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Copper-promoted iron oxides are commonly utilized in high-temperature water-gas shift (WGS) reactions. Although the promotional effect of Cu has been previously documented, the nature of the active sites for Cu/Fe 3 O 4 remains debated and the role of the crystallite size of Fe 3 O 4 has not been tackled. In this study, a wide range of Cu/Fe 3 O 4 catalysts were designed by hosting Cu species onto Fe 3 O 4 of two contrasting crystallite sizes (approximately 10 and 160 nm) and by utilizing different preparation methods (ammonia evaporation and deposition-precipitation). The evaluation of their catalytic WGS performances revealed a remarkable and previously undocumented phenomenon: the addition of Cu resulted in universal activity enhancements only for small Fe 3 O 4 crystals, while the larger analogues displayed decreased activity. This peculiar phenomenon can be explained by the creation of Cu–Fe 3 O 4 interfaces present in the iron oxides of small crystallite sizes. Thorough characterizations, such as advanced electron microscopic, in situ powder X-ray diffractions, in situ diffuse reflectance infrared Fourier transform spectroscopy, and computational studies, suggest strong electronic interactions between the different metal species, facilitated reductions of the individual oxides, and more favorable CO activation at the interfacial sites, all accounting for the promoted activity. [Display omitted] • Influence of Fe 3 O 4 crystallite size in water-gas shift reaction was examined. • Performance of Cu/Fe 3 O 4 in water-gas shift reaction was studied. • The formation of Cu–Fe 3 O 4 interfaces existed on small Fe 3 O 4 crystals. • Promotional effect of Cu was only found on small Fe 3 O 4 crystals. [ABSTRACT FROM AUTHOR]

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]

This work designed a mesoscale method of multi-step reduction of Fe 2 O 3 with H 2 based on Lattice Gas Cellular Automata (LGCA). Particles in the LGCA were marked to distinguish all the reactants, intermediates, products, and inert. A self-organized evolutionary mechanism is designed. The hydrogen reduction of Fe 2 O 3 in the temperature range of 460–550 °C and 650–800 °C was simulated. Results show that the intermediate product Fe 3 O 4 was found in both conditions, and its mass fraction quickly reach a peak at ∼0.8 and gradually decrease thereafter. An "induction period" can be identified in the initial stage of the reaction at 650–800 °C, where the reduction rate is slow due to the hindered formation of FeO. The porosity inside the Fe 2 O 3 particles increases continuously through the reduction process, resulting in significant changes in the flow field around the particles. Consequently, the wake vortex gradually decreases and disappears eventually. • The multiple step reduction of Fe 2 O 3 by hydrogen is investigated in mesoscale. • A mesoscale method with self-organized evolutionary mechanism is developed. • Three obvious reaction rate transitions can be identified at 650–800 °C by the method. • The flow field is altered from internal structural of Fe 2 O 3 changes during reduction. [ABSTRACT FROM AUTHOR]

The utilization of nanoparticles to enhance bacterial activity and boost hydrogen production in fermentation processes has gained significant attention due to their unique properties such as high specific surface area and quantum size. This research aimed to improve the biohydrogen yield from food waste by adding iron oxide nanoparticles (Fe 3 O 4) at various concentrations (50, 75, 100, 150, and 200 mg/l) and titanium dioxide (TiO 2) at different amounts (25–150 mg/l) to a single-stage hybrid (dark/photo) fermentation reactor. After obtaining the optimal amount of these two nanoparticles, the effect of synergic addition of nanoparticles on hydrogen production yield, was investigated at ratios of Fe 3 O 4 /TiO 2 = 50/50 and 100/50 mg/mg. At the ratio of Fe 3 O 4 /TiO 2 = 100/50, the cumulative hydrogen production and yield of hydrogen have increased from 1613 to 3392 ml and 101.60 to 213.66 mlH 2 /gVS, respectively, compared to the control experiment. We also found that the COD removal rate has enhanced from 28% to 40.1%. In the optimal value, the bacterial growth lag phase has also remarkably decreased from 8.19 to 4.81 h. • Synergic application of TiO 2 and Fe 3 O 4 significantly increased biohydrogen purity and production yield. • TiO 2 played an important role in the activity of bacteria in the photo fermentation process. • Fe 3 O 4 played an important role in the dark fermentation system. • Nanoparticles may act as a scaffold for enzyme and substrate binding. • Optimal nanoparticle concentration may differ for different bioreactors. [ABSTRACT FROM AUTHOR]

Fe 2-x Sn x O 3 structures grown by RF-DC magnetron co-sputtering. The band gap of Fe 2 O 3 , SnO 2 , Fe 2-x Sn x O 3 structure was calculated as 2.86, 4.06, 2.77 eV, respectively. The Fe 2 O 3 thin film has shown a tetragonal as well as the SnO 2 structure, however, the Fe 2-x Sn x O 3 (0 < x < 1) has shown rhombohedral structure. XPS measurements have shown change in binding energy which is due to the electron exchange of tin-iron with oxygen, and iron - tin oxide structure. This binding energy increases slightly with the chemical environment effect. The films were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM). In AFM images was seen that the iron oxide structure was pyramidal and the tin oxide structure was spherical, similar to the SEM image. The response of the film to hydrogen gas was measured at flow values of 100, 500 and 1000 ppm at 300 °C. Fe 2 O 3 thin films show 46%, SnO 2 61% and, Fe 2-x Sn x O 3 6.5% response to 1000 ppm H 2 gas. It is seen that the gas sensor response was affected by the morphological and structural features of the grown film. Current vs. time graph for thin films gas sensor. [Display omitted] • Thin films were successfully grown by RF-DC co-sputtering system. • Metal oxide hydrogen gas sensor devices were measured depending on different grown structures. • Fe 2 O 3 , SnO 2 , Fe 2-x Sn x O 3 thin films show 46%, 61%, 6.5% response to 1000 ppm H 2 gas. • Iron oxide and tin oxide have n-type carrier, while iron tin oxide has p-type carrier. [ABSTRACT FROM AUTHOR]

The recovery and extraction of uranium is vital to ensure sustainability of nuclear energy production and safety of environment. Herein, we report a facile method to synthesise diglycolamic-acid-functionalized iron oxide@titanium dioxide magnetic nanocomposite (Fe 3 O 4 @TiO 2 -DGA) as an efficient adsorbent for effective removal of uranium (VI) from aqueous medium. Fe 3 O 4 @TiO 2 -DGA showed high uranium adsorption performance, with a sorption capacity of 371.8 mg g–1 at pH 6.0 and reached equilibrium within 40 min. The adsorption isotherm fits well with Langmuir and the kinetics follows pseudo-second-order model, respectively. The plausible mechanism of U(VI) adsorption involves the electrostatic interaction between the diglycolamic acid and hydrolysed uranium species. Thermodynamic studies revealed that the adsorption was spontaneous and exothermic in nature. The U(VI)-loaded Fe 3 O 4 @TiO 2 -DGA could be conveniently separated from aqueous solutions using an external magnet, and further U(VI) is desorbed by adding dil. HCl. Fe 3 O 4 @TiO 2 -DGA showed exceptional selectivity for U(VI) in presence of various coexisting metal ions and it can be effectively reused for more than 5 times with negligible change in sorption capacity. Thus, Fe 3 O 4 @TiO 2 -DGA can be considered as an effective and potential sorbent for U(VI) remediation from aqueous solutions. [Display omitted] • Fe 3 O 4 @TiO 2 -DGA is synthesized through facile method for enhanced adsorptive removal of U(VI) from aqueous solutions. • Fe 3 O 4 @TiO 2 -DGA can selectively extract U(VI) with a maximum adsorption capacity (q max) of 371.8 mg g−1 at pH 6.0. • Equilibrium adsorption is achieved with minimum contact time of 40 min • The nanocomposite exhibited significant reusability even after several adsorption cycles. [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]

Materials composed of various constituents with distinct physical or chemical features are named composites. Merging components in the composite structure leads to new properties creation or the intrinsic properties magnification of the components, or synergetic effects. Here, the ternary nanocomposite of copper, nickel, and iron oxides was electrodeposited on the glassy carbon electrode (GCE) surface to facilitate the ethanol electro-oxidation reaction (EOR) and overcome the electrode fouling problem while prolonging its efficiency. The GCEs were modified by three different procedures and activated by CV cycling in an alkaline solution, and their electro-catalytic activity was tested toward EOR. The ternary electrocatalysts prepared by two-steps electrodeposition of their components (Ni,Fe 2 O 3 /Cu and Cu/Ni,Fe 2 O 3) demonstrated higher peak current and more negative peak potential (E pa = 476 mV, I pa = 492 μA, and E pa = 510 mV, I pa = 644 μA, respectively) than the binary electrocatalyst of Ni,Fe 2 O 3 toward EOR. The best electro-catalytic efficiency was acquired for the simultaneous electrodeposition of nano Cu, Ni, and Fe 2 O 3 on the GCE surface (Cu,Ni,Fe 2 O 3 , E pa = 530 mV, I pa = 3179 μA). The physicochemical and electro-catalytic characterizations of the fabricated electrocatalysts were evaluated by various techniques. The fast and facile engineered design of the GCE modification with the ternary Cu,Ni,Fe 2 O 3 components led to a high current density of about 101 mA/cm2 with increased tolerance against poisoning intermediates resulting in longtime stability for EOR in alkaline media. The synergistic effect between nano Ni, Cu, and Fe oxides provided promising properties for the EOR pursuing the construction of a powerful device with commercialization potential. • On-step electrodeposition of Cu,Ni,Fe 2 O 3 ternary nano-composite • Improvement of the electron transfer kinetic of EOR • High tolerance against poisoning intermediates and longtime stability for EOR • Promising electro-catalytic performance of Cu,Ni,Fe 2 O 3 /GCE for EOR • Achievement of a high current density of ∼101 mA/cm2 for EOR [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]

Microparticles of iron oxide (MPIOs) are increasingly used for contrast generation in magnetic resonance imaging (MRI). In particular, Dynabeads® MyOne™ Tosylactivated MPIOs have enabled sensitive and targeted molecular imaging, e.g. , to detect vascular inflammation. For the first time we measured the relaxivities as well as the molar susceptibility χ M of these MPIOs at 7 T in agarose gels. They are r1 = 0.69 ± 0.03 s−1/mM, r2 = 220 ± 6 s−1/mM, r2* = 679 ± 14 s−1/mM, and χ M = 0.66 ± 0.05 ppm/mM, when expressed with respect to the iron concentration. These material parameters are essential to optimize MRI protocols and progress toward quantitative imaging. To address the heterogeneous nature of the MPIO distributions over the size of a typical MRI voxel, we coupled the MPIOs to a fluorophore to create a bimodal phantom that can be imaged by both Light Sheet microscopy and MRI. In this phantom, the MPIOs produced contrast similar to that found in vivo. The submicron resolution of Light Sheet microscopy images provided a precise measurement of the MPIO spatial distribution in phantoms also imaged by MRI. MPIO aggregates occupying less than one MRI voxel were responsible for alterations in R2* and magnetic susceptibility χ across several MRI voxels. In these cases, the sum of R2* or χ over the affected MRI volume correlated better with the microscopically determined number of MPIOs. These findings were confirmed with simulations performed in the static dephasing regime. The microscopically determined MPIO distribution was also entered directly into the simulation framework, indicating that the bimodal phantom is a useful tool to test theoretical models against experimental measurements. [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]

[Display omitted] • Preparation of a biochar-iron oxide (BC-IO) composite via ultrasonication. • High specific surface area of BC-IO enables high heavy metal adsorption. • BC-IO outperformed unmodified BC in adsorption capacity. • BC-IO composite can be reused through adsorption and desorption. In this study, we aimed to develop an absorbent for efficient removal of heavy metals. We developed a composite (BC-IO x) using biochar (BC) obtained by carbonizing rice hull, a type of biomass, and iron(III) nitrate nonhydrate (IO). The bonding strength between BC and IO was increased through ultrasonication with high energy at 25 ℃ and a 2-h heat treatment process at 350 ℃. Brunauer-Emmett-Teller analysis showed that BC-IO x had an increased specific surface area, which was proportional to iron loading and provided an abundance of active heavy metal adsorption sites. This composite effectively removed Pb(II) and As(V). The addition of BC-IO 3 to Pb(II)-contaminated water for 120 min increased Pb(II) absorption capacity to 90.21 mg/g from 18.12 mg/g with unmodified BC. The As(V) adsorption capacity increased from 8.33 mg/g for unmodified BC to 65.34 mg/g for BC-IO 10. In addition, the potential adsorption mechanism was discussed using detailed chemical and physical analyses. The synthesis of a composite from biochar and iron oxide can inspire the cost-effective and straightforward production of heavy metal absorbents that can be utilized on a large scale. [ABSTRACT FROM AUTHOR]

We report the effective synthesis of polyaniline (PANi)-layered nitrogen-doped carbon-coated Fe 3 O 4 (FNC@PANi) nanocapsules (NCs) for electrocatalysis of oxygen evolution reaction (OER) as well as anode material for lithium (Li)-ion batteries (LIBs) via a simple hydrothermal method and oxidative polymerization technique. The prepared FNC@PANi NCs revealed a dual core-shell structure, in which an intermediate carbon layer allowed excellent electrical conduction between the Fe 3 O 4 NCs and PANi. The dual core-shell structure also allowed the Fe 3 O 4 NCs to expand freely during the Li-ion insertion/extraction and OER processes without breaking the outer layer, thus providing a high surface area (147.85 m2 g−1) and enhanced electrical conductivity. These properties facilitate the application of the dual core-shell FNC@PANi NCs as an advanced electrode material for LIBs, delivering a high reversible specific capacity of 1556.48 mAh g−1 at 0.1 A g−1, excellent rate performance (896.96 mAh g−1 at 1 A g−1), and durable cycling life (680.12 mAh g−1 at 5 A g−1 for 3000 cycles). The dual core-shell FNC@PANi NCs exhibited high electrocatalytic activity in the OER, with a small Tafel slope of 108.7 mV dec−1 owing to synergistic effects between the copious active sites of the Fe 3 O 4 NCs and the carbon core-shell structure and a modest overpotential of 219 mV at 10 mA cm−2. The electrodes showed excellent stability over 10 h, as determined by chronopotentiometry at 10 mA cm−1. The resultant dual-core-shell FNC@PANi NCs are efficient iron-oxide-based electrode materials for LIBs and OER electrocatalysts. Facile solvothermal method and chemical oxidative polymerization technique are reported for the synthesis of bifunctional electrocatalyst and high-performance LIB anode material, i.e., dual core-shell polyaniline layered nitrogen-doped carbon coated Fe 2 O 3 nanocapsules (dual core-shell FNC@PANi NCs). Compared to its counterparts, this FNC@PANi NCs electrode delivers excellent energy storage properties along with higher OER behavior. [Display omitted] • A bifunctional electrode material for lithium-ion battery (LIB) and oxygen evolution reaction (OER) electrocatalyst, namely dual core-shell FNC@PANi NCs, was synthesized via a hydrothermal method. • The material serves as an advanced LIBs electrode, exhibiting impressive cycling stability, excellent rate capability, and durable cycling life. • As an OER electrocatalyst, the FNC@PANi NCs demonstrate significant catalytic activity, evidenced by small Tafel slope and modest overpotential. [ABSTRACT FROM AUTHOR]

In this study, 15 % w/w polyvinylidene fluoride (PVDF)–Fe3O4 nanoparticle (NP) nanocomposite scaffolds were prepared using coaxial electrospinning with a high-speed conductive rotating collector to obtain aligned fibers. The effects of varying the Fe 3 O 4 NP size (6, 9, and 14 nm in diameter) on the fiber morphology, mechanical response, and piezoelectric phase content were investigated. In situ X-ray diffraction measurements during heating-cooling and tensile tests were carried out using synchrotron radiation to study the charge in the β-phase content and polymer chain orientation under different conditions. At zero strain, the presence of smaller NPs seems to impede the β-phase crystallization in PVDF. However, heating-cooling cycles revealed that the NPs acted as nucleation agents, promoting a higher β-phase content after cooling compared to pure PVDF. The mechanical response showed that nanocomposites with smaller NPs exhibited higher stiffness. While the initial degree of polymer chain orientation was higher in the nanocomposites, the presence of NPs hindered the α-to-β phase transformation and chain alignment under tensile deformation compared to pure PVDF. This study highlights the complex interplay among NP size, β-phase formation, mechanical properties, and chain orientation in PVDF-Fe 3 O 4 nanocomposites, providing insights into tailoring their piezoelectric performance for various applications. Graphical abstract: Comparison of two electrospun fibers: pure PVDF and PVDF + Fe₃O₄ nanoparticles. The pure PVDF fibers are thicker than the nanocomposite fiber, suggesting that pure PVDF fibers have a greater margin for deformation and alignment of polymer chains within the fiber structure. In contrast, the nanocomposite fibers, incorporating Fe₃O₄ nanoparticles, show reduced thickness, indicating less margin for deformation and orientation of polymer chains. However, both types of fibers exhibit a limit to polymer chain orientation before breakage occurs. [Display omitted] • We analyzed the microstructure at different length scales. We investigated the distribution of NPs as a function of their size. • A detailed description of the crystalline structure as a function of the NP size is provided under different conditions (mechanical and thermal loading). • This analysis provides details on the interaction at the NP length scale and the distribution of crystalline phases in the presence of the surrounding iron oxide NPs. [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]

Oxide materials are important for gas sensing applications. Unfortunately, most of the synthesis methods use many toxic chemicals and need long calcination at high temperatures. Thus, developing simple and green synthesis processes, which can be performed fast and at low temperatures, is imperative for both industrial manufacturers and our environment. Here, our fast and green synthesis method based on low-power laser sintering for producing FeO x (with Fe 2 O 3 as the main composition) is presented. Besides, FeO x particles were decorated on reduced graphene oxide (RGO) to form a resistive sensor. Notably, our FeO x material can reduce the response of RGO toward acidic gas (NO 2) but it enhances the RGO response toward the basic NH 3 gas. Particularly, our hybrid FeO x /RGO sensor can detect NH 3 gas at above 2 ppm under dry and humidified conditions (<85 % RH). That effect of FeO x is found due to the formation of alpha-phase Fe 2 O 3 which acts as a p-type semiconductor, which is explored and explained in the discussion section. Finally, our findings not only reveal the potential of our hybrid sensing materials for practical NH 3 sensing applications but also confirm the usefulness of laser-sintering to produce catalytic oxide materials environmentally friendly and at low cost. [Display omitted] • Fast and green production method of iron oxides (Fe 3 O 4 or Fe 2 O 3) is reported. • FeO x was directly formed on RGO resistive gas sensors via laser sintering. • p-type FeO x tuned the sensing behavior of RGO materials toward NH 3 basic gas. • The hybrid FeO x /RGO sensor can work at RT and under a wide humidity range. [ABSTRACT FROM AUTHOR]

Chitosan (CS) polysaccharide is expected to exhibit greater ionic conductivity, which can be attributed to its increased amino group content when it is blended with different semiconducting materials. Herein, the work used this conducting ability of chitosan and prepared a heterogeneous MoS 2 -induced magnetic chitosan (MF@CS) composite via the co-precipitation method, which was used to scrutinize the catalytic performance with Methylene Blue (MB) and Malachite Green (MG) dyes by visible light irradiation. The saturation magnetization value of the MF@CS composite is found to be 7.8 emu/g, which is less when compared to that of pristine Fe 3 O 4 (55.7 emu/g) particles. The bandgap of the MF@CS composite is ∼ 2.17 eV, which exceeds the bandgap (E g) of bare MoS 2 of 1.80 eV. The maximum color removal of 96.3 % and 93.4 % for MB and MG dyestuffs is recognized in the exposure of the visible spectrum, respectively. At a starting dye dosage of 30 mg/L, 0.1 g/L of MF@CS, a pH level of 8−11, and 70 min of contact with direct light. The photocatalyst provides extremely good durability for a maximum of five phases. Hence, the MF@CS matrix is a viable and appropriate substance for the efficient treatment of effluents containing dye molecules. [Display omitted] [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]

• Reduced graphene oxide/iron oxide nanocomposites-based humidity sensors exhibit superior sensing capabilities towards varying humidity levels compared to rGO. • The rGO/Fe 2 O 3 NC humidity sensors showed enhanced sensitivity, excellent sensing response, and quick response/recovery time towards different humidity level. • The humidity sensors displayed long-term stability and excellent selectivity towards different %RH levels. For the humidity sensing, rGO/Fe 2 O 3 nanocomposites were synthesized via an ultrasonic-assisted method, utilizing Hummers' and co-precipitation techniques for rGO and Fe 2 O 3 synthesis. XRD analysis confirmed the formation of rGO and rhombohedral Fe 2 O 3 NPs, while SEM revealed varied (rough sheet-like and dense compact) morphologies. UV–VIS spectra indicated characteristic absorption peaks for rGO, Fe 2 O 3 NPs, and their NCs. In addition, FTIR spectra validated graphene oxide reduction and Fe 2 O 3 NPs/NCs formation. Humidity sensing was assessed across 40–80 % RH at varying frequencies (100 Hz-10 kHz), with 100 Hz identified as the optimal frequency due to water molecule polarization limitations at higher frequencies. The rGO/Fe 2 O 3 (70/30) NC exhibited a rapid response recovery time (5 s/10 s) and high sensitivity (2715.541 %), attributed to additional active sites provided by Fe 2 O 3 , enhancing water molecule adsorption and sensor sensitivity. The sensors demonstrated long-term stability and repeatability, showcasing promising potential for humidity sensing applications. [ABSTRACT FROM AUTHOR]

• LIC is made with C-coated iron oxide anode, heteroatom-doped porous carbon cathode. • AC800–3 cathode exhibits 154 F g−1 with 76 % retention after 10,000 cycles at 1 A g−1. • IO550 anode delivers 545 mAh g−1 with 76% capacity retention after 2000 cycles. • LIC exhibits 91 and 65 Wh kg−1 at power densities of 467 and 9350 W kg−1. • LIC retains ∼77% specific capacitance at 1 A g−1 for 5000 cycles. Lithium-ion capacitors (LICs) are promising devices to balance the space between lithium-ion batteries and supercapacitors by merging the battery-type anode and capacitor-type cathode materials in a single device. This work represents a lithium-ion capacitor containing in-situ carbon coating on mix-phase iron oxide from ferrocene as an anode and heteroatom-doping on porous carbon as the cathode. This type of cathode facilitates better wettability and a good contact area between the electrode and electrolyte, leading to a capacitance of 154 F g−1, retaining 76 % capacitance after 10,000 cycles at 1 A g−1. In contrast, the anode half-cell exhibits 545 mAh g−1 at 1 A g−1 and ∼76 % retention in capacity after 2000 cycles. This is because of nano-structuring and mix-phase iron oxide, allowing a conversion-type reaction to store Li-ions at a high rate, and carbon coating provides electronic conductivity and structural strength upon cycling. The full cell LIC demonstrates energy densities of 91 and 65 Wh kg−1 at power densities of 467 and 9350 W kg−1, respectively. This hybrid device can retain ∼77 % specific capacitance at 1 A g−1 for 5000 cycles. Furthermore, this study analyzes the practical application of LICs by evaluating impedance, self-discharge, and leakage current characteristics. [Display omitted] [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]

Macroporous strong acidic resin (D001) is restricted in Pb(II) removal from water due to the interference of common environmental cations. A novel modified D001 (nFeOOH@D001) was developed by loading nanoscale α-FeOOH (nFeOOH) with a facile ethanol-dispersion-impregnation method to improve Pb(II) removal from aqueous solution. Solid-phase analysis showed that α-FeOOH of 10–100 nm was evenly loaded onto D001. The nFeOOH@D001 maintained the electrostatic adsorption ability of D001, and obtained the complexation adsorption capacity of nFeOOH. The nFeOOH@D001 therefore achieved a 20.2% higher Pb(II) removal rate of 74.5% as compared to the D001 of 54.3%. Under the competition of Ca2+ and Mg2+ ions, the nFeOOH@D001 showed better selectivity for Pb(II) through the complexation of hydroxyl and ferrite groups on nFeOOH. The pseudo-first order kinetics and Langmuir-adsorption models well fitted the Pb(II) removal data, indicating a chemistry and monolayer adsorption process. This process depended on pH and achieved a Pb(II) removal over 65% within a pH range of 3–7. During cyclic test, used nFeOOH@D001 could be refreshed with acetic acid as eluent. Spent nFeOOH@D001 could be remodified with nFeOOH by the above impregnation method after stripping iron oxides with hydrochloric acid. The regenerated nFeOOH@D001 obtained a regeneration rate of 97.6% as compared to virginal nFeOOH@D001. The results demonstrated that the introduction of nFeOOH could effectively improve the performance of D001 for Pb(II) removal from water. [Display omitted] • Nanoscale goethite-modified resin (nFeOOH@D001) was prepared with ethanol-dispersion-impregnation. • α-FeOOH of 10–100 nm on D001 provided additional adsorption sites to compensate for its occupation. • Hydroxyl and ferrite groups on nFeOOH removed Pb(II) by complexation. • nFeOOH@D001 had higher Pb(II) selectivity as compared to D001. • nFeOOH@D001 exhibited excellent stability and reusability. [ABSTRACT FROM AUTHOR]

The production of highly reactive oxygen carrier particles based on low-cost iron materials is explored for chemical looping processes. Ten different low-cost Fe-based materials in the micronized size, both minerals and industrial residues, have been tested as precursors of oxygen carrier particles. The redox reactivity of each of the materials is evaluated and compared to the state-of-the art with particulate materials, including one new material introduced in this work. Due to its excellent reactivity, Promifer material was used to produce oxygen carrier particles by pelletizing and granulation. Considering a trade-off between crushing strength and reactivity, pelletizing process was selected. This material calcined at 950 °C showed high reactivity with CH 4. If a higher operating temperature was required, e.g. 1000 °C with solid fuels, the reactivity decreased. Low attrition rates and good fluid-dynamic behavior with the pelletized particles, without agglomeration along the redox cycles, were found in a fluidized bed reactor. [Display omitted] • Identified iron oxides based on low-cost materials with high reactivity to methane. • Oxygen carrier particles prepared by clean methods with selected iron oxide precursor. • Characteristics of pelletized particles outperformed those of granulated particles. • Calcining temperature should be optimized considering reactivity and crushing strength. • Produced oxygen carrier improved characteristics of state-of-the-art Fe-based materials. [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]

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]

[Display omitted] • A grain-like morphology of Fe 2 O 3 was produced by the Co-precipitation method. • Mesoporous carbon composites with iron oxide nano granular with high specific surface area and porosity for antimicrobial studies. • The as-synthesized mesoporous carbon composite with iron oxide has a potential antimicrobial activity. Bacterial infections keep posing a severe hazard to human health. Investigating efficient innovative antibacterial methods is exceedingly crucial. In this instance, coprecipitation is used to produce iron oxide and mesoporous carbon-iron oxide nanostructures with surfaces that resemble grains for antibacterial treatment. More importantly, surfaces composed of iron oxide with embedded mesoporous carbon exhibit higher bacterial consistency, which is advantageous due to the efficient interaction of bacteria with nanostructures. In antibacterial studies, nanostructures are shown to have an all-encompassing combinatorial antibacterial action against Gram-positive Bacillus cereus (B. cereus), and Staphylococcus aureus (S. aureus), and Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). In the current study, a simple method to produce antibacterial agents for antibacterial applications is presented. This method involves constructing a combined formulation and morphological structure. In the successful prevention and cure of bacterial infections, iron oxide with a small quantity of mesoporous carbon has a lot of potential. [ABSTRACT FROM AUTHOR]

This work concerns research on the use of inorganic chemical compounds Fe 2 O 3 , Fe 3 O 4 , and Al and organosilicon modifiers used as additives controlling the properties of PLA for material extrusion in 3D printing technology. The addition of inorganic compounds reduces the temperature at the beginning of the composite decomposition, which is related to the presence of metal and metal oxides. An effect of inhibition of catalytic activity was also noticed as a result of the addition of organosilicon compounds. An increase in the melt flow index parameter was observed, making improving the extrusion and 3D printing process possible. The presence of inorganic additives results in a better fusion of the print paths, which leads to reduced structure defects and better interlayer adhesion. The tensile strength of the obtained composite samples decreases with the increase in the concentration of the metal and metal oxides. The addition of organosilicon substances increases the tensile strength regardless of the inorganic compound concentration. The highest increase in tensile strength was obtained for the PLA/12.5% Fe 3 O 4 /OSS-5OD-3TMOS sample and it was 24.35% compared to the sample without the addition of organosilicon compounds. The use of organosilicon additives resulted in an increase in the water contact angle. [Display omitted] [ABSTRACT FROM AUTHOR]

The study investigated removal of hexavalent chromium Cr (VI) from aqueous solution using graphene oxide‑iron oxide reinforced pectin/polyvinyl alcohol magnetic gel beads prepared through co-precipitation and freeze-drying technique. Scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, vibrating sample magnetometer, N 2 adsorption-desorption isotherm, and zeta potential are used for characterization. The surface area of magnetic gel beads calculated by BET method was determined to be 100.95 m2/g, significantly higher than that of GO and GO-Fe 3 O 4. The optimum removal efficiency of GO-Fe 3 O 4 /Pec/PVA was assessed by batch method at variables such as pH(1–6), adsorption time(0–180 min), and temperature(25–35 °C). Accordingly, 0.2 g GO-Fe 3 O 4 /Pec/PVA dose, pH 2, contact time: 120 min at 25 °C were found to be the optimal conditions, and maximum adsorption capacity of GO, GO-Fe 3 O 4 and GO-Fe 3 O 4 /Pec/PVA toward Cr(VI) removal was found to be 39.5, 62.5 and 78.55 mg g−1, respectively. Kinetic and isotherm studies indicate adsorption data follow pseudo-second-order kinetic and Langmuir isotherm models. Thermodynamic studies showed adsorption capacities of adsorbents decreased when temperature increased which indicated adsorption for Cr (VI) was an exothermic process. The activation energies were found to be 34.92, 26.57, and 35.23 KJ mol−1 for GO, GO-Fe 3 O 4 , and GO-Fe 3 O 4 /Pec/PVA, respectively, which illustrated adsorption of Cr(VI) onto the surface of adsorbents was a physical process. The beads exhibit excellent recoverability and reusability over five cycles. Overall, GO-Fe 3 O 4 /Pec/PVA demonstrates exceptional adsorption properties and can serve as an efficient, stable, less toxic, and magnetically separable adsorbent for removal of Cr(VI) from aqueous solution. • GO-Fe 3 O 4 reinforced pectin/polyvinyl alcohol magnetic gel beads prepared via co-precipitation and freeze drying. • Improved adsorption capacity of GO-Fe 3 O 4 /Pec/PVA for hexavalent chromium compared to GO and GO-Fe 3 O 4. • GO-Fe 3 O 4 /Pec/PVA demonstrated recoverability, magnetically separable and efficient adsorbent for environmental cleanup. [ABSTRACT FROM AUTHOR]

[Display omitted] • Identification and collection of raw magnetic sand from site. • Characterization of raw magnetic sand. • Synthesis of mesoporous iron oxide from the raw magnetic sand. • Characterization of synthesized mesoporous iron oxide. This paper presents the synthesis of iron oxide from natural magnetic sand that was obtained from Michika, Adamawa State, Nigeria. Characterization of the raw magnetic sand and the synthesized iron oxide was performed to investigate the effect of the synthesis method on functional groups, morphology, composition, crystallinity, acidity and surface area/pore distribution using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy – energy dispersive X-ray (SEM – EDX), X-ray fluorescence (XRF), X-ray diffraction (XRD), BET and pyridine FTIR, respectively. The XRF analysis of the two samples revealed a significant variation in oxide composition. The raw magnetic sand had an iron oxide content of 64.69 wt%, which increased to 85.20 wt% after synthesis. Furthermore, the SEM-EDX analysis indicated a decrease in average particle size from 114.6 and 36.8 µm for the respective samples. The XRD patterns revealed that the crystallinity increased after synthesis. FTIR showed the associations of functional groups present in the sample. The wavebands in the range 550 – 630 cm−1, which correspond to the Fe – O bond, improved clearly in the synthesized iron oxide sample, particularly at 582 cm−1. The pyridine FTIR depicts that the overall acidic site is higher in the synthesized sample. The N 2 adsorption–desorption procedure shows an increased BET surface area from 9.394 m2/g (raw) to 24.851 m2/g (synthesized). Overall, the results showed that the synthesized mesoporous iron oxide exhibits properties similar to materials that have a high potential for application as catalysts in chemical processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Glucose non-enzymatic electrochemical sensor based on polyaniline, graphene and MOF. • A large surface area, enhanced electron transfer and catalytic properties. • The sensor has a wide linear range and good sensitivity. • Acceptable performance in human fluids real samples including serum and plasma. In this study, a novel highly sensitive and selective non-enzymatic glucose sensor was fabricated by coating simple and cheap graphite sheet (GS) electrodes with a proper conductive nanocomposite containing nitrogen-doped functionalized graphene (NFG), conductive polyaniline (PANI), and core–shell nanoparticles (Fe 3 O 4 @MIL-101-NH 2). The results revealed that the core centers of iron oxide nanoparticles shelled by MIL-101-NH 2 enhanced the electron transfer and led to more conductivity, also their existence caused the limitation of the MOF's low conductivity. In addition, using Fe 3 O 4 @MIL-101-NH 2 in the nanocomposite structure led to more sensitivity and selectivity at glucose monitoring due to its amine groups and unique structure. The results showed that NFG/PANI/Fe 3 O 4 @MIL-101-NH 2 nanocomposite provided a large surface area besides enhanced electron transfer and catalytic properties that lead to proper oxidation of glucose with two linear ranges of 0.5 – 10 µM and 100 µM – 25 mM and a low detection limit of 0.3 µM (S/N = 3). Furthermore, the relative standard deviation (RSD%) in all detection processes was lower than 9 %. Finally, the performance of fabricated non-enzymatic sensor (GS/NFG/PANI/Fe 3 O 4 @MIL-101-NH 2) in human fluids real samples including serum and plasma was acceptable which significantly indicates that it is toward monitoring of glucose in clinical applications. [ABSTRACT FROM AUTHOR]

The use of sustainable, multifunctional inks in printed electronics has great utility for various devices, particularly at soft biointerfaces. Here, we discuss the development of a multifunctional nanocomposite ink, termed PS-IO-N ink, designed for applications, principally in the field of flexible and bio-electronics. The ink combines electrically conductive properties with magnetic capabilities, offering a dual-functionality that facilitates both physical and electrical connections. The PSION ink is composed of two main components: poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), a conducting polymer with favorable biocompatibility, and iron oxide (Fe 3 O 4) nanoparticles known for their ferromagnetic properties. The ink is formulated as a stable water dispersion, making it eco-friendly and suitable for aqueous processing. Key findings include the optimization of components to balance electrical conductivity and magnetic behavior, allowing the ink to function as both a physical connector and a conductor. The addition of an adhesion promoter enhances the ink's water stability and surface adhesion. The ink's applicability is demonstrated in various scenarios, such as forming flexible circuits on substrates like paper and silk fibroin, creating temporary magnetic connections for electronic devices, and enabling stable connections to sensors for parameter monitoring. The PSION ink provides an innovative solution for flexible and bioelectronic applications, offering the potential for reversible, adaptable connections in both dry and wet environments. [Display omitted] • Discuss a multifunctional water based ink. • Stable dispersion with conductive and magnetic properties. • Can facilitate transient on/off connections. • Easily dispensed on variety of substrates as micropatterns. • Connections to sensors and other functional devices shown. [ABSTRACT FROM AUTHOR]

• In operando x-ray absorption spectroscopy study of FeO x -based chemiresistive sensor. • Iron oxide (FeO x) nanoparticles are reduced in dry air with increasing temperature. • Iron oxide (FeO x) nanoparticles are reduced if exposed to trace amounts of acetone. • Response of FeO x chemiresistive sensor to acetone is reasoned by its chemisorption. Metal oxide thin films are archetypal active elements employed in chemiresistive gas sensors. Most existing metal oxide-based sensors operate at elevated temperatures; however, the sensing mechanism has generally been deduced considering the room-temperature properties of metal oxide compounds. We report an in-operando X-ray absorption spectroscopy study on a chemiresistive sensor of acetone vapours; namely, the chemical structure of iron-oxide nanoparticles (NPs) exposed to trace concentrations of acetone vapours under varying temperature conditions was examined. Our results show that the iron-oxide NPs, identified as maghemite/magnetite (γ-Fe 2 O 3 /Fe 3 O 4) compound, partially reduced with temperature. Likewise, the iron oxide NPs were partially reduced upon exposure to trace concentrations of acetone vapour (at constant temperature). The latter observation suggests that acetone molecules are chemically adsorbed on iron oxide. The chemical changes are discussed in terms of the conductive response of a consubstantial chemiresistive sensor. Acetone chemisorption requires a revision of the commonly accepted sensing mechanism based on the physical adsorption of acetone molecules. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) is a vital messenger molecule facilitating signal transmission within cellular systems. The accurate quantification of H 2 O 2 in complex environments, such as human serum, is instrumental in elucidating its diverse biological functions. In this study, we present the development of a robust electrode platform by integrating hemoglobin onto iron oxide (Fe 3 O 4) nanoparticles and reduced graphene oxide (rGO) as a conducting support for the sensitive detection of H 2 O 2 in human serum. The Fe 3 O 4 /rGO nanocomposite was synthesized via a facile single-step thermolysis reaction in the presence of oleylamine. Transmission electron microscopy (TEM) analysis revealed the formation of highly monodisperse Fe 3 O 4 nanoparticles that were uniformly dispersed over the reduced graphene surface. The rGO surface provided abundant active sites (Fe 3 O 4) for H 2 O 2 sensing. Consequently, the resulting Hb/Fe 3 O 4 @rGO modified electrode exhibited a wide linear range of H 2 O 2 concentrations from 1.5 to 2684 µM, demonstrating high sensitivity and low detection limit. Further characterization of the Hb/Fe 3 O 4 @rGO/GC electrode revealed a high surface coverage (τ = 3.0 × 10−9 mol cm−2), charge transfer coefficient (α = 0.83), and electron transfer rate constant (k s = 1.33 s−1). Subsequently, the Hb/Fe 3 O 4 @rGO/GC sensor probe was employed to analyze H 2 O 2 in real human serum samples, demonstrating excellent recovery rates ranging from 99.8 % to 104.0 %. The nanocomposite material, designed through the innovative combination of graphene oxide reduction, Fe 3 O 4 nanoparticle decoration, and oleylamine amide/amine bonding, serves as an excellent electrode material for H 2 O 2 concentration sensing. Thus, this study presents a promising platform for the future determination of H 2 O 2 biomarkers in clinical settings. [Display omitted] [ABSTRACT FROM AUTHOR]

The influence of the combination of sludge load control and iron oxide (IO) addition strategies on food waste anaerobic digestion (AD) was explored. The results showed that low sludge loads or IO addition could significantly enhance AD performance. Low sludge loads promoted substrate hydrolysis and volatile fatty acids degradation, which enhanced the biochemical methane potential (BMP) and production rate, respectively. IO addition promoted the CH 4 yield and maximum CH 4 production rate (R m) by 65.50% and 206.79%, respectively, by promoting hydrolysis and interspecies electron transfer among syntrophic microbes. Moreover, although the presence of IO could prevent the failure of AD in extremely high sludge load conditions, it could not ensure complete BMP recovery. In an IO-assisted reactor, low sludge loads decreased the methanogenic lag phase by 53.15% and increased the BMP and R m by 49.93% and 120.11%, respectively. Although adequate IO dosage could effectively improve the digester performance, excessive dosage may limit the economic benefits. Overall, the AD performance could be optimized by simultaneously controlling the sludge load and IO addition. [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]

Spray pyrolysis at various temperatures was employed to produce non-crystalline and crystalline iron oxide (α-Fe 2 O 3) thin films on glass. The amorphous and crystalline characteristics of α-Fe 2 O 3 thin films were affirmed via X-ray diffraction analysis. With low deposition times (5 min) and at various substrate temperatures, iron oxide seems almost in a non-crystalline structure. As for the increase in deposition time (40 min), the crystallinity's degree was enhanced. According to Tauc's law, the direct gap energy E d for both the amorphous and the crystalline phases, were found to be 1.95 and 2.125 eV, respectively. Moreover, the indirect gap energy, E in = 1.65 and 1.71 eV were obtained for the amorphous phases and the crystalline phases, respectively. The linear and non-linear optical features of amorphous and crystalline structure were meticulously and adaptably detailed. It is observed that the behavior of the refractive index n (λ) and extinction coefficient k (λ) of the crystalline state was lower than that of the amorphous state. The real and imaginary linear dielectric constant and also the thin film quality factor were estimated for both the amorphous and crystalline states as well as the volume and surface energy loss functions for the crystalline and amorphous states. In conclusion, amorphous and crystalline α-Fe 2 O 3 nanocrystalline films improved their optical properties, making them potential candidates for multifunctional applications such as optoelectronics and spintronics electronics devices. [ABSTRACT FROM AUTHOR]

• Experiments are performed in both CSS and MSS at different water depths in coated and uncoated absorber. • Increase in water depth decreases the fresh water generation from both cases. • The fresh water produced from CSS and MSS are 3.85 and 6.03 kg/m2 respectively. • The thermal and exergy efficiencies are found as 47.67 and 4.53 % respectively using the MSS. • CPL of fresh water produced is lowered by 29.96 % than the SS using uncoated absorber. The quantity of drinkable water that is easily accessible is dwindling at an extremely quick pace. An extra degree of complication has been added to the problem as a consequence of the depletion of freshwater resources brought on by human activities. The primary objective of the present study is to enhance the rate of fresh water generation through the low-cost solar desalination unit using iron oxide as coating material using different thickness of water placed in the absorber plate. The experimental results revealed that the influence of metal oxide nanoparticle as absorber coating material improved the rate of fresh water generation by 36.08 % than the conventional solar still at a minimum thickness of water as 1 cm in the absorber. The palatable fresh water generated from the SS without any absorber coating for the thickness of water as 10, 20 and 30 mm is found to be 3.85, 3.09 and 2.90 kg/m2 respectively. However, with effective coating of the absorber plate using Fe 2 O 3 nanoparticle, the cumulative daily palatable water generated from the solar still for different thickness of water as 10, 20 and 30 mm is enhanced to about 6.03, 5.36 and 4.72 kg/m2 respectively. There is a significant enhancement of about 38.47 to 60.15 % and 1.96 to 4.53 % in the daily energy, and exergy efficiencies of the solar still using coated absorber plate in the SS respectively while compared to the SS using uncoated absorber at the lowest thickness of water in the absorber of basin. Similarly, the CPL of fresh water produced from the SS using coated absorber is lowered by 29.96 % than the SS using uncoated absorber. [Display omitted] [ABSTRACT FROM AUTHOR]

Drinking of water polluted with heavy metals is a means by which heavy metals bio accumulate in the human body. The rise in galamsey (illegal mining) activities in Ghana has resulted in heavy metal pollution in most water bodies in the country. Above the permissible limits, these metals cause health issues such as cancer, brain damage, kidney damage and other respiratory diseases. Hence, a smart solution to this menace is urgently needed. In this study, iron oxides were recovered from cupola furnace slag by magnetic separation and froth flotation. The recovered iron oxide was modified using electrospinning with the aid of polyvinyl alcohol after which it was calcined and used as adsorbent to detoxify lead and arsenic from two galamsey polluted water bodies in Obuasi, Ghana. Samples of the adsorbent were characterized using X-ray Fluorescence (XRF), X-ray Diffractometry (XRD), Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscopy (SEM) and Brunauer-Emmer-Teller (BET) method. The highest recovery for iron oxide using magnetic separation was 99.42% and that of froth flotation was 90.64%. The recovered iron oxide used as adsorbent was composed 53.04% iron oxide, with major phases like magnetite, hematite, goethite and quartz. Moreover, the surface functional group were determined to be Fe–O and OH. Also, the calcined nano fibres which were spherical in shape with rough surfaces had a specific surface area of 1.1331 m2/g. The contaminated and detoxified water were also analyzed using Atomic absorption Spectroscopy (AAS). Both adsorbent (beneficiated iron oxide and calcined nano fibre) performed well in the adsorption process, with the recovered iron oxide having 97.33% maximum lead removal efficiency while an 81.00% maximum removal efficiency for arsenic. The calcined nano fibre had a maximum of 99.99% removal efficiency for lead and 88.40% maximum efficiency for arsenic. Additionally, the adsorption fits the Langmuirian isotherm model better than the Freundlich model, indicating mono layer coverage. • Cupola furnace slags are rich in iron oxides and can be recovered for various application. • Magnetic separation and froth flotation were used to recover the iron oxides from the cupola furnace slag. • The recovered iron oxides (Fe 3 O 4 , α -Fe 2 O 3 , FeO 2 H and γ -Fe 2 O 3) were used for lead and arsenic adsorption. • The iron oxides achieved high removal efficiency for the heavy metals (Pb and As). [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]

Liquid lead–bismuth eutectic (LBE) is a heavy metal alloy with great potential as a coolant and spallation target material for Generation IV nuclear reactors. For LBE technology to be widely accepted as reliable, a comprehensive understanding of LBE coolant chemistry is crucial. Specifically, precise determination of chemical interactions between corrosion products and dissolved oxygen in LBE is essential. For that purpose, the thermal cycling method is used in the present research, in which a well-controlled batch of LBE is repeatedly cooled while a potentiometric oxygen sensor monitors the dissolved oxygen concentration. According to the literature, magnetite ( Fe 3 O 4 ) is confirmed to be an important oxide to describe oxygen–iron interaction in LBE. However, thermal cycling experiments indicate the presence of another oxide, besides Fe 3 O 4 , participating in LBE bulk chemistry under conditions relevant for LBE-cooled reactors (200 °C–400 °C, 1 0 − 8 wt.%– 1 0 − 5 wt.% dissolved oxygen concentration). By varying iron impurity content, nickel impurity content and cooling rate in the experiments, the oxide has been identified as hematite ( Fe 2 O 3 ). Thermodynamic equilibrium calculations show that Fe 2 O 3 formation through the reaction of Fe 3 O 4 with dissolved oxygen can explain the observed oxygen trends. As Fe 2 O 3 could form during LBE cooling, an oxygen control strategy should take into account additional oxygen consumption in the reactor cold leg. [Display omitted] • As-received liquid lead–bismuth eutectic is studied by cycling temperature. • Electrochemical oxygen sensor measures the dissolved oxygen concentration in-situ. • A new oxide is found in the bulk near the oxygen saturation limit at 200 – 400 ° C. • Addition of nickel and iron reveals the oxide is hematite forming from magnetite. • A correlation is derived to calculate the oxide's equilibrium from JANAF database. [ABSTRACT FROM AUTHOR]

Atomic-scale wear, behaving distinctly from macroscale wear, has been gaining significant scientific interest. We previously proposed a semi-empirical wear model for covalent bonding materials, which primarily describes an interfacial-bond-dominant atomic-scale wear process. To assess the model's broader applicability on other material types, herein we selected the iron oxide (Fe 2 O 3) as a representative ionic bonding material and conducted the large-scale atomistic simulations. The simulations unveiled two main atomic-scale wear mechanisms of Fe 2 O 3 : plastic deformation/cracking of nano-asperities induced by the asperity collision, and atom-by-atom attrition caused by the interfacial O–Fe bond formation. Crucially, our simulations proved effective in capturing the atom-by-atom attrition wear, thus confirming its validity for ionic materials and expanding its potential usefulness to a broader range of materials. [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]

Platinum (Pt) electrodes modified with iron (Fe) have been used as electrocatalysts to split water, to reduce oxygen, and to oxidize methanol. The current study employed cyclic voltammetry and in situ scanning tunneling microscopy (STM) to probe the redox chemistry and spatial structure of an iron hydroxide thin film adsorbed on an ordered Pt(111) electrode in pH 3 sulfate solution (1 mM H 2 SO 4 + 0.1 M K 2 SO 4) containing 10 mM FeSO 4. The Pt(111) electrode was pretreated with the conventional annealing-and-quenching method, which resulted in a sub-monolayer native oxide. After this native oxide was stripped off, the adsorption of Fe2+ ions and the reduction of oxygen concurred to yield an ordered FeOH film on the Pt(111) electrode. In situ STM imaging revealed a unique spoke – wheel (SW) structure between 0.1 and -0.1 V (vs. Ag/AgCl). As opposed to the hexagonal FeO(111) bilayer structure observed on Pt(111) in the vacuum, a distorted hexagonal adlattice was seen with this SW pattern. Shifting the potential positively and negatively resulted in transformations of the SW structure into distorted moiré patterns. The same STM experiment performed with Fe 2 (SO 4) 3 led to a disordered film, indicating that ferrous, not ferric, ions were orderly adsorbed on the Pt(111) electrode. The role of anion in the formation of the FeOH film on the Pt(111) electrode was also conducted in pH 3 chloride solution (1 mM HCl + 0.1 M KCl + FeCl 2). [Display omitted] [ABSTRACT FROM AUTHOR]