Search

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]

Breakaway corrosion of Fe-base alloys remains a challenge in applications operated in harsh conditions. The material lifetimes are often determined by the corrosion propagation after breakaway. Nevertheless, detailed microstructural studies, linking the protective properties of the Fe-rich oxides formed after breakaway, are scarce. This study utilizes APT to investigate the Fe-rich oxides formed after breakaway, i.e., the secondary corrosion protection, of four Fe-based model alloys chosen to exhibit good and poor secondary protection at 600 °C. The APT investigation shows that the inward-growing scale is heterogeneous at the nanometer scale and that Fe-enriched regions form on the poorly protective oxides. [Display omitted] • Fe-rich oxides formed after breakaway of FeCrNi and FeCrAl(Si) alloys are studied. • Higher Si or Ni contents significantly reduce growth rates of Fe-rich oxide scales. • APT-measurements elucidates heterogeneous structure(nm) of the inward-growing scale. • Spinel-miscibility gap is suggested to be related to performance after breakaway. [ABSTRACT FROM AUTHOR]

Hematite nanoparticles commonly undergoes isomorphic substitution of Al3+ in nature, while how the Al-substitution-induced morphological change, defective structure and newly generated Al–OH sites affect the adsorption behavior of hematite for contaminants remains poorly understood. Herein, the interfacial reactions between Al-substituted hematite and Pb2+ was investigated via CD-MUSIC modeling and DFT calculations. As the Al content increased from 0% to 9.4%, Al-substitution promoted the proportion of (001) facets and caused Fe vacancies on hematite, which increased the total active site density of hematite from 5.60 to 17.60 sites/nm2. The surface positive charge of hematite significantly increased from 0.096 to 0.418 C/m2 at pH 5.0 due to the increases in site density and proton affinity (log K H) of hematite under Al-substitution. The adsorption amount of hematite for Pb2+ increased from 3.92 to 9.74 mmol/kg at pH 5.0 and 20 μmol/L initial Pb2+ concentration with increasing Al content. More Fe vacancies may lead to a weaker adsorption energy (E ad) of hematite for Pb2+, while the E ad was enhanced at higher Al content. The adsorption affinity (log K Pb) of bidentate Pb complexes slightly increased while that of tridentate Pb complexes decreased with increasing Al content due to the presence of ≡ AlOH−0.5 and ≡ Fe 2 AlO−0.5 sites. Tridentate Pb complexes were dominant species on the surface of pure hematite, while bidentate ones became more dominant with increasing Al content. The obtained model parameters and molecular scale information are of great importance for better describing and predicting the environmental fate of toxic heavy metals in terrestrial and aquatic environments. [Display omitted] • Adsorption of Al-hematite for Pb2+ was studied via CD-MUSIC and DFT calculation. • Al-substitution increased total active site density of hematite from 5.60 to 17.60 sites/nm2. • Al-substitution in hematite enhance its surface charge and Pb2+ adsorption. • Presence of ≡ AlOH−0.5 and ≡ Fe 2 AlO−0.5 sites altered the log K Pb and E ads of Pb2+ on hematite. • Bidentate Pb complexes became more dominant on hematite with increasing Al content. [ABSTRACT FROM AUTHOR]

Pesticides can have harmful impacts on the environment and living organisms. Thus, removing them from polluted water is crucial. In this study, a bionanocomposite of carboxymethyl tragacanth- grafted -poly(3-aminophenol)/zinc oxide@iron oxide (CMT- g -P3AP/ZnO@Fe 3 O 4) synthesized by in situ copolymerization as an efficient adsorbent to eliminate the acetamiprid pesticide from polluted water. The CMT- g -P3AP/ZnO@Fe 3 O 4 magnetic nanocomposite was analyzed utilizing various techniques including FTIR, EDX, FESEM, XRD, BET, CHNSO, and TGA. The results displayed that the resulting nanocomposite with maximum adsorption capacity (Q max) successfully removed the acetamiprid pesticide from polluted water under optimal conditions such as pH of 7.00, 5.00 mg of adsorbent, 20.0 min duration, and 400 mg/L acetamiprid concentration. According to the linear Langmuir isotherm, the Q max of the biosorbent was 833 mg/g. The experimental adsorption data fitted well with Temkin's nonlinear isotherm model. The adsorption kinetic data were closely related to the Weber-Morris intraparticle diffusion nonlinear model. After three repetitive cycles, CMT- g -P3AP/ZnO@Fe 3 O 4 can be outstandingly renewed and recycled without significant reduction in its adsorption efficacy, as evidenced by the adsorption-desorption experiments. In addition, the CMT-g-P3AP/ZnO@Fe 3 O 4 displayed the good antibacterial activity against E. coli and S. aureus. [Display omitted] • Antibacterial magnetic bionanocomposite based on carboxymethyl tragacanth synthesized. • Antibacterial magnetic bionanocomposite used as a sorbent for acetamiprid removal. • Maximum adsorption capacity of the bionanocomposite for acetamiprid was 833 mg/g. • Bionanocomposite showed good antibacterial activity against E. coli and S. aureus. [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]

[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]

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]

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 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]

The role of precipitates from acid mine drainage (AMD) in arsenic removal in water is a process to be investigated in more detail. The present study is focused on the potential use of two AMD precipitates using oxidation and Ca(OH)2 (OxPFe1) or CaCO3 (OxPFe2) as As(V) adsorbents and the comparison of their performance with two commercial adsorbents (nanohematite and Bayoxide®). The AMD’s supernatants and precipitates were characterized using several techniques and assessed with theoretical speciation and mass balance methods. Gypsum was identified by XRD and assessed as the main component of the precipitates. Amorphous iron hydroxide was assessed as the second component (22% in mass), and jurbanite or aluminum hydroxide were present in the third likely phase. The equilibrium adsorption of As(V) in water at a pH between 4 and 6 was tested with the four adsorbents, and the Langmuir model correlated well. The maximum adsorption capacity (qmax) had the highest value for OxPFe1 and the lowest value for nanohematite (that could be explained in terms of the adsorbent surface speciation). The two precipitates have limited application to the adsorption of very low concentrations of arsenic because they have a binding constant (b) lower than the commercial adsorbents and could release a small amount of the arsenic contained in the precipitate.

Methylene blue (MB) is a hazardous chemical that is widely found in wastewater, and its removal is critical. One of the most common methods to remove MB is adsorption. To enhance the adsorption process, magnetic adsorbents, particularly those based on superparamagnetic iron oxide nanoparticles (SPION), play a vital role. This study focuses on comparing recent novel SPION-based MB adsorbents and how to acquire the critical parameters needed to evaluate the adsorption and desorption mechanisms, including isotherms, kinetics, and thermodynamic properties. Moreover, the review article also discusses the future aspects of these adsorbents.

A dire need for real-time detection of toxic chemical compounds exists in both civilian and military spheres. In this paper, we demonstrate that inexpensive, commercially available Fe2O3 nanoparticles are capable of selective sensing of chemical warfare agents (CWAs) using frequency-dependent impedance spectroscopy, with additional potential as an orthogonal magnetic sensor. X-ray magnetic circular dichroism analysis shows that Fe2O3 nanoparticles possess moderately lowered moment upon exposure to 2-chloroethyl ethyl sulfide (2-CEES) and diisopropyl methylphosphonate (DIMP) and significantly lowered moment upon exposure to dimethyl methylphosphonate (DMMP) and dimethyl chlorophosphate (DMCP). Associated X-ray absorption spectra confirm a redox reaction in the Fe2O3 nanoparticles due to CWA structural analog exposure, with differentiable energy-dependent features that suggest selective sensing is possible, given the correct method. Impedance spectroscopy performed on samples dosed with DMMP, DMCP, and tabun (GA, chemical warfare nerve agent) showed strong, differentiable, frequency-dependent responses. The frequency profiles provide unique “shift fingerprints” with which high specificity can be determined, even amongst similar analytes. The results suggest that frequency-dependent impedance fingerprinting using commercially available Fe2O3 nanoparticles as a sensor material is a feasible route to selective detection.

We demonstrate the utilization of iron oxide (Fe2O3) as light-absorbing material in an erbium-doped fiber laser (EDFL) for the generation of Q-switched pulses. A sandwich-type saturable absorber (SA) with Fe2O3 nanoparticles between fiber ferrules is proposed. A fiber ferrule tip is tapped onto a cap of index-matching gel, which is then dipped into Fe2O3 nanoparticle powder to allow its deposition through the adhesion effect. By incorporating Fe2O3–SA in an EDFL, self-started and stable Q-switched pulses are attained at a threshold power of 50.1 mW. The pulse repetition rate is tunable from 9.92 kHz to 22.47 kHz, whereas the pulse duration reduces from 38.4 µs to 13.8 µs with the pump power increment. The maximum pulse energy achieved is 36.9 nJ. This work offers a simple integration method of Fe2O3 nanoparticles as potential SAs for the generation of Q-switched pulses.

In this study, a novel electrochemical assay for determining 17-β-estradiol (E2) was proposed. The approach involves modifying a glassy carbon electrode (GCE) with a nanocomposite consisting of α-Fe2O3 nanoparticles supported on carbon nanotubes (CNTs)—denoted as α-Fe2O3-CNT/GCE. The synthesis of the α-Fe2O3-CNT nanocomposite was achieved through a simple and cost-effective hydrothermal process. Morphological and chemical characterization were conducted using scanning electron microscopy (SEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The presence of the α-Fe2O3-CNT film on the GCE surface resulted in an enhanced electrochemical response to E2, preventing electrode surface fouling and mitigating the decrease in peak current intensity during E2 oxidation. These outcomes substantiate the rationale behind the GCE modification. After the optimization of experimental conditions, E2 was determined by the square wave voltammetry technique using 0.1 mol L−1 KCl solution (pH = 7.0) with 20% ethanol as a supporting electrolyte. A linear concentration range of 5.0–100.0 nmol L−1 and a low limit of detection of 4.4 nmol L−1 were obtained. The electroanalytical method using α-Fe2O3-CNT/GCE was applied for E2 determination in pharmaceutical, lake water, and synthetic urine samples. The obtained results were attested by recovery tests and by high-performance liquid chromatography as a comparative technique at a 95% confidence level. Thus, the developed electrochemical sensor is simple and fast to obtain, presents high accuracy, and is viable for determining E2 in routine analysis.

Nanoparticle-based drugs offer attractive advantages like targeted delivery to the diseased site and size and shape-controlled properties. Therefore, understanding the particulate flow of the nanodrugs is important for effective delivery, accurate prediction of required dosage, and developing efficient drug delivery platforms for nanodrugs. In this study, the transport of nanodrugs including flow velocity and deposition is investigated using three model metal oxide nanodrugs of different sizes including iron oxide, zinc oxide, and combined Cu-Zn-Fe oxide synthesized via a modified polyol approach. The hydrodynamic size, size, morphology, chemical composition, crystal phase, and surface functional groups of the water-soluble nanodrugs were characterized via dynamic light scattering, transmission electron microscopy, scanning electron microscopy-energy dispersive X-ray, X-ray diffraction, and fourier transform infrared spectroscopy, respectively. Two different biomimetic flow channels with customized surfaces are developed via 3D printing to experimentally monitor the velocity and deposition of the different nanodrugs. A diffusion dominated mechanism of flow is seen in size ranges 92 nm to 110 nm of the nanodrugs, from the experimental velocity and mass loss profiles. The flow velocity analysis also shows that the transport of nanodrugs is controlled by sedimentation processes in the larger size ranges of 110–302 nm. However, the combined overview from experimental mass loss and velocity trends indicates presence of both diffusive and sedimentation forces in the 110–302 nm size ranges. It is also discovered that the nanodrugs with higher positive surface charges are transported faster through the two test channels, which also leads to lower deposition of these nanodrugs on the walls of the flow channels. The results from this study will be valuable in realizing reliable and cost-effective in vitro experimental approaches that can support in vivo methods to predict the flow of new nanodrugs.

This comprehensive study investigates the properties of chemical nanomagnetic iron oxide particles (CNMIOPs) synthesized through a chemical method. The primary objective is to examine how pH levels and washing solvents affect the magnetism properties of these nanoparticles. Three different pH levels (1.2, 7.5, and 12.5) using NaOH and two washing solvents (ethanol and water) are employed. The characterization techniques include FTIR, SEM, TEM, XRD, ZSP, and VSM. Furthermore, the study incorporates two specific pH- and solvent-dependent CNMIOPs into PCL electrospun materials to analyze their performance in a targeted application. The results show that pH and the washing process significantly affect the CNMIOPs’ properties. Higher pH levels result in smaller particles with higher crystallinity and reduce crystalline anisotropy. SEM and TEM analysis confirm different morphologies, including cubic, spherical, and elongated shapes. Ethanol-washed CNMIOPs exhibit superior magnetic behavior, with the highest magnetization saturation at pH 12.5 (Ms = 58.3 emu/g). The stability of the CNMIOPs ranges from −14.7 to −23.8 mV, and higher pH levels exhibit promising antioxidant activity. Furthermore, the study explores the effects of pH and washing solvents on CNMIOP-infused nanofiber membranes, with better dispersion observed with ethanol washing. Overall, this research provides valuable insights into the properties and behavior of CNMIOPs under varying pH and washing conditions.

The ubiquitous presence of pharmaceutical pollution in the environment and its adverse impacts on public health and aquatic ecosystems have recently attracted increasing attention. Graphene oxide coated with magnetite (GO-Fe3O4) is effective at removing pharmaceuticals in water by adsorption. However, the myriad compositions in real water are known to adversely impact the adsorption performance. One objective of this study was to investigate the influence of pore blockage by natural organic matter (NOM) with different sizes on pharmaceutical adsorption onto GO-Fe3O4. Meanwhile, the feasibility of pore dimension tuning of GO-Fe3O4 for selective adsorption of pharmaceuticals with different structural characteristics was explored. It was shown in the batch experiments that the adsorbed pharmaceutical concentrations onto GO-Fe3O4 were significantly affected (dropped by 2–86%) by NOM that had size ranges similar to the pore dimensions of GO-Fe3O4, as the impact was enhanced when the adsorption occurred at acidic pHs (e.g., pH 3). Specific surface areas, zeta potentials, pore volumes, and pore-size distributions of GO-Fe3O4 were influenced by the Fe content forming different-sized Fe3O4 between GO layers. Low Fe contents in GO-Fe3O4 increased the formation of nano-sized pores (2.0–12.5 nm) that were efficient in the adsorption of pharmaceuticals with low molecular weights (e.g., 129 kDa) or planar structures via size discrimination or inter-planar π-π interaction, respectively. As excess larger-sized pores (e.g., >50 nm) were formed on the surface of GO-Fe3O4 due to higher Fe contents, pharmaceuticals with larger molecular weights (e.g., 296 kDa) or those removed by electrostatic attraction between the adsorbate and adsorbent dominated on the GO-Fe3O4 surface. Given these observations, the surface characteristics of GO-Fe3O4 were alterable to selectively remove different pharmaceuticals in water by adsorption, and the critical factors determining the adsorption performance were discussed. These findings provide useful views on the feasibility of treating pharmaceutical wastewater, recycling valuable pharmaceuticals, or removing those with risks to public health and ecosystems.

Octylamine (OTA), 1-dodecanethiol (DDT), and tri-n-octylphosphine (TOP) capped magnetite nanoparticles were prepared by co-precipitation method. Powder X-ray diffraction patterns confirmed inverse spinel crystalline phases for the as-prepared iron oxide nanoparticles. Transmission electron microscopic micrographs showed iron oxide nanoparticles with mean particle sizes of 2.1 nm for Fe3O4-OTA, 5.0 nm for Fe3O4-DDT, and 4.4 nm for Fe3O4-TOP. The energy bandgap of the iron oxide nanoparticles ranges from 2.25 eV to 2.76 eV. The iron oxide nanoparticles were used as photocatalysts for the degradation of methylene blue with an efficiency of 55.5%, 58.3%, and 66.7% for Fe3O4-OTA, Fe3O4-DDT, and Fe3O4-TOP, respectively, while for methyl orange the degradation efficiencies were 63.8%, 47.7%, and 74.1%, respectively. The results showed that tri-n-octylphosphine capped iron oxide nanoparticles are the most efficient iron oxide nano-photocatalysts for the degradation of both dyes. Scavenger studies show that electrons (e−) and hydroxy radicals (•OH) contribute significantly to the photocatalytic degradation reaction of both methylene blue and methyl orange using Fe3O4-TOP nanoparticles. The influence of the dye solution’s pH on the photocatalytic reaction reveals that a pH of 10 is the optimum for methylene blue degradation, whereas a pH of 2 is best for methyl orange photocatalytic degradation using the as-prepared iron oxide nano-photocatalyst. Recyclability studies revealed that the iron oxide photocatalysts can be recycled three times without losing their photocatalytic activity.

The hierarchical structure is an ideal nanostructure for conversion-type anodes with drastic volume expansion. Here, we demonstrate a tin-doping strategy for constructing Fe2O3 brushes, in which nanowires with exposed (001) facets are stacked into the hierarchical structure. Thanks to the tin-doping, the conductivity of the Sn-doped Fe2O3 has been improved greatly. Moreover, the volume changes of the Sn-doped Fe2O3 anodes can be limited to ~4% vertical expansion and ~13% horizontal expansion, thus resulting in high-rate performance and long-life stability due to the exposed (001) facet and the unique hierarchical structure. As a result, it delivers a high reversible lithium storage capacity of 580 mAh/g at a current density of 0.2C (0.2 A/g), and excellent rate performance of above 400 mAh/g even at a high current density of 2C (2 A/g) over 500 cycles, which is much higher than most of the reported transition metal oxide anodes. This doping strategy and the unique hierarchical structures bring inspiration for nanostructure design of functional materials in energy storage.

Soils are a globally important reservoir of organic carbon. There is a growing understanding that interactions with soil mineral phases contribute to the accumulation and retention of otherwise degradable organic matter (OM) in soils and sediments. However, the bioavailability of organic compounds in mineral-organic-associations (MOAs), especially under varying environmental conditions is not well known. To assess the impact of mineral association and warming on the decomposition of an easily respirable organic substrate (glucose), we conducted a series of laboratory incubations at different temperatures with field-collected soils from 10 to 20cm, 50-60cm, and 80-90cm depth. We added 13C-labeled glucose either directly to native soil or sorbed to one of two synthetic iron (hydr)oxide phases (goethite and ferrihydrite) that differ in crystallinity and affinity for sorbing glucose. We found that: (1) association with the Fe (hydr)oxide minerals reduced the decomposition rate of glucose by >99.5% relative to rate of decomposition for free glucose in soil; (2) the respiration rate per gram carbon did not differ appreciably with depth, suggesting a similar degree of decomposability for native C across depths and that under the incubation conditions total carbon availability represents the principal limitation on respiration under these conditions as opposed to reduced abundance of decomposers or moisture and oxygen limitations; (3) addition of free glucose enhanced native carbon respiration at all soil depths with the largest effect at 50-60cm; (4) in general respiration of the organo-mineral complex (glucose and iron-(hydr)oxide) was less temperature sensitive than was respiration of native carbon; (5) the addition of organic free mineral decreased the rate of soil respiration in the intermediate 50-60cm depth soil. The results emphasize the key role of MOAs in regulating the fluxes of carbon from soils to the atmosphere and in turn the stocks of soil carbon.

A carboxyl-terminated fullerene pyrrolidine derivative was synthesized by 1, 3-dipolar cycloaddition of imine ylide (FP-COOH). UV-Vis, FT-IR and MALDI-TOF respectively verified the effective synthesis of compounds. The compound (FP-COOH) was used as an intermediate, and then the hydrothermal chemical bonding method was used to load ferric oxide on the compound (FP-COOH). Its purpose was to form a magnetic targeting carrier system (FP-IONP-COOH). Then use the non-covalent method to combine FP-IONP-COOH with doxorubicin. The ultimate goal was to improve the side effects of doxorubicin. The solubility experiments showed that both FP-IONP-COOH and FP-IONP-COOH/DOX had good water solubility. The investigation of magnetism showed that FP-IONP-COOH has good magnetism. Finally, in vitro release experiments further verified the targeting of FP-IONP-COOH/DOX. The cumulative release of DOX at 48 h could be as high as 82 %, whereas the accumulated release of FP-IONP-COOH/DOX at 48 h was only 48 %, and was able to continuously release for more than 120 h, demonstrating its good sustained release in vivo.

In this study, we applied iron (-oxide) incorporated carbide nanofiber composites as heterogeneous catalysts with wide visible-light absorption ability, catalytic reactivity, and catalytic stability for the highly efficient decomposition performance. Notably, water vapor activated iron (-oxide) incorporated carbide nanofiber catalyst (Act-Fe-CNF) showed high crystalline Fe3O4 phase, saturation magnetization point (17.76 emu/g), and large surface area (508.2 m2/g). In water vapor activation, Fe3C particles inside carbide nanofiber oxidized and aggregated to larger Fe3O4 particles, thereby forming a meso/macroporous structure and improving surface area offering more available active sites for catalytic reactivity. Under both UV-/real solar-light irradiation, it was demonstrated that the Act-Fe-CNF catalysts exhibited unprecedentedly excellent removal capabilities (>98%, [k] = 4.06 h−1) for rhodamine B, leading to complete water purification. Interestingly, the AF-CNFs catalysts also showed strong antimicrobial activities against gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) under incandescent-light irradiation. These results indicated that the Act-Fe-CNF catalysts might have utility in important environmental and bio-medical applications.

Thermoset nanocomposites, due to their strength and special physical and mechanical properties compared to metal materials, are widely used in the manufacture of household appliances, electrical appliances, coatings and sports equipment, and sanitary wares. The thermal properties of epoxy nanocomposites depend on the adhesion between the nanoparticles and matrix. Also, designing high quality and efficient epoxy nanocomposites with suitable physical and mechanical properties requires understanding the phenomena that occur during the curing reaction. The reaction of epoxy resin and curing agent as well as the study of curing kinetics play an important role in controlling the deformation of the structure and physical and mechanical properties of the composites. Investigating the dispersion of nanoparticles and selecting the appropriate mixing method can improve the curing reaction or crosslinking of epoxy nanocomposites. It can also prevent the agglomeration of nanoparticles, that affect thermal reactions. Modified iron oxide nanoparticles reduce the reaction activation energy and the curing time. Reaction time and temperature are two important factors for evaluating chemical curing reactions. Modeling analysis of curing kinetics of epoxy nanocomposites is a solution to overcome the problems of thermal reactions that occur during the curing reactions. In this paper, the curing kinetics modeling of epoxy nanocomposites and the effect of adding modified and unmodified iron oxide nanoparticles on the amount of activation energy, curing index, and rheological, mechanical and thermal properties are introduced.

The purpose of this work was to study the oxidation and destruction processes of Fe3O4 nanoparticles. As a result, dynamic changes in structure and phase composition of Fe3O4 nanoparticles in various pH media was set. The acidity and time dependence of degradation degree on the pH medium was established. It was associated with the appearance of amorphous regions which is due to the presence of hydroxide compounds. By understanding of the nanoparticles degradation rate and degree it becomes possible to clarify the residence time for the nanoparticles, which in turn makes them potential materials for biomedical application. The causes are the high oxygen content and the formation of hydroxide compounds in the structure, as well as subsequent corrosion processes being capable of causing a destruction of the structure.

The influence of iron oxide, FeOx, on Pt for CO oxidation was investigated. A film of FeOx, nominally 0.8-nm thick, was added to a Pt/Al2O3 catalyst by Atomic Layer Deposition. The film was found to wet the Pt surface after oxidation at 773 K and 973 K, as shown by aberration-corrected, transmission electron microscopy. In-situ infrared spectra and CO chemisorption measurements showed that the addition of the FeOx greatly suppressed CO adsorption but enhanced CO oxidation rates due to FeOx-Pt interfaces. The FeOx layer also improved the stability of the catalyst by mitigating the sintering of Pt particles at 973 K.

The amount and characteristics of wastewater produced are determined by the process configuration. Refineries produce contaminated effluent of phenol levels up to 300–600 mg/L. For wet oxidation of phenol, multiloading and multifunctional MnO2/Fe2O3 were utilized in the present study to develop a cost-effective nanocatalyst to clean refinery wastewater at a high rate of phenol removal and a long lifetime of catalyst activity. The catalysts were doped with two different loading of 2% and 5% of MnO2. For full oxidation of carcinogenic phenolic compounds into the unharmful CO2 and H2O, the catalytic breakdown of H2O2 as an oxidation agent produces oxygen bubbles and hydroxyl radicals. The prepared catalysts were evaluated in a batch reactor and the results showed that the loading of MnO2 over the Fe2O3 has a positive impact on the oxidation of phenol as increasing the MnO2 loading increased the rate of phenol oxidation and did not result in the deactivation of the available catalyst pores. The highest conversion of phenol achieved was 94 wt% at 80 min and 75 °C over the 5% MnO2/Fe2O3 catalyst. Also, it was observed that the prepared catalyst sustained the deactivation for several cycles of catalytic oxidation of phenol as the catalyst activity remained almost constant as time proceeds to 120 min.

The objective of this research is to evaluate the heat and mass transfer in a water-based Darcy–Forchheimer hybrid nanofluid (HNF) flow across an expanding cylinder. The fluid flow has been studied under the influence of a magnetic field, viscous dissipation, heat source, thermal radiation, concentration stratification, and chemical reaction. Carbon nanotubes (CNTs) and iron ferrite (Fe3O4) nanoparticles (NPs) are added to the water, for the purpose of synthesizing the HNF. The fluid flow has been induced in the presence of gyrotactic microorganisms and the non-Fick’s model. Microorganisms are used to stabilize scattered nanoparticles through the hybrid nanofluid. The phenomena have been modeled in the form of a nonlinear system of partial differential equations (PDEs). The modeled equations are reduced to a dimensionless system of ODEs by using similarity substitution. The numerical solution of the derived sets of nonlinear differential equations is obtained by using the parametric continuation method. The impact of physical constraints on temperature, velocity, concentration, and microorganism profiles is presented through figures and tables. It has been observed that the heat and mass transport rates increase with the rising effect of the curvature parameter, while declining with the effect of the thermal stratification parameter.

Herein, a highly effective ɑ-MnO2/Fe3O4 nanocomposite was synthesized employing a hydrothermal process and characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), and UV–visible spectroscopy. The ɑ-MnO2/Fe3O4 photocatalyst flaunts two phases: magnetic magnetite (Fe3O4) nanoparticles of 22±5 nm agglomerated on ɑ-MnO2 1-D nanowire of ∼1.5 µm length and 50±10 nm in diameter. The results exhibited ∼100% photocatalytic degradation of 2,4-DCP under UV-visible irradiation within 80 min at pH 9. The photocatalytic experimental values were fitted linearly with first-order reaction exhibiting k = 0.065 min−1, t1/2 = 10.45 min, and R2 = 0.98 for UV-visible light and k = 0.028 min−1, t1/2 = 34 min and R2 = 0.97 for reaction under sunlight. Additionally, the nanocomposite photocatalyst was easily recoverable using an external magnetic field at room temperature with high stability. Therefore, a simple synthesis method, a synergistic effect between ɑ-MnO2 and Fe3O4, an excellent adsorption-induced photocatalytic activity, easy magnetic recovery, and robustness for reusability make the nanocomposite an outstanding material for environmental sustainability and solar energy harvesting.

To obtain more insight into the mechanisms of the decomposition of energetic compounds, we performed a computational study of the interaction of Fe13O13 nanoparticles with two energetic molecules such as 2,4,6-trinitrotoluene (TNT) and 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO). The density functional theory using M06-2X, B3LYP, and BLYP density functionals was applied. We found that the reactivity of these molecules strongly depends on the place of adsorption (so-called top and bottom planes of Fe13O13). Namely, only the interaction with the bottom plane results in the thermodynamic characteristics of the decomposition that provide a medium reaction rate for the studied processes. Several pathways for such decomposition were found. One of them is the inter-complex oxygen transfer of nitro-group oxygen to Fe13O13. This pathway results in the formation of adsorbed nitroso compounds. The second pathway describes a more complex decomposition that includes the transfer of the nitro-group oxygen accompanied by the hydrogen transfer. In all cases, the interaction of energetic molecules with Fe13O13 nanoparticles takes place along with a barrier-less electron transfer from Fe13O13 to TNT or NTO species. [ABSTRACT FROM AUTHOR]

Graphene has been widely tested as a lubricant material for steel sliding contact in engineering applications. The structural and chemical evolutions on friction surfaces are critical to understand the improvement of tribology performance in experiments. Here, we used the reactive molecular dynamics (ReaxFF-MD) simulations to study the friction and wear behaviors of a monolayer graphene oxide or graphene (GO/Gr) flake confined between two amorphous iron oxide substrates. The results show that when under lower loads (<4 GPa), the sliding shear between two substrates is accomplished by folding and unfolding behaviors of the confined GO/Gr flakes. When under relatively higher loads (≥4 GPa), the intensively formed interfacial C–Fe bonds promote the breakage and decomposition of the GO/Gr flakes and also the gradual damaging of the iron oxide surfaces, resulting in partial direct contacts between two substrates. We also found that the presence of functional groups on the GO flakes will affect the formation of interfacial C–Fe bonds, while the detached functional groups could passivate the iron oxide surfaces, thus having a remarkable influence on the tribological properties of steel sliding contacts. These atomistic insights into structural and chemical evolutions during friction can help to promote the usage of GO/Gr flakes as lubricant materials in engineering applications. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) is a key energy conversion process, which is critical for the efficient operation of fuel cells and metal–air batteries. Here, we report the significant enhancement of the ORR‐performance of commercial platinum‐on‐carbon electrocatalysts when operated in aqueous electrolyte solutions (pH 5.6), containing the polyoxoanion [Fe28(μ3‐O)8(L‐(−)‐tart)16(CH3COO)24]20−. Mechanistic studies provide initial insights into the performance‐improving role of the iron oxide cluster during ORR. Technological deployment of the system is demonstrated by incorporation into a direct formate microfluidic fuel cell (DFMFC), where major performance increases are observed when compared with reference electrolytes. The study provides the first examples of iron oxide clusters in electrochemical energy conversion and storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stronger Fe-Al interactions decrease FeC x /FeO x ratio but increase Fe 5 C 2 /Fe 7 C 3 ratio. • High content of FeC x is benefit for improving CO 2 hydrogenation activity. • Fe 5 C 2 is more favorable for the formation of heavy hydrocarbons than Fe 7 C 3. • Fe 7 C 3 phase is partially transformed into Fe 5 C 2 during CO 2 hydrogenation. Different iron species exhibit distinct activity and selectivity in CO 2 hydrogenation reaction. Herein, by controlling calcination temperature, Fe-Al interaction in Na promoted Fe-Al catalysts has been regulated, which further leads to various compositions of iron oxide (FeO x) and iron carbides (Fe 7 C 3 and Fe 5 C 2) after CO activation and CO 2 hydrogenation reaction. The phase compositions and structures of Fe-Al catalysts are carefully distinguished by multiple characterizations, including XRD, XPS, MES and TEM, and the reactivity of different phases is studied with the combination of experiments (kinetics, TP and in situ DRIFTS) and Density Functional Theory (DFT) calculations. Our FeAl350 with the highest FeC x content shows the highest CO 2 conversion of 48.2% and the lowest CO selectivity of 10.1%, and FeAl900 with the highest Fe 5 C 2 / FeC x ratio presents the highest C 5+ selectivity of 44.6%. Finally, a correlation between different compositions of iron species with the activity and selectivity of Fe-based for CO 2 hydrogenation to olefins was established. [ABSTRACT FROM AUTHOR]