Synthesis Of Goethite Research Articles

Iron oxyhydroxide nanoparticles: green synthesis and their cytotoxicity activity against A549 human lung adenocarcinoma cells

Iron oxyhydroxide (α-FeOOH, Goethite) is one of the most thermodynamically stable iron oxides and a widespread soil mineral. In this study, a mixture of two phenolic extracts of rosemary and Echinacea was utilized as stabilizing and reducing agents for the synthesis of Goethite (FeOOH) nanoparticles without utilizing harmful toxic solvents. The resulting nanoparticles were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM)-energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM), thermogravimetry/differential thermal analysis (TG/DTA), and Brunauer–Emmett-Teller (BET). MTT assay was applied for evaluating the possible toxicity of the nanoparticles against A549 human lung adenocarcinoma cells.

Study of the formation of ferrihydrite under prebiotic chemistry conditions: artificial seawater 4.0 Gy and ammonium thiocyanate

AbstractAmong the several steps involved in molecular evolution, molecular preconcentration is the first and most important. If the molecules are not preconcentrated the other steps of molecular evolution cannot occur. There are several ways to preconcentrate molecules: sorption, wetting/drying cycles, freezing/sublimation and sorption/precipitation with minerals. In the present work, the effect of NH4SCN and artificial seawater 4.0 Gy on the synthesis of ferrihydrite was studied. It should be noted that thiocyanate could play the same role as that of CN− in the Strecker reaction. Unlike today's seawater that has high Na+ and Cl− concentrations, the seawater used in this work has high Mg2+, Ca2+ and SO42− concentrations. Two results stand out, first SCN− and NH4+ were preconcentrated by sorption/precipitation in some syntheses and second, in some experiments, a mixture of goethite, hematite and magnetite was obtained. The sorption/precipitation of SCN− is always associated with the synthesis of goethite. This could be an indication that SCN− interacts with Fe3+ through the sulphur group of SCN−. In addition, the synthesis of magnetite could be an indication that the SCN− ion oxidized, forming thiocyanogen-(SCN)2 or trithiocyanate ion-(SCN)−3 and that Fe3+ reduced to Fe2+. Besides the sorption/precipitation of SCN− and NH4+, Fourier-transform infrared spectroscopy also showed that sorption/precipitation of SO42− and CO32− occurred. Ferrihydrite synthesized with artificial seawater presented the highest surface area and pore size. The pHpzc values of the samples were in the range of pHpzc described in the literature. The X-ray photoelectron spectroscopy (XPS) measurements performed show proportions of iron present in different oxidation states, however, the electronic similarities observed in the mixtures of iron oxides and oxy-hydroxides make it difficult to quantify them. Direct comparison between XPS spectra of the Fe2p and O 1s core-levels reveal no significant differences from the effect of artificial seawater 4.0 Gy on the synthesis of ferrihydrite.

The effects of selenate on goethite synthesis and selenate sorption kinetics onto a goethite surface - A three-step process with an unexpected desorption phase

Iron oxyhydroxides are widely spread in soils and sediments. They can considerably affect the migration of selenate in the environment, due to their high affinity towards oxyanions. To assess the sorptive properties of one of the most common oxyhydroxides, the selenate sorption onto goethite and its effects on goethite's structural properties during its crystallization were investigated. The sorption kinetics of selenate onto goethite at different pH revealed the presence of a desorption phase that had manifested extensively, especially at higher pH values. Also, an isotherm study indicated that the selenate sorption onto goethite is multi-layered at higher concentrations. Phosphate, which is one of the common naturally occurring oxyanions, affected selenate sorption onto goethite significantly, while chloride and sulfate influenced sorption only marginally. The Mössbauer spectrometry showed no structural changes after iron oxyhydroxides crystallization in the presence of selenate. However, changes outside the goethite lattice were manifested by the alterations in distributions of hyperfine magnetic fields obtained from Mössbauer spectra analyses, as well as by the changes in values of the selenate-treated samples' surface charge.

Beneficiation of acid mine drainage (AMD): A viable option for the synthesis of goethite, hematite, magnetite, and gypsum – Gearing towards a circular economy concept

Pollution of water resources by acid mine drainage (AMD) has been an issue of primary concern in recent decades. This is rooted to the fact that AMD negatively affects the environment and its suitability to foster life. As such, efforts to recover, valorise and beneficiate minerals acquired from AMD treatment process have been ongoing, albeit with minimal success. With that in mind, this study unpacks novel ways of beneficiating AMD via the synthesis of valuable minerals with myriads of industrial applications. To this end, real AMD was used to synthesize goethite, hematite, magnetite, and gypsum (product minerals). Drinking water was also reclaimed as part of the treatment process, hence rendering this system a zero-liquid-discharge (ZLD) process. For the synthesis of goethite, hematite, and magnetite, Fe(III) and Fe(II) were recovered via sequential precipitation in batch reactors. Lime was added to treated water to synthesize high-grade gypsum. Furthermore, reverse osmosis (RO) was employed to reclaim drinking water as per South African drinking water standards (SANS 241) specifications. Product minerals were ascertained using advanced analytical techniques. Concisely, this study proved that AMD can be beneficiated into valuable minerals, which could be utilized in a number of industrial applications. The profits from selling the product minerals can potentially aid in offsetting the running costs of the treatment process, hence making this process self-sustainable. This will also foster the concept of circular economy and waste beneficiating, thus curtailing the impacts of AMD to different spheres of the environment.

Synthesis of Goethite (α-FeOOH) Pigment by Precipitation Method from Iron Lathe Waste

<p>Lathe waste contains high iron content potential to be further processed into goethite pigment. The purpose of the research was to determine the effect of synthesis temperature on the structure, colour values, and morphology of goethite pigment. The synthesis was conducted with temperature variations of 60, 70, 80and 90°C. The XRD diffraction pattern shows that crystal structure of the product of all synthesis temperatures are goethite (α-Fe-OOH) with orthorhombic structure. The crystal size of the pigment ranges between 11.17 – 12.32 nm. Colour value analysis shows that product of 70°C synthesis temperature exhibits the highest lightness value about 40.5. Based on SEM-EDX imaging, the morphology of the samples is not uniform and forming agglomerates. Traces of impurities were detected, such as C and Na.</p><p> </p><p>Keywords: Iron lathe waste, goethite, temperature, precipitation</p>

Facile synthesis of goethite anchored regenerated graphene oxide nanocomposite and its application in the removal of fluoride from drinking water

AbstractDrinking water fluoride pollution is a worldwide environmental problem imposing serious menace to human health. Goethite anchoring regenerated graphene oxide (α-FeOOH@rGO) nanocomposite was synthesized via facile one-step hydrolysis pathway with ferrous sulfate as starting material. Fluoride adsorption efficiencies in aqueous solution were also testified through batch adsorption experiments. α-FeOOH@rGO has good defluoridation ability in a wide range of pH and has a strong anti-interference ability in the presence of high concentration foreign anions. Pseudo-second-order adsorption kinetics and Langmuir adsorption isotherms are fitted well involved in fluoride adsorption process. The FTIR and XPS results prove that defluoridation proceeds through an ion-exchange mechanism with sulfate-bearing in α-FeOOH@rGO crystal structure. It would be useful for the purpose of environmental protection in design and improvement of α-FeOOH@rGO as a cost-effective anion-exchange adsorbent.

Laboratory synthesis of goethite and ferrihydrite of controlled particle sizes

Iron oxyhydroxides, such as goethite and ferrihydrite, are highly abundant and ubiquitous minerals in geochemical environments. Because of their small particle sizes, their surface reactivity is high towards adsorption of anions and cations of environmental relevance. For this reason these minerals are extensively studied in environmental geochemistry, and also are very important for environmental and industrial applications. In the present work, we report the synthesis and characterization of goethite and ferrihydrite of controlled particle sizes. It has been shown that surface reactivity of these minerals is highly dependent on crystal sizes, even after normalizing by specific surface area. In order to investigate the reasons for this changing reactivity it is necessary to work with reproducible particle sizes of these minerals. We investigated here the experimental conditions to synthesize goethite samples of four different specific surface areas: ca. 40, 60, 80 and 100 m2 g-1, through the controlled speed of hydroxide addition during hydrolysis of acid Fe(III) solutions. In the case of 2-line ferrihydrite, samples with two different particle sizes were prepared by changing the aging time under the pH conditions of synthesis (pH = 7.5). The synthesized minerals were identified and characterized by: X-ray diffraction, N2 adsorption BET specific surface area, transmission electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and maximum Cr(VI) adsorption.

Hydrothermal synthesis of goethite (α-FeOOH) nanorods in the presence of ethylenediamine:thiourea

Goethite (α-FeOOH) nanorods were synthesized via the hydrothermal method with the assistance of coordinating ligands, i.e. ethylenediamine and thiourea. The homogeneity of the nanorod size distribution increased and the propensity to agglomerate decreased when ethylenediamine and thiourea were used in conjunction; contrary to goethite synthesis in the presence of a single ligand. The type and mode of structure-directing plays a critical role in the morphology of the final products. When using thiourea only or in combination with ethylenediamine, nanorods and nanoparticles of various morphologies were formed. Conversely, when exclusively using ethylenediamine, in addition to the nanorods, fine needles with a significantly smaller diameter were discernible. With all combinations, structurally uniform α-FeOOH nanorods were formed. This improved nanorod formation in the presence of both ligands might be attributed to a more ordered alignment and regular conformation of ethylenediamine molecules in the presence of thiourea and thus less susceptibility to thermal perturbations. Finally, higher concentrations of ligand influence the final product and increases particle aggregation.

Kinetics of crystal growth of nanogoethite in aqueous solutions containing nitrate and sulfate anions

Iron oxyhydroxide nanoparticles, relatively abundant and highly reactive components of most natural ecosystems, are known to grow via the oriented attachment (OA)-based crystal growth pathway. Here, we conducted experiments in highly alkaline solutions containing sulfate and nitrate anions to test the differential impact of these anions on the various steps in this growth pathway. Nanogoethite (α-FeOOH) was prepared by reacting ferric sulfate or ferric nitrate with potassium hydroxide, and aging at room temperature, 50, 60 and 70 °C. X-ray diffraction (XRD) was used to confirm the synthesis of goethite and Rietveld analyses were used to determine the particle sizes in samples with different aging times. Particle morphology and microstructure of some samples were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM images confirmed growth of goethite nanorods via OA. OA growth kinetics were modeled using a previously reported kinetic equation. An Arrhenius plot indicated the activation energy for OA-based crystal growth in the sulfate system was 45.2 kJ mol−1, higher than in the nitrate system (23.1 kJ mol−1). The magnitude of the activation energy suggests that the rate-limiting step for OA growth is diffusion of nanoparticles in solution, a first step necessary for particle–particle attachment. We attribute the larger effect of sulfate compared to nitrate on the activation energy to greater structuring of water by sulfate. The kinetic pre-exponential factor for the sulfate system is much higher than that for the nitrate system, and results in faster growth kinetics at high temperature. Sulfate may accelerate the dehydration of the interface, a subsequent step required for OA-based growth, possibly through increasing the rate of water exchange at the nanoparticle surfaces. These findings motivate conduction of new experiments to further probe the kinetics of individual steps in OA-based crystal growth, suggest routes to inhibit or promote OA relative to atom-by-atom growth pathways, and provide clues to how variation in solution chemistry could impact mineral growth in natural systems.

Synthesis and Characterization of Iron Oxyhydroxide Nanowires

A very simple method of synthesis of goethite, α-FeOOH, nanowire is reported. To fabricate the nanowires, an anodized alumina nanoporous template (AAO) is used. AAO has pores with an average diameter of 60 nm. The synthesis is based on a self-combustion reaction of the chemical precursor (Fe(NO3)3 saturated solution) which occurs inside the nanopores. The geometry of AAO determines the morphology of the nanowires and the confinement conditions in which the heat treatment determines the composition of the nanostructure. The nanowires are characterized using scanning electron microscopy, high resolution transmission electron microscopy and magnetometry [magnetization versus applied field (M versus H)]. TEM analysis indicates that nanowires are composed of several α-FeOOH single crystals. The nanowires have a clear magnetic oriented structure.

Synthesis of goethite in solutions of artificial seawater and amino acids: a prebiotic chemistry study

AbstractThis study investigated the synthesis of goethite under conditions resembling those of the prebiotic Earth. The artificial seawater used contains all the major elements as well as amino acids (α-Ala, β-Ala, Gly, Cys, AIB) that could be found on the prebiotic Earth. The spectroscopic methods (FT-IR, EPR, Raman), scanning electron microscopy (SEM) and X-ray diffraction showed that in any condition Gly and Cys favoured the formation of goethite, artificial seawater plus β-Ala and distilled water plus AIB favoured the formation of hematite and for the other synthesis a mixture of goethite and hematite were obtained. Thus in general no protein amino acids (β-Ala, AIB) favoured the formation of hematite. As shown by surface enhanced Raman spectroscopy (SERS) spectra the interaction between Cys and Fe3+ of goethite is very complex, involving decomposition of Cys producing sulphur, as well as interaction of carboxylic group with Fe3+. SERS spectra also showed that amino/CN and C-CH3 groups of α-Ala are interacting with Fe3+ of goethite. For the other samples the shifting of several bands was observed. However, it was not possible to say which amino acid groups are interacting with Fe3+. The pH at point of zero charge of goethites increased with artificial seawater and decreased with amino acids. SEM images showed when only goethite was synthesized the images of the samples were acicular and when only hematite was synthesized the images of the samples were spherical. SEM images for the synthesis of goethite with Cys were spherical crystal aggregates with radiating acicular crystals. The highest resonance line intensities were obtained for the samples where only hematite was obtained. Electron paramagnetic resonance (EPR) and Mössbauer spectra showed for the synthesis of goethite with artificial seawater an isomorphic substitution of iron by seawater cations. Mössbauer spectra also showed that for the synthesis goethite in distilled water plus Gly only goethite was synthesized and in artificial seawater plus Cys a doublet due to interaction of iron with artificial seawater/Cys was observed. It should be pointed out that EPR spectroscopy did not show the interaction of iron with artificial seawater/Cys.

Oxygen isotope effects associated with substitution of Al for Fe in synthetic goethite: Some experimental evidence and the criterion of oxygen yield

Measurements of the fractional abundance (m) of high temperature nonstoichiometric (HTN) hydrogen in goethite are shown to predict the reduction in O2 yield associated with removal of HTN oxygen by routine pre-treatment of a sample with BrF5 at 22°C. The predicted relationship between smaller O2 yields and m is linear and defines an “oxygen yield limit” (OYL), which is introduced for use in oxygen isotope analyses of goethite. The OYL sets lower limits for O2 yields that would be consistent with: (1) removal of all HTN oxygen during pre-treatment and (2) complete recovery of the goethite structural oxygen during subsequent reaction with BrF5 at 450°C. Measured O2 yields that are less than those predicted by the OYL are anomalously low and indicate probable partial loss of structural oxygen during pre-treatment at 22°C. After such partial loss, measured δ18O values of the residue are more negative than the actual δ18O of the total structural oxygen. Therefore, the OYL can be used to distinguish between robust and suspect δ18O analyses of goethite.This OYL criterion was applied to some newly analyzed synthetic goethites in which Al substitutes for Fe up to mole fractions (XAl) of ∼0.13. As expected, the robust δ18O values indicate that 1000ln18α (where, 18α=[18O/16Omineral]/[18O/16Owater]) increases with increasing XAl, but comparison of these results with the predictions of a published solid solution model suggests that the relationship between 1000ln18α and XAl is sensitive to very high pH and possibly to the concentration of aqueous Cl− during synthesis of goethite. The cause of the apparent sensitivity to Cl− remains unknown. The various relationships are: (A)T=42°C,pH=1.5–2.5,[Cl-]≈0.16M:1000ln18α=18±5XAl+1.8±0.3(B)low-pH model,[Cl-]=0.00M:1000ln18α=13(±2)XAl+4.1(±0.3)(C)T=22°C,pH=14,[Cl-]=0.00M:1000ln18α=5(±3)XAl+1.6(±0.3)(D)low-pH model,[Cl-]=0.00M:1000ln18α=13(±2)XAl+6.5(±0.3)However, for natural freshwater goethites, the low-pH, no-Cl, solid solution model (e.g., isothermal equations B and D) best predicts the oxygen isotope effects associated with substitution of Al for Fe. Thus, for goethites from freshwater systems with acidic to circum-neutral pH, the following expression can be used to calculate end member goethite (FeOOH) δ18O values from the measured values of δ18O and XAl:δ18OFeOOH=δ18Omeasured-13(±2)XAlBecause the slope of the preceding expression appears to be relatively insensitive to temperature, the equation should be applicable over the range of temperatures at which goethite commonly crystallizes in natural systems (0°C⩽T⩽∼70°C). However, the value of δ18OFeOOH is sensitive to temperature via the temperature dependence of 1000ln18α for pure goethite at acidic to circum-neutral pH in freshwaters as follows (T in degrees Kelvin):1000ln18α=1.66×106T2-12.6The results of this study affirm the need to correct measured δ18O values of goethite for the effects of substituent Al to obtain useful paleoenvironmental information, and they support the existing model for doing so.

Synthesis of Goethite by Separation of the Nucleation and Growth Processes of Ferrihydrite Nanoparticles Using Microfluidics

Microfluidic synthesis is used to form nanoparticles by separate nucleation and growth processes using two microreactors (see picture) operating under different temperature and flow conditions. Ferrihydrite nanoparticles precipitated in the first microreactor are aged under continuous flow in a second microtubular reactor, leading to goethite nanoparticles. TMAOH = tetramethylammonium hydroxide.

Synthesis of Goethite by Separation of the Nucleation and Growth Processes of Ferrihydrite Nanoparticles Using Microfluidics

AbstractEine mikrofluidische Synthese von Nanopartikeln nutzt getrennte Keimbildungs‐ und Wachstumsphasen in zwei Mikroreaktoren, die bei unterschiedlichen Temperaturen und Flussbedingungen arbeiten (siehe Bild). Ferrihydrit‐Nanopartikel werden im ersten Mikroreaktor abgeschieden und in einem Mikroströmungsrohr unter kontinuierlichem Fluss gealtert, wodurch Goethit‐Nanopartikel resultieren. TMAOH=Tetramethylammoniumhydroxid.magnified image

Synthesis of goethite by separation of the nucleation and growth processesof ferrihydrite nanoparticles using microfluidics

Synthesis of goethite by separation of the nucleation and growth processesof ferrihydrite nanoparticles using microfluidics

Synthesis of goethite from Fe(OH) 2 precipitates: Influence of Fe(II) concentration and stirring speed

Magnetic methods are efficient tools in soil and environmental science. But in such natural environments, several magnetic minerals are generally present. So, synthetic standard samples are necessary for calibration of laboratory techniques. The aim of this study was to synthesise goethite free of magnetic impurities (concentration <∼1 μg kg −1) with different crystal sizes. Goethite was prepared by oxidation of aqueous suspensions of Fe(OH) 2 precipitates. Final products were characterised by X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy and magnetic methods. Goethite could be obtained in the absence of any trace of strong magnetic minerals using FeSO 4·7H 2O and NaOH as reactants with the following experimental conditions: temperature=45 °C, [FeSO 4·7H 2O]=0.50 mol L −1, [NaOH]=0.20 mol L −1, stirring speed=760 rpm. The Fe(II) concentration and the stirring speed were varied. It proved possible to modify the size of the goethite crystals by varying the Fe(II) concentration and the stirring speed, but important changes of these parameters induced the formation of other phases, lepidocrocite when the oxidation reaction was drastically accelerated and Fe 3O 4 when the reaction was slowed down. In any case, for weak magnetic fields, a low-coercivity magnetic mineral saturating at weak magnetic fields was observed. It may correspond to traces of δ-FeOOH or to domains structurally similar to δ-FeOOH inside the multidomainic crystals of δ-FeOOH.

Catalytic properties of goethite prepared in the presence of Nb on oxidation reactions in water: Computational and experimental studies

Nb-substituted goethites have been prepared and characterized by Mössbauer spectroscopy, XRD, FTIR and BET surface area measurements. The doublet formation in Mössbauer spectra and the decreasing of the crystallinity shown in XRD analyses indicated that the Fe domain size is small, which may be the result of either Fe3+ substitution for Nb5+ in the goethite structure or simply the formation of small particle-size goethite when Nb is present. FTIR analyses showed shifts and broadening of the bands as result of the incorporation of Nb5+ ions into the α-FeOOH structure. The insertion of Nb in the goethite structure caused a significant increase in the BET surface area of the material. The prepared materials were investigated for the H2O2 decomposition and the Fenton reaction in the oxidation of methylene blue dye. It was observed that the introduction of Nb during the synthesis of goethite produced a strong increase in the activity for the dye contaminant oxidation by H2O2. Theoretical quantum DFT calculations were carried out in order to understand the degradation mechanism for methylene blue with goethites.

Synthesis of Goethite as a Model Colloid for Mineral Liquid Crystals

We describe the synthesis and modification of lathlike goethite (α-FeOOH) model colloids, where we focused on the reduction of the size polydispersity (determined from transmission electron microscopy pictures.) The length polydispersity could be strongly reduced from 55% down to 17% using a combination of a forced hydrolysis method and an improved centrifugation procedure. Preliminary small-angle X-ray scattering experiments demonstrated the potential of these model particles to study the influence of the length polydispersity on the occurrence of different liquid crystalline phases. A coating of polyisobutene was applied on the goethite surface to obtain a stable dispersion of hard-core laths in toluene, which retained the peculiar magnetic alignment behavior of aqueous goethite particles (changing from parallel to perpendicular orientation at increasing field strength.) The goethite laths could further be coated with a silica layer of tunable thickness which also allowed the incorporation of a fluorescent dye. Finally, the goethite core of silica-coated goethite was dissolved with acid to obtain hollow silica laths. These modifications give additional possibilities for the use of goethite as model colloids.

Oxygen isotopes in synthetic goethite and a model for the apparent pH dependence of goethite–water 18O/ 16O fractionation

Goethite synthesis experiments indicate that, in addition to temperature, pH can affect the measured value of the 18O/ 16O fractionation factor between goethite and water ( α G–W). A simple model was developed which expresses α G–W in terms of kinetic parameters associated with the growth of goethite from aqueous solution. The model predicts that, at a particular temperature, the range of pH over which α G–W changes as pH changes is expected to be comparatively small (∼3 pH “units”) relative to the range of pH values over which goethite can crystallize (pH from ∼1 to 14). Outside the range of sensitivity to pH, α G–W is predicted to be effectively constant (for constant temperature) at either a low-pH α G–W value or a high-pH α G–W value. It also indicates that the values of α G–W at high pH will be disequilibrium values. Values of α G–W for goethite crystallized at low pH may approach, but probably do not attain, equilibrium values. For goethite synthesized at values of pH from ∼1 to 2, data from two different laboratories define the following equation for the temperature dependence of 1000 ln α G–W ( T in degrees Kelvin) (IV) 1000 ln α G – W = 1.66 × 10 6 T 2 - 12.6 Over the range of temperatures from 0 to 120°C, values of 1000 ln α G–W from Eq. (IV) differ by ⩽0.1‰from those of a published equation [Yapp C.J., 1990. Oxygen isotopes in iron (III) oxides. 1. Mineral–water fractionation factors. Chem. Geol. 85, 329–335]. Therefore, interpretations of data from natural goethites using the older equation are not changed by use of Eq. (IV). Data from a synthetic goethite suggest that the temperature dependence of 1000 ln α G–W at low pH as expressed in Eq. (IV) may be valid for values of pH up to at least 6. This result and the model prediction of an insensitivity of α G–W to pH over a larger range of pH values could explain the observation that Eq. (IV) yields values of α G–W which mimic most 18O/ 16O fractionations measured to date in natural goethites.

Acicular Metallic Particles Obtained from Al-Doped Goethite Precursors

Acicular metallic particles of different sizes were obtained by thermal treatment under a hydrogen flow of undoped and Al-doped goethite precursors. The acicular goethite particles were synthesized by the controlled oxidation−precipitation of iron (II) sulfate and aluminum nitrate solutions by addition of a base. Microstructural studies showed that the Al-doped goethite precursors consist of acicular particles with the aluminum mainly concentrated at the particle outer layers even though it was initially added during the synthesis. The mechanism for this rather atypical enrichment of aluminum can be explained in terms of the different stability of an Al-carbonate green rust phase formed during the goethite synthesis. Moreover, it was observed that the aluminum enrichment on the goethite particle surface is later enhanced during the reduction to iron. A detailed characterization of the final metal particles was carried out to correlate their chemical and magnetic properties with the structural properties o...