Fe Salts Research Articles

FeOx-carbon composite-based catalytic degradation of bisphenol-A in heterogeneous Fenton system: Structure regulation mechanism of different Fe precursors and natural organic acids

Bisphenol A (BPA) is ubiquitous in the environment and can cause human health risks; therefore, its efficient removal from the environment is an essential issue. Catalytic degradation of BPA in heterogeneous Fenton oxidation system (HFO) is of great concern; however, trials for improving the reactivity of HFO are needed. The impacts of Fe precursors and crystalline structure of Fe oxides on the reactivity of FeOx-based carbon composites (FeCC) and their efficient catalytic degradation of BPA have not yet been explored. Also, the promoting effect of different natural organic acids (NOAs) on the degradation mechanisms of BPA using FeCC in HFO has not yet been verified. Therefore, five FeOx-carbon (biochar; BC) composites i.e. FeCl3@BC, FeCl2@BC, FeNO3@BC, Fe2(SO4)3@BC, and FeSO4@BC derived from different Fe salt (e.g. FeCl3, FeCl2, FeNO3, Fe2(SO4)3, and FeSO4, respectively) were prepared, characterized using advanced techniques, and used as catalysts for BPA degradation in HFO, as affected by NOAs addition. FeCl3@BC showed the highest BPA degradation efficiency (˃ 99.9 %), within 1 min; while it was <20 %, within 10 min, for all FeCC, particularly FeSO4@BC (<10 %). BPA degradation using FeCl3@BC was ˃ 99.9 % at pH = 3, 38.5 % at pH = 5, and <1.0 % at pH = 7–9. Addition of NOAs significantly improved the efficiency of FeSO4@BC for BPA degradation under a wide range of pH (3–9). The complexation and reduction capacities of NOAs significantly promoted the Fe3+/Fe2+ cycle, improving the degradation efficiency of BPA. Four types of reaction intermediates (C15H16O3, C15H16O4, C9H12O3, C9H10O4) were generated during degradation. This work sheds lights on development of FeCC for BPA catalytic degradation.

Improved mercury removal performance and leaching stability of Fe/Br co-doped biochars synthesized through one-step pyrolysis

Mercury removal from oxyfuel combustion flue gas remains challenging owning to the shortage of cost-effective, sulfur- and water-resistant sorbents without secondary pollution. In this study, Fe/Br co-doped biochars synthesized via one-step pyrolysis of iron-loaded biomass and brominated flame retarded plastic were adopted for Hg0 immobilization from oxyfuel combustion flue gas. After iron doping, the Br content of Fe/Br co-doped biochars was sharply improved. Both highly developed pore structure and abundant active components were acquired because of the catalytic effect of iron. The Fe/Br co-doped biochars presented superior Hg0 removal performance than Br-doped biochars across a broad temperature interval from 25 °C to 240 °C. The optimized pyrolysis temperature and wood /Fe salt mass ratio for the synthesis of Fe/Br co-doped biochars were respectively 500 °C and 8:1. The Fe/Br co-doped biochars exhibited excellent resistance to H2O and SO2. The Hg0 removal mechanism was revealed, where Fe3+, CBr and chemisorbed oxygen served as active components for Hg0 chemisorption. The Hg/Br leaching behavior of Fe/Br co-doped biochars was further compared with Br-doped biochars and traditional brominated activated carbon. Iron doping significantly enhanced the stability of Hg/Br in Fe/Br co-doped biochars because partial inorganic bromine was converted into organic bromine during co-pyrolysis.

Food Supplements Containing Iron-Comparison of Actual Content with Declared Content and Health Consequences.

The use of food supplements (FSs) is becoming an increasingly common trend observed in society. This is related to frequently observed nutritional deficiencies and the inability to provide sufficient amounts of nutrients, including vitamins and minerals, through the diet. The ease of registering FSs sometimes results in low-quality preparations on the market. Therefore, our research aimed to assess the content of one of the most popular trace element components, iron (Fe), in FSs available in Poland. This study covered 109 preparations purchased from stationary pharmacies and online pharmacies. The following criteria were used to characterize FSs in the data analysis: the Fe content declared by the manufacturer, pharmaceutical form, type of Fe salt, manufacturer's country of origin, contents of other trace elements or minerals, presence of additional ingredients, age of the target group, and addition of vitamins B2, B6, B12, and C. The Fe content was quantified using atomic absorption spectrometry after mineralization using microwaves. It was demonstrated that 69.73% of the preparations contained more Fe than the value declared by the manufacturer (and corrected for permissible deviations), 11.00% contained less Fe than declared, and only 19.27% were within the norm. In summary, the FS market requires the improvement of manufacturing processes and increased control, which should translate into patient safety.

Templating Iron(III) Oxides on DNA Molecules.

Fe(III) oxides were prepared as free nanoparticles and on DNA templates via the precipitation of Fe(III) salts with NaOH in the presence/absence of DNA. Through control of the pH and temperature, FeOOH and Fe2O3 were synthesised. The formation of templated materials FeOOH/DNA and Fe2O3/DNA was confirmed using UV-Vis absorption and FTIR spectra. The direct optical gap of Fe2O3/DNA was estimated as 3.2 eV; the absorption by FeOOH/DNA and Fe2O3/DNA at longer wavelengths is weaker, but consistent with indirect gaps near 2 eV. X-ray photoelectron spectra confirmed the presence of Fe(III) and DNA in the templated samples. Analysis of the X-ray diffraction patterns of both templated and non-templated FeOOH and Fe2O3 demonstrated that the materials were the α-FeOOH and α-Fe2O3 polymorphs with crystallite diameters of the DNA-templated materials estimated as 7.6 nm and 6.8 nm. Transmission electron microscopy showed needle-like crystals of both FeOOH and Fe2O3, but the Fe2O3 contains some globular structures. In contrast, the morphology of FeOOH/DNA and Fe2O3/DNA consists of needle-like crystallites of the respective oxides organised into complex dendritic structures with a length on the 10 μm scale formed by the DNA molecules. Finally, scanned conductance microscopy provided evidence for the conductivity of the FeOOH/DNA after alignment via molecular combing on an Si/SiO2 substrate. Fe2O3/DNA did not exhibit any detectable conductivity.

Impact of organic matter constituents on phosphorus recovery from CPR sludges.

This study evaluated the influence of organic matter (OM) constituents on the potential for recovery of P from wastewaters when FeCl3 treatment is employed for P removal. The presence of OM constituents did not influence P release from Fe-P sludges when alkaline and ascorbic acid treatments were employed. However, the overall recovery of P from wastewater was impacted by the presence of selected OM constituents through the reduction of P uptake during coagulation. The presence of protein and humic matter showed remarkably low P removal values (3.0±0.4% and 23 ±1% respectively) when compared to an inorganic control recipe (62 ±2%). Elevated soluble Fe (SFe) residuals in the presence of proteins (87 ±5%) and humics (51 ±1%) indicated interactions between Fe(III) cations and negatively charged functional groups like hydroxyl, carboxyl, and phenolic groups available in these organics. Significant negative correlations between P removal and residual SFe were observed suggesting Fe solubilization by OM constituents was the mechanism responsible for reduced P removal. The findings of this study identify, for the first time, the impact of OM constituents on overall P recovery when Fe(III) salts are employed and provide insights into recoveries that can be expected when Fe is added to primary, secondary treated, and industrial wastewaters. PRACTITIONER POINTS: Low P removal values were observed for protein and humic dominated wastewater recipes. Iron(III) solubilization counted for P removal reduction by proteins and humic acids. There is no effect of OM on P release from Fe-P sludge at pH 10 and ascorbic acid treatments. OM and agent employed to release P from sludges affected overall recovery of P.

Phosphorus inactivation mitigates the effect of warm winters in a temperate shallow lake (Mielenko Lake, Poland)

Direct and indirect anthropopressure on water ecosystems is the serious problem throughout the world.. In the Northern Hemisphere, an increase in average air temperatures is observed, which implies the occurrence of a shorter period of snow and ice cover during the winter season. The winter 2019/2020 was unusual, because that was the first time in the record, that a complete lack of permanent ice cover was observed on numerous lakes in Poland. Such unusual conditions could influence lake functioning. Hence we analyzed the chemistry of the water–sediment interface (near-bottom and interstitial water and sediment) in the shallow, eutrophic Mielenko Lake (area 7.9 ha, max depth 1.9 m) in 2013 and 2019–2022 period to assess the influence of prolonged water circulation on the bottom zone. Mielenko Lake was subjected to a phosphorus inactivation procedure using Al and Fe salts (PAX 18, PIX 111) in 2020 and 2021. Our research revealed that unusually prolonged winter circulation caused a significant decrease in organic matter content in bottom sediment in 2020, as well as a decrease in NaOH-nrP fraction and TP amounts. That effect was short-term and it did not significantly influence the NaOH-rP fraction amounts. The released P was probably built in macrophytes biomass during vegetation season, because P inactivation has been limiting phytoplankton proliferation, and it favored shifting to a clearwater state with macrophytes domination. This was confirmed by decreasing in phytoplankton biomass, and a massive expansion of the macrophytes range noted in the second year of restoration. Our study shows, that P inactivation could mitigate the negative effects of warm winters in shallow lakes.

Structurally optimized rosette-like microspheres carbon with Fe-Ni single atom sites for bifunctional oxygen electrocatalysis in Zinc-Air batteries

Developing a secure and effective bifunctional oxygen catalyst for the ORR and OER is still a significant obstacle in the design of rechargeable zinc-air batteries. Here, a hollow rose-shaped bifunctional electrocatalyst is synthesized with an sacrificial template strategy (FeNi-NC). X-ray absorption fine structure analysis reveals the FeNi-NC catalyst contains FeN4 and NiN4 active sites as well as FeNi3 alloy. This hollow, flower-like structure performs low density, large specific surface area, and high permeability. Its inner cavities not only provide additional triple-phase interfaces to accelerate the reduction and oxidation of O2, but also enhance the diffusion of reactants on the catalyst. By controlling the input of Fe and nickel metal salts, the dispersion of active sites can be effectively tuned. Owing to the large number of exposed active sites on the carbon nanosheets, the synthesized FeNi-NC catalysts exhibit high electrocatalytic activity in both ORR (E1/2 = 0.852 V) and OER (ηj=10 = 359 mV). The construction of rechargeable zinc-air batteries resulted in a high power density of 135.78 mW cm−2, a better specific capacitance of 726.9 Wh kgZn−1 and 210 h enduring durability. More importantly, density functional theory (DFT) calculations indicate that the electronic interactions between Fe/Ni and nitrogen-doped carbon matrices play a pivotal role in enhancing the electrocatalytic performance of functional groups. These interactions effectively disrupt the electronic neutrality of carbon atoms, thereby accelerating the kinetics of the reaction. This research provides a new method for the preparation of single atom catalysts with bifunctional activities.

The [(Bn-tpen)FeII]2+ Complex as a Catalyst for the Oxidation of Cyclohexene and Limonene with Dioxygen.

[(Bn-tpen)FeII(MeCN)](ClO4)2, containing the pentadentate Bn-tpen-N-benzyl-N,N',N'-tris(2-pyridylmethyl)-1,2-diaminoethane ligand, was studied in the oxygenation of cyclohexene and limonene using low-pressure dioxygen (0.2 atm air or 1 atm pure O2) in acetonitrile. 2-Cyclohexen-1-one and 2-cyclohexen-1-ol are the main products of cyclohexene oxidations, with cyclohexene oxide as a minor product. Limonene is oxidized to limonene oxide, carvone, and carveol. Other oxidation products such as perillaldehyde and perillyl alcohol are found in trace amounts. This catalyst is slightly less active than the previously reported [(N4Py)FeII(MeCN)](ClO4)2 (N4Py-N,N-bis(2-pyridylmethyl)-N-(bis-2-pyridylmethyl)amine). Based on cyclic voltammetry experiments, it is postulated that [(Bn-tpen)FeIV=O]2+ is the active species. The induction period of approx. 3 h during cyclohexene oxygenation is probably caused by deactivation of the reactive Fe(IV)=O species by the parent Fe(II) complex. Equimolar mixtures of Fe(II) salt and the ligand (in situ-formed catalyst) gave catalytic performance similar to that of the synthesized catalyst.

Ir-Fe bimetallic catalysts for selective glycerol hydrogenolysis

This work studied the effect of adding Fe to an Ir/γ-Al2O3 catalyst in different Fe/Ir molar ratios (0.5, 1.0, and 2.0) on the conversion and selectivity of the glycerol hydrogenolysis reaction. Additionally, the effect of the calcination of the solids was evaluated. The catalysts were prepared by incipient wetness impregnation of the Ir and Fe salts on the support and were characterized by textural analysis, XRD, TPR, XPS, and TEM-EDS techniques. The interaction between Ir and Fe was evidenced in the characterization of the catalysts. The addition of Fe to the Ir catalyst led to an increase in activity; however, this effect was better observed for the non-calcined catalyst series. The calcined catalyst series did not present a significant increase in glycerol conversion and selectivity to 1,2-PDO, probably due to the sintering of Ir occasioned by the catalyst's calcination, as observed in the characterization. For non-calcined bimetallic catalysts, the conversion increased from 7 % to 21.5 % for IrFe2.0/γ-Al2O3 catalyst, probably due to the synergic effect between both metals and the formation of Ir-Fe bimetallic particles, as evidenced in EDS mapping and XPS analysis. In the presence of this catalyst, selectivity to 1,2-PDO remained high (90.1 %).

Studies of some Mixed Ligand-Metal complexes of 4-((2-(phenylcarbamothioyl)hydrazinylidene) methyl) benzoic acid in search of potential antimicrobial activity

This paper reports the synthesis and structural characterization of novel mixed ligand-metal complexes derived from 4-((2-(phenylcarbamothioyl)hydrazinylidene)methyl)benzoic acid (L1) and 4-((2-carbamothioylhydrazineylidene)methyl)benzoic acid (L2). The ligands, and their complexes with Fe(II), Co(II), Cu(II), and Zn(II) salts, were characterized using elemental analysis, FT-IR (Fourier-transform infrared spectroscopy), UV (Ultra-violet), 1H and 13C NMR (Nuclear Magnetic Resonance), EDX (Energy-dispersive X-ray spectroscopy), AAS (Atomic absorption spectroscopy) and molar conductivity measurements. Elemental analysis and conductance data confirmed the formation of non-electrolytic complexes in a 1:1:1 molar (L1:M:L2) ratio. The ligands bound to the metal ions in a bidentate manner as shown by the IR spectral data. The complexes exhibited an octahedral geometry. DFT (Density functional theory) calculations at B3LYP/6-311++G(d,p) level supported the experimental findings. Molecular docking studies were performed with four antimicrobial protein targets mainly enoyl-acyl carrier protein reductases (PDB ID:1D70, 2WYW, 1P9G and 4XRE) to comprehend their binding with the chosen targets. Both the ligands were shown to be non-toxic as depicted by the cytotoxicity test performed using MTT assay. Antimicrobial activity evaluation revealed that the metal complexes exhibited enhanced activity as compared to the free ligands, with the Co(II) complex showing the highest inhibition zones. These findings suggest that the mixed ligand-metal complexes could also be explored for diverse applications.

Facile Carbothermal Synthesis of Metal Phosphides-Based Multifunctional Electrocatalysts via Polyaniline Doped with Phosphoric Acid

Transition metal phosphides (TMPs) and their composites are promising non-platinum electrocatalysts for hydrogen evolution (HER), oxygen evolution (OER), and oxygen reduction (ORR) reactions. But traditional methods to obtain these electrocatalysts are usually multi-step and include the participation of hazardous phosphorus compounds during phosphidation. Here, the possibility of using a polyaniline doped with phosphoric acid (PANI∙H3PO4)—as a source of C, N and P simultaneously - to obtain composites based on N,P-doped carbon and nano- and/or submicron TMP particles as HER, OER and ORR electrocatalysts is demonstrated. The pyrolysis of PANI∙H3PO4 together with Co, Ni, Mo, or Fe salt allows the formation of such composite electrocatalysts by the carbon thermal reduction route. Regardless of the pH of the electrolyte, the MoP-based electrocatalyst is characterized in HER by the smallest Tafel slope and overpotential of hydrogen evolution and also exhibits high stability during long-term operation. At the same time, other composites are multifunctional electrocatalysts possessing activity not only in HER, but also in OER and ORR. The proposed approach can be a starting point for a simple, universal in choice of d-metal, and environmentally attractive preparation of multifunctional TMP-based electrocatalysts with further improvement of their performance.

Microplastics removal from natural surface water by coagulation process

The present study aimed to compare the efficiency of microplastic removal from natural surface water by coagulation with ferrous and aluminum sulfate in the presence and without the selected coagulant aids. Coagulation with Fe(II) and Al(III) sulfates at doses conventionally used for drinking water treatment (10 – 80 mg.L−1) was effective in polystyrene and polyvinyl chloride removal. Fe(II) salts showed up to 5 % efficiency higher in microplastic removal under the conditions of the experiment. The addition of the flocculating agent to support the aggregation of flocs allowed for the improvement of microplastic removal efficiency at the same dose of up to 10 %. Based on the results, flocculating agents are recommended for microplastic removal. Coagulation without flocculating agent amendment is enough to remove most microplastics if filtration is applicable.

TEMPLATE-ENGINEERED TRIVALENT IRON AND CHROMIUM CONTAINING MACROCYCLIC COMPLEXES: CHARACTERIZATION AND IN VITRO STUDIES

A novel series of tetraaza macrocyclic complexes of biological importance was synthesized by “in situ” template reaction between triethylenetetramine and dibenzoylmethane in the presence of trivalent Fe and Cr metal salts in 1:1:1 molar ratio. These complexes are represented by molecular formula [M(C[Formula: see text]H[Formula: see text]N[Formula: see text]X]X2; [Formula: see text](III) and Cr(III); [Formula: see text], NO[Formula: see text], −OAc; C[Formula: see text]H[Formula: see text]N[Formula: see text] ligand. The reported complexes were characterized by using various physicochemical and spectroscopic techniques including elemental analyses, molar conductance, thermo-gravimetric analysis, FTIR, UV–Visible and mass spectral studies. The results obtained from analytical techniques and spectroscopic techniques together suggested the complexes have a square pyramidal geometry. Various computational studies were performed including molecular docking and modeling. Further, macrocyclic complexes were also screened for their “in vitro” antimicrobial activity against selected bacterial and fungal strains. The antioxidant activity of these complexes was also evaluated. Some of the complexes were found to possess remarkable antimicrobial activity and antioxidant activity. However, complex [Fe(C[Formula: see text]H[Formula: see text]N[Formula: see text](NO[Formula: see text]](NO[Formula: see text] was found to be most potent against selected bacterial and fungal strains. On the other hand, complex [Cr(C[Formula: see text]H[Formula: see text]N[Formula: see text](NO[Formula: see text]](NO[Formula: see text] was found to show best antioxidant activity with lowest value of IC[Formula: see text].

Electrodeposited NiFeCo + Tb and Dy for enhanced magnetostrictive properties and soft magnetism

Magnetostrictive thin films have numerous applications in communications, sensors, and microelectronic devices. Such devices usually require magnetostrictive thin films with large magnetostriction and soft magnetic properties. Nickel-Iron-Cobalt (NiFeCo) alloys have excellent soft magnetic properties and can be easily fabricated as thin films. However, their main drawback for these sensing applications is that they have very low magnetostriction. On the other hand, Iron-Rare Earth (RE) alloys such as Fe-Tb-Dy or Fe-Ga have large magnetostriction at the cost of some soft magnetic properties. Moreover, their magnetostrictive properties are degraded when reduced to thin films as opposed to bulk materials due to structural imperfections and oxidation of the REs. In this paper, we report the development of NiFeCo thin films with incorporated rare earth elements prepared via electrodeposition. Electrochemical cells were prepared using Ni, Fe, and Co sulfate salts. Tb and Dy sulfates were added to the electrochemical cell in order of increasing concentration. Electrodeposition was then carried out under galvanostatic control for each RE concentration in the bath. The produced films were analyzed for composition, crystallinity, and magnetic properties to draw out trends based on the initial concentrations of rare earth salts in the bath. The produced thin films retained soft magnetic properties while exhibiting giant magnetostriction of up to ∼370 ppm depending on the type and amount of incorporated REs within the film. The combination of soft magnetism and giant magnetostriction makes these NiFeCo thin films with added Tb and Dy excellent candidates for developing resonant frequency sensing devices.

Fe(III) dihydroxybenzoquinone-based metal organic framework for sodium battery cathodes: Properties, charge-discharge kinetics and redox reaction mechanisms

Sodium batteries are promising energy storage devices that could promote the transition to clean energy. For this purpose, it is desirable to develop safe cathode materials that can be easily produced from cheap and abundant elements. One of the attractive options is Fe2(dhbq)3, a metal-organic framework (MOF) that is synthesized from 2,5-dihydroxybenzoquinone (H2dhbq) and Fe(III) salts. This work provides a comprehensive analysis of Fe2(dhbq)3, including its structure, properties, charge-discharge kinetics, and redox reaction mechanism in sodium batteries. Using a set of experimental and theoretical methods, we show that sodiation of Fe2(dhbq)3 in the potential range of 1.1–3.8 V vs. Na+/Na is accompanied by a reversible two-electron reduction of dhbq ligands, while iron is only marginally involved and formally remains in +3 state. The material delivers a high specific capacity of up to ∼180 mAh g−1. Diffusion of Na+ ions in NaxFe2(dhbq)3 at low-to-moderate sodiation degrees (≥2.2 V vs. Na+/Na) is so fast that it is kinetically indistinguishable from supercapacitance. Additionally, we show that Fe2(dhbq)3 can be synthesized by simply mixing solutions of H2dhbq and salts of Fe(III) at room temperature, which makes its production especially simple and scalable.

Investigation of Earth-Abundant Metal Salts for the Inhibition of Asphalt-Derived Volatile Organic Compounds.

Asphalt is used globally in construction for roads, pavements, and buildings; however, as a fossil-derived material, it is known to generate volatile organic compounds (VOCs) upon exposure to heat and light that can be harmful to human health. Several heterogeneous strategies have been reported for the inhibition of these VOCs; however, the direct use of inexpensive, accessible Earth-Abundant metals has not been extensively explored. In this study, simple metal salts are examined for their coordination capability toward asphalt-derived VOCs. From UV-visible (UV-vis) spectroscopic studies, FeCl3 emerged relative to other metal salts (metal = Mn, Co, Ni, Cu, Zn) as a promising candidate for the adsorption and retention of Lewis basic compounds. Coordination of an example oxygen-containing VOC, benzofuran (Bf), to Fe yielded a paramagnetic semi-octahedral complex Fe(Bf)3Cl3. Evaluation by thermal gravimetric analysis (TGA) coupled to infrared spectroscopy (IR) demonstrated that the complex was stable up to 360 °C. Spectroscopic evaluation demonstrated the stability of the complex upon visible light irradiation and in the presence of a variety of organic pollutants. The potential application of Fe was demonstrated by subjecting biochar to FeCl3 followed by the addition of Bf. It was discovered that this Fe-rich biochar was successful at adsorbing Bf suggesting the possibility of introducing Fe to biochar late-stage in processing to deter asphalt degradation and VOC emissions. An understanding of the binding and stability of Fe salts to VOCs provides insight into how a sustainable infrastructure can be achieved.

Migration of various ions based on pH shifts triggered by the application of sediment microbial fuel cells.

Sediment microbial fuel cells (SMFCs) represent a technology that can enhance sediment quality through processes such as nutrient suppression while simultaneously generating electricity from microorganisms. Despite its importance in elucidating the principles of nutrient suppression, the complex behavior of various ions within this context has been rarely explored. Herein, we applied an SMFC and systematically evaluated alterations in ion concentrations in interstitial and overlying waters. The SMFC deployment substantially decreased Na+ concentrations and increased Cl- levels in the interstitial water. This intriguing phenomenon was attributed to reactions driven by the electrodes. These reactions induced remarkable shifts in pH. Consequently, this pH shift triggered the leaching of heavy metals, particularly Fe, and decreased HCO3- concentrations within the interstitial water, thereby inducing the migration of other ions, including Na+ and Cl-, as compensation. Moreover, the PO43- concentration in interstitial water showed an increasing trend upon SMFC application, which contradicts the results of several previous reports. This increase was primarily attributed to the release of PO43-caused by the leaching of Fe salts, which was triggered by the pH shift. These findings provide new insights into sediment improvement research through SMFCs, enhancing our understanding of the fundamental principles and broadening the potential applications of this technology.

A simple melamine-assisted cellulose pyrolysis synthesis of magnetic and mesoporous N-doped carbon composites with excellent adsorption of Congo red

A magnetic and mesoporous metal/N-doped carbon composite is prepared using a melamine-assisted pyrolysis method of hydroxypropyl methylcellulose with Fe(NO3)3. The magnetic composite has a 3D hierarchical structure composed of 1D nanostructure interlaced with each other and a large pore volume distributed mainly in mesopores. Meanwhile, its N-doped carbon surface with sp2 hybridized structure is positively charged due to the promotion action of its mixed Fe phase, Fe3C and Fe3N, inducing the production of electron deficient conjugated structures as electron acceptors. Its characteristic microstructure determines that the adsorption of anionic Congo red on its surface is achieved mainly through multiple adsorption mechanisms of electrostatic and π-π interaction. Thus, the magnetic composite has an excellent dye adsorption capacity, even improved dramatically at high pH conditions, and simultaneously, the spent composite is quickly separated from wastewater solution by using its magnetic properties. In contrast, these undoped or N-doped carbon composites prepared in the absence of melamine and Fe salts have very poor or partially improved adsorption efficiencies to the Congo red dyes due to their inactive characteristic microstructures, such as lower pore volume, more microporous structures and negatively charged mesoporous surface.

Plant-Mediated Synthesis of Magnetite Nanoparticles with Matricaria chamomilla Aqueous Extract.

Magnetite nanoparticles (NPs) possess properties that make them suitable for a wide range of applications. In recent years, interest in the synthesis of magnetite NPs and their surface functionalization has increased significantly, especially regarding their application in biomedicine such as for controlled and targeted drug delivery. There are several conventional methods for preparing magnetite NPs, all of which mostly utilize Fe(iii) and Fe(ii) salt precursors. In this study, we present a microwave hydrothermal synthesis for the precipitation of magnetite NPs at temperatures of 200 °C for 20 min and 260 °C for 5 min, with only iron(iii) as a precursor utilizing chamomile flower extract as a stabilizing, capping, and reducing agent. Products were characterized using FTIR, PXRD, SEM, and magnetometry. Our analysis revealed significant differences in the properties of magnetite NPs prepared with this approach, and the conventional two-precursor hydrothermal microwave method (sample MagH). FTIR and PXRD analyses confirmed coated magnetite particles. The temperature and magnetic-field dependence of magnetization indicate their superparamagnetic behavior. Importantly, the results of our study show the noticeable cytotoxicity of coated magnetite NPs-toxic to carcinoma cells but harmless to healthy cells-further emphasizing the potential of these NPs for biomedical applications.

Fe/Cu doped black ceramic coating on magnesium alloy by plasma electrolytic oxidation method based on first principles

The absorption of visible light by a solid material can correspond to its color. If all visible light is absorbed, the material is black, and the band width of the material defines the wave limit of visible light absorption. Based on this, the transition metal elements Fe and Cu were chosen to dope MgO, and the transition metal elements Fe or Cu were substituted to dope MgO using first-principles simulation. The doped elements' 3d and 4 s levels were introduced to shift the locations of MgO's valence and conduction bands, respectively, lowering the band gap width of MgO. The MgO ceramic coating may respond to light wave wavelength redshifting to 780 nm and entirely absorb visible light; The black MgO ceramic coating was prepared on the surface of AZ31 magnesium alloy utilizing Fe salt and Cu salt as plasma electrolytic oxidation (PEO) electrolyte additions, and the visible light absorption rates were 94.2 % and 94.1 %, respectively. The test findings show that the band gap of the MgO ceramic coating has been lowered from 4.97 eV to 1.58 eV and 1.60 eV, respectively, which is the primary reason for the achievement of strong absorption in all visible light bands. The first principle calculation of the influence of doping elements on the band gap of MgO ceramic coating can serve as a theoretical guidance for selecting coloring elements for the fabrication of black ceramic coating.