Mixture Of Fe2O3 Research Articles

High removal of PS and PET microplastics from tap water by using Fe2O3 porous microparticles and photothermal irradiation with NIR light

This work reports the synthesis of Fe2O3 (FeO) microparticles using the Pechini method and their use to remove microplastics from tap water. The analysis by electronic microscopy revealed that the FeO microparticles (FeMicroPs) have a porous structure and are formed by interconnected grains with sizes of 80-120 nm. In addition, the X-ray diffraction analysis pointed out that the FeMicroPs are composed of γ- Fe2O3 and α- Fe2O3 phases. To remove the PS and PET microplastics with sizes of 0.1-3 μm from the tap water, FeO was added to the contaminated water and the mixture of FeO+microplastics was irradiated with focused NIR light (980 nm). This provoked the melting of the microplastics on the FeO surface. Later, the FeMicroPs with adsorbed microplastics was recovered with magnets. This last procedure permitted a high removal of microplastics from the tap water, and the adsorption capacity was 1000 mg/g. In the next step, the microplastics adsorbed on the FeO were irradiated with NIR light to induce its thermal decomposition by photothermal irradiation, this in turn, produced the elimination of the microplastics from the FeO surface and allowed its reuse to remove more microplastics from the tap water. The elimination of the microplastics from the FeO surface was confirmed by the FTIR and Raman techniques, since the vibrational peaks associated with the microplastics disappeared from the FeO surface after the photothermal irradiation. Thus, the results of this investigation suggest that the photothermal irradiation with NIR light not only facilitates the removal of microplastics from the tap water, but also, it was useful to degrade the microplastics definitively without producing more contamination. This technique could be used to remove microplastics in water treatment plants.

Corrosion Properties and Passive Film Interface of Inconel 718 in NaNO3 Solution for Laser-Assisted Electrochemical Machining.

Laser-assisted electrochemical machining (ECM) is an ideal manufacturing method for Inconel 718 (IN718) because of the method's high efficiency and good surface quality, and the basis for and key to laser-assisted ECM is its anodic electrochemical dissolution behavior. In this study, IN718 in a 10 wt % NaNO3 solution was subjected to innovative electrochemical testing and laser-assisted ECM experiments to investigate its corrosion properties and the passive film characteristics formed on its surface. The passivation-related behaviors and structures of the passive film were investigated based on open-circuit potentials, dynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy. It was found that there was obvious active-passive-transpassive transition behavior, and the structure of the passive film in laser-assisted ECM exhibited pores and defects, resulting in weak corrosion resistance, compared with IN718 under ECM without laser irradiation. The chemical composition of the passive film was obtained by X-ray photoelectron spectroscopy. The results showed that the passive film was composed mainly of a mixture of NiO, Ni(OH)2, Cr2O3, CrO3, Fe2O3, α-Fe2O3, α-FeOOH, Nb2O5, NbO, MoO3, MoO2, and TiO2. The passive film formed by laser-assisted ECM was rich in NiO and TiO2 and lacked Cr2O3 and MoO3, which validated its pores and defect structures. A corresponding schematic model was also proposed to characterize the interface structure between the IN718 substrate and the passive film. Laser-assisted ECM tests were performed under different current densities and machining times, and the corrosion morphology of IN718 was identified. Corrosion pits and a loose product layer appeared on the machined surface at low current densities, and the dissolution mechanism was pitting. The quantity and depth of the corrosion pits dispersed on the machined surface clearly decreased as the current density increased. Finally, a quantitative corrosion model was established to characterize the dissolution behavior of IN718 in NaNO3 solution during laser-assisted ECM.

Essential oil analysis of Rhaponticum repens (L.) Hidalgo, and its application in green synthesis of iron nanoparticles to remove Cr (VI) ions from aqueous solutions

Acroptilon repens is a widespread weed in Asia, and has a complicated taxonomy. Recent taxonomical treatment explored that Acroptilon species must be classified in the genus Rhaponticum. Therefore, the scientific name of this species has been converted into Rhaponticum repens. In the current study, essential oil composition, and its ability to green synthesis of iron nanoparticles for future use to adsorb Cr (VI) ions pollution of aquatic solution were evaluated for the first time. The GC-MS analysis revealed oxygenated monoterpenes constituted great proportion of the essential oil, with 1,8-cineole and camphor as the main essential oil components. Several appropriate methods, including UV-Vis, FTIR, XRD, SEM, DLS, and VSM revealed the green synthesis of a mixture of Fe3O4 and Fe2O3 nanoparticles by the extracted essential oil. Sizes of the produced nanoparticles were not equal and detected in the range of 3 to 50 nm, with an average size of 31.5 nm and the magnetic property of 15 emu/g. The green-synthesized nanoparticles could adsorb Cr (VI) ions pollution from aquatic solutions. However, under an optimum condition, the Cr (VI) ions adsorption capacity and removal were 167.6 mg/g and 91%, respectively. Findings revealed the major essential oil composition highly differed from those reported in the previous phytochemical studies. Although the synthesized nanoparticles were not uniform, they could remove Cr (VI) ions pollution.

Synthesis of NiFe-layered double hydroxides using triethanolamine-complexed precursors as oxygen evolution reaction catalysts: effects of Fe valence.

The synthesis of highly efficient NiFe-layered double hydroxides (NiFe-LDHs) to catalyze the oxygen evolution reaction (OER) is urgent and challenging. Herein, NiFe-FeCl3-x and NiFe-FeCl2-x samples (where FeCl3 and FeCl2 represent the Fe sources and x represents the imposed reaction time: 6, 12, and 24 h) were prepared via one-pot hydrothermal synthesis using Fe sources characterized by Fe(III) or Fe(II) valence states. In the presence of triethanolamine, when FeCl3 was used as the Fe source, pure NiFe-LDH was obtained, whose crystallinity increased with increasing hydrothermal treatment time. In contrast, when FeCl2 was used as the Fe source, a mixture of NiFe-LDH, Fe2O3, and trace amounts of Fe3O4 was obtained. The content of NiFe-LDH in the mixture increased under longer hydrothermal treatment and NiFe-FeCl3-x catalysts exhibited better OER performance than NiFe-FeCl2-x catalysts. Specifically, NiFe-FeCl3-6 afforded the highest OER performance with an overpotential of 246.8 mV at 10 mA cm-2 and a Tafel slope of 46.1 mV dec-1. Herein, we investigated the effects of the valence state of Fe precursors on the structures and OER activities of the prepared catalysts; the mechanism of NiFe-LDH formation via hydrothermal synthesis in the presence of triethanolamine was also proposed.

Role of iron oxide in retarding the graphitization of de-oiled asphaltenes for amorphous carbon.

The solvent deasphalting (SDA) process is widely recognized as a significant technology in processing inferior oil. However, de-oiled asphaltene (DOA), which accounts for about 30% of feedstocks, is not well utilized in conventional processing methods to date. Considering its complicated structure and high heteroatom and metal contents, DOA is suitable for preparing amorphous carbon. Herein, we obtained amorphous carbon from inferior de-oiled asphaltene through direct carbonization of a mixture of DOA and Fe2O3 and revealed the mechanism of iron oxide in retarding graphitization to increase the disordered structure content. After the addition of Fe2O3, XRD results showed that the content of amorphous carbon increased from 25.57% to 59.48%, and a higher defect degree could also be observed in Raman spectra, thus resulting in better electrochemical performance in Na-ion half-cells. As a coke core, Fe2O3 could accelerate the polycondensation of asphaltene molecules; meanwhile, oxygen species derived from Fe2O3 could capture excess H free radicals in the initial pyrolysis stage, which inhibited the formation of planar polycyclic aromatic molecules and weakened π-π interactions. Moreover, O atoms could embed into the carbon skeleton by reacting with DOA at higher temperatures, which could further twist and break the intact carbon layer. Both of the factors enhanced the proportion of amorphous carbon. This work not only provides a new understanding of controlling the carbonization process, but it also promotes the development of the SDA process.

Magnetic properties of Sr1.5La0.5FeMoO6-δ depending on the phase composition of the reaction mixture

This paper presents investigations of phase transformations during the crystallization of Sr1.5La0.5FeMoO6-δ by the solid-phase technique from a stoichiometric mixture of oxides MoO3, La2O3 and Fe2O3 and SrCO3 and precursors Sr0.5La0.5FeO3 and SrMoO4. Using XRD and thermogravimetric analyses, the influence of synthesis modes on the chemical processes occurring during the formation of double perovskite was studied. It has been established that the synthesis of lanthanum-strontium ferromolybdate in a mixture of oxides proceeds through a number of series-parallel stages. At the initial stage of interaction, the resulting lanthanum-strontium ferromolybdate is enriched with iron and its composition changes during the reaction towards an increase in the molybdenum content. As the temperature increases, the content of double perovskite increases, and the concentration of the secondary phase SrMoO4 does not disappear to zero until the synthesis temperature, which indicates that solid-phase reactions with the formation of a solid solution Sr1.5La0.5FeMoO6-δ from oxides are difficult to occur. It was determined that to minimize the influence of intermediate reaction products it is necessary to use precursors Sr0.5La0.5FeO3 and SrMoO4. Based on the results of studying the temperature dependences of the degree of phase transformations during the crystallization of double perovskite, combined heating modes were optimized. The use of optimized synthesis modes made it possible to obtain single-phase Sr1.5La0.5FeMoO6-δ powder with the superstructural ordering (82%), the Curie temperature of 450 K and a magnetization value of 40.9 A · m2 · kg-1 at T = 77 K in a magnetic field with induction B ≥ 0.86 T.

Trapping and Methanation of CO2 in a Domestic Microwave Oven Using Combinations of Sorbents and Catalysts

CO2 trapping and methanation allow to reduce greenhouse gas emissions and recycle CO2 into a sustainable fuel, provided renewable H2 is employed. Microwave (MW)-based reactors provide an efficient means to use electrical energy for upgrading chemicals, since MW can selectively heat up the load placed in the reactor and not the reactor itself. In this study, CO2 capture and methanation were investigated using solid adsorbents (ZrO2 and Fe3O4), microwave absorbers (SiC and Fe3O4) and Ru/SiO2 as CO2 the methanation catalyst. The sorption and catalyst beds were located in a domestic MW oven that was used to trigger CO2 desorption and methanation in the presence of H2. The working Fe-based structure turned out to be a mixture of FeO and Fe, which allowed for MW absorption and local heating; it also acted as a CO2 sorbent and reverse water–gas shift catalyst. Various reactor configurations were used, leading to different performances and selectivity to CO and CH4. To the best of our knowledge, this is the first report of its kind showing the potential of using inexpensive microwave technology to readily convert trapped CO2 into valuable products.

Heterogeneity effects in micro-beam XRF scanning spectroscopy of binary powdered mixtures and lake sediments

Micro-beam X-ray fluorescence (XRF) scanning spectroscopy is very useful for analyzing heterogeneous samples from earth and environmental sciences with high spatial resolution. However, XRF intensity depends on grain size and mineralogical composition, known as the heterogeneous effect, although little quantitative evaluation has been conducted. In this study, the binary powdered mixtures of Fe2O3 in the CaCO3 or SiO2 matrix with nine grain size fractions (0.3–605 μm), four Fe2O3 concentrations (5–20 wt%), and fine-grained sedimentary cores from Lake Baikal were used for analysis, using a scanning X-ray analytical microscope (SXAM), and then evaluated by making a simple modification of the Berry–Furuta–Rhodes model. The results of binary powdered samples show that the Fe intensity decreases as the grain size increases, but if the grain size is constant, its intensity has a linear relationship with the composition of Fe2O3. The experimental data are in good agreement with theoretical curves. The theory predicts that if a phase that contains fluorescent elements has narrow ranges of concentration and grain size, the micro-beam XRF spectroscopy enables highly precise calibration from the XRF intensity to element concentration. The theoretical curves of the Lake Baikal sediment core suggest that the Fe intensity has about a 30% maximum difference in the median grain size range of 3.9–28.2 μm. This variation appears in a scatter of regression between Fe intensity and concentration, but it scarcely affected the XRF intensity variability of sediment composition.

Characterization of the Radiation Contamination in an 18MV Linac Treatment Room Made of some Nanoparticles Mixture

Purpose: Shielding against radiation in radiotherapy and radiology requires deep knowledge of radiation physics and shielding design methods. The application of nanoparticles in the photon and neutron dose moderation has been proven in the literature.
 Materials and Methods: Effective neutron mass removal cross-section (ΣR/ρ) was for the ordinary concrete doped with 50nm in diameter nanosphers mixture of Fe2O3(5%), WO3(5%), B4H (5%), Pb2O3(5%) was estimated with MCNP5 Monte Carlo (MC) code and N-XCOM computational program. An 18MV linac room made of the nanoparticles dopped ordinarily simulated. Additionally, the room was considered with three legs in the maze and photoneutron and capture γ-ray Dose Equivalent (DE) were estimated at the modeled rooms maze.
 Results: Total ΣR/ρ with energies 100 keV-2000keV was estimated using MC and N-XCOM as 0.02802-0.02687 cm2/gand 0.02810- 0.02687 cm2/g, respectively. Total ΣR/ρ of the neutron for the pure ordinary concrete was estimated by MC code and N-XCOM with energies 100 keV-2000keV as 0.02802-0.02687 cm2/g and 0.02810- 0.02687 cm2/g. Borated Polyethylene (BPE) and Lead required thickness calculated as 7.43×10-06 mm and 4.73×10-06 mm for the capture γ-ray shielding.

Pb diffusion in magnetite: Dating magnetite crystallization and the timing of remanent magnetization in banded iron formation

The ferrimagnetic mineral magnetite (Fe3O4) is abundant in banded iron formation (BIFs), and has the potential to provide UPb or PbPb age information on these rocks because it incorporates small amounts of U during growth. Combined with age measurements, paleomagnetic studies of BIF magnetites may also yield insight into the history of Earth's magnetic field and its relationship to early evolution of Earth's interior and atmosphere.Reliable magnetite ages utilizing Pb isotopes require knowledge of Pb diffusion in the magnetite structure. For this reason, we undertook an experimental investigation of Pb diffusion in magnetite by diffusing Pb2+ ions into pre-polished slabs of natural magnetite oriented parallel to {001} or {111}. A mixture of PbSO4 and Fe2O3 was used as a surface powder source to supply Pb2+ diffusant at the sample surface and at the same time buffer the oxygen fugacity of the system at magnetite-hematite (MH)—a typical fO2 for banded iron formations (BIFs) due to the common presence of both iron oxides (and where Pb2+ is stable relative to other Pb valence states). Diffusion experiments spanned temperatures of 500–675 °C and durations of 75 to 2035 h. Following each experiment, in-diffused Pb was depth-profiled using Rutherford backscattering spectroscopy (RBS) and Pb diffusivities were calculated from the profiles using an infinite half-space diffusion model. The following diffusion law for Pb2+ in magnetite is based upon 12 independent diffusivity measurements:DPb (m2·s−1) = (9 × 10−17 m2·s−1) exp.(−98,000 J·mol−1)/RT)where the uncertainties in the pre-exponential constant and activation energy are ±6% and ± 15%, respectively.Pb diffusion in magnetite over the temperature range of our study is orders of magnitude slower than projected for other divalent cations based on down-temperature extrapolation of previously measured diffusion laws (e.g., for Mn2+, Fe2+, Co2+, and Ni2+). This finding is encouraging in terms of the potential suitability of magnetite for UPb age determinations of BIFs and other magnetite-bearing rocks. Indeed, classical Dodson closure temperatures well above 500 °C are not unrealistic in cases where magnetite crystals having large diffusion domains (e.g., >100 μm in radius) are cooled relatively rapidly (e.g., at 100 °C/MYr). This is of particular significance for paleomagnetic studies, since the Curie temperature of magnetite is 580 °C and therefore the age of magnetization in magnetite-bearing rocks may be directly dated. However, slow cooling of magnetites having small diffusion domains can lead to Pb loss at temperatures of 200 °C or lower. Pb mobilization is evaluated for various time-temperature scenarios that involve both heating and cooling as well as “closed-loop” time-temperature paths. We conclude that UPb or PbPb age determinations of BIF magnetites are potentially reliable, but isotopic results should be assessed in concert with knowledge of the thermal history of the host rock and the effective grain size of the magnetites.

Electrochemical and Surface Characterisation of Carbon Steel Exposed to Mixed Ce and Iodide Electrolytes

The protection of ferrous metals in acidic environments is important in many industries. Extending the pH range of organic inhibitors to low pH has been achieved with the addition of iodide ions, which facilitate adsorption. It was of interest to see whether similar outcomes could be achieved with inorganic inhibitors. To this end, this paper examines the influence of potassium iodide addition on the level of corrosion protection provided by Ce(NO3)3 in 3.5% NaCl electrolytes over a pH range of 2.5 to 8. Potentiodynamic polarization was used to assess percentage inhibitor efficiency (IE%), and scanning electron microscopy, energy dispersive X-ray spectrometry, and X-ray photoelectron spectroscopy were used to characterize the corrosion product. It was found that KI alone provided only poor corrosion inhibition except at pH 2.5, where nearly 85IE% was achieved. Its addition to the cerium electrolytes was generally in excess of 90% and over 97% for the optimum concentration. The addition of KI seemed to change the mechanism of formation of corrosion products from predominantly Fe2O3 to a mixture of FeOOH, Fe3O4, and Fe2O3, which were more adherent. Corrosion protection was extended to pH 4, but under the conditions explored here, no additional protection was evident at pH 2.5.

Hematite α‐Fe2O3(0001) in Top and Side View: Resolving Long‐Standing Controversies about Its Surface Structure

AbstractHematite is a common iron oxide found in nature, and the α‐Fe2O3(0001) plane is prevalent on the nanomaterial utilized in photo‐ and electrocatalytic applications. The atomic‐scale structure of the surface remains controversial despite decades of study, partly because it depends on sample history as well as the preparation conditions. Here, a comprehensive study is performed using an arsenal of surface techniques (non‐contact atomic force microscopy, scanning tunneling microscopy, low‐energy electron diffraction, and X‐ray photoemission spectroscopy) complemented by analyses of the near surface region by high‐resolution transmission electron microscopy and electron energy loss spectroscopy. The results show that the so‐called “bi‐phase” termination forms even under highly oxidizing conditions; a (1 × 1) surface is only observed in the presence of impurities. Furthermore, it is shown that the biphase is actually a continuous layer distorted due to a mismatch with the subsurface layers, and thus not the proposed mixture of FeO(111) and α‐Fe2O3(0001) phases. Overall, the results show how combining surface and cross‐sectional imaging provides a full view that can be essential for understanding the role of the near‐surface region on oxide surface properties.

Entropy generation analysis of multi-mass diffusion in a nanofluid-interfaced three-phase viscous fluid in an inclined channel

The primary aspect of the present study is to analyze the velocity and thermal slip effects on the entropy in the three-phase flow of viscous liquid amid nano liquids (NFs), hybrid nano liquids (HNFs) and tri-hybrid nano liquids (THNFs) with different shaped nanomaterials in an inclined channel. Moreover, entropy generation (EG) analysis is conducted for all three fluids i.e., viscous fluid sandwiched between Fe2O3 water NFs, viscous fluid sandwiched between Fe2O3−Cu water HNFs, and viscous fluid sandwiched between Fe2O3−Cu−MoS2 water THNFs. The uniqueness of the present study is the inclined nature of the channel as no study is present on three-phase immiscible flow in an inclined channel. In oil recovery systems, an immiscible mixture of nanofluids and viscous fluid can be used to recover the remaining oil from reservoirs. It can be used in a reservoir through an inclined channel to improve displacement efficiency. Furthermore, nanoparticles present in the above-mentioned immiscible mixture can reduce interfacial tension amid oil and injected fluid for increased oil recovery. The solution of the mathematical model (systems of PDEs) of three immiscible fluids flow is obtained via the perturbation method. The momentum and heat transport results are presented via graphical and tabular illustrations using the MATHEMATICA program. Our findings show that the velocity and heat fall when the inclination angle is varied. So, the inclined behavior of a channel can be used for a controlled flow of heat and fluid. The enhanced momentum and heat flow can be seen when we consider an immiscible mixture of Fe2O3−Cu−MoS2 water THNF and viscous fluid as compared to Fe2O3−Cu water HNF and Fe2O3 water NF. Moreover, heat flow is more significant in the case when differently shaped nanoparticles are considered as compared to the same spherical-shaped nanoparticles.

The Role of Oxygen Reduction Reaction in Determining Pit Stability of FeCr Alloys

Pitting corrosion is one of the most dangerous forms of corrosion, leading to sudden catastrophic failures in engineering system. Once initiated, pit propagation rates are largely dependent on the magnitude of the supporting cathodic current available from the oxygen reduction reaction (ORR) occurring on the external passive film. Here the ORR kinetics on conventional and high Cr content FeCr alloys made by arc-melter were investigated by experimental and computational methods. DFT calculations suggested that the overpotentials for the ORR on FeCr oxides are in the order Cr2O3 > Fe3O4 > Fe2O3 > FeCr2O4, which was experimentally confirmed on the FeCr alloys by rotating disc electrode experiments in both O2 saturated 0.1 M NaOH and 3.5 wt% NaCl. Koutecký-Levich analysis demonstrated that ORR follows a 4-electron pathway on all surfaces investigated. Moreover, the investigation of the Pourbaix diagrams of FeCr revealed that at potentials where pitting corrosion initiates the main constituents of the passive films should be a mixture of Fe2O3 and Cr2O3, rather than FeCr2O4, which is proved to be a good ORR catalyst. The results support the postulation that one role Cr additions play in the prevention of pitting corrosion is to suppress the ORR reaction.

An oxalato-bridged dimetallic heptanuclear [K5IFe2III] complex anion with guanidinium as counter cation: Synthesis, crystal structure, Hirshfeld surface analysis and magnetism

An oxalato-bridged heterometallic heptanuclear [K5IFe2III] hybrid salt, (CH6N3)[K5(H2O)4Fe2(C2O4)6] (1) (CH6N3+ = guanidinium cation) has been synthesized and characterized by elemental and thermal analyses, IR spectroscopy, single-crystal X-ray diffraction, EPR and SQUID magnetometry. The asymmetric unit in 1 is composed of a dimetallic heptanuclear [K5(H2O)4Fe2(C2O4)6]− anionic complex and a guanidinium CH6N3+ cation insuring the charge compensation. Each Fe3+ center in the anionic complex is six-coordinate in a distorted octahedron defined by three chelating oxalato(2-) ligands. In contrast, the coordination numbers for K+ centers range from 7 to 9. The structural feature of focal interest in 1 is formation of an extended anionic network encapsulating guanidinium cations. This structure can be considered a sheet-MOF, where metal ions and oxalates (linkers) form infinite 2D units. The 3-D supramolecular architecture is stabilized by OH∙∙∙O and NH∙∙∙O hydrogen bonds linking polymeric oxalato-bridged anionic assemblies and organic cations. The thermal studies confirmed the anhydrous character of salt 1 and showed a three-step decomposition to yield a mixture of Fe2O3 and K2O as final residue. EPR spectrum of 1 is in accordance with the oxidation state + 3 of the iron center in an octahedral environment. Temperature-dependence susceptibility measurements investigated in the temperature range 2–300 K revealed weak antiferromagnetic coupling at low temperatures in salt 1. The distributions of different types of intermolecular interactions in the crystal structure were quantified by Hirshfeld surface analysis and their associated fingerprint plots.

Hybrid nanofluid flow within cooling tube of photovoltaic-thermoelectric solar unit

In this work, the thermoelectric generator (TEG) layer has been combined with conventional layers of photovoltaic-thermal (PVT) modules to use the waste heat and increase the efficiency. To reduce the cell temperature, there exists a cooling duct in the bottom of the PVT-TEG unit. Type of fluid within the duct and structure of duct can change the performance of the system. So, hybrid nanofluid (mixture of Fe3O4 and MWCNT with water) has been replaced instead of pure water and three various configurations of cross section [STR1 (circular), STR2 (rhombus), STR3 (elliptic)] have been implemented. Through the tube incompressible laminar flow of hybrid nanofluid has been solved while in solid layers of panel, pure conduction equation has been simulated involving heat sources resulting from optical analysis. According to simulations, the third structure (elliptic) has the best performance and rise of inlet velocity causes overall performance to enhance about 6.29%. The values of thermal and electrical performances for elliptic design with equal fractions of nanoparticles are 14.56% and 55.42%, respectively. With the best design, electrical efficiency improves about 16.2% in comparison with an uncooled system.

Photocatalytic Efficiency of TiO2/Fe2O3 and TiO2/WO3 Nanocomposites

The photocatalytic proprieties of TiO2/FeO3 and TiO2/WO3 nanocomposites have been investigated using methylene blue as a pollutant. We propose a non-conventional approach for material preparation, i.e., the Doctor Blade technique, which is an easy and inexpensive method for coating materials. Several drawbacks related to the use of powders can be alleviated by using solid substrates, and this deposition method allows us to take advantage of the high surface area of nanoparticles, avoiding dispersion in the solution. The possibility of coating a material with a photoactive molecule with an easy and inexpensive method leads to the use of photocatalysis in the real world. The structural, optical, and textural characterizations of these materials were carried out using UV-vis. Diffuse Reflectance Spectroscopy (DRS) was used to calculate the energy band gap with the Kubelka-Munk method, and N2 absorption-desorption measurements were used to study the exposed surface area (SBET). The photocatalytic activity was evaluated in nanocomposites containing 0.1/0.2/0.3/0.5 wt.% of Fe2O3 or WO3 or both Fe2O3 and WO3. An enhancement of about 60% was achieved by adding 0.2% wt. of WO3 after 2 h of exposure to UV light. The TiO2@Fe2O3 and TiO2@WO3/Fe2O3 mixtures showed the same behavior as the TiO2@WO3 mixture. Therefore, the photoactivity of these photocatalysts is not related to the oxide itself. These solid results are due to the energy band structure of the materials. In fact, there is an important band matching among TiO2, WO3, and Fe2O3, which gives these nanocomposites a substantial improvement in photodegradation. The pH evaluated was neutral pH both at the beginning and at the end of the experiment, which is consistent with the well-known photodegradation pathway of methylene blue.

Computational Single and Multiphase Approaches to Investigate the Hydrothermal Behavior of Hybrid Nano-fluid in Plain and Wavy Tubes

The newest class of heat transfer improvement is accomplished by using hybrid Nano-fluids. Therefore, the heat transfer and pressure drop of a mixture of Iron oxide (Fe3O4) and Magnesium oxide (MgO) nanoparticles suspended into the base fluid under a turbulent regime through a plain and wavy tube are computed employing commercial software ANSYS Fluent. A mixture of Fe3O4 and MgO nanoparticles in pure water is considered a brand-new type of hybrid Nano-fluid for boosting heat transfer. The simulation procedures were performed utilizing the single and multiphase (mixture) approaches at Reynolds number in the range of (3,916 - 31,331) and volume concentrations range of (0.5% ≤ φ ≤ 2%). The plain and wavy walls are subjected to a constant heat flux of 18,189 W/m2, and the flow is presumed as fully developed. The computed outcomes are validated with the correlation equations and experimental data of literature. The outcomes demonstrate that boosting the nanoadditives fraction leads to a remarkable improvement of heat transfer and hydrothermal performance indicator (HPI) of MgO-Fe3O4 /H2O Hybrid Nano-fluid through the considered tubes compared with the conventional base fluid. However, the increment is slightly higher with a wavy wall tube than with the plain one. Moreover, new correlations were suggested for specific water-based hybrid Nano-fluid volume concentrations.

Synthesis of Fe-deficient eudialyte analogues: Relationships between the composition of the reaction system and crystal-chemical features of the products

AbstractEudialyte-related compounds have been synthesised hydrothermally at T = 600°C and P = 2 kbar from a stoichiometric mixture of Na2CO3, CaO, Fe2O3, ZrOCl2 and SiO2 using the Na:Ca:Fe:Zr:Si ratios corresponding to the eudialyte end-member Na15Ca6Fe3Zr3Si(Si25O73)(OH)Cl2⋅H2O, in the presence of 1 M aqueous solutions of NaCl and NaF. The synthesis was carried out in platinum ampoules over 10 days. Natural raslakite (a Ca-deficient member of the eudialyte group) was used as a seed and added in amounts corresponding to 2 wt.% of the whole charge. The products were characterised by powder X-ray diffraction, IR and Raman spectroscopy, morphological features, and electron probe microanalyses. In experiments with NaCl, almost pure eudialyte-type compounds were obtained. Synthesis in the presence of a NaF solution resulted in the formation of a F-dominant eudialyte-type compound related to raslakite as the main product and aegirine, vlasovite and lalondeite as by-products. All synthesised eudialyte-type compounds are Zr-rich and Fe-deficient, similar to eudialyte-group minerals from hyperagpaitic rocks related to foyaites. The increased NaCl contents in the reaction system results in increased Ca content in the synthesised eudialyte-related compounds. The crystal-chemical formulae of the synthesised eudialyte-type compounds are derived based on general regularities established earlier for eudialyte-group minerals.

Development of FexOy particle onto bacterial cellulose network by forced hydrolysis and its electrical conductivity

FexOy particle and bacterial cellulose composite sheet was successfully prepared by forced hydrolysis. The presence of Fe3+ ions in bacterial cellulose suspension significantly provided the positive charge due to electrostatic force as reported by Zeta potential. With the pH of 12 of bacterial cellulose suspension, particle was nucleated between bacterial cellulose networks. Fourier transform infrared exhibited Fe-O stretching. X-ray diffraction reported that the mixture of Fe2O3 and Fe3O4 was existed onto bacterial cellulose composite. Scanning electron microscope reported that FexOy particle was randomly distributed in bacterial cellulose network. Intensity of Fe was qualitatively observed by energy dispersive analysis. With the existence of FexOy particle, the composite illustrated the inferiority of thermal stability of 150℃. Furthermore, it was noted that the resistivity was reduced with respect to increment of FexOy particle, suggesting that electrical conductivity was then enhanced. It was remarkable to note that FexOy particle and bacterial cellulose composite sheet prepared from forced hydrolysis showed the excellent properties as a candidate for flexible electrode.