases from 500 g/m3 to 3000 g/m3, the weakening effect of 10 % Fe2O3 on the explosion pressure decreases from 38.45 % to 2.24 %, and 10 % Fe3O4 decreases from 46.21 % to 10.63 %. Unlike coal, biomass or aluminum dusts, the iron dust explosion was found to have a unique secondary acceleration of pressure rise rate for the first time. These results provide a fundamental basis to mitigate the iron dust explosion via solid inerting method without adding extra elements.

Promoting Ex-Solution from Metal-Organic-Framework-Mediated Oxide Scaffolds for Highly Active and Robust Catalysts.

Ex-solution catalysts, in which a host oxide is decorated with confined metallic nanoparticles, have exhibited breakthrough activity in various catalytic reactions. However, catalysts prepared by conventional ex-solution processes are limited by the low surface area of host oxides, the limited solubility of dopants, and the incomplete conversion of doped cations into metal catalysts. Here, the design of the host oxide structure is reconceptualized using a metal-organic framework (MOF) as an oxide precursor that can absorb a large quantity of ions while also promoting ex-solution at low temperatures (400-500°C). The MOF-derived metal oxide host can readily incorporate metal cations, from which catalytic nanoparticles can be uniformly ex-solved owing to the short diffusion length in the nano-sized oxides. The distinct ex-solution behaviors of Pt, Pd, and Rh, and their bimetallic combinations are investigated. The MOF-driven mesoporous ZnO particles functionalized with PdPt catalysts ex-solved at 500°C show benchmark-level of acetone oxidation activity as well as acetone-sensing characteristics by accelerating both oxygen chemisorption and acetone dissociation. Their findings provide a new route for the preparation of highly active catalysts by engineering the architecture and composition of the host oxide to facilitate the ex-solution process rationally.

Recent and Emerging Trends in Remediation of Methylene Blue Dye from Wastewater by Using Zinc Oxide Nanoparticles

Due to the increased demand for clothes by the growing population, the dye-based sectors have seen fast growth in the recent decade. Among all the dyes, methylene blue dye is the most commonly used in textiles, resulting in dye effluent contamination. It is carcinogenic, which raises the stakes for the environment. The numerous sources of methylene blue dye and their effective treatment procedures are addressed in the current review. Even among nanoparticles, photocatalytic materials, such as TiO2, ZnO, and Fe3O4, have shown greater potential for photocatalytic methylene blue degradation. Such nano-sized metal oxides are the most ideal materials for the removal of water pollutants, as these materials are related to the qualities of flexibility, simplicity, efficiency, versatility, and high surface reactivity. The use of nanoparticles generated from waste materials to remediate methylene blue is highlighted in the present review.

Nucleation mechanisms of titanium oxide particles at high temperature based on cluster-assisted nucleation

The properties of functional particles are intrinsically linked to their nucleation process. However, for such particles at high temperature, it is difficult to observe their nucleation in real time, and so the corresponding properties are rarely well understood. In the reported study, the nucleation of titanium oxide particles was systematically investigated by means of both classical nucleation theory and first principles. In high-temperature experiments, three samples (T1-T3) with differing titanium content were processed into metallographic samples and subjected to electrolytic extraction for observations via scanning electron microscopy-energy dispersive spectroscopy, X-ray microdiffraction, and transmission electron microscopy. It was determined that the titanium oxide particles in the three samples were Ti2O3, Ti3O5, and TiO2. The nucleation rate and radius of these particles were calculated using classical nucleation theory, and the results were consistent with the experimental results for the Ti2O3 particles but not the Ti3O5 ones. The theoretical and experimental values for T1–T3 decreased in the order T1>T2>T3, and there were considerable differences of as much as an order of magnitude between some of the theoretical and experimental values. The size effect on the nucleation was analysed by constructing (Ti2O3)n, (Ti3O5)n, and (TiO2)n (n = 1–6) nanoclusters, and the thermodynamic properties of the nanoclusters and nano-sized titanium oxide particles were analysed. The thermodynamic properties of the titanium oxide particles estimated using density functional theory generally coincided with those determined experimentally. Based on cluster-assisted nucleation, four nucleation pathways for titanium oxide particles were summarized as follows: (i) [Ti]atom + [O]atom → (TiO2)n → (TiO2)5 → TiO2 particle or (TiO2)5-cluster core–shell nanoparticle → (TiO2)bulk, (ii) [Ti]atom + [O]atom → (Ti3O5)n → (Ti3O5)2 → Ti3O5 particle or (Ti3O5)2-cluster core–shell nanoparticle → (Ti3O5)bulk, (iii) [Ti]atom + [O]atom → (Ti2O3)n → (Ti2O3)3 → Ti2O3 particle or (Ti2O3)3-cluster core–shell nanoparticle → (Ti2O3)bulk, and (iv) [Ti]atom + [O]atom → (TiO2)n, (Ti3O5)n, (Ti2O3)n → (Ti2O3)3 → Ti2O3 particle or (Ti2O3)3-cluster core–shell nanoparticle → (Ti2O3)bulk.

Effect of Al/Ti ratio on γ′ and oxide dispersion strengthening in Ni-based ODS superalloys

Oxide dispersion strengthened (ODS) Ni-based superalloys with high Al and Ti content (Ni–20Cr-xAl-yTi-0.6Y2O3-0.6Zr, x/y = ∼1, 1.8 and 16, named ST, SAT and SA alloy, respectively) and reference ODS alloy with low Al and Ti contents were produced by mechanical alloying and spark plasma sintering to investigate effect of Al/Ti atomic ratio on microstructure and Vickers hardness. The results showed that ST, SAT and SA alloys are strengthened by both γ′ phases and nanoscale oxides while the reference alloy is strengthened by only nanoscale oxides. The average size of γ′ increases but volume fraction decreases with decreasing Al/Ti atom ratio. The size and type of nanoscale oxides are different for the alloys with different Al/Ti ratios. The average size of nano-sized oxide is 10.7 nm for ST alloy, 14.7 nm for SAT and 10.2 nm for SA. Y4Zr3O12 and Y2Ti2O7 are identified in ST. Y4Zr3O12, Y2Ti2O7 and YAG(Y3Al5O12) are observed in SAT. Y4Zr3O12, YAM(Y4Al2O9), YAP (orthorhombic YAlO3) and YAH (hexagonal YAlO3) are confirmed in SA. Only Y4Zr3O12 is found in reference alloy. The hardness of ST, SAT and SA alloys is higher than reference alloy and increases with the decreasing Al/Ti ratio. The dependence of γ′ and nanoscale oxides on Al/Ti ratio and their contributions (oxide dispersion strengthening and γ′ precipitation strengthening) to mechanical properties are analyzed.

Reduction and removal of methylene blue from aqueous solutions via recyclable magnetic gold nanomaterials

Nano-sized iron oxide particles displaying superparamagnetism (SPIONs), were synthesised using the co-precipitation method. Gold-coated SPIONs stabilised by phosphine ligands (1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine (PPh3)), were immobilised on the surface of these SPIONs. A total of 19 nanomagnetic systems were synthesised, with varying Au loading, stabilisers and reducing agents employed. The obtained nanomaterials were fully characterised by ultraviolet visible spectroscopy (UV–Vis), Fourier-transform infrared spectroscopy (FT-IR), powder X-Ray diffraction (PXRD), high-resolution transmission electron microscopy (HRTEM) and inductively coupled plasma spectroscopy (ICP). The PTA ligand was a better stabiliser than the PPh3 ligand, resulting in more monodisperse nanoparticles for the former. These nanomaterials were subsequently used for the treatment of wastewater from the textile industry, specifically methylene blue (MB) reduction. The kinetics of this reaction using our range of nanomaterials are discussed. It was found that the adsorbents not only reduce the MB, but also remove it completely from the aqueous solution when extracting the nanomaterial by applying an external magnetic field. The MB was desorbed from the nanoparticle surface by acetonitrile, after which the adsorbent could easily be recycled up to 5 times. This reaction was also possible without using NaBH4 as a reducing agent, albeit to a slower extent. The PTA-stabilized nanomaterials prepared with NaBH4 as opposed to sodium citrate, proved to be the best adsorbent for the removal of MB from aqueous solution.

Influence of NiO and La2O3 nanoparticles on the optical, mechanical and electrical properties of PVAc–PMMA blend: a comparative study

Nano-sized metal oxides are fascinating materials as fillers used for improving the polymeric materials’ performance and expanding their multifunctionality. Two metal oxides; NiO and La2O3 nanoparticles (NP) were prepared and introduced into poly(vinyl acetate)/poly(methyl methacrylate), PVAc/PMMA blend via solution casting route. XRD and HR-TEM analysis confirmed the preparation of a cubic NiO and a hexagonal La2O3 NP with an average crystallite size of 59.85 and 29.13 nm, respectively. Introducing NiO and La2O3 increases the films’ amorphous structure. FTIR analysis confirmed the existence of all blend’ functional groups and hydrogen bond formation. SEM investigation showed that NiO or La2O3 loading affects the blend surface morphology. A UV–vis-NIR study showed that NiO narrowed the direct bandgap of the blend from 4.1 to 3.3 eV, whereas La2O3 reduced it to 3.4 eV. 1.0 wt% NiO significantly improved the various optical constants of the blend. DMA revealed that storage modulus G′ increased with loading of 1 wt% NiO or La2O3 by 79.3% and 51.0%, respectively while G′ decreased with heating. The dielectric behavior of films is analyzed using several dielectric parameters. The maximum σ ac reported for 1.0 wt% NiO/blend film is 5.8 × 10−6 (S/cm). The AC conduction mechanism is discussed for all films in the temperature and frequency ranges (298−373 K) and (5 Hz−2 MHz). 1.0 wt%/PVAc/PMMA nanocomposite showed enhanced optical and mechanical properties, making it suitable for architectural, flexible display screens, and photovoltaic cell devices. Moreover, loading NiO and La2O3 improved the dielectric properties of the blend to be used in the semiconductor industry, besides energy storage devices and supercapacitors.

A Confinement-Driven Nucleation Mechanism of Metal Oxide Nanoparticles Obtained via Thermal Decomposition in Organic Media.

Thermal decomposition is a very efficient synthesis strategy to obtain nanosized metal oxides with controlled structures and properties. For the iron oxide nanoparticle synthesis, it allows an easy tuning of the nanoparticle's size, shape, and composition, which is often explained by the LaMer theory involving a clear separation between nucleation and growth steps. Here, the events before the nucleation of iron oxide nanocrystals are investigated by combining different complementary in situ characterization techniques. These characterizations are carried out not only on powdered iron stearate precursors but also on a preheated liquid reaction mixture. They reveal a new nucleation mechanism for the thermal decomposition method: instead of a homogeneous nucleation, the nucleation occurs within vesicle-like-nanoreactors confining the reactants. The different steps are: 1) the melting and coalescence of iron stearate particles, leading to "droplet-shaped nanostructures" acting as nanoreactors; 2) the formation of a hitherto unobserved iron stearate crystalline phase within the nucleation temperature range, simultaneously with stearate chains loss and Fe(III) to Fe(II) reduction; 3) the formation of iron oxide nuclei inside the nanoreactors, which are then ejected from them. This mechanism paves the way toward a better mastering of the metal oxide nanoparticles synthesis and the control of their properties.

Heterogeneous Fenton catalyst based on clay decorated with nano-sized amorphous iron oxides prevents oxidant scavenging through surface complexation

• Crystalline and amorphous Fe-oxide-clay composites were compared as Fenton catalysts. • Nano-sized amorphous iron-oxide-clay best-promoted phenanthrene oxidation. • A stable H 2 O 2 complex was formed with the amorphous iron-oxide-clay surface. • Single oxygen was primarily responsible for phenanthrene degradation. • Oxidation of phenanthrene was achieved with minimal H 2 O 2 waste. Heterogeneous Fenton catalysts based on iron-oxides are of great interest due to their low cost and high reactivity. Herein, the activity of nano-sized amorphous iron-oxide particles deposited on montmorillonite clay (MMT) was compared to crystalline hematite and magnetite-coated MMT. Hematite, magnetite, and their respective clay composites showed little catalytic activity and almost no phenanthrene (PHE) oxidation at circumneutral pH - in part, due to the decomposition of hydrogen peroxide. In contrast, the amorphous iron oxide (Fe)-MMT, showed very high catalytic activity (over 60% PHE degradation in 60 min) with only minimal consumption of H 2 O 2 (3.3%). In-depth characterization of the Fe-MMT coupled with kinetic and mechanistic experiments was performed to understand the reaction pathway and mechanism. The results suggest that initially H 2 O 2 is complexed to the nano-sized iron oxide catalytic sites on the surface, forming a stable Fe-MMT-H 2 O 2 complex that is activated primarily when the pollutant is introduced. The reactive species, ∙OH and 1 O 2 , were detected upon the diffusion of PHE to the surface - leading to oxidation and mineralization with a minimal decomposition of H 2 O 2 . Quenching experiments further revealed that 1 O 2 played an important role in the extensive mineralization of PHE. The amorphous Fe-MMT also exhibited high stability and performance in semi-continuous cycle batch experiments. Thus, this low-cost and simple Fe-MMT catalyst was found to be highly efficient towards the activation of H 2 O 2 , oxidizing PHE rapidly while reducing radical scavenging and unwanted side reactions. These findings, regarding the role of amorphous phases in the reactivity of iron-oxides, have the potential to improve the design and implementation of solid Fenton catalysts for pollutant remediation in engineered and natural systems.

Screening of biohydrogen production based on dark fermentation in the presence of nano-sized Fe2O3 doped metal oxide additives

Increasing the biohydrogen production efficiency through the dark fermentation process has become the biggest challenge in recent years. We aim to enhance biohydrogen production yield by adding nano-sized iron oxide doped metal oxides prepared by the wet impregnation method. Biohydrogen production in the presence of additives was evaluated by the screening of (i) type (Fe 2 O 3 @Al 2 O 3 , Fe 2 O 3 @ZrO 2 , and Fe 2 O 3 @TiO 2 ) and (ii) concentration (0–200 mg/L) of additives. During the screening of additive type, approximately 14 wt% nano-sized (6 nm) hematite (Fe 2 O 3 ) doped Al 2 O 3 showed the highest improvement for biohydrogen production yield among all additives. Batch experiments conducted through dark fermentation demonstrated that 50 mg/L Fe 2 O 3 @Al 2 O 3 addition caused an acceleration in biohydrogen production by 34% and an increment in yield by 15%, despite even low concentrations Al 2 O 3 addition inhibited the process. • Hematite doped metal oxides synthesized using hydrothermal methods. • Biohydrogen production activity of Fe 2 O 3 @Al 2 O 3 , Fe 2 O 3 @ZrO 2 , Fe 2 O 3 @TiO 2 were tested. • Buffer solution and concentration selection carried out. • Fe 2 O 3 @Al 2 O 3 showed best enhancement with 15% increment in yield. • 50 mg/L Fe 2 O 3 @Al 2 O 3 accelerated biohydrogen production 34%.

Effect of thermal exposure on microstructure evolution and mechanical properties of cast beta-solidifying TiAl-based alloy doped with Gd

Evolution of an initial nearly-lamellar (γ+α2+β0) structure of a new cast β-solidifying TiAl-based alloy Ti-44.5Al-2V-1Nb-2Cr-0.1Gd (at.%) after isothermal exposures at 800 °C for up to 10,000 h has been systematically investigated using SEM, TEM, EDS, and XRD analyses. During the exposures the alloy microstructure degraded by the α2 laths and β0 phase dissolution, resulting in coarsening of lamellar structure and rising of the γ phase volume fraction. A 2.5- and 3-fold increase in the number of nano-sized gadolinium oxide (Gd2O3) particles have been observed after 10,000-h exposure in lamellar colonies and in grain boundaries, respectively. The gadolinium oxides had monoclinic (C2/m) and cubic (Ia-3) structures and precipitated predominantly along γ/α2 and γ/β0 interfaces and inside the γ lamellae. Furthermore, the applied creep loading was found to contribute significantly to the precipitation process of Gd2O3 nano-particles, since dislocation networks being the sites for their preferred formation. Nanohardness of the γ phase increased from 4.4 ± 0.3 to 5.0 ± 0.4 GPa after the exposures, but no changes were observed for the β0 phase. As a result of structure evolution the tensile strengths reduced by 10–12 and 11–14 % measured at 20 and 750 °C testing temperatures, respectively. Meanwhile, the plastic elongation values remained essentially unchanged. We interpret this as insignificant effect of the precipitation of Gd-rich oxide nano-particles on the alloy ductility.