Iron Nitrate Solution Research Articles

Radiation-chemical synthesis and characterization of ferrihydrite from iron (III) nitrate

In this study, 2-line ferrihydrite (2L Fh) nanoparticles (NPles)were synthesized by radiation-chemical method from an alcoholic solution of iron (III) nitrate for the first time. The X-ray diffraction analysis confirmed that the synthetic powder exhibited the characteristic pattern of 2L Fh NPles. DSC-TG analysis conducted in air atmosphere further verified the formation of 2L Fh. SEM analysis showed the presence of mesoporous plate-like structures in the 2L Fh powder, consisting of aggregates of NPs with an average size of approximately 20 nm. The absence of impurity peaks on the X-ray diffractograms and energy dispersion spectra (EDX) confirmed the chemical purity of the produced 2L Fh NPles. Additionally, the XPS method detected the presence of nitrogen and carbon adsorbed to the developed surface of the 2L Fh plates. 2L Fh NPles, when dried in air at a temperature of 50 °C, rapidly dissolved in water. 2L Fh NPles alcohol suspensions were stabilized using surfactants polyethylenimine (PEI) and acetylacetone (AcAs). 2L Fh NPles showed good photocatalytic properties when irradiated with ultraviolet light of methyl violet (MV) dye. These 2L Fh NPles, synthesized using an environmentally friendly radiation-chemical method, have immense potential for applications in biomedicine and photocatalysis.

Incorporation of iron(III) into nanoporous silica spheres

Iron(III) containing silica spheres with the average diameter of 800 nm were prepared by the hydrolysis and the condensation of tetraethoxysilane in the presence of hexadecyltrimethylammonium chloride and subsequent reaction with aqueous or ethanol solution of iron(III) nitrate. The iron(III)-containing silica spheres were calcined in air at 400 °C to obtain nanoporous silica spheres containing iron(III). The location and the states of the iron in the nanoporous silica spheres were examined using scanning electron microscopy, transmission electron microscopy, elemental mapping, diffuse reflectance ultraviolet-visible absorption as well as Fe K-edge X-ray absorption spectroscopy. Iron(III) was located at the surface of the spheres as octahedrally coordinated species when iron(III) was adsorbed from ethanol solution of iron(III) nitrate. When the incorporation of iron(III) was done from the aqueous solution of iron(III) nitrate, tetrahedrally coordinated iron(III) was dispersed homogeneously through the spherical silica particles. Both of the silica spheres were microporous with the large BET surface area (ca. 1000 m2/g). The iron(III) containing silica spheres absorbed UV and were inactive for the photocatalytic degradation of methylene blue.

Interfacial charge transfer in sheet Ni2P-FePx heterojunction to promote the study of electrocatalytic oxygen evolution.

The substantial expense associated with catalysts significantly hampers the progress of electrolytic water-based hydrogen production technology. There is an urgent need to find non-precious metal catalysts that are both cost-effective and highly efficient. Here, the porous Ni2P-FePx nanomaterials were successfully prepared by hydrothermal method, nickel foam as the base, iron nitrate solution as the caustic agent and iron source, and finally phosphating at low temperature. The obtained porous Ni2P-FePx nanosheets showed excellent catalytic activity under alkaline PH = 14, and an overpotential of merely 241 mV was required to achieve a current density of 50 mA cm-2. The morphology of the nanosheet can still be flawlessly presented on the screen after 50 h of working at high current density.

ВЛИЯНИЕ ПОРОШКООБРАЗНЫХ ОКСИДНЫХ ДОБАВОК НА СИНТЕЗ ОКСИДА ЖЕЛЕЗА (III)

Nanocomposites are widely used in many fields of science due to their impressive physical and chemical characteristics. Despite the fact that this class of composite materials has appeared relatively recently, there are a considerable number of methods for their production. When designing such materials, a special role should be given to nanocomponents and their production. This work examines the possibility of synthesizing nanosized iron (III) oxide and its mixtures with silicon dioxide and aluminum oxide in solutions of iron (III) nitrate with glycine, which can be used as a component of composite dispersion-strengthened materials. The synthesis of iron (III) oxide and its mixture with aluminum oxide and dioxide was carried out in the self-propagation mode for the system in the solid state. The solid state of the mixture corresponds to the residual amount of bound water - two moles per mole of Fe(NO₃)₃. When studying the process of preparation for synthesis, it was shown that the introduction of additives does not have a significant effect on the residual moisture content, but helps to reduce the combustion temperature by 22-175 ° C and intensify the moisture removal process, i.e. the time for producing a solid solution is reduced by 31-56%. The mixture used Fe(NO₃)₃ ·9 H₂O (75%) + NH₂-CH₂-COOH (25%) as a result of synthesis by combustion makes it possible to obtain Fe₂O₃ with Ssp = 12 m2/g. The introduction of additives makes it possible to increase the efficiency of synthesis in the self-propagation mode and increases the specific surface area, but in the case of SiO2, Al₂O₃ it leads to contamination of the product with these components. It was found that the introduction of oxides into the composition allows one to regulate the surface area of the reaction products over a wide range. Input of 5% SiO2 allows you to achieve Ssp = 30-32 m2/g, iron (III) oxide and aluminum oxide leads to an increase in specific surface area to 20-25 m2/g.

Eggshell-Mediated Hematite Nanoparticles: Synthesis and Their Biomedical, Mineralization, and Biodegradation Applications

The present study demonstrates the synthesis of phase pure hematite (α-Fe2O3) nanoparticles (NPs) using collagen protein and calcium carbonate extracted from eggshell membranes and eggshells, respectively, as organic additives. To test the influence of organic additives on the quality of the resulting NPs, the amount of eggshell powder was varied between 1 to 5 g in aqueous iron nitrate solution. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and RAMAN analysis confirmed the formation of hematite NPs without any impurities. FTIR spectra revealed the presence of polyphenolic constituents on the surface of the resulting NPs as stabilizers, which may potentially be responsible for the observed antioxidant and antibacterial properties. Furthermore, the stable phase and the presence of low defects divulged the high hardness value (~983 HV) and fracture toughness (8.59 MPa m1/2), which can be exploited for bone implantation. The FE-SEM results demonstrate the formation of spherical particles, which are well-separated NPs. The results of a biodegradation study which was carried out in phosphate-buffered saline (PBS) revealed that the as-prepared NPs retained their hardness even after 72 h of soaking. These prepared NPs showed 95% radical scavenging activity (RSA) and were good carriers against S. aureus bacteria. Moreover, the SEM images of the mineralization of iron oxide NPs confirmed the formation of new bone. After 5 weeks, all pores were filled, and the minerals were deposited on the surfaces of the scaffolds.

MIL-100(Fe)/Diatomite Composites for Photo-Fenton Degradation of Phenol

Porous materials based on metal-organic framework MIL-100(Fe) and diatomite were synthesized. Composites possess specific surface area of 322 and 441 m2/g and hierarchical porous structure with broad pores of diatomite and narrow pores of MIL-100(Fe) particles. Influence of synthesis strategy on structure of materials and their catalytic properties in photocatalytic degradation of phenol was investigated. Composite obtained with preliminary wet impregnation of iron nitrate solution show predominant formation of MIL-100(Fe) particles inside the pores of diatomite. Materials demonstrate catalytic activity in phenol degradation by photo-Fenton process. Composite synthesized without preliminary wet impregnation displays highest catalytic activity with predominant formation of MIL-100(Fe) particles on external surface of diatomite.

Multi-core shell nanoparticles for efficient removal of nitrophenols from contaminated streams

This study aims to investigate the application of multi-core shell nanoparticles in heterogeneous Fenton processes for efficient removal of specific nitrophenols (2 and 4-nitrophenol) from contaminated wastewater. The synthesis of superparamagnetic magnetite (Fe3O4) was achieved through solution combustion synthesis (SCS) using a citric acid and iron nitrate solution. The mFe3O4@C catalyst was obtained via an adapted Stöber procedure. The material was characterized to identify specific chemical compositions related to the formation of the multi-core shell desired architecture. The carbon coated catalyst exhibited superior performance compared to the bare core catalyst, leading to notable increases in the removal of 2-NP and 4-NP. Moreover, the decomposition of H2O2 was significantly enhanced, indicating the system's potential in efficiently breaking down hazardous compounds. The findings of this study highlight the tremendous potential of the system as a highly effective and viable alternative for the efficient cleansing of contaminated streams polluted with 2-nitrophenol and 4nitrophenol.

Hierarchical porous Fe2O3 derived from willow branch slices biotemplate with fast response and excellent selectivity for acetone

Acetone is an important biomarker for clinical diagnosis of diabetes. Therefore, the development of a semiconductor oxide gas sensor with a detection limit below the diagnostic threshold of diabetes (1.8 ppm) is necessary to monitor human health. In this work, hierarchical porous Fe2O3 microtubes with large pore size were prepared by using willow branches as biotemplates. Fe2O3 microtubes (Fe2O3-D2) were obtained by calcining slices of willow branches after soaking in iron nitrate solution for two days, which were assembled from cross-linked nanoparticles in a hierarchical porous structure. Fe2O3-D2 has the largest specific surface area (22.19 m2g−1) compared to Fe2O3-D1 (17.89 m2g−1) and Fe2O3-D3 (10.46 m2g−1), which can provide more reactive sites and facilitate the adsorption of gas molecules on its surface. The Fe2O3-D2-based sensor exhibited high response (16.3) and fast response time (2 s) to 20 ppm acetone at the optimal operating temperature (230 °C). The response of Fe2O3-D2 to 1 ppm acetone is 3.2, which indicates that the detection limit of the sensor is below the threshold of acetone concentration for clinical detection of diabetes. Moreover, the response of the Fe2O3-D2-based sensor to acetone was over 2.7 times higher than that to other test gases such as formaldehyde, toluene, xylene, benzene, methanol, and ethanol, indicating that the sensor has well selectivity for acetone.

Effects of Coexisting Anions on the Formation of Hematite Nanoparticles in a Hydrothermal Process with Urea Hydrolysis and the Congo Red Dye Adsorption Properties

Crystalline hematite nanoparticles as adsorbents for anionic Congo red dye were prepared by a hydrothermal process using urea hydrolysis. To examine the effects of coexisting anions in a solution on the formation of hematite nanoparticles, different iron(III) salts, including iron chloride hexahydrate, iron nitrate nonahydrate, iron sulfate n-hydrate, ammonium iron sulfate dodecahydrate, and basic ferric acetate, were employed as iron-ion sources. After the hydrothermal treatment of the solution, consisting of an iron salt and urea at 423 K for 20 h, a single phase of hematite was formed from the iron-nitrate solution. The results suggested that the hydrothermal formation of hematite depended on the stability of iron complexes formed in the starting solution. The average crystallite size and median diameter of hematite nanoparticles also depended on the coexisting anions, suggesting that the appropriate selection of the coexisting anions in the starting solution can allow for control of the crystallite size and particle diameter of hematite nanoparticles. The Congo red adsorption kinetics and isotherms of the hematite nanoparticles were described by the Elovich model and Langmuir model, respectively. The adsorption thermodynamics parameters were estimated, which suggested an exothermic and spontaneous process. The results demonstrated good adsorption properties for Congo red adsorption.

Influence of Hydrogen Reduction Stage Conditions on the Microwave Properties of Fine Iron Powders Obtained via a Spray-Pyrolysis Technique

The relationship between the chemical purity of one-size particles and microwave properties in ferromagnetic materials is not clearly studied. Ferromagnetic nanostructured iron powders were synthesized from iron nitrate solution using ultrasonic spray-pyrolysis and then reduced in H2 flow at 350, 400, 450, and 500 °C. A rise in the concentration of solutions of a precursor from 10 to 20 wt. % led to an increase in mean particle size. The interrelationship was studied between chemical composition and the microwave dispersion of the powders obtained. An increase in the temperature of reduction changes the chemical composition and increases the amplitude of complex microwave permeability, which was studied using solid-state physics methods (XRD, STA, SEM, and VNA). It was found that annealing at 400 °C is the optimal treatment that allows the production of iron powders, consisting of about 90% of α-Fe phase, possessing a particle surface with low roughness and porosity, and demonstrating intense microwave absorption. Annealing at a higher temperature (500 °C) causes an even higher increase in permeability but leads to the destruction of nanostructured spheres into smaller particles due to grain growth. This destruction causes an abrupt increase in permittivity and therefore significantly reduces potential applications of the product. The insight into chemical–magnetic relationships of these materials enhances the data for design applications in magnetic field sensing.

Low-temperature and high-selectivity butanone sensor based on porous Fe2O3 nanosheets synthesized by phoenix tree leaf template

The development of gas sensors with high selectivity to volatile ketones at low temperature has recently been a hot topic. However, the reported good response to butanone is usually achieved above 200 °C. Herein, based on the conception of biomimicry, we chose waste phoenix tree leaves (PTL) as template and simply immersed them in iron nitrate solution. Subsequently, biomorphic Fe2O3 nanosheets were controllably replicated by calcining immersed PTL precursor in air. Thereinto, Fe2O3-600 nanosheets obtained by calcining precursor at 600 °C are cross-linked by nanoparticles and have broad pore structure and large surface area. Such unique microstructure induced by bio-template imprinting not only facilitates the fast gas diffusion, but also exposes more active sites to accelerate gas adsorption and its chemical reaction with adsorbed oxygen species. In this sense, it firstly realizes the highly selective detection of Fe2O3-based material to trace butanone. At 170 °C, Fe2O3-600 sensor shows high sensing response (S = 25.8) and short response time (Tres = 5 s) to 100 ppm butanone vapor. This sensor still possesses small detection limit (100 ppb), good reversibility and anti-humidity. In addition, we explored the sensing mechanism of Fe2O3-600 nanosheets to butanone by O2-TPD, XPS and GC-MS techniques.

Biomimetic synthesis of iron oxide nanoparticles from Bacillus megaterium to be used in hyperthermia therapy

The suitable structural characteristics of magnetic nanoparticles have resulted in their widespread use in magnetic hyperthermia therapy. Moreover, they are considered a proper and operational choice for pharmaceutical nanocarriers. Using the biomimetic method, we were able to produce iron oxide magnetic nanoparticles from the bacterial source of PTCC1250, Bacillus megaterium, for therangostic diagnosis systems and targeted drug delivery. Some of the benefits of this method include mitigated environmental and biological dangers, low toxicity, high biocompatibility, cheap and short-term mass production possibilities in each synthesis round compared to other biological sources, simple equipment required for the synthesis; and the possibility of industrial-scale production. Bacillus megaterium is a magnetotactic bacteria (MTB) that has a magnetosome organelle capable of orienting based on external magnetic fields, caused by the mineralization of magnetic nanocrystals. Utilizing this capability and adding an iron nitrate solution to the bacterial suspension, we synthesized iron oxide nanoparticles. The extent of synthesis was measured using UV–visible spectrophotometry. The morphology was evaluated using FESEM. The crystallized structure was characterized using RAMAN and XRD. The size and distribution of the nanoparticles were assessed using DLS. The surface charge of the nanoparticles was measured using zeta potential. The synthesis of iron oxide nanoparticles was confirmed using FT-IR, and the magnetic property was measured using VSM. This study is continued to identify industrial and clinical applications.

The Size Dependence of Microwave Permeability of Hollow Iron Particles.

Hollow ferromagnetic powders of iron were obtained by means of ultrasonic spray pyrolysis. A variation in the conditions of the synthesis allows for the adjustment of the mean size of the hollow iron particles. Iron powders were obtained by this technique, starting from the aqueous solution of iron nitrate of two different concentrations: 10 and 20 wt.%. This was followed by a reduction in hydrogen. An increase in the concentration of the solution increased the mean particle size from 0.6 to 1.0 microns and widened particle size distribution, but still produced hollow particles. Larger particles appeared problematic for the reduction, although admixture of iron oxides did not decrease the microwave permeability of the material. The paraffin wax-based composites filled with obtained powders demonstrated broadband magnetic loss with a complex structure for lesser particles, and single-peak absorption for particles of 1 micron. Potential applications are 5G technology, electromagnetic compatibility designs, and magnetic field sensing.

Formation of Iron (III) Trimesate Xerogel by Ultrasonic Irradiation

AbstractFe−BTC materials have attracted vast attention owing to their high chemical stability, adaptable synthesis, and potential applications. Herein, we describe, for the first time, the preparation of iron trimesate gels by ultrasonic (US) irradiation of an aqueous solution of Iron (III) nitrate and trimesic acid. Two different procedures were used: (1) sonication for 10 or 20 minutes, (2) 3 minutes sonication under controlled pH (pH 3–5). After drying, stable Fe−BTC xerogels were obtained from both procedures. The xerogels consisted of interconnected spherical nanoparticles with similar microstructure when analyzed by FT‐IR and PXRD and similar thermal behavior under oxygen in the range of 25–900 °C. When analyzed by Nitrogen adsorption‐desorption at 77 K, all samples showed a permanent porosity with a narrow micropore distribution below 10 Å. Different textural properties were found among samples obtained with the same procedure. The product of 10 minutes sonication had a specific surface area (SSA) of 1042 m2/g.

Identification of a Two-Coordinate Iron(I)-Oxalate Complex.

Exotic oxidation states of the first‐row transition metals have recently attracted much interest. In order to investigate the oxidation states of a series of iron–oxalate complexes, an aqueous solution of iron(III) nitrate and oxalic acid was studied by infrared free liquid matrix‐assisted laser desorption/ionization as well as ionspray mass spectrometry. Here, we show that iron is not only detected in its common oxidation states +II and +III, but also in its unusual oxidation state +I, detectable in both positive‐ion and in negative‐ion modes, respectively. Vibrational spectra of the gas phase anionic iron oxalate complexes [FeIII(C2O4)2]−, [FeII(C2O4)CO2]−, and [FeI(C2O4)]− were measured by means of infrared photodissociation spectroscopy and their structures were assigned by comparison to anharmonic vibrational spectra based on second‐order perturbation theory.

Catalytic Pyrolysis of Methane to Hydrogen over Carbon (from cellulose biochar) Encapsulated Iron Nanoparticles

The catalytic performance of carbon encapsulated iron nanoparticles (CEINPs) for methane decomposition was investigated over a range of temperatures between 700 and 800 °C with varying iron concentrations (20, 30, and 40 wt %) in a semicontinuous flow fixed bed reactor. CEINPs were prepared by impregnating a cellulose biochar support (carbon source) with iron nitrate solution. This mixture was dried at 110 °C for 72 h in air followed by pyrolysis at 1000 °C in a N2 atmosphere. Unlike conventional iron-based catalysts, in CEINPs, the iron nanoparticles were encapsulated in a graphitic shell that prevented atmospheric oxidation and sintering at high temperature, improving the thermal stability of the catalysts. The fresh CEINPs did not contain any metal oxides and had only the following phases: elemental iron, iron carbides, activated carbon, and graphitic carbon, which allowed for the catalyst reduction step (in H2) to be eliminated. The decomposition of methane being an endothermic reaction showed better catalytic activity with an increase in temperature with the highest conversion of 95.7% observed at 800 °C. There are four different active sites in the catalyst, namely, graphite, graphite encapsulated iron nanoparticles, uncovered iron nanoparticles, and activated carbon. In the case of 20 wt % CEINP, the presence of higher amounts of activated carbon and graphite with a lower amount of Fe negatively impacted methane decomposition, confirming the importance of Fe as an active site. At 800 °C, the maximum catalytic performance was exhibited by 30 wt % CEINP where the initial methane conversion was 95.7% and dropped to 36.8% after 180 min of reaction. The higher conversion was due to the combined optimum amounts of Fe, graphite, and activated carbon active sites. In the case of 40 wt % CEINP, the higher amount of Fe resulted in the agglomeration of Fe nanoparticles and reduction in surface area, leading to lower methane conversions. The surface area of the spent catalysts reduced appreciably in all cases due to carbon deposition from CH4 in the form of coke and graphite (on non-encapsulated Fe nanoparticles), resulting in catalyst deactivation.

Photometric Screening of Tetrabromobisphenol A in Resin Using Iron(III) Nitrate/Hexacyanoferrate(III) Mixture as a Colorimetric Reagent.

This study aims to provide a simple way to identify the possibility of tetrabromobisphenol A (TBBPA) present in polymers without the need for complicated separation with expensive equipment. Since the presence of phenolic hydroxyl groups is known to be identifiable by the reduction of Fe3+ to Fe2+ in a ferric coloring reagent, the possibility of TBBPA being present in a polymer can be screened by a photometric measurement. A mixed solution of iron(III) nitrate and potassium hexacyanide(III) acid was used as a ferric coloring reagent. With this method, the concentration of TBBPA can be estimated from the photometric absorbance corresponding to the depth of the blue color produced by reduction of the ferric reagent in the presence of Fe(NO3)3. The limit of detection (LOD) was determined to be approximately 2 mg/kg using the Student's t-test (99% confidence), and a reproducibility of approximately 3% was determined by the relative standard deviation (RSD) from measurements of calibration samples (n = 7). Furthermore, TBBPA in actual polymer samples was screened without the need for any complex processing steps. Because this colorimetric method measures TBBPA by detecting phenolic groups, it may overestimate the TBBPA concentration in the presence of other similar phenolic substances. Nonetheless, this simple colorimetric method should help to quickly identify the presence of TBBPA in various polymers.

Recycling of iron-rich sediment for surface modification of filters for underground water deironing

Groundwater is one of the cleanest natural sources of drinking water available, which, at the same time, often requires deironing – removal of the dissolved iron ions – before the water could be used. In this paper, there are describe the preparation, characterization, and deironing properties of surface-modified refractory chamotte granules, used as active components of fillers for deironing filters. For this research, chamotte surface modification was made by solution combustion synthesis (SCS) approach of an aqueous solution of synthetic iron nitrate and citric acid with the different iron-to-chamotte ratios. An iron-rich precipitate from deironing filters was used as a source of iron for the preparation of a precursor solution. Obtained materials were characterized using diffraction, spectroscopic and microscopic methods. The SCS modification resulted in the formation of layers of hematite Fe3O4 nanocrystallites of ~5–15 nm on the surface of refractory chamotte granules. It was shown the effect of the dose of iron nitrate on the absorbed iron oxide species content on the surface of the modified chamotte granules and its influence on the surface and operational characteristics. Pilot-plant deironing tests showed that an increase in the concentration of iron on the chamotte granules surface from 5.8 wt% for unmodified samples, to 19.0, 48.7, and 55.8 wt% for the modified ones, led to the respective increase in the deironing efficiency from 41% to 65%, 73% and 78%, respectively.

Dry reforming of lignin: the effect of impregnation with iron

Dry reforming of lignin was carried out in the presence of a catalytic amount of iron introduced into lignin by impregnation with a solution of iron(III) nitrate. Organic products with low molecular weight have been obtained at lower temperatures, including aromatic, aliphatic and phenolic compounds.

Dry reforming of lignin: the effect of impregnation with iron

Dry reforming of lignin was carried out in the presence of a catalytic amount of iron introduced into lignin by impregnation with a solution of iron(III) nitrate. Organic products with low molecular weight have been obtained at lower temperatures, including aromatic, aliphatic and phenolic compounds.