Search

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]

The phase equilibria of the ZnO-"FeO 1..5 ", ZnO-"FeO 1.5 "-SiO 2 , PbO–ZnO-"FeO 1.5 " and PbO–ZnO-"FeO 1.5 "-SiO 2 slag systems in equilibrium with air or metallic lead/iron were studied as part of the investigation of the 19-component PbO–ZnO–Cu 2 O–FeO–Fe 2 O 3 –CaO–SiO 2 –Al 2 O 3 –MgO–S-(As, Sn, Sb, Bi, Ag, Au, Ni, Cr, Co as minor elements) slag/matte/metal/speiss/gas system, supporting the operation/development of existing and emerging pyrometallurgical processes. In the experimental part of the study, samples underwent high temperature equilibration followed by quenching, and the direct measurement of the lead, zinc, iron and silicon concentrations in the liquid slag, solid oxide, and metal phases by electron probe microanalysis (EPMA). The a) massicot (PbO), b) spinel ((Zn, Fe)Fe 2 O 4), c) zincite ((Zn,Fe)O 1+x , 2 polymorphs), d) lead ferrite (Pb 2+x Fe 2 O 5+x), e) plumboferrite (Pb 4 Fe 22-x Zn x O 37), f) magnetoplumbite (Pb(Fe 2 O 3 ,PbFeO 2 ,PbZnO 2)Fe 10 O 16), and g) W-ferrite (PbZn 2-x Fe 16+x O 27) primary phase fields of the PbO–ZnO-"FeO 1.5 " system in equilibrium with air were studied between 780 and 1300 °C. The ZnO-"FeO 1.5 ", ZnO-"FeO 1.5 "-SiO 2 and PbO–ZnO-"FeO 1.5 "-SiO 2 systems in equilibrium with air were studied up to 1745 °C, significantly improving the availability of information on the composition range of the high- and low-Fe zincite ((Zn,Fe)O 1+x) phases, and on the liquid slag composition at the boundaries of their primary phase fields. Lastly, the solubilities of iron in larsenite (Pb(Zn,Fe)SiO 4) and melilite (Pb 2 (Zn,Fe)Si 2 O 7) in equilibrium with air or metal were studied between 700 and 800 °C. The newly obtained and existing experimental data were used to develop a self-consistent set of thermodynamic parameters describing all phases in the system using the FactSage computer package. [ABSTRACT FROM AUTHOR]

Nickel isotope fractionation during continental weathering is not well constrained due to the limited research on Ni isotopes during weathering of mafic rocks such as basalt. This study investigated two weathering profiles (strongly and extremely weathered) derived on basalts in tropical China. The strongly weathered profile was dominated by kaolinite and divided into three layers with depth (soil, saprolite and rock). The extremely weathered profile was mainly composed of Fe- and Al-(oxyhydr)oxides and kaolinite, and included a special ferricrust layer, iron-rich duricrust with ferruginous nodules, between the soil and saprolite. We analysed the Ni speciation (e.g. Fe-oxide phases and residual phase) and isotopic composition of soil, ferricrust, saprolite, rock and water samples in the weathering profiles. Pore water and groundwater were collected underlying the extremely weathered profile, and the size-distribution of particulate Ni (1 kDa–450 nm) in water samples was analysed. Nickel in both profiles was mainly hosted in the residual phase (>71% of total Ni) which included primarily secondary silicates and Al-(oxyhydr)oxides. Weathering intensity controlled the mineral compositions and physico-chemical properties of the weathering profiles as well as Ni isotopic variations. Nickel redistribution (∼30%) and isotope fractionation (Δ60Ni regolith-rock = −0.08‰ to 0.07‰) were slight in the strongly weathered profile due to the dominance of secondary silicates in Ni speciation. For the extremely weathered profile, significant Ni depletion (∼67%) and isotope fractionation (Δ60Ni regolith-rock = −0.25‰ to 0.32‰) were related to the transformation of secondary silicates into Fe- and Al-(oxyhydr)oxides during lateritic weathering. The positive correlation of δ60Ni and Ni concentrations indicated that Ni isotope fractionation was controlled by Ni adsorption and incorporation of secondary minerals. In the lower saprolite, the calculated isotope fractionation between Ni remaining in the profile and leaching to the solution (Δ60Ni solid-solution = −0.47‰) indicated that Ni isotope fractionation was mainly controlled by the preferential adsorption of isotopically light Ni on Fe- and Al-(oxyhydr)oxides. However, in the soil and ferricrust, acidic pH (∼5.0) might reduce Δ60Ni solid-solution to −0.28‰ by releasing the isotopically light adsorbed Ni, leading to the predominance of incorporated Ni in Fe- and Al-(oxyhydr)oxides. Specifically, the highest δ60Ni value (0.27 ± 0.05‰) and Ni concentration in the upper saprolite indicated that the isotopically heavy Ni leached from the soil and ferricrust was scavenged by precipitating secondary silicates. Finally, the estimated isotopic composition of Ni leached from the extremely weathered profile (δ60Ni output = 0.02 ± 0.15‰) was close to that of pore water (0.06 ± 0.01‰) where Ni was mainly present in the particulate phase. Compared with groundwater (δ60Ni = 0.33 ± 0.04‰) dominated by dissolved Ni, Ni output from the profile likely consisted of isotopically heavy dissolved Ni and light particulate Ni. Overall, this study provides a comprehensive understanding of Ni redistribution and speciation in basalt weathering profiles, highlighting the significance of weathering intensity in controlling Ni isotope fractionation and its implications for Ni outputs from continental weathering. [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]

Chemical Looping Hydrogen (CLH) allows the direct production of pure hydrogen exploiting the redox properties of Fe, with high flexibility on the type of reductant used. In this work, a highly pure hydrogen stream suitable for the direct use into Proton Exchange membrane Fuel Cells was produced, using bioethanol as renewable fuel. The influence of both redox temperature (675°C–750 °C) and chemical composition of the Fe-based particles (2 wt% and 40 wt% of alumina added) on the carbon formation rate during reduction step was also deeply analyzed. Al 2 O 3 changed both Fe x O y redox kinetics and equilibrium phases, leading to a complete iron deactivation at high Al 2 O 3 concentration. The addition of an air oxidation step (3 steps CLH) is fundamental to restore the redox activity, with a constant efficiency of about 30% at 750 °C for 10 cycles. Furthermore, Al 2 O 3 promotes the ethanol conversion into carbon, undermining the hydrogen purity. [Display omitted] • Pure H 2 suitable for PEMFCs is obtained using bioethanol as renewable fuel. • The influence of Fe/Al interaction on H 2 yields and H 2 purity was studied. • 3 steps CLH allows the use of Fe 2 O 3 -40 wt% Al 2 O 3 with no reduction in performance. • Fe 2 O 3 -2 wt% Al 2 O 3 withstands 10 redox cycles in the temperature range 675–750 °C. • A process efficiency of 30% was achieved at 750 °C for 10 consecutive redox cycles. [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]

[Display omitted] • Bioenergy recovery from a continuous two-stage process was greatly improved by IO. • IO promoted butyrate metabolic pathway in hydrolytic–acidogenic stage. • IO stimulated the activity of hydrolytic enzyme, dehydrogenase and coenzyme F420. • IHT between Syntrophomonas and Methanobacterium was enhanced by IO. • IO triggered DIET between Geobacter sulfurreducens and Methanosarcina. The food waste (FW) digestion performance can be enhanced by introducing iron oxide (IO) into digesters. However, the role of IO in continuous two-stage digesters in enhancing the FW anaerobic digestion remains unclear. In this study, the effect of IO on the bioenergy recovery from a two-stage digestion process was investigated. The bioenergy recovery was significantly increased by up to 208.43 % with IO addition. The activities of dehydrogenase, α-amylase, and protease increase by 0.82–1.44, 7.24–14.56 and 7.97–20.45 times, respectively, as compared with that of the blank. With IO addition, the metabolic pathway in hydrolytic–acidogenic (HA) reactor shifted from lactic acid fermentation to butyric fermentation, which promoted stable methane production in methanogenic (MG) reactor. The activity of coenzyme F420 increased by 19.19–39.01 times, indicating that IO facilitated FW digestion by promoting hydrogenotrophic methanogenesis. The enhancement in the enzyme activity was attributable to the Fe2+ generated by dissimilatory iron reduction. According to the microbial analysis, IO enhanced interspecies hydrogen transfer between Methanobacterium and Syntrophomonas. Furthermore, IO improved direct interspecies electron transfer between Geobacter sulfurreducens and Methanosarcina. The effluent recirculation strategy greatly facilitated the hydrolysis and acidification of FW, which was critical for improving the two-stage process performance. [ABSTRACT FROM AUTHOR]

With technological and economic developments, the amount of domestic and industrial solid waste is gradually increasing. It is important to investigate the methods that will ensure the disposal of waste in the roof tile industry, which is one of these solid wastes. In this study, the pigment effect of waste roof tile in ceramic glaze formulations was investigated. Waste roof tiles were added at the rate of 5-10-15-20% to the ceramic glaze formulations. Two different grinding times, 10 min and 45 min, were applied to the formed formulations, and their effects were compared. The chemical analysis of the waste tile used in the formulations by X-ray Fluorescence (XRF), the effect on the glaze surface hardness by the Vickers hardness method, and the surface properties and characterizations of the obtained samples were examined by Scanning Electron Microscopy (SEM). It is foreseen that the roof tile waste will contribute to the usability and economic/environmental aspects of the ceramic industry. [ABSTRACT FROM AUTHOR]

Fe 2 O 3 is an appealing anode material due to its high specific capacity (1007 mAh g−1), low cost, natural abundance, and nontoxicity. However, its unstable structure during cycling processes has hindered its potential. In this study, we present a "green" synthesis method to fabricate stable porous Fe 2 O 3 encapsulated in a buffering hollow structure (p -Fe 2 O 3 @ h -TiO 2) as an effective anode material for Li-ion batteries. The synthesis process only involves glucose as an "etching" agent, without the need for organic solvents or difficult-to-control environments. Characterizations of the nanostructures, chemical compositions, crystallizations, and thermal behaviors for the intermediate/final products confirm the formation of p -Fe 2 O 3 @ h -TiO 2. The synthesized Fe 2 O 3 anode material effectively accommodates volume change, decreases pulverization, and alleviates agglomeration, leading to a high capacity that is over eleven times greater than that of the as-received commercial Fe 2 O 3 after a long cycling process. This work provides an attractive, "green" and efficient method to convert commercially abundant resources like Fe 2 O 3 into effective electrode materials for energy storage systems. [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]

Baicalin obtained from natural plants has essential medical value, so the development of accurate and sensitive quantitative methods for it is one of the most important tasks. Here, the FeO X /Fe@porous carbon composite (Fe@C) was synthesized by solvothermal method and carbonized at different temperatures under an N 2 atmosphere, and an electrochemical sensor designed based on this material was applied to the accurate and rapid determination of baicalin. According to the results of physical and electrochemical characterization, Fe@C at different pyrolysis temperatures exhibited different morphologies and different electrochemical properties, while the Fe@C pyrolyzed at 800 °C had the optimum performance. Compared with NH 2 -MIL-88B, the pyrolysis greatly reduces the charge transfer internal resistance of the material and has a larger porosity and specific surface area, resulting in an eminent electrochemical signal for the detection of baicalin. The sensor Fe@C-800/GCE not only has a linear range of 4 nM–700 nM with a low limit of detection of 1.16 nM for the detection of baicalin, but also has outstanding repeatability, anti-interference and stability for the detection of baicalin in several natural plant samples and herbal medicines samples. This work presents several pyrolytic NH 2 -MIL-88B as electrochemical sensors for the detection of baicalin for the first time, providing a novel idea for the application of MOFs derivatives in environmental analysis. [Display omitted] • Pyrolyzed NH 2 -MIL-88B has large specific surface area and high catalytic activity. • The optimal pyrolysis temperature and catalytic properties of Fe@C has been found. • The baicalin sensor based on Fe@C has been constructed for the first time. • The sensor has high sensitivity and wide linear range for detection of baicalin. • The sensor has shown excellent performance in analysis of actual samples. [ABSTRACT FROM AUTHOR]

A simple and easily operated supercritical CO 2 dryer was designed and manufactured with the aim of producing high-surface-area mesoporous α-Fe 2 O 3 (hematite) and NiO aerogels. The gels were synthesized by a sol−gel method with the aid of propylene oxide (PO), as the gelation agent, and then dried and calcined at different conditions. The effects of drying and calcination conditions on the physicochemical properties of the final aerogels were investigated using X-ray diffraction (XRD), N 2 adsorption-desorption, Fourier-transformed infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FE-SEM) analyses. It was demonstrated that α-Fe 2 O 3 and NiO aerogels with high surface areas and mesoporosities could be successfully synthesized using the home-made supercritical CO 2 dryer. Supercritical drying of the gels resulted in α-Fe 2 O 3 (186 m2/g) and NiO (178 m2/g) aerogels with 186% and 34% higher surface areas, respectively, than xerogels obtained via simple drying at 80°C using a laboratory oven. In addition, the results showed that supercritical CO 2 drying could enhance preservation of the porous network of the oxide nanostructures at high calcination temperatures via suppression of sintering phenomenon. Calcination of α-Fe 2 O 3 and NiO aerogels at 600°C yielded 225% and 53% higher surface areas than the corresponding xerogel, confirming the significance of drying step in the sol − gel method. Asphaltene adsorption from a model oil with asphaltene concentration of 3000 ppm indicated that the aerogels possessed higher adsorption capacities for the bulky asphaltene molecules than xerogels calcined at the same temperature of 600°C, which was due to their enhanced textural properties. [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]

• Co 2 O 3 and CeO 2 were doped in Fe 2 O 3 as anode material of Lithium-ion battery. • The cobalt and cerium oxides doping was beneficial to particles refinement. • Co 2 O 3 and CeO 2 doping could significantly improve the electrochemical stability. Lithium-ion batteries offer several advantages, including high specific energy, extended lifespan, portability, and environmental friendliness. Transition metal oxides are attractive candidates for negative electrode materials due to their higher theoretical specific capacity. To address issues related to poor stability and volume expansion, cobalt trioxide and cerium oxide were introduced as dopants in iron oxide. This study involved the preparation of Co 2 O 3 -Fe 2 O 3 and CeO 2 -Co 2 O 3 -Fe 2 O 3 composites, followed by structural characterization and investigation of their electrochemical properties. The doping of cobalt and cerium oxide proved advantageous in refining particle size. Notably, 1% Co 2 O 3 -Fe 2 O 3 particles displayed uniform sizing and tight binding. Additionally, the sample containing 0.05% CeO 2 exhibited the smallest particle size and a more homogeneous distribution. Furthermore, cobalt and cerium oxide doping significantly improved electrochemical stability. The discharge capacity of 1% Co 2 O 3 -Fe 2 O 3 and 0.05% CeO 2 -1% Co 2 O 3 -Fe 2 O 3 after undergoing 100 constant-current charge and discharge cycle respectively remained at 553.17 mAh/g, 698.57 mAh/g. As a negative electrode material in lithium-ion batteries, the composite oxide 0.05% CeO 2 -1% Co 2 O 3 -Fe 2 O 3 demonstrated superior reversibility and stability during the process of lithium-ion insertion and removal, while also exhibiting low contact resistance and charge transfer resistance. [ABSTRACT FROM AUTHOR]

This work presents a magnetic purification method of human erythrocyte Acetylcholinesterase (EC 3.1.1.7; AChE) based on affinity binding to procainamide (Proca) as ligand. Acetylcholinesterase is an acetylcholine-regulating enzyme found in different areas of the body and associated with various neurological disorders, such as Parkinson, Alzheymer and Amyotrophic Lateral Sclerosis. AChE from human erythrocyte purification has been attempted in recent years with low degree of purity. Here, magnetic nanoparticles (MNP) were synthesized and coated with polyaniline (PANI) and procainamide (PROCA) was covalently linked to the PANI. The extracted human erythrocyte AChE formed a complex with the MNP@PANI-PROCA and an external magnet separated it from the undesired proteins. Finally, the enzyme was collected by increasing the ionic strength. Experimental Box-Behnken design was developed to optimize this process of human erythrocyte AChE purification protocol. The enzyme was purified in all fifteen experiments. However, the best AChE purification result was achieved, about 2000 times purified, when 100 mg of MNP@PANI-PROCA was incubated for one hour with 4 ml hemolysate extract. The SDS-PAGE of this preparation presented a molecular weight of approximately 70 kDa, corroborating with few previous studies of AChE from erythrocyte purification. • Acetylcholinesterase dysregulation is associated with several neurological diseases and could be useful to a possible biomarker. • Iron Magnetic Particles revested with polyaniline (PANI) were synthesized using procainamide as a specific ligand. • Hemolysate with Erythrocyte AChE was exposed to MNP@PANI-Proca, washed to remove unbound proteins by magnetic field and AChE was leached under high ionic strength. • Purification was optimized to obtain purified enzyme up to 2,000 times higher and a yield up to 400%. [ABSTRACT FROM AUTHOR]

The conductivity spectra of the iron oxide Ba 0.25 Sr 0.25 Fe 0.25 O 4 revealed that sample exhibits a semi-conductor behavior within the temperature and frequency. Based on the direct current analysis, charge carrier transport was assisted by a disorder energy below θ D / 4. For θ D / 4 ≤ T ≤ θ D / 2 , electrical conductivity was attributed to the contribution of the Mott-VRH mechanism. However, for T ≥ θ D / 2 , conduction phenomena were supported by the thermal activation of the small polaron hopping mechanism. At higher frequencies, the electrical characteristics of our sample were clarified through the application of a superlinear power law. The contributions of different conduction processes were predicted using temperature dependent frequency exponents. The hopping energy was found to decrease as the frequency increased, a trend that can be linked to variations in the polaron radius. The impedance results validate the involvement of the resistive grain boundary in the electrical properties and indicate the presence of multiple electrical relaxation phenomena in the Ba 0.25 Sr 0.25 Fe 0.25 O 4 sample. [ABSTRACT FROM AUTHOR]

[Display omitted] • Prepared Shell-Fe/ZnO composite photocatalyst through high-temperature annealing. • Shell-Fe/ZnO catalyst exhibited excellent removal efficiency with structural stability and reusability. • Developed of sustainable, highly efficient, and recyclable catalysts. In this work, a solvothermal approach was employed to load Fe and Zn elements onto processed diatom frustules, and Shell-Fe/ZnO composite photocatalyst was prepared through high-temperature annealing. The prepared Shell-Fe/ZnO composite demonstrated a degradation efficiency of 96.56 % towards TC-HCl within 120 min. Shell-Fe/ZnO was characterized using TGA, XRD, SEM, EDS. TEM, XPS and UV–vis DRS. Furthermore, the study also explored potential influencing factors such as pH, TC-HCl concentration and catalyst dosage. The results indicated that Shell-Fe/ZnO composite exhibits remarkable structural stability and reproducibility in practical applications. Burst experiments demonstrated that both components O 2 - and h + contributed to the decomposition of TC-HCl. The verification of burst experimental results was supported by TOC testing and first-order kinetic modeling. The renewable nature of diatom frustules and the ferromagnetic properties of Fe reduced the production and usage costs of the catalyst, paving the way for the development of sustainable, highly efficient, and recyclable catalysts, thereby providing a novel direction for the photochemical degradation of TC-HCl. [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]

• The solid electrolyte of iron compound powder ingots can enhance battery capacity. • The ferrous chloride will be converted into Fe 8 O 8 (OH) 8 Cl 1.35 during the charge-discharge cycle. • After charging-discharging, an abnormal layer forms at the interface of solid electrolyte and electrode, leading to interface expansion, cracks, and reduced electrode adhesion. This study investigates a Fe/SSE/GF battery. Iron (Fe) as cathode material contains higher electrical capacity and competitive advantages. The solid-state electrolyte (SSE) material is sodium silicate powder mixed with iron compound powders. There are four types of iron compounds: 1) iron oxide, 2) chlorinated/Na-rich iron oxide, 3) Cl-rich iron oxide, 4) ferrous chloride, which are compared with sodium silicate powder. The negative electrode material is graphite film (GF). According to experiments, converting iron into iron oxide or ferric chloride can enhance battery capacity (beyond 200 mAh/g) and cycle life. The reliability of the Fe/SSE/GF battery was assessed by substituting sodium silicate powder with an iron compound electrolyte and adding binder (Polyvinyl Alcohol, PVA) into powder to enhance the performance of Fe/SSE/GF. This experimental research is not only innovative but also represents a significant milestone in the field of solid-state energy storage. [ABSTRACT FROM AUTHOR]

The unsaturated behavior of permeable reactive barriers (PRB) is a critical component in predicting the removal efficiency through the adsorption of contaminants. This study investigates the framework to estimate the soil water characteristic curve (SWCC) and hydraulic conductivity function (HCF) for iron oxide-coated sand (IOCS) and zeolite, which are common materials used in PRBs. A multistep outflow (MSO) experiment was performed and the results of the MSO experiment were used to optimize associated parameters in Kosugi's SWCC and HCF. In addition, three scenarios of optimization analysis were investigated to evaluate the best-fitting model for estimating SWCC and HCF. The low root mean square error (RMSE) of fitted parameters indicates the Kosugi model well described the observed suction profiles in MSO experiments. In addition, the lowest RMSE and coefficient of variation suggested the inclusion of the additional parameter β provided the best estimation of the three materials (clean sand, IOCS, and zeolite). The physically reasonable estimation of SWCC and HCF of the three materials from the optimized parameters suggests the proposed framework is a reasonable model for the unsaturated behavior of PRBs. [Display omitted] • Multistep outflow experiment of soils was performed for predicting SWCC. • Iron oxide coated sand and zeolite were selected for PRB applications. • Fitting parameters in Kosugi's SWCC was optimized from MSO experiment. • Reliable prediction of SWCC and HCF of clean sand, IOCS, and zeolite was obtained. [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]

Iron oxide-based adsorbents showed potential to reach ultra-low phosphorus (P) concentrations to prevent eutrophication and recover P. High affinity, high capacity at low P concentrations (<1 mg L−1), good stability, and reusability of the adsorbent are key factors for economic viability. In this study, nanoparticles of goethite (α-FeOOH), a highly stable phase, have been synthesized with increasing Zn2+-doping, 0–20 %at. Zn/Fe, to manipulate the surface properties, following the results of a previous work. Mössbauer spectroscopy showed preserved goethite phase and increased point of zero charge (pzc) at low Zn-doping percentages, while at higher percentages (>5%at.) co-existing phases with increased specific surface area formed. Low concentrations (0.1–10 mg L−1) batch adsorption tests showed increased P removal per unit mass with increasing doping. However, the highest pzc, affinity and P removal per unit area were observed for the 5%at. doped sample, suggesting this dopant concentration to provide the most effective surface. A regeneration test, performed at a lower pH than usual, showed preserved, even improved P desorption with increasing doping. Mössbauer spectroscopy showed that the nanoparticle phase and composition, up to 5%at., doping was preserved throughout the process. These results are promising to develop a stable effective Zn-doped goethite-based adsorbent for P recovery at ultra-low concentrations. [Display omitted] [ABSTRACT FROM AUTHOR]

• Nb5+-doped γ - Fe 2 O 3 were synthesized by sol–gel method. • As the Nb doping increases (≥3.8 at.%), the transformation from γ - Fe 2 O 3 to α-Fe 2 O 3 was suppressed up to 600 °C. • At elevated temperature of 700 °C, γ - Fe 2 O 3 went through full transformation to α-Fe 2 O 3 by expelling large amount of Nb to the surface of α-Fe 2 O 3 forming FeNbO 4. Nb5+-doped γ - Fe 2 O 3 was synthesized by sol–gel method followed by calcination at various temperatures from 200 to 700 °C, analyzed using Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS) and Mössbauer Spectroscopy. PXRD results show the formation of γ - Fe 2 O 3 at 300 °C and it begins to transform to α-Fe 2 O 3 at 350 °C for pure and 2 at.% Nb-doped samples. As the Nb doping increases (≥3.8 at.%), the transformation was suppressed up to 600 °C. TEM EDS confirms the incorporation of Nb to γ - Fe 2 O 3 lattice in 9.1 at.% Nb sample calcined at 500 °C. At elevated temperature of 700 °C, γ - Fe 2 O 3 went through full transformation to α-Fe 2 O 3 by expelling large amount of Nb to the surface forming FeNbO 4. TEM EDS confirms the compositional change during this process with reduced Nb content in α-Fe 2 O 3 and Nb-rich nanoparticle on the surface of α-Fe 2 O 3. Superparamagnetic properties were observed for Mössbauer spectra when the Nb doping increased, which is caused by decreased particle size. The slight increase in internal magnetic field also indicated the transformation from γ - Fe 2 O 3 to α-Fe 2 O 3. High Nb doping with 20 and 40 at.% shows the formation of FeNbO 4 at lower temperature where limited or almost no Nb substitution in α-Fe 2 O 3 was detected by EDS. [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]

[Display omitted] • Fe x /ACF adsorption materials were prepared by impregnation and calcination. • Fe 0.03 /ACF-500 presented the optimal adsorption performance of toluene. • The adsorption of Fe 0.03 /ACF-500 due to its surface adsorption and pore filling. To enhance the adsorption performance of activated carbon fiber (ACF) on volatile organic compounds such as toluene, a series of Fe x /ACF adsorption materials were prepared by impregnation and anaerobic atmosphere calcination. The various adsorption effects of Fe x /ACF on toluene under different synthesis conditions were discussed, and both the modified and unmodified adsorption materials were characterized by using N 2 adsorption–desorption isotherms, XRF, XRD, FT-IR, SEM, and XPS etc methods. The results indicated that iron modified ACF demonstrated the optimal adsorption performance when ACF was loaded with 3 % iron and calcined at 500 °C, and it achieved a saturated toluene adsorption capacity of 218.12 mg/g, which was 24 % higher than that of the unmodified sample. And its adsorption process of toluene followed Yoon-Nelson model. The adsorption capacity was maintained at approximately 70 % when four adsorption/desorption cycle tests. The toluene adsorption performance of Fe 0.03 /ACF-500 on toluene mainly involved surface adsorption (such as n-π interaction, and π-π interaction), pore filling, and complexation between the loaded metal iron and toluene. [ABSTRACT FROM AUTHOR]

[Display omitted] • MCGHCOF beads were prepared and used for fluoride adsorption studies. • MCGHCOF beads remove fluoride both in standard and field water. • MCGHCOF beads are regenerable and regenerated upto six cycles. • MCGHCOF beads are providing water with safe fluoride levels. The developed biocompatible materials like covalent organic frameworks (COFs) and hydroxyapatite acquire significant defluoridation capacity (DC). But because of their powder nature, creates column blockage, pressure drop during field investigations and difficult in separation after fluoride adsorption. To address these problems, COFs and hydroxyapatite were fabricated in the usable form of beads using chitosan, gelatin and iron oxide materials as magnetic chitosan–gelatin/hydroxyapatite/covalent organic frameworks (MCGHCOF) bio-beads were developed and it was potentially applied for the removal of fluoride from water. The MCGHCOF bio-beads surface and their properties were described with FTIR, EDAX, SEM and XRD analysis. The adsorption studies were performed under the batch method. The HCO 3 – ion has a vital inhibitory effect on DC and this may be because of the similar ionic size of fluoride and HCO 3 –. The enhanced DC of MCGHCOF beads was found to be 4992 mgF-.kg−1 in 30 min at pH 7. Isotherm experimental data of fluoride adsorption was apt with Langmuir isotherm than Fruendlich and D-R isotherm models. The defluoridation system is endothermic and its spontaneous nature was demonstrated with thermodynamic studies. Kinetic studies of experimental data of fluoride adsorption were well-fitted with pseudo-second-order and intraparticle diffusion. The complexation and electrostatic interaction play a predominant role in fluoride adsorption by MCGHCOF beads. The MCGHCOF bio-beads are stable and are reusable upto six cycles. The collected field water sample was examined using MCGHCOF beads and it reduced the fluoride concentration to the tolerable drinking water threshold as recommended by WHO (1.5 mg L−1). [ABSTRACT FROM AUTHOR]

In this work, we prepared sodium borate glass doped with different amounts of iron oxide (Fe 2 O 3) and samarium oxide (Sm 2 O 3). The effects of replacing Fe 2 O 3 with Sm 2 O 3 on the absorbance, optical band gap, Urbach energy, and radiation shielding parameters were studied. With further additions of Sm 2 O 3 , the optical band gap values increased from 2.50 to 2.67 eV, while Urbach energy values decreased from 0.49 to 0.42 eV. Further, we explored the effect of sunlight on the absorbance, optical band gaps, and Urbach energy at 90 min of irradiation time. With further exposure to sunlight, the values of the optical band gaps decreased and Urbach energy increased as the exposure time increased from 0 to 90 min. Moreover, the percent of change in absorbance, optical band gap, Urbach energy, refractive index, nonlinear refractive index and third order susceptibility for the glass samples containing the highest concentration of Sm 2 O 3 is insignificant (< 10 %). The small percentage changes in absorbance, optical band gap, and Urbach energy show that the glasses are stable when exposed to sunlight. On the other hand, the inclusion of higher concentrations of Sm 2 O 3 leads to improved radiation shielding capabilities, as seen by the increased values of the mass attenuation coefficient and half-value layer. Herein, the investigated glasses are both more transparent and more effective at shielding radiation; they're prime candidates for use in this field. • With further additions of Sm 2 O 3 , the optical band gap values increased while Urbach energy values decreased. • The absorbance of all glass specimens showed reduced behavior in the ultraviolet (UV) region. • With further exposure to sunlight, the values of the optical band gaps decreased and Urbach energy increased. • The percent of changes in all parameters of the glass sample containing the highest concentration of Sm 2 O 3 & 10 %. • With higher concentrations of Sm 2 O 3 , the increased values of the mass attenuation coefficient and half-value layer. [ABSTRACT FROM AUTHOR]

Hydrogen purification by removing CO traces was studied via the preferential CO oxidation (PROX) reaction using highly dispersed Pt catalysts supported on dual oxide FeO x /TiO 2. These catalysts were prepared by the strong electrostatic adsorption (SEA) method by varying the pH of synthesis and the calcination temperature. By measuring the point of zero charge (PZC) of the support components, it was possible to determine the pH in which Pt can be selectively deposited onto one of the support components, obtaining Pt dispersion values above 90%. The selective SEA of a Pt precursor onto the co-support (FeO x) was achieved at a synthesis pH between the PZCs of the support components (i.e., TiO 2 PZC = 5.2 and Fe 2 O 3 PZC = 6.9) by using a Pt anionic complex. The catalytic activity for the PROX reaction, expressed in terms of the CO conversion, O 2 selectivity to CO 2 , apparent activation energy, and turnover frequency, confirmed that the SEA prepared catalysts were active and selective for the PROX reaction. XPS and TPR results of the Pt/FeO x /TiO 2 catalysts showed the formation of Pt-FeO x interfaces, called as (Pt-FeO x) i interfacial sites, which enhanced the stability and catalytic activity for the PROX reaction. The concentration of these sites can be controlled by the synthesis conditions used, mainly pH and to a lower extent the calcination temperature. [Display omitted] • Pt/FeO x /TiO 2 catalysts were prepared by SEA at a pH that ensures a Pt selective deposition onto Fe-based support. • 1 nm Pt crystallites were selectively deposited over FeO x at a pH between the PZCs of the support components. • The formation of (Pt-FeO x) i interfacial sites were detected by XPS, TPR, TEM and operando DRIFTS analyses. • The concentration of (Pt-FeO x) i interfacial sites is affected by the calcination temperature and the synthesis pH. • The concentration of (Pt-FeO x) i interfacial sites was correlated with the activity of Pt–Fe catalysts in the PROX reaction. [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]

[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]

Nanofluid-based direct absorption of solar heat results in thermal efficiencies superior to conventional solar thermal technology. In addition, convection of nanofluid can be sustained pump-free in the collector. In this article, we study an aqueous magnetic nanofluid capable to establish the photothermal convection in a lab-scale direct absorption solar collector equipped with a solenoid. The nanofluid consisted of 60-nm Fe 2 O 3 particles dispersed in distilled water at concentration in the range 0.5% wt.-2.0% wt. An empirical model of the photothermal convection was developed based on the experiments. The model accounted for magnetic and thermophoretic forces acting within the nanofluid. The nanofluid with up to 2.0% wt. iron oxide nanoparticles obtained the velocity of ∼ 5 mm/s under the magnetic field of up to 28 mT. This resulted in the maximum thermal efficiency of the collector equal to 65%. [Display omitted] • Nanofluid-based direct absorption solar collector is studied. • Nanofluid is produced with 0.5% and 2.0% of Fe 2 O 3 nanoparticles. • Magnetic field up to 28 mT is applied to nanofluid. • Photothermal convection is established in the fluid with the velocity of 2-5 mm/s. • Maximum thermal efficiency of the collector is 65%. [ABSTRACT FROM AUTHOR]

A porous hematite/alumina nanocomposite is produced by sol-gel combustion synthesis. The XRPD, Raman and FTIR methods show the presence of α-Fe 2 O 3 phase while SEM, TEM, EDS and BET techniques further reveal the formation of porous ellipsoid-like nanostructure of hematite nanoparticles coated by amorphous alumina. Hematite nanoparticles have a size of ~40 nm whereas the porous hematite/alumina nanocomposite particles are ~100 nm in size with characteristic pores of ~7 nm. The M(H) at 300 K exhibits coercivity H C = 293 Oe and magnetization M S = 2.71 emu/g and at 5 K H C = 1150 Oe and M S = 9.25 emu/g. The M(T) under H = 100 Oe shows a bifurcation between ZFC/FC magnetization curves at all measurement temperatures T irr >350 K (irreversibility temperature) and blocking temperature at TB ~ 305 K. Unexpectedly, the M(T) measurements under H = 10 kOe reveal the suppressed Morin transition at T M = 225 K. The analysis of the results and data from the literature reveal that the porous surface structure of hematite induces the atypical magnetic properties. A magnetic resonance imaging (MRI) properties show the transverse relaxivity rate (r2) of 0.44 mM−1s−1 at 7 T and 1.06 mM−1s−1 at 15.2 T. The investigated nanocomposite particles could be useful in biomedical applications due to their low cytotoxicity and porous nanostructure. [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]

A peerless inexpensive electrochemical engineering of spherical Pt nanoparticles (nano-Pt: ca. 100 nm in average diameter) was achieved with intersected ferric oxyhydroxide nanotubes (α-FeOOH (goethite): ca. 20 nm in average diameter). The FeOOH@Pt catalyst exhibited ca. 2.5 and 1.94-times increases in the catalytic activity and poisoning tolerance, respectively, of the formic acid electro−oxidation (FAO) – the anodic reaction in the direct formic acid fuel cells (DFAFCs). Surprisingly, with a post-activation of the FeOOH@Pt catalyst at 0.48 V vs. reversible hydrogen electrode (RHE) in 0.2 mol L−1 NaOH, a favorable Fe2+/Fe3+ transformation succeeded to eliminate the permanent CO poisoning of Pt that impaired the catalytic performance of DFAFCs. This was synchronized (relatively to nano-Pt) with a four-fold increase in the catalytic efficiency, ca. −174 mV shift in the onset potential, and eightfold enhancement in the catalyst's durability for FAO. The activated FeOOH@Pt catalyst also showed a mass activity of 296 mA mg−1 Pt (at 0.8 V), which was ca. nine times higher than that (34 mA mg−1 Pt) of the commercial Pt/C catalyst. The ascertained improvement in the electron transfer at the FeOOH@Pt surface foresees quick industrialization for DFAFCs. TOC. A simple layer-by-layer electrochemical assembly and a post-activation of a peerless inexpensive FeOOH/Pt/GC nanostructured catalyst was recommended for "mitigated CO-poisoning" formic acid electro−oxidation. [Display omitted] • An efficient and robust FeOOH/Pt anodic catalyst was developed for the direct formic acid fuel cells (DFAFCs). • The catalyst's activation at 0.48 V vs. RHE in NaOH resulted in a boosted (fourfold) catalytic performance. • The activation enriched the catalyst surface with α-FeOOH (goethite phase). • The electronic properties of Pt were tuned to accelerate the charge transfer of FAO. • The peerless inexpensive modification of Pt with FeOOH will sustain the market to realize DFAFCs. [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]

Iron-based materials are extensively employed as oxygen carriers in chemical looping processes, but their long-term performance is often inhibited by sintering and agglomeration. Here, we developed a yolk–shell structured Fe 2 O 3 @Y 2 O 3 oxygen carrier, with each unit consisting of a Y 2 O 3 shell encapsulating a nano-sized Fe 2 O 3 core. The Y 2 O 3 shell could protect the redox-active cores from sintering, and the void between the yolk and the shell is capable of tolerating cyclic volume and phase changes. During the simulated chemical looping cycles at 600 °C, the Fe 2 O 3 @Y 2 O 3 oxygen carriers exhibit a consistent oxygen carrying capacity of 3 wt% over 50 cycles, without any distinguishable structural deterioration. With rational structure optimization, the Fe 2 O 3 @Y 2 O 3 oxygen carriers with porous shell could enhance the mass transfer across the shell and enable higher reaction rates. The satisfactory sintering resistance of the Fe 2 O 3 @Y 2 O 3 nanostructure demonstrates the feasibility of employing well defined yolk–shell structured oxygen carriers for chemical looping applications. [Display omitted] • Facile synthesis of well-defined Fe 2 O 3 @Y 2 O 3 yolk–shell nanostructured oxygen carriers. • A consistent oxygen carrying capacity of ∼3 wt% over 50 consecutive redox cycles. • The Yttria shell could protect the redox-active cores from sintering and agglomeration. • Enhanced mass transfer was achieved by modifying the shell porosity. [ABSTRACT FROM AUTHOR]

The catalytic performance of modified hydroxyapatite nanoparticles, Ca 10-x Fe x-y W y (PO 4) 6 (OH) 2 , was applied for the degradation of methylene blue (MB), fast green FCF (FG) and norfloxacin (NOR). XPS analysis pointed to the successful partial replacement of Ca by Fe. Under photo-electro-Fenton process, the catalyst Ca 4 FeII 1·92 W 0·08 FeIII 4 (PO 4) 6 (OH) 2 was combined with UVC radiation and electrogenerated H 2 O 2 in a Printex L6 carbon-based gas diffusion electrode. The application of only 10 mA cm−2 resulted in 100% discoloration of MB and FG dyes in 50 min of treatment at pH 2.5, 7.0 and 9.0. The proposed treatment mechanism yielded maximum TOC removal of ∼80% and high mineralization current efficiency of ∼64%. Complete degradation of NOR was obtained in 40 min, and high mineralization of ∼86% was recorded after 240 min of treatment. Responses obtained from LC-ESI-MS/MS are in line with the theoretical Fukui indices and the ECOSAR data. The study enabled us to predict the main degradation route and the acute and chronic toxicity of the by-products formed during the contaminants degradation. [Display omitted] • New modified hydroxyapatite nanoparticles as catalysts to produce.●OH in the MB, FG dyes and NOR degradation; • High recyclability of the heterogeneous catalyst was verified due to magnetic properties. • MB, FG dyes and NOR reached high degradation rate by Photo-Electro-Fenton process using GDE. • Acute and chronic theoretical toxicological was evaluated to NOR. • The by-product identification study resulted in low toxicity compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • α-Fe 2 O 3 was evaluated as anode of solid-state batteries using oxide electrolyte. • Smaller Fe 2 O 3 particles showed better anode performance. • Contact area between Fe 2 O 3 and the electrolyte was increased to improve performance. • Fe 2 O 3 anode operated for the first time in oxide-based solid-state Li batteries. As Li-ion battery anode materials, two types of hematite (Fe 2 O 3 (big), Fe 2 O 3 (ultrafine)) were evaluated by using liquid electrolyte and oxide-based solid electrolyte. Although the anode using Fe 2 O 3 (ultrafine) with larger specific surface area showed a high initial reversible capacity in the liquid-electrolyte cell, there was a steep capacity decay in the cycling test. In the solid-electrolyte cell, we obtained very low reversible capacities of 40 mA h g−1 for the anode using Fe 2 O 3 (big) with smaller specific surface area. In contrast, the capacity of Fe 2 O 3 (ultrafine) anode was as high as 400 mA h g−1 at the 20th cycle. This is the first demonstration of charge–discharge reactions for Fe 2 O 3 anode in oxide-based solid-state batteries. The Fe 2 O 3 (ultrafine) particles were dispersed relatively uniformly between solid electrolyte in the active layer, suggesting that the contact area between Fe 2 O 3 and solid electrolyte becomes large. Consequently, Fe 2 O 3 (ultrafine) could benefit from larger contact area delivering the suitable reaction site for Li+ to improve the anode performance. [ABSTRACT FROM AUTHOR]

Reverse loading of inert Al 2 O 3 support onto reactive FeO x nanoparticles generates nanocomposite with unusually improved reactivity and stability for H 2 O 2 activation and pollutant removal, compared to the analogue traditional nanocomposite which was prepared via the loading of FeO x nanoparticles onto inert Al 2 O 3 support. [Display omitted] • Reverse loading of inert Al 2 O 3 onto reactive FeO x to generate FeO x @Al 2 O 3 -R. • FeO x @Al 2 O 3 -R shows much improved reactivity in H 2 O 2 activation than its traditional analogue. • FeO x @Al 2 O 3 -R also shows greatly enhanced stability featuring suppressed ion leaching. • The inert Al ions modify the electronic environment and properties of the surface Fe reactive sites. Developing heterogeneous iron-based catalysts with superior reactivity and stability is a long-term goal for hydrogen peroxide (H 2 O 2) activation in Fenton-like technique for water remediation. Supported iron-based nanocomposites are of great interest due to their earth abundance, environmental friendliness, and tunable structure. However, existing iron-based Fenton catalysts are normally designed via the loading of iron-derived nanoparticles onto various inert substrates, where the surface reactive sites are hardly affected by the substrate. Here, we report the first example of reversely loaded FeO x -Al 2 O 3 nanocomposite via overturning the loading direction, i.e., loading inert Al 2 O 3 support onto reactive FeO x nanoparticles. The resultant FeO x @Al 2 O 3 -R catalyst demonstrated much improved reactivity for H 2 O 2 activation and bisphenol A removal (by 14 times in terms of first-order rate constant) than its analog FeO x /Al 2 O 3 -T, which was prepared via the loading of FeO x nanoparticles onto inert Al 2 O 3 support. Moreover, FeO x @Al 2 O 3 -R exhibited excellent stability with Fe leaching only one sixth of FeO x /Al 2 O 3 -T. Systematic characterization results revealed that the inert Al ions modify the electronic environment and properties of the surface Fe reactive sites. This work provides an alternative reverse loading strategy to traditional loading method for the preparation of iron-based nanocomposite catalyst that is highly efficient for H 2 O 2 activation and pollutant removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Plastic waste fuelled SOFCs gain highly improved performance by Fe 2 O 3 modified anode. • Pseudofuel nature of iron oxide in SOFCs is systematically examined. • Structural optimization of Fe 2 O 3 greatly enhances the discharge capacity of FeO. • Discharge capacity of FeO reaches 91% of theoretical value via FeO-Ag-GDC synergism. Waste plastics-to-power conversion via fuel cells is very attractive for its potential to be efficient and eco-friendly. Here we report a solid oxide fuel cell (SOFC) operating directly on waste polyethylene terephthalate (PET) with significantly improved performance due to the modification of anode with iron oxide (Fe 2 O 3) that functions as pseudofuel in its reduced form (FeO). The pseudofuel performance, namely the discharge capacity of FeO, was improved significantly by optimizing the structure of Fe 2 O 3 , and owing to the synergistic interaction of FeO with the anodic materials, i.e. silver and gadolinia doped ceria. A mechanism is proposed to reveal the synergistic effect of these materials in the discharge process. The maximum discharge capacity of 340 mAh/g for FeO was obtained, approaching 91 % of the theoretical value. Based on the optimized pseudofuel, the electrochemical performance of SOFCs directly fueled by waste PET was markedly enhanced: The peak power density of the cell increased from 115 to 320 mW cm−2, and the electric energy output of the PET fuel did from 0.0018 to 0.26 Wh/g (140-fold more). This work shows that SOFCs with Fe 2 O 3 modified Ag-based anode offer a promising platform for direct conversion of plastic waste to power in an efficient and green manner. [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]

The forefront hydrogel nanocomposite, resulting from the integration of Agarose (Aga), Graphene Quantum Dots (GQDs), and α-Fe2O3, offers a novel approach to pH-responsive drug delivery, specifically tailored for the controlled release of Quercetin (QC), a potent anti-cancer agent. The incorporation of the surfactant Span 80 enhances the unique properties conferred by the integration of α-Fe2O3 into the Aga-modified GQDs hydrogel, resulting in the production of stable nanocarriers that improve QC retention. Thorough analyses utilizing Fourier-transform Infrared Spectroscopy (FT-IR) and X-ray Diffraction (XRD) shed light on the characteristics of the nanocarriers. The presence of nanoparticles within the nanocarriers was confirmed by Dynamic Light Scattering (DLS), revealing a spherical morphology with an average size of approximately 279.04 nm and a polydispersity index (PDI) of 0.24. Measurements of the zeta potential indicated a positive surface charge of about 52.8 mV. In the Aga/GQDs configuration, loading and encapsulation efficiencies reached 35 % and 67 %, respectively. With the inclusion of α-Fe2O3, improvements were observed, with loading and encapsulation efficiencies reaching 47 % and 86.25 %, respectively, surpassing previous values. Cellular tests conducted on the HepG2 cell line demonstrated the heightened anticancer efficacy of QC-loaded nanoparticles while assessing potential adverse effects. These results underscore the exciting potential of the nanocarrier as a promising strategy for cancer treatment. • Development of a pH-responsive hydrogel nanocomposite integrating Agarose, Graphene Quantum Dots, and α-Fe2O3 for controlled drug delivery. • Optimization of loading and encapsulation efficiencies through the inclusion of α-Fe2O3, surpassing previous benchmarks. • Demonstrated efficacy against HepG2 cancer cells, highlighting the potential of the nanocomposite as a promising strategy for cancer treatment. [ABSTRACT FROM AUTHOR]

The presence of arsenic in groundwater, and through this in drinking water, has been shown to present a serious risk to public health in many regions of the world. In this study, two iron-rich carbonous adsorbents were compared for the removal of arsenate (As(V)) from groundwater. Biochars (FeO-biochar and FeO-pyrochar) derived from biomass waste were functionalised in two different ways with iron chloride for comparation. Batch and dynamic parameters were optimised to achieve >99% As(V) removal efficiency. Experimental data were best described by the pseudo-second order kinetic model, while multi-stage diffusion appeared to limit mass transfer of As(V). Among the isotherm models evaluated, the Freundlich model best described the experimental results with high correlation coefficients (R 2 ≥ 0.94) for both adsorbents. Monolayer adsorption capacities were found to be 4.34 mg/g and 8.66 mg/g for FeO-biochar and FeO-pyrochar, respectively. Batch studies followed by instrumental characterisation of the materials indicated the removal mechanisms involved to be electrostatic interactions (outer-sphere), OH− ligand exchange (inner-sphere complexation) and hydrogen bonding with functional groups. Higher pH pzc (9.1), S BET (167.2 m2/g), and iron/elemental content for the FeO-pyrochar (compared with the FeO-biochar) suggested that both surface chemistry and porosity/surface area were important in adsorption. Dynamic studies showed FeO-pyrochar can be used to remove As(V) from groundwater even at low 'environmental' concentrations relevant to legislative limits (<10 μg/L), whereby 7 g of FeO-pyrochar was able to treat 5.4 L groundwater. [Display omitted] • Surface chemistry and structure were crucial for determining As(V) adsorption. • As(V) adsorption was governed by Fe content, pH pzc and porosity. • Adsorption of As(V) on biochar occurred through complexation and hydrogen bonding. • Successful desorption even with highly diluted NaOH. • Efficient treatment of As(V) contaminated groundwater in dynamic column. [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]

There is a growing interest in eco-friendly and cost-effective organic-inorganic nanocomposites due to their alignment with the principles of "green" chemistry, as well as their biocompatibility and non-toxicity. This study focused on producing Chitosan-PEG-Fe 2 O 3 @NiO nanomagnetic composites to improve the stability, dielectric properties, and antimicrobial effectiveness of these nanocomposite materials. The process involved synthesizing Fe 2 O 3 @NiO via sol-gel and polymerizing chitosan-PEG. The nanocomposites were characterized by XRD, TEM, FTIR, optical, dielectric, and VSM. Incorporating Fe 2 O 3 @NiO significantly improved stability, and the interaction with Fe2O3 during the sol-gel process facilitated the formation of NiFe 2 O 4 with an increase in the crystallinity within the chitosan-PEG matrix. The study examined optical and dielectric properties, highlighting that the 3 NiO-doped chitosan-PEG-Fe 2 O 3 composites had high electrical conductivity (1.8 ∗ 10−3 S/cm) and a significant dielectric constant (106 at low frequencies). As the ratio of NiO NPs within the chitosan-PEG-Fe 2 O 3 increases, the energy band gap of chitosan-PEG-Fe 2 O 3 films decreases up to 3.7 eV. This decrease is owing to the quantum confinement effect. These composites also demonstrated improved antimicrobial activity against E. coli and S. aureus and higher activity in the presence of nanomagnetic particles. The minimum inhibitory concentrations of CS-PEG-Fe 2 O 3 /NiO NPs against (Bacillus cereus , M. luteus , S. aureus and (S. enterica , H. pylori , E. coli) were (22–35 mm) and (21–34 mm), respectively. [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]