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Iron oxide-based ferrite ceramics, widely applied in high-frequency applications, are conventionally produced through high-temperature sintering processes, often resulting in grain growth and phase transformation. In this study, we used a cold sintering process (CSP) with oxalic acid (OA) as a solvent to consolidate iron oxide (Fe 3 O 4) ceramics at a low temperature of 160 °C. The OA-assisted CSP technique has demonstrated a remarkable capacity to facilitate the dissolution and redeposition of iron oxide ions, leading to the interconnection of Fe 3 O 4 particles, forming densely packed ceramics even at low-temperature sintering. Importantly, CSP maintained particle sizes and hindered phase transitions of Fe 3 O 4. The OA concentrations in CSP had a minimal impact on crystal structure and magnetic properties, but it significantly enhanced microstructural features, density, hardness, and electrical resistance. Compared to reference samples prepared without an aqueous solution or with water alone, the CSP-prepared Fe 3 O 4 ceramics with OA exhibited substantially improved density (a relative density of ∼80 %), mechanical properties (Vickers hardness of 3.5–4.0 GPa), magnetic properties (saturation magnetization >70 emu/g), and electrical resistance (electrical conductivity ∼10−3 S/cm at 102–106 Hz). These findings demonstrate a novel approach to fabricating Fe 3 O 4 ceramics at significantly lower temperatures while still achieving properties comparable to those sintered at high temperatures. [ABSTRACT FROM AUTHOR]

An advanced version of the solution combustion synthesis (SCS) method was developed to prepare iron oxide (IO) nanoparticles, through controlling the agglomeration, size and shape of nanoparticles by assisting a cationic surfactant, "cetyltrimethylammonium bromide (CTAB)" and ethanol. Various IO nanoparticles were prepared in the presence of different CTAB:ethanol molar compositions of 0:0, 0.27:0, 0.55:0, 0.27:17.1, 0.55:17.1 and 0.82:17.1. The morphological evolution from agglomerated-shape particles to the well-dispersed as well as the size- and shape-controlled particles depended directly on the CTAB:ethanol molar composition. A shift from ferromagnetic behavior to superparamagnetic was observed by the application of CTAB along with ethanol, where the lowest blocking temperature (T b , 60 K), highest saturation magnetization (M s , 83.5 emu g−1), zero coercivity and remanance magnetization were revealed for the particles prepared by CTAB:ethanol molar compositions of 0.55:17.1. These particles showed an acceptable specific absorption rate (SAR) value (320 W g−1) as well as no obvious hemolytic and cytotoxic effects. This work provides new insights into advancing the SCS method and thus controlling the morphology, size and shape of metal oxide nanoparticles. [Display omitted] • Controlling the agglomeration, size and shape of nanoparticles in SCS method. • Structural and magnetic properties of particles depended on the CTAB:ethanol ratio. • The agglomerated-free, size- and shape-controlled IO-EC2 structure was developed. • IO-EC2 represented an acceptable SAR value, and no hemolytic and cytotoxic effects. [ABSTRACT FROM AUTHOR]

Multicore magnetic iron oxide nanoparticles, nanoflowers (NFs), have potential biomedical applications as efficient mediators for AC-magnetic field hyperthermia and as contrast agents for magnetic resonance imaging due to their strong magnetic responses arising from complex internal magnetic ordering. To realise these applications amenable surface chemistry must be engineered that maintain particle dispersion. Here a catechol-derived grafting approach is described to strongly bind polyethylene glycol (PEG) to NFs and provide stable hydrogen-bonded hydrated layers that ensure good long-term colloidal stability in buffers and media even at clinical MRI field strength and high concentration. The approach enables the first comprehensive study into the MRI (relaxivity) and hyperthermic (SAR) efficiencies of fully dispersed NFs. The predominant role of internal magnetisation dynamics in providing high relaxivity and SAR is confirmed, and it is shown that these properties are unaffected by PEG molecular weight or corona formation in biological environments. This result is in contrast to traditional single core nanoparticles which have significantly reduced SAR and relaxivity upon PEGylation and on corona formation, attributed to reduced Brownian contributions and weaker NP solvent interactions. The PEGylated NF suspensions described here exhibit usable blood circulation times and promising retention of relaxivity in-vivo due to the strongly anchored PEG layer. This approach to biomaterials design addresses the challenge of maintaining magnetic efficiency of magnetic nanoparticles in-vivo for applications as theragnostic agents. Application of multicore magnetic iron-oxide nanoflowers (NFs) as efficient mediators for AC-field hyperthermia and as contrast agents for MR imaging has been limited by lack of colloidal stability in complex media and biosystems. The optimized materials design presented is shown to reproducibly provide PEG grafted NF suspensions of exceptional colloidal stability in buffers and complex media, with significant hyperthermic and MRI utility which is unaffected by PEG length, anchoring group or bio-molecular adsorption. Deposition in the selected pancreatic tumour model mirrors liposomal formulations providing a quantifiable probe of tissue-level liposome deposition and relaxivity is retained in the tumour microenvironment. Hence the biomaterials design addresses the longstanding challenges of maintaining the in vivo magnetic efficiency of nanoparticles as theragnostic agents. [Display omitted] [ABSTRACT FROM AUTHOR]

Fe 3 O 4 has the advantages of unique magnetic stability and low biological toxicity, which can improve pollutants separation efficiency. MXenes are two-dimensional materials and easy surface functionalization that can provide suitable carriers for Fe 3 O 4. In this work, we synthesized magnetic MXene composites by a one-pot method that relies on doping Fe 3 O 4 particles onto Ti 3 C 2 MXene nanosheets by heat treatment. The Fe 3 O 4 /Ti 3 C 2 MXene was analyzed by SEM, XRD, FTIR and XPS techniques, which showed that the material has good tetracycline (TC) removal properties and magnetic separation ability. The results showed that the adsorption capacity of it was 46.42 mg g−1, and the removal efficiency of 0.06 g adsorbent for 50 mL of 30 mg L−1 TC could reach 92.1% in a wide pH range of 4–10, when the adsorption temperature was 25 °C, and the adsorption time was 3 h. The adsorption data were consistent with Langmuir and the proposed second-order kinetic model, and the thermodynamic experiments confirmed that the adsorption of TC was a monolayer physicochemical adsorption coexisting heat-trapping process (ΔH = 15.72 kJ mol−1). In addition, the adsorption of TC by Fe 3 O 4 /Ti 3 C 2 MXene was attributed to the synergistic effect of electrostatic attraction, hydrogen bonding and π-π packing. In conclusion, the saturation magnetization of Fe 3 O 4 /Ti 3 C 2 MXene is 27.3 emu/g and it can not only be separated from water using its strong magnetic properties to avoid secondary contamination, but also can be used as a promising material to effectively remove antibiotics from aqueous media. [Display omitted] • A kind of magnetically recyclable, regenerative adsorbent for tetracycline adsorption (Q max = 46.42 mg g−1) has been obtained. • The mechanisms of Fe 3 O 4 /Ti 3 C 2 adsorbing tetracycline: endothermic adsorption; the quick absorption of pollutants is facilitated by the electrostatic interactions, π−π bonds and hydrogen bonds. • The adsorption occurs over a wide pH range of 4–10. [ABSTRACT FROM AUTHOR]

The respiratory effects of particulate matter (PM) in subway station platforms or tunnels have attracted considerable research attention. However, no studies have characterized the effects of subway PM on allergic immune responses. In this study, iron oxide (α-Fe 2 O 3 and Fe 3 O 4) particles—the main components of subway PM—were intratracheally administered to BALB/c mice where ovalbumin (OVA) induced allergic pulmonary inflammation. Iron oxide particles enhanced OVA-induced eosinophil recruitment around the bronchi and mucus production from airway epithelium. The concentrations of type 2 cytokines, namely, interleukin (IL)-5 and IL-13, in bronchial alveolar lavage fluids were increased by iron oxide particles. Iron oxide particles also increased the number of type 2 innate lymphoid cells and CD86+ cells in the lung. Moreover, phagocytosis of particles in lung cells was confirmed by Raman spectroscopy. In a subsequent in vitro study, bone marrow-derived antigen-presenting cells (APCs) isolated from NC/Nga mice were exposed to iron oxide particles and OVA. They were also exposed to outdoor ambient PM: Vehicle Exhaust Particulates (VEP) and Urban Aerosols (UA) as references. Iron oxide particles promoted the release of lactate dehydrogenase, C-X-C motif chemokine ligand 1 and IL-1α from APCs, which tended to be stronger than those of VEP. These results suggest that iron oxide particles enhance antigen presentation in the lungs, promoting allergic immune response in mice; iron oxide particles-induced death and inflammatory response of APCs can contribute to allergy exacerbation. Although iron oxide particles do not contain various compounds like VEP, iron oxide alone may have sufficient influence. [Display omitted] • α-Fe 2 O 3 /Fe 3 O 4 particles were used as the components of subway particulate matters. • Iron oxide particles exacerbated allergic airway inflammation in mice. • Iron oxide particle-enhanced antigen-presenting can trigger allergies. • Iron oxide particles increased type 2 innate lymphoid cells in murine lungs. • α-Fe 2 O 3 and Fe 3 O 4 were detected in lung macrophages by Raman spectroscopy. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ iron oxide nanoparticles were synthesized into heavy crude oil. • Magnetite and akaganeite nanoparticles in situ presented sizes of 20–43 nm. • Reaction conditions were at 200 nm3/m3 of H 2 /heavy crude oil ratio, 380 °C and 1 h. • Residue conversion was approximately 20 %. • Spent catalyst showed the iron sulfide phase, although no presulfiding was realized. We proposed a direct in situ synthesis method for iron oxide nanoparticles (NPs) along with catalytic erformance upgrading of heavy crude oil (HCO). Our method compares the upgrading of a HCO where other iron oxide nanoparticles were synthesized by a traditional thermal decomposition method of organometallic compounds in the presence of stabilizing agents and solvents of high boiling points. Furthermore, the in situ nanoparticles were extensively characterized by XRD, Mössbauer spectroscopy and TEM microscopy which confirmed the presence of magnetite and akaganeite phases, with an average diameter of 20−43 nm. Nanoparticles by thermal decomposition method were investigated by XRD, UHR-FE-SEM and HRTEM and showed the formation of magnetite nanoparticles with an average diameter of 6.7 ± 1.4 nm. Subsequently, the nanoparticles were evaluated in a batch reactor using HCO from the Golden Lane of Mexico at 44.1 bar (initial H 2 pressure) and 380 °C, for 1 h at 500 rpm. It was observed that, even under hydrogen limited conditions, there are better physicochemical properties in terms of viscosity, API gravity and heavy fractions decrease, for example, the residue conversion was about 20 % and the kinetic model was adjusted to a five lump model. The formation of the iron sulfide phase (FeS) was detected during the analysis of the spent catalyst. [ABSTRACT FROM AUTHOR]

Controlled spatial arrangements of superparamagnetic iron oxide nanoparticles (SPIONs) in complex nanostructures determine fine tuning of physico-chemical properties which, in turn, may lead to new practical applications. We report here on newly observed properties of hierarchical SPIONs nanostructure with bundle-like morphology, also known as nanobundles. Colloidal chemical processes and sol-gel synthesis were used for the synthesis of nanobundles, i.e. i) self-assembly of SPIONs into magnetic nanoparticle clusters, ii) their magnetic assembly to the nanochains, and finally iii) formation of bundle-like hierarchical nanostructure. An XRPD measurements show spinel crystal structure of maghemite/magnetite nanoparticles, EDS analysis reveals Fe, Si and O as main elements whereas SEM/TEM analysis show silica-coated magnetic nanoclusters (∼100 nm) and their hierarchical assemblies with bundle-like morphology of ∼8 μm length and ∼1 μm width. TEM analysis revealed core-shell nature of iron oxide nanoparticle clusters with their size of around 80 nm that were coated by an amorphous silica shell with thickness of ∼15 nm. The nanoclusters in the core are constructed of maghemite/magnetite nanoparticle assembly with primary iron oxide nanoparticle size about 10 nm. The magnetization M data as a function of an applied external magnetic field H were successfully fitted by the Langevin function, whence the magnetic moment μ p = 19256 μ B , and the diameter d = 9.6 nm of nanoparticles were determined. Microsized bundle-like particles are superparamagnetic, magnetically guidable and possess high transverse relaxivity of r 2 = 397.8 mM−1s−1. Magnetic properties and such high value of transverse relaxivity holds promise for nanobundles application in MRI imaging (MRI contrast agent), as nanobundles may enhance the magnetic field in their surroundings and enhance proton relaxation processes. Our nanobundles can open new opportunities in the biomedical applications, magnetic separation, photonic crystals and magnetic liquid manipulation and can be inspiration for synthesizing novel self-assembled nanoparticle structures. [ABSTRACT FROM AUTHOR]

In this study, the influence of temperature (40, 60 and 80 ∘C) and light exposure on the dissolution of ▪ particles in aqueous, oxalic acid (0.45 mol/l) is experimentally investigated. A novel experimental setup, consisting of a vessel with undistorted optical access, allows the recording of dissolving particles using a video system. During post-processing, particles are automatically identified and their size and morphology are determined. Binning particles into discrete time-steps during the reaction yields heavy-tailed distributions characterized by a single parameter estimated through a maximum-likelihood estimation of a doubly truncated power-law fit. For the first time, up to three consecutive phases could be identified during the dissolution process of iron oxide particles. The contribution of each phase to the overall dissolution process is determined by a complex interplay between particle fragmentation, different reaction mechanisms and solid product formation. The initial phase is characterized by the fragmentation of larger particles with a more complex morphology, resulting in greater surface area available for reaction. In the second phase, fragmentation is less apparent and the available particle surface area is reduced. The transition to the third phase relies primarily on the supply of short wavelength light, which leads to the formation of a solid product that can increase the tracked particle diameter. • Up to three consecutive phases during iron oxide particle dissolution. • First phase dominated by particle fragmentation leading to increasing surface area. • Second phase dominated by surface area reduction, less by particle fragmentation. • Third phase occurs only at low temperatures and short-wavelength light exposure. • The third phase is characterized by solid product formation. [ABSTRACT FROM AUTHOR]

Flexible supercapacitors (SCs) are pivotal in the development of wearable and portable electronic devices because of their exceptional power density, high charge/discharge rates, extended cycle life, lightweight, and flexibility. Graphene (G)-based macroscopic materials, such as one-dimensional fibers, two-dimensional films, and three-dimensional aerogels, exhibit a large specific surface area, low mass, excellent flexibility, and high conductivity. These properties make them highly suitable for use as flexible electrode materials in SCs. However, the low energy density of G-based materials hinders their application in certain fields. Iron oxide (Fe 2 O 3) has garnered considerable attention as a negative electrode material because of its low cost, high theoretical capacity, and environmentally friendly nature. However, its practical application is limited because of its poor cycling stability, easy agglomeration, and low electrical conductivity. The combination of G with Fe 2 O 3 to form a composite material not only addresses the issues of volume change and agglomeration associated with Fe 2 O 3 , but also establishes a robust conductive network that improves the electrochemical performance of composite electrodes. Therefore, the construction of SCs using Fe 2 O 3 /G composite electrodes has gained considerable research attention in recent years. We present a comprehensive review of the recent progress in the design of Fe 2 O 3 /G composites as electrode materials for flexible SCs. In addition, we discuss the current challenges and future prospects associated with the use of Fe 2 O 3 /G composites in flexible SCs. [Display omitted] • Recent progress in the design of iron oxide/graphene composites as electrode materials for flexible SCs is reviewed. • The fabrication methods are discussed in depth to provide insight into various development strategies. • The design strategies of iron oxide/graphene composites with different dimensions were comprehensively discussed. • Challenges in iron oxide/graphene composites-based flexible supercapacitors development were described. [ABSTRACT FROM AUTHOR]

In this study, the anodized iron oxide films with micro-nano structure were prepared by a combination of heat treatment and anodization. The adjustment of these oxide films at the micron-scale was achieved by heat treatment on substrate to modify the position of the cementite and ferrite. The distribution and existing forms of carbon on cementite and ferrite determine the morphology of their respective anodization. It was found annealing at 300 °C can improve the crystallinity of iron oxide and maintain the original micro-nano structure. Although the crystal quality of iron oxide can be further improved with higher annealing temperature, it would result in the collapse of nanoporous structures and the reconstruction of the surface morphology. Furthermore, anodized samples made from those with lamellar ferrite and cementite show better specific capacitance. The iron oxide film on the annealed substrate obtained the highest specific capacitance of 35.3 mF/cm2 at a scan rate of 20 mV/s in our samples. [ABSTRACT FROM AUTHOR]

Salt-assisted solution combustion synthesis (SSCS) method is a promising technique for synthesizing various nanopowders with ultra-fine particle size and high surface area. It is known that the introduced soluble salt into the synthesis process plays a role as a particle separator which leads to the particle size reduction. However, the potential effects of soluble salts on the thermodynamic aspects of SSCS procedure and the other physical and chemical properties of the obtained nanopowders have not been investigated in detail. In this study, various amounts of sodium chloride (1–15mol for obtaining 0.3mol iron oxide) were introduced to the iron nitrate-glycine system to investigate effect of alkali metal salt on the thermodynamics aspects of the synthesis process and the final properties of the prepared nanoparticles. Obtained results indicated that the phase composition of the synthesized nanopowders was varied from a mixture of Fe 3 O 4 +α-Fe 2 O 3 to γ-Fe 2 O 3 +α-Fe 2 O 3 , and eventually to single-phase α-Fe 2 O 3 by increasing the amount of sodium chloride. Such phase transformation suggested that the phase composition of multi-phase compounds prepared via SSCS method can be controlled by sodium chloride. Ultra-fine powders with 9 nm particle size and surface area of 148 m2/g were obtained when 11mol sodium chloride was used in the synthesis process. Magnetization of the synthesized nanoparticles were decreased from 34emu/g to 2.7emu/g due to the decrement of particle size. The combusted single-phase hematite nanopowders were submitted to the 100 mL nickel ion (Ni2+) solution with the ion concentration of 50 mg/L to explore the effect of salt on the adsorption activity of the nanoparticles. 0.4g of the synthesized powders adsorbed ~ 90% of the nickel ions within 120 min. Note that the removal percentage of the nickel ion using the synthesized hematite nanoparticle (90%) was higher than that of prepared hematite powders in the previous studies (35%). [ABSTRACT FROM AUTHOR]

In this work, a novel organic–inorganic hybrid heterogeneous catalyst was fabricated for Knoevenagel condensation. First, the surface of carbon nanotube (CNT) was covalently functionalized with poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) polyelectrolyte (i.e., organic polybase) through the surface-initiated atom transfer radical polymerization (SI-ATRP) method. Subsequently, magnetic iron oxide nanoparticles (Fe 3 O 4 NPs) (i.e., inorganic Lewis acid) are densely and homogeneously grown on the CNT surface using the CNT- g -PDMAEMA template. The as-prepared acid–base bifunctional catalyst (i.e., CNT- g -PDMAEMA/Fe 3 O 4 NPs) was investigated in the model reaction, i.e., Knoevenagel condensation between naphthol, malononitrile and benzaldehyde. The CNT- g -PDMAEMA/Fe 3 O 4 NPs catalyst shows high catalytic activity in the Knoevenagel condensation between naphthol, malononitrile and benzaldehyde due to its unique structure and specific chemical constitution. In addition, this acid–base bifunctional catalyst can be readily recovered with an applied magnetic field and reused with negligible loss in the catalytic activity even after six cycles. [Display omitted] • The acid–base bifunctional CNT- g -PDMAEMA/Fe 3 O 4 NPs catalyst exhibited high activity. • The tiny Fe 3 O 4 NPs on the CNT as acid catalyst can activate the benzaldehyde. • The rich PDMAEMA brushes on the CNT as base catalyst may activate the malononitrile. • One-pot synthesis of 2‐amino‐4 H‐chromene product was achieved under green condition. • The magnetic CNT- g -PDMAEMA/Fe 3 O 4 NPs was a reusable catalyst with ease of separation. [ABSTRACT FROM AUTHOR]

Hybrid polyion complexes (HPICs) obtained from the complexation in aqueous solution of a double hydrophilic block copolymers and metal ions can act as efficient precursors for the controlled synthesis of hybrid nanoparticles. Hence, HPICs based on a mixture of ferrous and ferric ions with poly(ethylene oxide)-block-poly(acrylic acid) were used to initiate, after the addition at 70 °C of a solution of NH 4 OH, the formation of iron oxide nanoparticles. The careful choice of the molar ratio between polymer and metal ions within HPICs enables to tune the morphology and size of the obtained iron oxide nanoparticles while maintaining the same surface composition. This control of size and composition was further used to highlight the relationship between the size of these particles and their catalytic and magnetic properties. [Display omitted] [ABSTRACT FROM AUTHOR]

An in situ molten salt strategy is developed for the convenient preparation of iron oxide-supported platinum catalysts with high performance for o -xylene elimination. The high catalytic performance of the supported platinum catalysts is due to the improvement in redox ability and o -xylene activation. • Supported Pt catalyst is prepared using an in situ molten salt method. • Supported Pt catalyst exhibits high catalytic activity for o -xylene removal. • Pt loading enhances the redox ability of the supported Pt catalyst. • Pt loading improves the adsorption and activation of o -xylene. • Improvement in redox ability and o -xylene activation benefit high activity. Supported noble metal catalysts are highly effective for eliminating volatile organic compounds (VOCs). A catalyst with less noble metal loading is always desirable. Using a mixture of NaNO 3 and NaF as molten salt, Fe(NO 3) 3 and Pt(NH 3) 4 (NO 3) 2 as metal precursors, x Pt/Fe 2 O 3 catalysts (x = 0–0.3 wt%) were fabricated after calcination at 350 °C for 3 h. At space velocity of 40,000 mL/(g h), 0.22 wt% Pt/Fe 2 O 3 showed the best catalytic activity, and o -xylene could be completely oxidized into CO 2 and H 2 O at 225 °C. Furthermore, 0.22 wt% Pt/Fe 2 O 3 exhibited good stability, and high resistance to water vapor, CO 2 , and SO 2. We deduce that the excellent catalytic performance of 0.22 wt% Pt/Fe 2 O 3 was associated with the high dispersion of the Pt species and good low-temperature reducibility. The possible reaction mechanism of o -xylene oxidation over 0.22 wt% Pt/Fe 2 O 3 involved the adsorption of o -xylene molecules, partial decomposition into small organic intermediates (e.g. maleic anhydride and aliphatic carboxylate species), and total oxidation into CO 2 and H 2 O. Due to the high efficiency, good stability, low cost, and convenient preparation, the present catalysts are promising for the practical removal of VOCs. [ABSTRACT FROM AUTHOR]

We here couple Nb 2 O 5 with Fe 2 O 3 to form visible-light active heterojunctions. The formed heterojunctions are responsive to visible light, and more importantly, photoactive for the mineralization of refractory organic compounds upon exposure to visible light. The sensitizer, Fe 2 O 3 , is found to govern the photocatalytic activity of the heterojunction. Therefore, the local structure of the sensitizer is investigated in-depth with X-ray absorption spectroscopy, including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). Results show that the local structure of Fe 2 O 3 is generally insensitive to the Fe 2 O 3 loading amount, as confirmed by EXAFS. The lengths of the Fe–O coordination and Fe–Fe coordination in the heterojunctions are 1.93 and 2.92 Å, respectively, which are shorter than those in bulk Fe 2 O 3. At a Fe 2 O 3 loading amount that is higher than the optimum value, trace amounts of isolated Fe 2 O 3 and bulk Fe 2 O 3 are likely formed at the heterojunction. This is unfavorable for electron-hole separation, and hence, detrimental to the photocatalytic activity. Image 1 • Heterojunctions composed of Nb 2 O 5 as host and Fe 2 O 3 as sensitizer are prepared. • The heterojunctions are visible light active for photomineralization of organics. • Local structure of the sensitizer, Fe 2 O 3 , is examined in-depth by XANES and EXAFS. • Visible light photoactivity of the heterojunctions is proposed based on light-induced IR. [ABSTRACT FROM AUTHOR]

• Iron oxide nanoparticles recovered from the acid mine drainage treatment are suitable to produce nanofluids. • Iron oxide nanoparticles in concentration 0.10–0.75 wt% can be used to produce stable nanofluids. • Additional 7–10% oil recovery is achieved after flooding due to injection of iron oxide-based nanofluids. Oil is one of the most intensively used energy sources in the world and, as a fossil fuel, it is a finite resource. Different methods have been explored to increase oil recovery from mature fields, particularly using enhanced oil recovery (EOR) with the help of nanofluids. This study performed EOR tests using iron oxide nanoparticles added to brine and sodium dodecyl sulfate solutions. Three types of iron oxide nanoparticles were examined: commercial (IO), derived from the acid drainage of an underground coal mine (SIO), and temperature-sensitive functionalized (TSIO). The nanoparticles were well characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, high-resolution X-ray photoelectron spectroscopy, and transmission electron microscopy. The nanofluids were evaluated through dynamic light scattering measurements and determination of the viscosity, turbidity, contact angle and surface tension. There was not significant variation in the surface tension of the samples, which ranged between 25.46 and 28.28 mN m−1. However, the contact angle exhibited notable fluctuations depending on the nanoparticles concentration, ranging from 7.39° to 24.43°. Furthermore, the zeta potential suggests that the stability of the nanofluid samples falls within the moderate to medium range. An improvement in oil recovery reached 10% with the commercial nanoparticles (0.50 wt%), followed by 8.5% using the synthesized (0.25 wt%) and 7.5% using the functionalized (0.25 wt%). Moreover, all nanofluids showed good stability for up to 30 days, and their viscosity showed a direct relationship with the enhancement in oil recovery. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pigment adsorption onto iron oxides is mainly due to electrostatic attraction. • The pigment-binding capacity is in the order of ferrihydrite > goethite > hematite. • The affinity of iron oxide towards pigment is in the sequence of AR > TA > BB. • Different mechanisms involved in pigment adsorption vary with pH values. • Pigments and Cu2+ have a mutual promotion effect on their adsorption. The knowledge about the adsorption properties of pigments onto different iron oxide minerals is still limited. The adsorption behaviors of three typical pigments, including amaranth (AR), tartrazine (TA), and brilliant blue (BB), onto three iron oxides (ferrihydrite, goethite, and hematite) were investigated. The primary mechanism of their interactions was the electrostatic attraction. The affinities of iron oxides toward any pigment were generally in the sequence of ferrihydrite > goethite > hematite (e.g., the maximum adsorption amounts (q max) of AR onto the three iron oxides were 35.5 mg/g, 11.6 mg/g, and 4.2 mg/g, respectively), which was related to the differences in physicochemical properties of minerals (e.g., specific surface area, surface hydroxyl density, and crystal structure). Interestingly, for a given iron oxide, the pigment-binding capacity of the mineral was in the order of AR > TA > BB. This effect was attributed to variations in pigment molecular sizes and electrostatic interactions between pigments and minerals. The pigment-binding capabilities of iron oxides changed as the solution pH varied. Hydrogen-bonding and electrostatic interactions were the main mechanisms below and above pH > pH PZC (pH value at zero point charge), respectively. Furthermore, adding Cu2+ facilitated pigment adsorption, mainly stemming from the surface-bridging effect. Pigments also enhanced Cu2+ adsorption onto iron oxides due to the decreasing electrostatic repulsion between Cu2+ and particles as well as the complexion between Cu2+ with pigment molecules adsorbed on mineral surfaces. The insightful information demonstrates that ubiquitous iron oxide minerals can affect the fate of pigments in natural environments. [ABSTRACT FROM AUTHOR]

• Iron oxide with variable quantities of Feδ+ and SO 4 2− mediated by temperatures of SO 2 mixed with O 2. • Iron oxide with surface Feδ+ (δ ≤ 2) functioning as H 2 O 2 activators to form aqueous OH. • Iron oxide with SO 4 2− functionalities converted to surface SO 4 •- via radical transfer from aqueous OH. • Iron oxide with SO 4 − species used to degrade aqueous pollutants via heterogeneous catalysis. • Iron oxide with SO 4 − species acting as recyclable crackers of aqueous contaminants. OH or SO 4 − are powerful oxidants that efficiently degrade recalcitrant contaminants. The productions of OH and SO 4 − via activation of their precursors (H 2 O 2 and Na 2 S 2 O 8), however, can be sustainable only after continuously feeding such precursors into the activators. Motivated by the advantages of SO 4 − over OH as an environmental cracker, this study highlighted a simple and proficient way to persist solid-supported SO 4 − species used to accelerate the decomposition of recalcitrants in the presence of an electric potential. While using ubiquiotous iron oxide as a platform to accomodate SO 4 −, we functionalized iron oxide surface with SO 4 2- species, which could be transformed into surface SO 4 − species via radical transfer from aqueous OH species. Specifically, a series of SO 4 2--modified iron oxide catalysts were synthesized using SO 2 and O 2 at 300–600 °C in order to vary their surface properties such as the contents of surface Fe δ+ species acting as H 2 O 2 activators to form OH, the contents of surface SO 4 2- species functioning as surface SO 4 − precursor, and the character of S O bonds innate to SO 4 2- functionalities linked to their long-term stability. In addition to the comparison of energetics between SO 4 2- functionalities and their SO 4 - analogues via computation, a kinetic assessment of reaction runs were conducted under controlled environments to gather convincing evidence that the formation of surface SO 4 − via its radical interconversion with aqueous OH was highly plausible and that surface SO 4 − would be the major decomposer of phenol (model compound of recalcitrants). In addition, 500 °C was found to be the optimized temperature to greatly populate Fe δ+ and SO 4 2- species rigidly immobilized on iron oxide surface among all temperatures studied, thereby providing the greatest activity and recyclability to degrade phenol. [ABSTRACT FROM AUTHOR]

Fe 2 O 3 nanoparticles (NPs) coated by the SiO 2 shell with a thickness up to ˜6.5 nm were synthesized by a fast and facile microwave irradiation approach. The thickness of the SiO 2 shell around Fe 2 O 3 NPs could be controlled by varying tetraethoxysilane (TEOS) concentration as well as avoiding individual SiO 2 particle formation. The synthesized Fe 2 O 3 @SiO 2 core-shell nanocomposites (NCs) were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) spectroscopy. The bigger particle size compared to the uncoated Fe 2 O 3 NPs and Si O Si asymmetric stretching vibrational band at 1101 cm−1 in the prepared NCs obtained by FE-SEM and FT-IR study, respectively anticipated the successful SiO 2 coating on Fe 2 O 3 NPs. The presence of homogeneous silica layer was authenticated by TEM observation. The change in binding energy of Fe 2p3 and Si 2p in the synthesized NCs compared to the uncoated Fe 2 O 3 and pure SiO 2 NPs corroborated the formation of Fe O Si bond at the interface of Fe 2 O 3 (core) and SiO 2 (shell). The existence of magnetic property in the prepared NCs, even above the Curie temperature of Fe 2 O 3 , was assured by vibrating sample magnetometer (VSM) study. This observation will undoubtedly inspire to design and fabricate novel heterostructures of iron oxide to retain its magnetization at high temperature. [ABSTRACT FROM AUTHOR]

In this research, Fe 3 O 4 particles were magnetically manipulated to create porous scaffolds using a tri-axial nested Helmholtz coils-based freeze-casting setup. This novel setup allowed for a uniform magnetic field to be applied in any direction and for it to effectively change directions at any time. Applying a uniform low magnetic field of 7.8 mT in various directions was investigated to fabricate a variety of tailored microstructures and mechanical properties in the resultant scaffolds. It was observed that using the magnetic field aligned up to 81% of the lamellar walls and also altered the area and shape of the pores of the resultant scaffolds. This lamellar wall alignment occurred at every applied magnetic field direction due to the Fe 3 O 4 particles aligning during the freeze-casting process. As a result of this alignment, increases in the mechanical properties of up to 4.1× were observed. The results provide a novel experimental technique for the fabrication of user-defined microstructures in Fe 3 O 4 -based freeze-cast materials that provides significant advantages over previous experimental setups for magnetic freeze casting. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Naphthols are industrial contaminants occurring widely in soils and waters. Remediation of organic pollutants can be done by chemical oxidation using persulfate. However, most research experiments testing degradation of organic pollutants have been done in ideal conditions, e.g. using a pure compound in pure water, and thus are weakly representative of real natural conditions where pollutants occur in complex mixtures of numerous organic compounds. Therefore we tested here the effect of the presence of small organic acids, as typical compounds occurring in natural media, on the degradation of 1-napthol with persulfate and iron oxides. Results show that organic acids decreased naphthol transformation by 3.7% for malic acid, 53.2% for tartaric acid, 72.3% for citric acid and 77% for oxalic acids, in a magnetite/persulfate system during 10 h. Meanwhile, the dissolved Fe species increased gradually with the reaction time; the highest concentration of Fe ions reached to ∼18 μM L−1 in aqueous phase. Electron paramagnetic resonance technique was applied to determine reactive oxygen species (ROS). The spin density of ·OH, detected as the main ROS, decreased initially, followed by gradually increase, suggesting that organic acids might inhibit the degradation of 1-naphthol by competing with ·OH. These findings disclose the high inhibition of the transformation by organic acids, and thus, more generally, imply that studies using only pure contaminants are weakly representative for remediation of real, natural samples. Graphical abstract Image 1 Highlights • LMWOAs exhibit inhibitory effect on 1-naphthol degradation in iron oxide/PS systems • Both of LMWOA molecular structure and iron oxide type affect 1-naphthol degradation • LMWOAs inhibit the heterogeneous activation via competition sorption on Fe surface • LMWOAs can dissolve iron oxides ions and improve the homogeneous activation of PS [ABSTRACT FROM AUTHOR]

Design of a multifunctional magnetic bionanosystem has become increasingly important towards advancing the future of clinical medicine. While hollow iron oxide nanoparticles with enhanced surface areas allow for more drug molecules to be attached to the particles, their relatively low saturation magnetization (M S) hinders their practicality in medicinal applications such as drug delivery and hyperthermia therapy. We demonstrate that this limitation can be overcome by utilizing 1D magnetic nanotubes that possess both enhanced surface areas and high M S. In this study, highly crystalline, tunable aspect ratio Fe 3 O 4 nanotubes have been successfully synthesized using a hydrothermal method. Magnetic measurements showed a clear Verwey transition (∼120 K) and high M S (∼75 emu/g) at 300 K, confirming the high quality of the synthesized Fe 3 O 4 nanotubes. Calorimetric experiments on randomly dispersed Fe 3 O 4 nanotubes in water with concentration of 1 mg/mL showed a large Specific Absorption Rate (SAR) value of 400 W/g for an AC magnetic field of 800 Oe, which increased to 500 W/g when the nanotubes were aligned parallel to the DC magnetic field and suspended in a 2% agar solution. Our study shows the possibility of using the Fe 3 O 4 nanotubes as a highly effective multifunctional nanoscale tool for targeted hyperthermia and on-demand drug delivery. • Hydrothermal synthesis of highly crystalline, tunable aspect ratio Fe 3 O 4 nanotubes. • Systematic study of the growth mechanism of the nanotubes. • The presence of Verwey transition and high M S (75 emu/g) at 300 K. • Nanotubes exhibited large SAR value compared to their hollow counterparts. • Dual-purpose applications in hyperthermia and on-demand drug delivery. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Hematite (α -Fe 2 O 3) is one of the most widely studied materials for the application of water oxidation in the field of renewable energy. In order to push hematite toward maximal efficiency, a better understanding of the intrinsic limitations is essential. In this review, we cover our latest results on identifying and finding ways to overcome bottlenecks by modelling the electrochemical processes in hematite at three regimes: 1. at the bulk, the calculated hole effective mass is unfavorably high and conductivity can be improved through doping and alloying, 2. at the surface, catalysis is slow and involves long-lived surface states, but the catalytic overpotential can be reduced by adding a doping gradient or overlayers without strain, and 3. at the back contact the losses can be improved by selecting a proper metal contact. We provide unique analysis approaches that reveal fundamental understanding of electrochemistry with hematite. These models have made an impact on understanding experimental observations and have influenced subsequent theoretical investigations. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Despite the advances in molecularly targeted therapies, delivery across the blood-brain barrier (BBB) and the targeting of brain tumors remains a challenge. Like brain, bone is a common site of metastasis and requires therapies capable of discerning the tumor from its healthy cellular milieu. To tackle these challenges, we made a variation on the previously proposed concept of the earthicle and fabricated an aqueous, surfactant-free ferrofluid containing superparamagnetic iron oxide nanoparticles (SPIONs) coated with silicate mesolayers and carbon shells, having 13 nm in size on average. Nanoparticles were synthesized hydrothermally and characterized using a range of spectroscopic, diffractometric, hydrodynamic and electron microscopy techniques. The double coating on SPIONs affected a number of physicochemical and biological properties, including colloidal stability and cancer targeting efficacy. Nanoparticles decreased the viability of glioblastoma and osteosarcoma cells and tumors more than that of their primary and non-transformed analogues. They showed a greater preference for cancer cells because of a higher rate of uptake by these cells and a pronounced adherence to cancer cell membrane. Even in an ultralow alternate magnetic field, nanoparticles generated sufficient heat to cause tumor death. Nanoparticles in MDCK-MDR1 BBB model caused mislocalization of claudin-1 at the tight junctions, underexpression of ZO-1 and no effect on occludin-1 and transepithelial resistance. Nanoparticles were detected in the basolateral compartments and examination of LAMP1 demonstrated that nanoparticles escaped the lysosome, traversed the BBB transcellularly and localized to the optic lobes of the third instar larval brains of Drosophila melanogaster. The passage was noninvasive and caused no adverse systemic effects to the animals. In conclusion, these nanoparticulate ferrofluids preferentially bind to cancer cells and, hence, exhibit a greater toxicity in these cells compared to the primary cells. They are also effective against solid tumors in vitro , can cross the BBB in Drosophila, and are nontoxic based on the developmental studies of flies raised in ferrofluid-infused media. Statement of Significance We demonstrate that a novel, hydrothermally synthesized composite nanoparticle-based ferrofluid is effective in reducing the viability of osteosarcoma and glioblastoma cells in vitro , while having minimal effects on primary cell lines. In 3D tumor spheroids, nanoparticles greatly reduced the metastatic migration of cancer cells, while the tumor viability was reduced compared to the control group by applying magnetic hyperthermia to nanoparticle-treated spheroids. Both in vitro and in vivo models of the blood-brain barrier evidence the ability of nanoparticles to cross the barrier and localize to the brain tissue. These composite nanoparticles show great promise as an anticancer biomaterial for the treatment of different types of cancer and may serve as an alternative or addendum to traditional chemotherapies. [ABSTRACT FROM AUTHOR]

Abstract Time-resolved x-ray imaging is used to capture high-resolution images of the Al/Fe 2 O 3 thermite reaction as it proceeds in an extended burn tube. The observed thermite reaction products are generally large, multi-phase composite particles. Image processing algorithms are developed to extract a continuous record of composite particle size as a function of time and distance from the ignition point. Small particles are observed immediately after ignition, followed by a rapid increase in particle size and a gradual decline toward late times. Correlating the dynamic particle size with visible light emission from the reaction, we propose a two-stage mechanism where the combination of early ignition and delayed expansion causes the material closest to the ignition point to undergo substantial coalescence before it begins moving down the tube. We also identify two mechanisms that may contribute to particle size refinement at late times, both based on the collapse of large gas bubbles that are observed preferentially in particles at earlier times. A new approach to extracting burn times from luminous intensity data is explored, and we find that a more nuanced analysis of burn time and luminous intensity may help to improve reactivity assessments when data from in situ studies is unavailable. [ABSTRACT FROM AUTHOR]

Abstract The super-paramagnetic iron oxide nanoparticles (SPIONs) were synthesized using an environmentally friendly method. The SPIONs with mainly carbohydrate coatings were simply synthesized using a natural, zero calorie sweetener (Stevia) extract (as both reducing and stabilizing agents). The resulting SPIONs were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), vibrating-sample magnetometer (VSM) and Zeta potential test. The SPIONs (smaller than 25 nm) are very stable due to bio-molecular coating because having a zeta potential of −41.1 mV creates opposing forces between nanoparticles and prevents them from gathering. The biogenic SPIONs were able to counteract the effects of oxidative metabolites as studied with the antioxidant activity with an IC 50 of 65 μg/ml. This feature shows the capability of these nanoparticles in designing potential biomedical applications. Graphical abstract Schematic representation of green synthesis of the magnetic iron oxide nanoparticles. Image Highlights • Fe 3 O 4 iron oxide nanoparticles was smaller than 25 nm in size. • The magnitude of the potential Zeta was calculated −41.1 mV. • These biogenic NPs can easily be collected or removed from the environments. [ABSTRACT FROM AUTHOR]

Highlights • Morphology engineering on iron oxides is carried out via an electrochemical method. • Morphology transition from zero-dimension to one-dimension is realized. • Iron oxide electrode delivers a high capacity of 184 mAh g−1 at 2 A g−1 (∼6C rate). • The Ni/Fe full cell exhibits a good energy density of 82.3 Wh kg−1. Abstract Aqueous rechargeable Ni/Fe batteries possess potential advantages for large-scale energy storage applications due to their low cost, high safety and fast ion diffusions in electrolyte. However, the electrochemical performance of the iron-based anode is still far from ideal due to particle aggregations. Herein, we carry out the morphology engineering on the iron oxide active materials via a facile electrochemical method to improve its charge storage capability. The morphology transition from zero-dimensional particles to one-dimensional nanorods is realized by tuning the electrolyte composition, while subsequent annealing treatment results in further morphology modification into 3D interconnected nanoparticles (10–20 nm). The hierarchical structure allows facile ion and electron transfers, and the large surface provides various active sites for the charge storage conversion reaction. As a result, even at the high current density of 2 A g−1 (∼6C rate), the iron oxide electrode can still deliver a high specific capacity of 184 mAh g−1. At the same time, the morphology integrity and stability of the electrode leads to a good cycle life, with 87.5% capacity retained upon 5000 cycles. The Ni/Fe full cell assembled with the iron oxide anode and a Ni-Co double hydroxide cathode exhibits a good energy density of 82.3 Wh kg−1 at the power density of 3.3 kW kg−1. Our fundamental study would provide new insights for the electro-deposition of iron-based materials and endow new opportunities for the fabrication of high-performance iron-based electrodes for energy storage systems. [ABSTRACT FROM AUTHOR]

The effectiveness of the current UK iron oxide powder suspension formulation, 'C-IOPS-09' (Triton X-100 based), for fingermark or latent fingerprint visualization is shown to be affected by variations between batches of the recommended iron oxide powder from Fisher Scientific (I/1100/53). When incorporated into the C-IOPS-09 formulation, a 2015 powder batch resulted in the detection of ∼19% fewer fingermarks, of broadly reduced contrast, when compared to powder suspension prepared with a 2008 batch of the same product. Furthermore, the 2015 powder batch was found to be unsuitable in experimental reduced-surfactant concentration powder suspension, because it caused surface-wide or background staining. The studies in this paper also investigated the use of Tween 20 surfactant as an alternative to the currently utilised Triton X-100, in preparation for the potential unavailability of Triton X-100 in the future. Powder suspensions prepared with Tween 20 surfactant solutions of 4% and 40% were shown to offer similar effectiveness to the currently recommended C-IOPS-09 formulation, when compared using the same batch of Fisher Scientific iron oxide powder (2008 or 2015). The difference between the 2008 and 2015 iron oxide batches was hence also evident with these alternative surfactant solutions. Particle size distribution analysis of the iron oxide powders in Tween 20 and Triton X-100 based surfactant solutions show that the more effective powder exhibits a higher sub-micrometre particle population than the less effective powder. This work leads to an improved specification for powder suspension formulations. This is demonstrated with an example powder suspension formulation which uses a 10% Tween 20 surfactant solution and iron oxide nanopowder (50-100nm) from Sigma Aldrich, which was shown to visualise 27% more fingermarks than the C-IOPS-09 formulation prepared with the 2015 Fisher Scientific powder batch, in a comparative study. [ABSTRACT FROM AUTHOR]

Today, one of the most important global tasks is the treatment of waste water from various pollutants, including heavy metal. Adsorption is a promising method of wastewater treatment in terms of efficiency and cost. In this paper, the Al/Fe oxide-oxyhydroxide composite powders, prepared by hydrothermal method using metal sulfate solutions and urea as precursors, are investigated as adsorbents for chromium. The influence of the [Al 3+ ]:[Fe 3+ ] ratio on the phase composition, textural properties, morphology, and thermal effects of composites was also investigated. It is shown that the maximum specific surface area (190 m 2 /g) is reached for samples synthesized from solutions with [Al 3+ ]:[Fe 3+ ] = 1:0 and 1:1. Cr(VI) adsorption from solutions was performed under static (batch adsorption) and dynamic (column adsorption) conditions. It is shown that the presence of sulfate ions on the surface of Al-containing samples suppresses the Cr(VI) adsorption. The maximum adsorption capacity in batch adsorption (3.66 mg/g) has a sample synthesized from solutions with [Al 3+ ]:[Fe 3+ ] = 1:6, which is characterized by a high (but not maximal) surface area (102 m 2 /g), a low content of sulfates and maximum zeta potential. Sorption experiments showed that the mean free adsorption energy is below 8 kJ/mol for all samples, indicating the adsorption process as the physical in nature and suggesting the possibility of Cr(VI) desorption and adsorbent regeneration. Based on the results of fixed-bed adsorption experiments, an atypical form of breakthrough curves is noted, as well as an increase in sorption capacity of about 4–5 times as compared with batch adsorption. [ABSTRACT FROM AUTHOR]

Experimental and field measurements have shown that, in the presence of both iron-containing aerosols and sunlight, oxidized mercury species such as HgCl 2 and HgBr 2 undergo reduction to elemental mercury (Hg°), which remains in the atmosphere longer than oxidized mercury species due to its higher volatility. We performed density functional theory (DFT, PW91+ U ) calculations to elucidate the reduction mechanism for atmospheric HgCl 2 and HgBr 2 to Hg° on several iron-oxide aerosol surfaces relevant in the troposphere. On the OH-Fe-R-terminated α-Fe 2 O 3 (0001) surface, predicted to be most prevalent under ambient conditions, we show that: (1) the first Hg-X bond is broken via either thermal or photolytic activation depending on the ambient temperature; (2) photons with an energy of 2.69 eV (461 nm) are required to break the second Hg-X bond; and (3) a photo-induced surface-to-adsorbate charge-transfer process can promote Hg° desorption with an excitation energy of 2.59 eV (479 nm). All the calculated excitation energies are below the threshold value of 3.9 eV (320 nm) for photons in the troposphere, suggesting that sunlight can facilitate mercury reduction on iron-oxide aerosol surfaces. In contrast, the gas-phase reduction of HgCl 2 (HgBr 2 ) involves photoexcitation requiring an energy of 4.98 (4.45) eV (249 (279) nm); therefore, the energy range of sunlight is not suitable for gas-phase reduction. Our computational results provide the first evidence on the detailed mechanism for the combined role of aerosols and photons in the reduction of HgCl 2 and HgBr 2 . Our methodology can be adapted to study other photochemical heterogeneous processes in the atmosphere. [ABSTRACT FROM AUTHOR]

In vivo read-out of autophagy is of great therapeutic and fundamental significance, and yet being conducted exclusively in high cost transgenic animal models. As an attempt to readily monitor the autophagy flux, we herein proposed an autophagy-responsive magnetic resonance imaging based on radical-conjugated magnetic nanoparticles. In principle, both the NO· radical and Fe 3 O 4 nanoparticles are stable, and separately contributing to an observation of enhanced T 1 -and T 2 -weighted imaging, respectively. Meanwhile, the onset of autophagy concomitantly simulates the mass production of reactive species, and consequently quenches the T 1 -signal of NO·. On this basis, the content of autophagy flux is reflected by the ratio of T 1 -signal intensity to that of T 2 -signal, which is condition-insensitive, as a function of time. Assisted with such strategy, an unprecedented protection role autophagy played in respond to heat stress has been revealed, through which the killing effect of magneto-hyperthermia was greatly impeded. Furthermore, we noticed that the impairment of autophagy through the sequential chemotherapy, can markedly improve the therapeutic outcome, in a manner monitored and thoroughly analyzed using the strategy reported herein. We therefore believe that such a study offers a feasible method for in vivo read-out of autophagy and gives us insights how autophagy influences the therapeutic index of cancer treatments. [ABSTRACT FROM AUTHOR]

This study was aimed to explore the effect of phase separation on the Jian ware blue colored glaze with iron oxide. In order to analyze the forming cause of glaze patterns and their coloring mechanism, the phase, microstructure and chemical state of the samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrum. The results indicated that the addition of calcium phosphate introduced highly-active Ca 2+ and P 5+ into the glaze. Since Ca 2+ with high ionic potential had a greater ability to appeal O 2− than Si 4+ , the glaze melt was separated into calcium-rich phase and silicon-rich phase. The difference of viscosity caused the non-uniform distribution of quartz and glass phase, and then affected the distribution of iron ions in two phases, which formed glaze patterns. Adding P 5+ that had a strong effect of reversed polarization on the Fe-O increased the contents of Fe 2+ and Fe 3+ -O-Fe 2+ , and thus deepened the blue-green of glaze surface. In addition, it promoted the formation of worm-like phase-separated structures and the existence of structural color. Therefore, phase separation enriched not only patterns but also glaze colors of the Jian ware blue colored glaze. [ABSTRACT FROM AUTHOR]

• Fe-clay composite is an efficient adsorbent material for phenol removal. • Textural and chemical properties of the adsorbent have been assessed. • Kinetics and thermodynamics studies of phenol adsorption have been performed. • Statistical physics models were applied to understand the adsorption mechanism. Water pollution by phenolic compounds is considered a primary environmental concern. The adsorption of phenol on iron-modified clay and its mechanism were evaluated in this study. A new hybrid material, "Clay-Iron oxide," has been synthesized for its possible use in phenol removal from wastewater. Textural and chemical properties of this new composite have also been assessed using a variety of techniques such as XRD, XRF, SEM-EDX, FTIR, and BET. On the other hand, phenol adsorption performance has been studied in terms of pH, temperature, and initial concentration. Theoretically, the phenol adsorption onto modified clay was satisfactorily modeled with pseudo-second-order kinetics and the Langmuir isotherm; the maximum phenol adsorption capacities, obtained with the Langmuir model, are 15.24, 17.55, 20.24, and 20.10 mg/g at 303, 313, 323, and 333 K, respectively. Furthermore, five advanced statistical physics models were adopted to understand the adsorption mechanism better. The combination of experimental and modeling approaches revealed that: i) the present material is competitive compared to other adsorbents, ii) phenol molecules interact with clay/iron oxide functional groups via several mechanisms, iii) the number of phenol molecules adsorbed per site increases with temperature, iv) phenol adsorption process is spontaneous, physisorption and endothermic, and v) Iron increases the phenol removal efficiency. Thus, the novelty of this research paper lies in the phenol adsorption mechanism study based on the spatial and energetic properties, the determination of the adsorption process effect on the adsorbent, and finally, the assessment of the iron-modified clay's efficiency in removing phenol from wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon nanotube (CNT)-Fe x O y composites (CFs) are developed for lithium-ion batteries. • CNT-guided combustion waves offer scalable synthesis-optimization strategy for CFs. • CNTs provide path of thermochemical reaction and help disperse iron oxide particles. • CNTs form conductive network and prevent loose Fe x O y particles during pulverization. • Optimized CFs exhibit notably high cycle capacity, rate capability and cycle life. The design and synthesis of suitable transition metal oxide (TMO) with carbonaceous material are crucial to produce high-performance anodes for Lithium-ion batteries (LIBs). Here, we show a facile synthesis method for iron oxide and carbon nanotube (CNT) composite via CNT-guided combustion waves. The combustion waves propagate through a freestanding film composed of multi-walled CNTs (MWCNTs), iron nitrate, and combustible nitrocellulose, synthesizing the composite in one-pot within a few seconds. The resulting composite consists of MWCNT networks encapsulating iron oxide submicron particles (CFs). The composite electrode employing optimized CFs provides exceptional initial specific capacity and rate capability (792 mAh/g at 0.1C and 588 mAh/g at 5C) and an increased capacity of 1215 mAh/g after 500 charge–discharge cycles at 1C. The morphological and electrochemical characterization reveal pulverized nanoparticles encapsulated within MWCNT networks, entailing hybrid capacities of redox conversion and pseudocapacitance. This facile synthesis method for TMO–MWCNT composites provides a feasible family of low-cost composite electrodes for high-performance LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel catalytic system consisted of iron oxide magnetic nanoparticle and catechol. • Catechol-generated ROS further converted to hydroxyl radical by iron. • Initiates polymerization of wide ranges of monomers in an oxygenated solution. • Magnetic, bilayer hydrogels were formed with improved mechanical property. Phenol and its derivatives are the most used polymerization inhibitors for vinyl-based monomers. Here, we reported a novel catalytic system composed of mussel inspired adhesive moiety, catechol, in combination with iron oxide nanoparticles (IONPs) to generate hydroxyl radical (OH) at pH 7.4. Catechol-containing microgel (DHM) was prepared by copolymerizing dopamine methacrylamide (DMA) and N -hydroxyethyl acrylamide (HEAA), which generated superoxide (O 2 −) and hydrogen peroxide (H 2 O 2) as a result of catechol oxidation. In the presence of IONPs, the generated reactive oxygen species were further converted to OH, which initiated free radical polymerization of various water-soluble acrylate-based monomers including neutral (acrylamide, methyl acrylamide, etc.), anionic (2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt), cationic ([2-(methacryloyloxy)ethyl]trimethylammonium chloride), and zwitterionic (2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide) monomers. Compared with the typical free radical initiating systems, the reported system does not require the addition of extra initiators for polymerization. During the process of polymerization, a bilayer hydrogel was formed in situ and exhibited the ability to bend during the process of swelling. The incorporation of IONPs significantly enhanced magnetic property of the hydrogel and the combination of DHM and IONPs also improved the mechanical properties of these hydrogels. [ABSTRACT FROM AUTHOR]

Fe 2 O 3 films were deposited on transparent conductive substrates (fluorine doped tin oxide (FTO) on glass) by aerosol pyrolysis. The intrinsic nature of as-deposited films requires the addition of a suitable metal dopant. Sn proved to be well adapted to this task, as it increased photocurrents in junctions with an aqueous electrolyte by one order of magnitude as compared to undoped films. The maximum IPCE value (incident photon to current conversion efficiency) was 0.21 at 400 nm for a 120 nm thick film and a maximum photocurrent of 1630 μA/cm 2 at 0.65 V vs. Ag/AgCl under simulated solar irradiation. [ABSTRACT FROM AUTHOR]

Urchin-like α-Fe 2 O 3 /MnO 2 hierarchical hollow composite microspheres have been synthesized by using carbon as sacrificial templates. By combining the advantages of Fe 2 O 3 with high electrical conductivity and MnO 2 with high theoretical capacity, the urchin-like α-Fe 2 O 3 /MnO 2 composites present better electrochemical performances as a lithium ion battery anode compared with α-Fe 2 O 3 hollow spheres and MnO 2 hollow spheres. The α-Fe 2 O 3 /MnO 2 composites exhibit high initial discharge capacity of 1531 mAhg −1 and excellent reversible capacity of 860 mAhg −1 after 150 cycles at 0.1Ag −1 . Furthermore, the composites retain a discharge capacity of 494 mAhg −1 after 500 cycles at 0.5 Ag −1 . The excellent performances may originate from reinforced structural stability, large surface area and good electrical conductivity. The urchin-like α-Fe 2 O 3 /MnO 2 composite material may serve as a potential anode material for lithium-ion battery. [ABSTRACT FROM AUTHOR]

Organoarsenicals are widely used as antibiotics in the livestock industry and largely discharged into water environment directly, their safe, efficient and cost-effective treatment are actively perused. Herein, a heterogeneous iron-based Fenton-like technology was designed and validated with much reduced secondary pollution, mainly attributed to the bi-functional properties of both Fenton-active and arsenic-affinitive iron oxides. This simple one-step strategy not only exhaustively degraded organoarsenicals, but also selectively adsorbed the released high-toxicity arsenic from treated water. With Roxarsone as target, the FeOOH-based Fenton-like system exhibited a much superior capacitie for both Roxarsone degradation and arsenic adsorption in various water matrices, compared to typical homogeneous systems under similar conditions. More than 80% of Roxarsone was degraded after 3.0 h, and most of the released AsO 4 3− was removed simultaneously, without any additional post-treatment. The superior capacity of FeOOH might be mainly attributed to its strong redox-cycling capacity of surface central Fe atoms from their thermodynamically favorable electronic structure. Taking the important advantages of iron oxides and Fenton technology into account, our findings might provide a new chance to develop simple and efficient technologies for organoarsenicals removal from water with much reduced secondary pollution at a low cost. [ABSTRACT FROM AUTHOR]

Solar-driven water splitting by photoelectrochemical method is a prospective approach for clean energy hydrogen production. Reduced graphene oxide (RGO) and Ag nanoparticles are deposited on α- Fe 2 O 3 nanorod arrays by hydrothermal and photodeposition methods forming α- Fe 2 O 3 /RGO/Ag photoelectrode. An optimum photocurrent density is obtained at 0.72 mA/cm 2 with 0.23 V (1.23 V vs RHE), together with the maximum photoconversion efficiency of 0.15%, much higher than pure α- Fe 2 O 3 of 0.07%. The enhanced photoelectrochemical properties could be resulted from its broadened light absorption, decreased electro-hole recombination rate and improved charge carriers transport. This work provides potential applications in fields of the photocatalyst and photo-water splitting. [ABSTRACT FROM AUTHOR]

The thermal decomposition behavior and burning characteristics of ammonium nitrate(AN)/ammonium perchlorate(AP) propellants supplemented with Fe 2 O 3 were investigated. Based on these data, the performance differences between the propellants with Fe 2 O 3 and those without Fe 2 O 3 were investigated to reveal the influence of Fe 2 O 3 on the thermal decomposition behavior and burning characteristics of AN/AP-based composite propellants. TG-DTA showed the peak temperature and temperature range of thermal decomposition due to AN decomposition to be independent of the presence of Fe 2 O 3 . The peak and the offset temperature of thermal decomposition due to AP decomposition decreased owing to the addition of Fe 2 O 3 , while the onset temperature did not vary. The burning rate of the AN/AP propellant was increased by the addition of Fe 2 O 3 ; the effect of Fe 2 O 3 on increasing the burning rate was influenced by the type of oxidizer, AP content in the oxidizer ( ξ ), and AP size. Furthermore, Fe 2 O 3 allowed the suppression of the remarkable heterogeneity of the combustion wave of the AN/AP propellant without Fe 2 O 3 . The ignitability of the AN/AP propellant was improved by the addition of Fe 2 O 3 , except for the propellant with a ξ of 0.4. The cause of depressed ignitability by the addition of Fe 2 O 3 for the propellant with a ξ of 0.4 is discussed based on thermogravimetry-differential thermal analysis, the visual observations of the unignited propellant surfaces, and the decomposition phenomena of the propellants using a high-temperature observation equipment. A large quantity of AN remained on the surface of the unignited propellant at 0.5 MPa. The cause of the depressed ignitability is that AN, AP, and HTPB do not simultaneously decompose and as a result AN remains on the burning surface. Thus, the burning surface of AN did not regress simultaneously with the burning surface of the AP-filled region, the matrix of AP, and HTPB. [ABSTRACT FROM AUTHOR]

Recent high temperature H 2 S corrosion study reported that a thermodynamically less stable iron oxide layer can also form in addition to iron sulfide. In this work, H 2 S corrosion experiments were conducted at 120 °C for different exposure times, ranging from 1 to 21 days. The inner layer was identified by Transmission Electron Microscopy (TEM) as Fe 3 O 4 (magnetite); Fe 3 O 4 was always present over time despite it being less stable than iron sulfide. The observed formation sequence of iron sulfide at high temperature was mackinawite → troilite → pyrrhotite → pyrite. The role of the different corrosion product layers in corrosion is discussed. [ABSTRACT FROM AUTHOR]

Porous Clays Heterostructures (PCH) from natural pillared clays (bentonite with a high proportion of montmorillonite) have been used as supports of iron oxide for two reactions of environmental interest: i) the elimination of toluene (a representative compound of one of the most toxic subsets of volatile organic compounds, aromatics) by total oxidation and ii) the selective oxidation of H 2 S to elemental sulfur. For both reactions these catalysts have resulted to be remarkably more efficient than similar catalysts prepared using conventional silica as a support. Thus, in the total oxidation of toluene it has been observed that the catalytic activity obtained using siliceous PCH is two orders of magnitude higher than that with conventional silica. The catalytic activity has shown to be dependant of the capacity of the support for dispersing iron oxide in a way that the higher the dispersion of iron oxide on the surface of the support, the higher is the activity. In the case of the selective oxidation of H 2 S to S both higher catalytic activity and higher selectivity to S have been observed using siliceous porous clays heterostructures than using conventional silica. Highly dispersed FeOx species have been shown as highly selective towards elemental sulfur whereas more aggregated FeOx species favour the formation of sulphur oxides decreasing the selectivity to S. Analyses of the surface by XPS have shown the predominance of sulfate species in the catalysts presenting low selectivity to elemental sulfur. [ABSTRACT FROM AUTHOR]

This study reports on the synthesis of a novel composite Fe-N/O catalyst for the enhancement of oxidative capacity of persulfate at ambient temperature. The fabricated composite was characterized by XRD, FTIR and TEM techniques. Results showed that the composite Fe-N/O catalyst consist of Fe3N and Fe3O4 crystal phases. The performance of Fe-N/O in the oxidation of Acid Red 73 (AR 73) by persulfate was investigated and it was found that the decolorization efficiency and total organic carbon removal (TOC) were 96% and 72.5% in 10 min at 22 °C, respectively. It was concluded that the interface between the Fe3N and Fe3O4 phases might account for the high efficiency observed. [ABSTRACT FROM AUTHOR]

In this research, a novel one-pot fabrication platform was developed for the preparation of Dy 3+ -doped iron oxide nanoparticles (Dy-IONPs). In the procedure, Dy-IONPs are electro-deposited from an additive-free aqueous mixed solution of iron(III) nitrate, iron(II) chloride and dysprosium chloride salts through applying a current density of 10 mA cm –2 for 30 min. The analytical data obtained from X-ray diffraction (XRD), field emission electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) confirmed the deposited Dy-IONPs to be composed of magnetite nanoparticles (size≈20 nm) containing about 10 wt% of Dy 3+ cations as the doping agent. The electrochemical data obtained through galvanostatic charge-discharge (GCD) tests showed that Dy-IONPs provide specific capacitances values of as high as 202 and 111 F g −1 at the discharge loads of 0.5 and 5 A g −1 , respectively, and reveal capacity retentions of 93.9% and 77.2% after 2000 GCD cycling. These could be held as proof that the electro-synthesized Dy 3+ -doped Fe 3 O 4 NPs are suitable candidates for use in supercapacitors. Furthermore, the results of vibrating sample magnetometer (VSM) measurements indicated better superparamagnetic behavior of the Dy-IONPs ( Mr = 0.34 emu g –1 and H Ci = 6.25 G) as opposed to pure IONPs ( Mr = 0.95 emu g –1 and H Ci = 14.62 G), which originates from their lower Mr and Hci values. Based on the results, the proposed electro-synthesis method offers a facile procedure for the preparation of high- performance metal-ion-doped IONPs. [ABSTRACT FROM AUTHOR]

Iron oxide impregnated hollow carbon spheres (HCS-Fe 3 O 4 ) samples were fabricated by impregnating Fe(NO 3 ) 3 into hollow carbon spheres (HCS) through an incipient wetness procedure and subsequent heat treatment. Through controlling the amount of iron species stored in HCS, different samples were selectively prepared. Pristine HCS and the samples with different Fe 3 O 4 loading (HCS-Fe 3 O 4 -1, HCS-Fe 3 O 4 -2 and HCS-Fe 3 O 4 -3) were characterized by TEM, XRD, TGA and N 2 adsorption/desorption isotherms in detail, respectively. As electrode materials of supercapacitor, their capacitive performances have been investigated by CV, galvanostatic charge/discharge and EIS measurements in two-electrode system using different kinds of electrolytes. Owing to the optimal pore size and partially filled cavity structure, electrolyte ions exhibit easy and reversible transport through HCS-Fe 3 O 4 -2. So that HCS-Fe 3 O 4 -2 presents the highest specific capacitance of 193 F g −1 at a scan rate of 1 mV s −1 and retains 94.75% up to 10,000 cycles. The capacitance performance of this material tested by symmetric system showed even higher value than the results by three-electrode system from some other researches, indicating the potential applications of HCS-Fe 3 O 4 -2 in industrial and energy field. [ABSTRACT FROM AUTHOR]

Aqueous-phase hydrogenolysis (APH) and reforming (APR) are intertwined reactions with great interest for biomass valorization, as APR generates hydrogen in situ at preferred APH reaction conditions instead of using external sources. We investigated iron oxide-supported Pt, Pd and Ni as catalysts for these reactions using glycerol as starting material. Catalysts were characterized by ICP, N2 physisorption, H2 chemisorption, XRD, TPR, CO2-TPD, FTIR of pyridine adsorption, XPS and TEM. The catalyst tests were performed in an autoclave extended with an in situ pre-reduction setup. Hydrogen spillover was found from hydrogen chemisorption of Pt catalysts, and after the development of a custom-made methodology, the Pt particle size was found to be 1.8 nm for the 2.5Pt/Fe 3 O 4 catalyst, which agrees with TEM analysis (1.56 nm). Both for hydrogenolysis and APR, the activity order was Pt > Pd > Ni, directly related to the stability of reduced small nanoparticles, which has an impact on acid-base properties of the support. Pt showed the best performance in hydrogenolysis even at a low content (81% conversion, 79% 1,2-propanediol selectivity for 1.0Pt/Fe 3 O 4 ). The 2.5Pd/Fe3O4 catalyst showed the highest hydrogen yield in APR (69.2% at 513 K and 78.9% conversion). First order kinetic fits were made for 2.5Pt/Fe 3 O 4 , from which an apparent activation energy of 61.1 kJ mol −1 was obtained and an initial turnover frequency (TOF 0 ) of 0.121 s −1 . [ABSTRACT FROM AUTHOR]

The present work describes the successful fabrication of iron oxide nanoparticles (Fe 3 O 4 NPs) through a green approach using the gum extract of the Bombax malabaricum (B. malabaricum) plant. The bioactive molecules/phytochemicals present in the gum extract of B. malabaricum were found to be responsible for the synthesis and fabrication of engineered nanoparticles (NPs). The Fe 3 O 4 NPs were characterized via UV-VIS, FTIR, and TEM. As indicated by TEM micrographs, the uniform rounded-shaped NPs with an average mean diameter of 09 ± 02 nm were observed. The antibacterial activity of Fe 3 O 4 NPs was investigated against 3 g-positive bacterial strains (Staphylococcus aureus , Bacillus halodurans, and Micrococcus luteus) and 1 g-negative bacterial strain (Escherichia coli) respectively. The antifungal activity of Fe 3 O 4 NPs against the fungal species of Aspergillus niger and Aspergillus flavus was also investigated. The methodologies of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydrogen peroxide (H 2 O 2) radical scavenging assays were also utilized to evaluate the antioxidant potential of synthesized NPs. The enhanced biomedical applications of these NPs were attributed to the extremely small size of the synthesized NPs. Furthermore, the photocatalytic potential of Fe 3 O 4 NPs was also studied by using the degradation reaction of the model pollutant of methylene blue (MB) dye. The influence of the reaction variables on the response (i.e. degradation percentage; D%) was investigated by using two different optimization approaches designated as one-factor-at-a-time (OVAT) and response surface methodology (RSM) approaches. The comparative analysis of these strategies adds to the novelty of our work as the modeling of the photocatalytic reaction via statistics is a rare approach and requires investigation. The RSM exhibited better D% results (98.721%) in comparison to OVAT (94.23%) indicating that rather than the conventional OVAT approach, the RSM should be utilized for the optimization of the MB dyes. Furthermore, it was observed that MB dose acted as the main rate-limiting factor for optimizing the reaction. These additional insights regarding photocatalysis can only be acquired by using the statistical modeling approach. [ABSTRACT FROM AUTHOR]

The present study shows that TiC x O y ceramics and TiC x O y -Fe cermets could be fabricated from nanocrystalline powders of TiC and TiC-Fe 2 O 3. The ball-milled TiC contains a high amount of oxygen impurities, which are accommodated by the oxycarbide phase. Upon heating, oxycarbide partially decomposes via evolution of CO and promotes the reduction of Fe 2 O 3 to a mix of Fe 3 O 4 /Fe starting from 400 °C. In the 550–700 °C range, Fe 3 O 4 is converted to plain iron by oxidation of TiC, which increases the oxygen content in TiC x O y and leads to segregation of Ti 4 O 7. At higher temperatures, oxide and oxycarbide phases of titanium continue to release CO, while Fe-based alloys melt at about 1400–1450 °C and facilitate densification. Depending on the starting content of Fe 2 O 3 , sintered samples demonstrate 0–24 vol% of metallic binder, 0.8–1.4 μm grains, hardness of 7–18 GPa and toughness of 4–8 MPa·m1/2. [Display omitted] • Nanocrystalline TiC contains oxygen impurities accommodated by TiC x O y oxycarbide. • Oxycarbide releases CO during heating and promotes reduction of Fe 2 O 3 to Fe 3 O 4. • Fe 3 O 4 converts to Fe via oxidation of TiC which increases oxygen content in oxycarbide. • Sintering of milled TiC and TiC-Fe 2 O 3 provides TiC x O y ceramics and TiC x O y -Fe cermets. [ABSTRACT FROM AUTHOR]

Efficient recycling of iron oxide from industrial BOF (basic oxygen furnace) slags has always been an issue in metallurgy. In this study, a new method was developed for the efficient recycling of iron oxide: It was transformed into magnesioferrite spinel (MgFe 2 O 4 ) by mixing the industrial BOF slag with 6.00% SiO 2 first, and then the modified slag got cooled down from 1400 °C to 1270 °C at a rate of 1 °C/min. Finally, the Fe resources were recycled by magnetic separation. Various experiments and analyses such as XRD, SEM–EDS analyses, Factsage thermodynamic simulation, magnetization characterization, dry magnetic separation, and chemical analysis were carried out. The results show that the obtained MgFe 2 O 4 has a high melting point (1716.76 °C in theory) and ferromagnetism (specific magnetic susceptibility of (8.03–206.84) × 10 −5 m 3 /kg). Therefore, it could be separated from the weakly magnetic industrial BOF slag (specific magnetic susceptibility of (0.024–0.136) × 10 −5 m 3 /kg). Furthermore, this new method could be applied to different BOF slags. The yield of MgFe 2 O 4 increased to above 80% when the content of Fe 2 O 3 was in the range 25.81–46.90%. After the modification and magnetic separation, the total Fe content increased by 15.80%, from 21.20% in the industrial BOF slag to 37.00% in the magnetic slag. This is better than the direct magnetic separation of iron oxide without any treatment. The magnetic slag could be reused as either a sintering or slag splashing material. The nonmagnetic slag can be used to produce high value-added building materials. Hence, this new method can be used to recycle the iron oxide from industrial BOF slags, achieving the sustainable development of the iron and steel industry. [ABSTRACT FROM AUTHOR]

Soft magnetic composites (SMCs) containing Fe powders embedded in insulating matrix have been fabricated via alkaline bluing as a new method. Effects of reaction time on the magnetic properties of the SMCs have been investigated. Mechanism of the oxidation process has also been revealed, which involves initial oxidation of Fe into Fe 2+ (Na 2 FeO 2 ) and Fe 3+ (Na 2 Fe 2 O 4 ) by NaNO 2 and NaNO 3 followed by hydrolysis of Fe 2+ and Fe 3+ into Fe 3 O 4 . Hydrolysis of the excessive Fe 3+ leads to the formation of Fe 2 O 3 which reduced the effective permeability of the SMCs. To form pure Fe 3 O 4 coating, the reaction process has been improved to suppress the Fe 3+ hydrolysis. The obtained ferromagnetic Fe 3 O 4 coating effectively reduces magnetic dilution, while its high electrical resistivity allows satisfactory insulation between the Fe powders, giving rise to simultaneous high effective permeability (97.7) and low core loss (771.3 mW/cm 3 ) of the SMC. [ABSTRACT FROM AUTHOR]