Formation Of Iron Oxides Research Articles

Green synthesis of iron oxide nanorods using Withania coagulans extract improved photocatalytic degradation and antimicrobial activity

Present work compares the green synthesis of iron oxide nanorodes (NRs) using Withania coagulans and reduction precipitation based chemical method. UV/Vis confirmed the sharp peak of Iron oxide NRs synthesized by biologically and chemically on 294 and 278 nm respectively. XRD and SEM showed highly crystalline nature of NRs with average size 16 ± 2 nm using Withania extract and less crystalline with amorphous Nanostructure of 18 ± 2 nm by chemical method. FTIR analysis revealed the involvement of active bioreducing and stabilizing biomolecules in Withania coagulans extract for synthesis of NRs. Moreover, EDX analysis indicates 34.91% of Iron oxide formation in biological synthesis whereas 25.8% of iron oxide synthesis in chemical method. The degradation of safranin dye in the presence of Withania coagulans based NRs showed 30% more effectively than chemically synthesized Nanorods which were verified by the gradual decrease in the peak intensity at 553 nm and 550 nm respectively under solar irradiation. Furthermore, Withania coagulans based NRs showed effective Antibacterial activity against S.aureus and P. aeuroginosa as compared to NRs by chemical method. Finally, we conclude that green synthesized NRs are more effective and functionally more efficient than chemically prepared NRs. Therefore, our work will help the researchers to boost the synthesis of nanoparticles via biological at commercial level.

High-temperature corrosion of aluminized-AISI 1020 steel with NaCl and $${\hbox {Na}}_{2}{\hbox {SO}}_{4}$$ deposits

High-temperature corrosion of aluminized-American Iron and Steel Institute (AISI) 1020 steel with sodium chloride (NaCl) and sodium sulphate ( $${\hbox {Na}}_{2} {\hbox {SO}}_{4}$$ ) deposits was studied using isothermal oxidization in a dry air environment at $$700{^{\circ }}\hbox {C}$$ for 49 h. NaCl and $${\hbox {Na}}_{2} {\hbox {SO}}_{4}$$ deposits on the aluminide layer interfered with protective alumina/aluminium oxide ( $${\hbox {Al}}_{2} {\hbox {O}}_{3}$$ ) scale formation on the steel substrate. Chlorine and sulphur gases ( $${\hbox {Cl}}_{\mathrm{2g}}$$ and $${\hbox {S}}_{\mathrm{g}}$$ , respectively) released into the atmosphere corroded the protective $${\hbox {Al}}_{2}{\hbox {O}}_{3}$$ layer. Corrosion of the $${\hbox {Al}}_{2}{\hbox {O}}_{3}$$ layer was also due to local formation of iron oxide ( $${\hbox {Fe}}_{2}{\hbox {O}}_{3}$$ ). $${\hbox {Fe}}_{2}{\hbox {O}}_{3}$$ growth is attributed to ferric chloride ( $${\hbox {FeCl}}_{3}$$ ) vaporization. $${\hbox {S}}_{\mathrm{g}}$$ diffusion into the $${\hbox {Al}}_{2} {\hbox {O}}_{3}$$ scale via $${\hbox {Al}}^{3+}$$ vacancy defects led to the formation of aluminium sulphide on the aluminide layer surface. Cl and S consequently induced hot corrosion of the aluminized steel, thereby increasing cyclic oxychloridation and sulphidation rates at high temperatures.

Mechanism and influence factors of 2,4‐D dechlorination by sodium citrate‐activated bimetallic palladium‐zero valent iron nanoparticles

Nanoscale zero‐valent iron (nZVI) has high removal efficiency and strong reductive ability to organic contaminants, but this reactivity soon ceases and is attributed to rapid passivation of the nZVI surface due to the formation of iron oxides. In the present study, bimetallic palladium‐zero valent iron nanoparticles were activated with sodium citrate (SC‐nPd/Fe) to enhance 2,4‐D dechlorination from aqueous solutions. FTIR and XRD analyses showed that there was no passivation layer on the surface of nZVI after the addition of SC, and XPS analysis confirmed the nZVI after the reaction still maintained high reactivity and surface Pd ratio. The existence of SC facilitated the transfer of electrons from Fe0 to contaminants, thus accelerating the reductive dechlorination of 2,4‐D. The dechlorination efficiency of 2,4‐D on nPd/Fe was only 56.4% in 210 min, while complete dechlorination could be achieved on SC‐nPd/Fe under the same conditions, and simultaneously 97.1% of phenoxyacetic acid (PA) was generated. Moreover, the effect of reaction conditions on the dechlorination such as Pd ratio, SC dosage, initial pH and temperature was also investigated, and it was well described by pseudo‐first‐order kinetic model. In particular, The chelating abilities of SC is similar to EDTA, but it is an environmentally‐friendly chelating agent. Findings from the present study suggested that the SC could be a promising substitute for application in the remediation of 2,4‐D contained water.

Thermomechanical Wear Testing of Metal Matrix Composite Cladding for Potential Application in Hot Rolling Mills

Laser metal deposition (LMD) is utilized to clad the surface of a miniaturized test roll (Ø 40 mm) of tool steel. The cladding consists of two layers: a nickel alloy as intermediate layer deposited onto the surface of the steel substrate, and a metal matrix composite (MMC) as top layer consisting of spherical tungsten carbide particles embedded into the nickel alloy matrix. The thermomechanical wear behavior of the cladding is investigated on a test rig, where the test roll is pressed against an inductively heated load roll. Multiple test runs up to several hours simulating industrial loading conditions are performed. The presented testing procedure enables predicting the time‐dependent abrasive wear behavior of the cladding, in particular for hot rolling mill applications. After testing for 8 h at temperature of 650 °C and at contact pressure of approximately 1 GPa, the maximum depth of the wear mark is about 0.12 mm. Partial cracking, debonding and dissolution of the tungsten carbide particles, as well as formation of iron and chromium oxides at the surface of the wear marks occur. However, as low abrasive wear is observed, the investigated MMC may potentially be applicable for cladding rolls in steel hot rolling mills.

Soil morphology of an alluvial chronosequence from the Little River, North Carolina Coastal Plain, USA

A soil chronosequence on terraces of the Little River in the North Carolina Coastal Plain was characterized to evaluate age-related trends in pedogenesis. Five representative pedons per landform were studied from six late Quaternary fluvial surfaces, and temporal trends were assessed by regression of morphological parameters against previously reported terrace optical age estimates. Solum, B horizon, and Bt horizon thickness, subsoil clay content, and Buntley-Westin Index rubification have strong, positive correlations with age and together distinguish between soils of the floodplain (≤200yr BP), the first terrace (9.9±2.0 ka), intermediate surfaces (T2, T3b, T4; 17.4±4.2–74.6±10.4 ka), and the oldest terrace (T5b, 94.0±15.9 ka). Over time, soils develop from Entisols with respective A-C and A-E-Bw-C profiles on the floodplain and first terrace to Ultisols with increasing argillic horizon thickness, rubification, and clay content on T2-T5b. Solum thickness, Bt horizon thickness, and clay content display linear increases through time, with soil thickening reflective of downward pedogenesis through permeable, coarse-grained alluvium. Increasing argillic horizon clay content is attributable to illuviation, and possibly also to a combined bioturbation-translocation process, whereby clays scattered throughout sandy parent sediments are delivered to the surface by bioturbation, then concentrated in B horizons by eluviation-illuviation. Rubification increases with age and reflects transformation and subsoil concentration of inherited free iron, rather than iron oxide formation from primary mineral weathering. T5b pedons display morphologies comparable to those of 200 ka to >1 Ma soils along Coastal Plain rivers that also drain the Appalachian Piedmont, probably because sandy, Coastal Plain-derived Little River alluvium has a higher hydraulic conductivity that promotes faster rates of downward weathering, clay translocation, and rubification than the more finely-grained sediments of Piedmont-draining rivers. Thus, textural differences related to sedimentary provenance should be recognized when interpreting chronosequences from the region. Although rates of pedogenesis differ among Coastal Plain alluvial soils, linear trends in the ≤100 ka Little River chronosequence may nonetheless correspond to the early, more linear phases of development in studies from the region that span much longer intervals of time.

Unravelling nanoporous anodic iron oxide formation

We studied the formation of self-ordered nanopores in the anodization of iron foils. Different anodization conditions (e.g. water content and applied voltage) were tested, and anodization curves were obtained for each case to establish the optimal parameters for fabricating homogeneous nanoporous films. Samples were characterized by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and high-resolution scanning transmission electron microscopy. Moreover, the bandgap of 2.1 ± 0.1 eV was measured in nanostructured films, and electrochemical impedance spectroscopy measurements were taken at each step. Finally, we propose a mechanism for the formation of iron oxide by anodization that takes into account the chemical reactions involved.

Kinetics and mechanism of natural wolframite interactions with sodium carbonate

The kinetics and mechanism of natural wolframite interactions with sodium carbonate during air heating were studied. X-ray phase and X-ray microanalysis were used to establish that the initial monocrystalline wolframite consists of Fe0.5Mn0.5WO4 and Fe0.3Mn0.7WO4. Differential thermal analysis showed that the interaction of wolframite with sodium carbonate begins above 450°C with the formation of tungstate, sodium ferrite, iron oxides, and manganese. Model experiments on sintering with the subsequent removal of water- soluble compounds (leaching) tracked the change in the structure of wolframite. The atomic ratio of Fe/Mn in wolframite does not change up to 600°C, and subsequently decreases to 0.2 during heating, which allows the mechanism of the process to be identified and indicates the greater reactivity of wolframites with an increased proportion of iron. Thermal analysis with data processing using non-isothermal kinetics established that the interaction of wolframite with sodium carbonate in an air stream proceeds via a two-stage mechanism, wherein the first stage is limited by diffusion (activation energy, E = 243 kJ/mol) and the second stage is limited by autocatalysis (activation energy, E = 212 kJ/mol) due to the formation of a Na2WO4–Na2CO3 eutectic.

Fe-, N-Embedded Hierarchically Porous Carbon Architectures Derived from FeTe-Trapped Zeolitic Imidazolate Frameworks as Efficient Oxygen Reduction Electrocatalysts

During the design and construction of an efficient iron–nitrogen–carbon (Fe–N–C) electrocatalyst, it was difficult to avoid the formation of iron oxides along with the hierarchical carbon framework...

Genome Sequence of Mariprofundus sp. Strain EBB-1, a Novel Marine Autotroph Isolated from an Iron-Sulfur Mineral.

Mariprofundus sp. strain EBB-1 was isolated from a pyrrhotite biofilm incubated in seawater from East Boothbay (ME, USA). Strain EBB-1 is an autotrophic member of the class Zetaproteobacteria with the ability to form iron oxide biominerals. Here, we present the 2.88-Mb genome sequence of EBB-1, which contains 2,656 putative protein-coding sequences.

Structure-activity relationships in metal organic framework derived mesoporous nitrogen-doped carbon containing atomically dispersed iron sites for CO2 electrochemical reduction

Mesoporous nitrogen-doped carbon nanoparticles with atomically dispersed iron sites (named mesoNC-Fe) are synthesized via high-temperature pyrolysis of an Fe containing ZIF-8 MOF. Hydrolysis of tetramethyl orthosilicate (TMOS) in the MOF framework prior to pyrolysis plays an essential role in maintaining a high surface area during the formation of the carbon structure, impeding the formation of iron (oxide) nanoparticles. To gain inside on the nature of the resulting atomically dispersed Fe moieties, HERFD-XANES, EXAFS and valence-to-core X-ray emission spectroscopies have been used. The experimental spectra (both XAS and XES) combined with theoretical calculations suggest that iron has a coordination sphere including a porphyrinic environment and OH/H2O moieties responsible for the high activity in CO2 electroreduction. DFT calculations demonstrate that CO formation is favored in these structures because the free energy barriers of *COOH formation are decreased and the adsorption of *H is impeded. The combination of such a unique coordination environment with a high surface area in the carbon structure of mesoNC-Fe makes more active sites accessible during catalysis and promotes CO2 electroreduction.

Mineralogical and geochemical characterization of radioactive minerals and rare earth elements in granitic pegmatites at G. El Fereyid, South Eastern Desert, Egypt

The present work deals with the mineralogical and geochemical investigations of radioactive minerals and rare earth elements associated with granitic pegmatites at Gabal El Fereyid area exposed in the south Eastern Desert of Egypt. The study area is occupied by tonalite and monzogranites, the latter is intruded by pegmatites with a distinctive distribution of economically important mineralization. The studied pegmatitic bodies occur as veins that are ranging in size from few meters to 25 m long and their width usually less than 7 m; although small pockets are present. The latter display zoning structure (concentric layering) consisting of feldspar-rich zones enveloping pockets of mica (mainly muscovite) and all zoning internal quartz core. Field work using gamma spectroscopy measurements over these pegmatites shows that some bodies are radiometrically anomalous, especially the muscovite-rich zones. The mineralogy and geochemistry (trace and rare earth elements contents) of the radioactive zones in such pegmatites were achieved.Mineral characterization of the highly radioactive zones shows enrichment in thorite, uranothorite, ishikawaite, samarskite and fergusonite minerals. The spectrometric measurements of the studied pegmatites show that they possess the highest content of radioelements as well. They show enrichment in large ion lithophile elements (LILE; Pb, Rb, Sr) and high field strength elements (HFSE; Y, Zr, Th, U, Nb) and depletion in K, P and Ti. The studied granitic pegmatites indicate moderate to large negative Eu anomaly and show clear M-type tetrad effect of REE.The mineralogical and geochemical signature of investigated pegmatites represents a NYF-type (Niobium–Yttrium–Fluorine family), whereas the enrichment of rare element is an indication of high degrees of fractional crystallization of a suite of volatile-rich magmas. Uranium and thorium mineralization in the studied pegmatite are related to magmatic (syngenetic) origin with hydrothermal (epigenetic) input. The magmatic mineralization is evidenced by occurrence of thorite and zircon, whereas the hydrothermal activity is represented by alteration of feldspars and formation of pyrite and iron oxides associated with the radioactive minerals.The high levels of radioactivity and rare earth elements mineralization in the studied granitic pegmatite bodies make them a target to exploration and to enlarge the potentiality of the highly mineralized localities.

Development of magnetically separable mesoporous N doped TiO2-SiO2 coated Fe3O4 nanomaterial as solar photocatalyst for environmental application

Present paper deals with the synthesis of visible light sensitive, easily separable mesoporous magnetic titania material having Fe3O4 in the core as solar photocatalyst. Core Fe3O4 was synthesized by two different methods for comparative evaluation. Top titania layer was found to be mesoporous thus providing more active sites. Synthesized materials were characterized by UV–vis, XPS, XRD, TEM and Raman. Core Fe3O4 prepared from Fe(II) and Fe(III) salts showed higher magnetic moment having nanosized particles. On the other hand, the hydrazine method resulted in the formation of tubular iron oxide having low magnetic moment. XRD and Raman spectra support the formation of porous anatase phase on the top and below SiO2 layer properly shielded magnetic core. The final magnetic moment of 7.8 emu in case of iron oxide obtained from Fe(II) and Fe(III) salts indicates that the magnetic separation by applying an external magnetic field is easy. Nitrogen doping of top titania layer increases the visible light absorption and photocatalytic efficiency. Comparative evaluation towards the photocatalytic decomposition of para-nitrophenol and methylene blue was carried out to observe the effect of N doping. The synthesized material is found to be stable and reusable for at least five times without any marked change in the catalytic activity and magnetic moment. Synergistic effect of mesoporosity, presence of oxygen vacancy and N doping on titania facilitates the higher rate of MB and p-NP degradation under visible light.

Effect of TiO<sub>2</sub> on Plasma Sprayed Al<sub>2</sub>O<sub>3</sub> Based Composite Coatings at 900℃ in Molten Salt Environment

The present work investigates the effect of hot corrosion on ASTM-SA213-T-22 Steel with different coatings of Al2O3-TiO2 at 900℃ in molten salt environment (40wt %Na2SO4+60wt%V2O5). The experimentation consisted of 50 cycles of heating coated and uncoated specimens for 1 hour at 900℃ in muffle furnace and cooling for 20 minutes at ambient temperature. The corroded specimens were analyzed using visual examination, weight change measurement, X-ray diffraction technique and Scanning electron microscopy/Energy-disperse X-ray analysis. The results showed that the uncoated substrate had been more affected with corrosion and gained more mass due to formation of iron oxide (Fe2O3) as compared to coated substrate because of better adhesion of Al2O3 coating with base metal SA213-T22 due to presence of TiO2. The presence of TiO2 increased the strength and durability of Al2O3 coating to withstand with high temperatures.

Recycling of a wastewater to iron oxide micro structures

The proposed work describes new perspectives for recycling of a salty industrial wastewater to micro-structured iron oxides with capturing potential for minor carbon- and metallic contaminations. By-products generated by electrochemical treatment of a rubber wastewater with sacrificial steel anode were separated, dried, desalinated, and thermally processed at 800 and 1100 °C in a nitrogen atmosphere to investigate the effects of chemically bound oxygen on iron oxide formation. The obtained powder products were different phases of iron oxides, such as hematite, maghemite, magnetite; depending on the annealing temperature. All of the phases are interesting from a recycling point of view, the microstructure, elementary composition and crystallinity of the solid products before and after thermal treatment were investigated via SEM-EDX and PXRD techniques.

Recovery of Iron Values from Discarded Iron Ore Slimes

The ever-increasing demand for steel and the subsequent depletion of high-grade ores requires the massive utilization of low-grade iron ores. In the present study, an iron ore slime sample containing 56.1% Fe was investigated using physical beneficiation, carbothermal reduction, and a microwave-assisted process; however, physical beneficiation and microwave exposure were found to be inefficient as they yielded lower iron recovery. Using coconut shell as an alternative reductant was found to be promising and does not lead to the formation of higher iron oxides, such as fayalite and wustite phases. The microwave-assisted carbothermal reduction was found at par with conventional reduction, saving time and heating. The optimum magnetic concentrate obtained in both carbothermal reduction routes (microwave and muffle furnace: Fe grade, Fe recovery, and yield of 64.3, 97, and 84%, and 67, 99, and 83%, respectively) are suitable for alternative iron-making or blast furnace units.

Recovery of iron from electric arc furnace slag: effect of heating temperature and time

This work presents the iron oxide recovery from electric arc furnace slag with different temperature and time using acid leaching method. The results showed that formation of iron oxide from electric arc furnace (IO-EAFS) was influenced by the temperature and time of heating. This is evidenced by constant acid concentration and liquid to solid ratio, 5 hours of heating time was exhibited the highest amount of iron ion in extracted solution. The maximum of iron extract in heating temperature was at 100 °C. Throughout the characterization using Scanning Electron Microscopy (SEM), the iron oxide illustrated the microstructures were agglomerates predominantly with irregular shapes and XRD results further colobrated the presence of hematite combined with other metal oxide exists in the IO-EAFS. From the TGA analysis, it was identified that the recovered iron oxide was totally decomposed at 525°C. This results indicate that electric arc furnace slag is potential material of iron oxide for the future appliction.

Solar Irradiation Induced Transformation of Ferrihydrite in the Presence of Aqueous Fe2.

Ferrihydrite commonly occurs in soils and sediments, especially in acid mine drainage (AMD). Solar irradiation may affect Fe(II)-catalyzed transformation of metastable ferrihydrite to more stable iron oxides on AMD surface. We investigated the Fe(II)-catalyzed transformation process and mechanism of ferrihydrite under light irradiation. In nitrogen atmosphere, Fe2+aq could be oxidized to goethite and lepidocrocite by hydroxyl radical (OH•), superoxide radical (O2•-) and hole (hvb+) generated from ferrihydrite under ultraviolet (UV) irradiation (300-400 nm) at pH 6.0, and O2•- and hvb+ were mainly responsible for Fe2+aq oxidation. In addition, the ligand-to-metal charge-transfer (LMCT) process between Fe(II) and ferrihydrite could be promoted by UV irradiation. Goethite proportion increased with increasing Fe2+aq concentration. Both visible (vis) and solar irradiation could also lead to the oxidation of Fe2+aq to goethite and lepidocrocite, and the proportion of lepidocrocite increased with increasing light intensity. Fe2+aq was photochemically oxidized to schwertmannite at pH 3.0 and 4.5, and the oxidation rate was higher than that under dark conditions in air. The photochemical oxidation rate of Fe2+aq decreased in the presence of humic acid. This study facilitates a better understanding of the formation and transformation of iron oxides in natural environments and ancient Earth.

Zero valent iron supported biological denitrification for farmland drainage treatments with low organic carbon: Performance and potential mechanisms

In this work, the feasibility and performance of zero valent iron (ZVI) coupled anaerobic microorganisms in nitrogen removal under low organic carbon condition were investigated, through the comparison of mono-ZVI system and mono-cell system. Coupled system showed the highest total nitrogen (TN) removal efficiency of 67.85% with the addition of 15 g L−1 iron shavings at pH 7.0, which was higher than 29.62% in the mono-ZVI system and 43.86% in the mono-cell system. Besides, the activities of nitrate reductase (NAR), nitrite reductase (NIR), nitric oxide reductase (NOR) and nitrous oxide reductase (N2OR) were significantly improved at ZVI dosage of 15 g L−1 and pH 7.0, which contributed to the higher TN removal efficiency in coupled system. The extent of sludge granulation was greater in the coupled system than mono-cell system, which benefited to the high operational performance and stability of coupled system. The promoted generation of extracellular polymeric substances (EPS) and formation of iron oxides in the coupled system also took advantages on nitrogen removal through adsorption. In addition, ZVI could largely enrich the functional species related to nitrogen removal in the system at phyla and genera level, which could be reasoned for the enhanced nitrogen removal efficiency. In conclusion, this study will improve the understandings of nitrogen removal in the coupled system and be useful to ensure the application of ZVI-supported biological process in the remediation of farmland drainage.

Magnetic susceptibility as a pedogenic proxy for grouping of geochemical transects in landscapes

Magnetic susceptibility (χlf) is a sensitive, fast, and accurate technique to detect soil pedogenic processes and features, and can improve understanding of soil-forming factors. The aim of this study was to determine catenary groupings of geochemical segments by identifying the relationship between magnetic susceptibility and the soil-forming factors within and along the landscape. Soil physical and chemical properties, as well as soil mineralogy were evaluated in twenty-two topsoil samples from three different landscapes in southern Brazil. The bulk χlf and frequency-dependent susceptibility (χfd) were also measured, represented by i) air-dried fine earth (< n μm, χlf ADFE) ii) after dithionite-citrate-bicarbonate treatment (χlf CBD), and iii) the parent material (χlf ROCK). Geochemical segments were grouped using multivariate analysis. Our results indicate that soil parent material and climate, are first order factors for the pedogenic enhancement of magnetic minerals. Magnetic susceptibility of air-dried fine earth (χlf ADFE) is widely variable, from 11.00 to 2.075 × 10−8 m3 kg−1. χlf was higher in soils developed on basalt, and much lower for soils developed on sandstone. χlf ADFE also reveals a strong positive linear correlation with χlf CBD (r = 0.96) and a moderate positive linear correlation with “free” and total Fe content (r = 0.49 and 0.69, respectively). The χfd (< 2%) indicates samples in which either non-SP grains dominate the assemblage or where the SP fraction is <0.03 nm. After CBD dissolution there is an increase in χlf values. The rate of iron weathering and iron release, driven by hydrolysis and oxidation, and reductive dissolution of magnetite affect the formation and/or persistence of secondary iron oxides in some of the soil transects. Both principal component analysis (PCA) and cluster analysis group soils from a) crest and upper slope locations, b) down slope and sandstone areas, and c) valley floors, indicating that magnetic susceptibility is an effective proxy for soil properties for grouping and identifying pedogenic/geochemical segments along a landscape of 360 km2.

Pyrite oxidation in shales: Implications for palaeo-redox proxies based on geochemical and SEM-EDX evidence

Pyrite oxidation in marine shales during weathering has been widely studied, however, the effects of this process on geochemical proxies commonly used to reconstruct ocean redox conditions, or the details of pyrite oxidation at the mineral grain scale, have not received much scientific attention. We conducted a four-week laboratory experiment designed to stimulate pyrite oxidation at shale outcrops, and to assess effects on the chemical phase of iron and sulphur in the samples both in bulk sediments (useful for comparison to palaeo-environmental geochemistry) and at a finer scale (to gain a better understanding of the nature of these changes). Geochemical and scanning electron microscopy (SEM) techniques provide evidence for pyrite oxidation, carbonate dissolution, and iron (oxyhydr)oxide formation during the experiment. The net effect of the experiment on the ratio of highly reactive iron phases (FeHR) to total iron (FeT) is minimal (≪0.03% difference), suggesting that this redox proxy behaves relatively conservatively during weathering. The effect of weathering on the ratio of pyrite-bound iron to highly reactive iron (FePY/FeHR), used to investigate the availability of sulphur, in contrast, is pronounced (up to 32.5% difference) due to the oxidation of pyrite and the precipitation of iron (oxyhydr)oxides in the shale samples. Electron microscopy provides evidence that iron (oxyhydr)oxides precipitated in situ as rims around cores of pyrite particles, “passivating” and protecting them from further oxidation. The quantification of these partly oxidised pyrite particles is now possible using a novel automated particle analysis method coupled to chemical mapping, developed in this study. We conclude that this method can be of wide use, both to quantify pyrite oxidation, and assess the significance of FePY/FeHR at measured in shale outcrop samples.