FeO Content Research Articles

Conservation tillage enhances the sequestration and iron-mediated stabilization of aggregate-associated organic carbon in Mollisols

Conservation tillage practices, which involve minimal or no soil disturbance and crop residue retention, are known to help preserve soil organic carbon (SOC). However, the mechanisms underlying the minerals-mediated chemical and physical stabilization of SOC remain unclear. Here, a long-term field experiment was initiated in 2012 to investigate the effects of tillage managements on the contents and chemical composition of SOC density fractions, iron oxides transformation and aggregate stability in Mollisols. We utilized three treatments: conventional tillage (CT) without crop residue, reduced tillage (RT) and no tillage (NT) with straw mulching. Compared to CT, RT and NT significantly increased SOC content by 13.6 % and 17.9 % in the 0–20 cm soil layer due to an increase in the aromatic compound contents. Furthermore, NT and RT increased the mean weight diameter by 17.7 % and 10.7 %, respectively, indicating increased aggregate stability compared to CT. Additionally, the contents of amorphous iron oxides (Feo) and complex iron oxides (Fep) increased under NT and RT by 10.6–14.4 % and 12.7–41.1 %, respectively, in bulk soil and silt + clay fractions within macroaggregates (>0.25 mm). The contents of Feo and Fep were strongly positively correlated with aggregate stability (p < 0.001, r2 = 0.64), and promote the physical protection of SOC. Both NT and RT enhanced the aromatic-C content and aromatic-C/aliphatic-C ratio by 13.6 %–24.6 % and 16.5 %–38.9 % in macroaggregates compared with CT. Moreover, the aromatic-C/aliphatic-C ratio increased with increasing Feo plus Fep contents (p < 0.001, r2 = 0.73), which led to an increased in the recalcitrant-C proportion, and this shift was benefit for the accumulation of mineral-associated OC. These results indicate that long-term conservation tillage can augment the accessibility of Fe for binding C, possibly by forming organo-Fe complexes, which subsequently improve soil aggregation, and thus promoted the chemical stability and long-term sequestration of SOC in Mollisols of Northeast China.

Discrimination of Fe-Ni-Laterites from Bauxites Using a Novel Support Vector Machines-Based Methodology on Sentinel-2 Data

Currently, the global shift towards green energy is at the forefront of efforts introducing a new era, thus rendering exploration for critical raw materials essential. To this purpose, the utilization of advanced machine learning methods in remote sensing has emerged as a rapid and cost-effective approach. This study proposes a new methodology, utilizing Sentinel-2 satellite data, to distinguish ferronickel (Fe-Ni-) laterite from bauxite across pre-mining, mining, and post-mining occurrences worldwide. Both ores contain mineral raw materials such as nickel, iron, cobalt, and alumina and their discrimination is generally macroscopically challenging, especially when their locations are often in geographical proximity. The proposed method is based on Support Vector Machines (SVM) classification using spectral signatures of known Fe-Ni-laterite and bauxite-bearing pixels in Greece, Cuba, and Jamaica. The highest classification accuracies are obtained by combining 𝑏12 with 𝑏6 or 𝑏7 spectral bands. Comparisons with specific ore mineralogies show that 𝑏6 and 𝑏7 are strongly linked to the ferric phase, while 𝑏12 is mainly associated with the argillic mineralogies, the latter probably being the key discriminating factor between the two ores. From laboratory chemical analyses, we also establish that 𝑏12 and 𝑏6 or 𝑏7 are strongly associated with Al2O3 and Fe2O3 content correspondingly. The proposed method is accurate, it has reduced prospection costs, and it can facilitate the initial screening of broad areas by automatically characterizing whether an ore is bauxite or Fe-Ni-laterite. This underscores the methodology’s significance in ore differentiation and exploration within the context of green energy endeavors.

Effect of dissolved oxygen on corrosion behavior and mechanism of X70 pipeline steel in simulated low temperature bentonite-containing alkaline chloride environment

Effect of dissolved oxygen (DO) on the corrosion behavior of X70 pipeline steel in low temperature bentonite-containing alkaline chloride environments was comprehensively investigated. The cathodic reduction reaction is inhibited and corrosion current density gradually descent as the DO decreases, resulting in a significant improvement in the corrosion resistance of X70 pipeline steel. The content of Fe3O4 and α-FeOOH in the corrosion products film increases, refinement of rust grains and crack decreases effectively suppressing the penetration of corrosive substances. Pitting initiates within ferrite grains and at phase interface, while reducing the DO can restrain the chemical dissolution of MnS to retard the pit initiation.

The high-hardness ceramic glazes based on basalt from Bali Province for ceramic body coatings

The ceramic glaze method is not only done to add color aesthetics but also to increase the hardness of the glaze. Basalt is one of the raw materials developed as a ceramic glaze material because it is cheap, easy to find, and has good characteristics. This research aims to determine glaze characteristics by varying the concentration of basalt rocks from the Ababi area, Karangasem Regency, Bali Province. The experiment used basalt at 45%-61%, Feldspar 27%-37%, Kaolin 3%-8%, and ZnO 7%-10% as raw materials for glaze, not frit glaze. Heating the glaze material layer at 1,250 °C for 3 hrs. The product characteristics of glaze ceramics include chemical composition, crystal phase, microhardness, porosity, density, thermal expansion coefficient, and surface morphology. Basalt from Bali is characterized by its high Fe2O3 content, reaching 20.07 wt%. Compared to basalt in generally, it has a different impact on the physical and mechanical characteristics of the ceramic glaze produced. Based on the observation of ceramic glaze products, the glaze composition with 56% basalt, 32% feldspar, 5% kaolin, and 7% ZnO showed the best coating, with a yellowish-brown color and an average thickness of 79.82µm. The hardness value of the glaze layer is 6.5 GPa, exceeding the standard hardness value of glazes on the market. Glazed ceramics contain the minerals Gahnite (ZnAl2O4) and Coesite (SiO2), which can increase the hardness of the glaze. This research demonstrates the tremendous potential and added value of using basalt from Bali Province as a raw material for glazed ceramics.

Iron borophosphate glasses: Merging optical transparency, structural integrity, and radiation shielding efficacy for sustainable uses

The research work explored the influence of iron doping on the optical behavior, structural characteristics, and radiation shielding capabilities of soda lime borophosphate glass system of composition xFe2O3-(42.5-x)B2O3-26CaO-28.7Na2O-2.8P2O5 (x up to 8 mol%). The glass samples doped with varying iron concentrations were synthesized via the conventional melt-quenching method. A comprehensive characterization approach was employed, integrating X-ray diffraction (XRD) analysis to probe the structural aspects, Fourier transform infrared (FTIR) spectroscopy to examine the molecular vibrations and bonding, and UV–visible spectroscopic techniques to investigate the optical properties. Furthermore, the study evaluated the potential of these iron-doped glasses as effective radiation shielding materials by assessing their attenuation performance against various radiation types. The influence of iron oxide (Fe2O3) addition on the borophosphate network, coordination environment, and optical absorption was examined. The radiation shielding characteristics, such as mass attenuation coefficient, half-value layer, mean free path, and other parameters, were assessed using Phy-x freeware program calculations. The results revealed the formation of an amorphous glass structure and the incorporation of iron ions into the borophosphate network. The addition of Fe2O3 influenced the borate superstructural units, the conversion of BO3 to BO4 units, and the optical absorption bands. The glasses exhibited promising radiation shielding properties combined with increasing Fe2O3 content.

A supergene-hydrothermal origin of the itabirite-hosted high-grade iron ores in the Mbarga prospect, Mbalam iron ore district, southern Cameroon, Congo Craton

The Mbarga itabirite deposit in the Mbalam iron district on the northwest edge of the Congo Craton (CC) hosts two main types of iron ore enrichments: supergene and specularite ores. This study presents mineralogical, geochemical, and isotopic datasets on these ores to determine their genesis.Ore microscopic studies indicate that the itabirites are of the oxide facies type, with magnetite showing partial to extensive alteration to hematite-martite. The supergene ores consist of hematite + martite + goethite ± gibbsite ± magnetite ± quartz, while the specularite ores are mainly composed of hematite + martite ± quartz. Magnetite microchemistry suggests formation under low-T hydrothermal conditions (~200–300 °C) with high fO2. Geochemical analyses show that the supergene and specularite ores have higher Fe2O3 (88.27 to ~100 wt%) and lower SiO2 (<0.01 to 0.18 wt%) contents than the itabirites (31.95 wt% Fe2O3, 67.16 wt% SiO2). The enrichment of Fe in the supergene ores is attributed to the depletion of major oxides and trace elements due to weathering and supergene enrichment, while the high Fe content in the specularite ores stems from the precipitation of iron-rich, but trace- and rare earth elements (REE)-deficient hydrothermal fluids. The slightly higher Al2O3 content and positive Ce anomalies in the supergene ores suggest the retention of Al-bearing minerals (gibbsite) and reveal highly oxidative conditions during martitization. Stable isotope analyses reveal that the supergene and specularite ores have δ18O values of −2.5 to −0.3 ‰ and − 2.0 to −3.4 ‰, and δ2H values of −75 to −123 ‰ and − 70 to −119 ‰, respectively, suggesting the involvement of isotopically light-evolved meteoric water in their formation. In contrast, the itabirites exhibit heavier δ18O (8.5 to 10.2 ‰) and δ2H (−85 to −91 ‰) values, suggesting formation from mixed magmatic and metamorphic fluid sources. A “polygenic-supergene-hydrothermal” model is suggested for the formation of the Mbarga itabirite-hosted iron ores.

Preparation of Fe3O4/NiO Nanomaterials by Electrodeposition and Their Adsorption Performance for Fluoride Ions

The high concentration of fluoride ions in industrial wastewater poses a threat to both human safety and the ecological environment. In this paper, three types of magnetic NiO nanomaterial (MNN) with nickel–iron ratios of 3:1, 2:1, and 1:2 were successfully prepared using the electrodeposition technique to eliminate fluoride ions (F−) from industrial wastewater. The surface morphology, phase composition, and chemical structure of the nanomaterials were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results demonstrate the MNN material’s exceptional adsorption capabilities for fluoride ions (F−) at a nickel–iron ratio of 3:1, with a maximum adsorption capacity of up to 58.3 mg/g. The adsorption process of fluoride on the MNN material was further examined using Langmuir and pseudo-second-order kinetic models, revealing predominantly monolayer adsorption and chemisorption characteristics. When the amount of FeSO4•9H2O added is minimal, only the distinctive peaks of NiO are visible in the product’s spectrum. However, as the Ni/Fe ratio decreases, characteristic peaks of Fe3O4 crystals begin to appear and gradually intensify, indicating an increase in Fe3O4 content within the MNN material. Additionally, the pH level significantly affects the adsorption of fluoride ions (F−) onto the MNN material, with the highest adsorption capacity observed at pH 7.

Differences in bulk Fe content and density between type I and type II ordinary chondrite chondrules: Implications for parent body heterogeneities in oxidation state and O‐isotopic composition

AbstractType II chondrules have higher oxidation states than type I chondrules; in ordinary chondrites (OC), type II chondrules tend to be larger, richer in bulk Fe, and have higher densities than type I chondrules. Magnesian type IA chondrules tend to be richer in 16O than type II chondrules. Because the aerodynamic behavior of a particle is a function of the product of its size and density, type I and type II chondrules (or their precursors) were partly separated in the ordinary chondrite zone of the solar nebula prior to the accretion of OC parent asteroids. LL chondrites acquired a chondrule population with the highest type II/type I ratios, L chondrites acquired chondrules with an intermediate ratio, and H chondrites acquired chondrules with the lowest type II/type I ratios. This contributed to the observed differences among OC groups in oxidation state and O‐isotopic composition: in going from H to L to LL, mean oxidation state increases and mean Δ17O values increase. Higher oxidation is marked by increases in the FeO contents of olivine, low‐Ca pyroxene, chromite, and ilmenite; increases in the TiO2 content of chromite; and increases in the Co content of kamacite.

A color prediction model for mending materials of the Yuquan Iron Pagoda in China based on machine learning

During the restoration of iron cultural relics, the removal of rust from these artifacts is necessary. However, this rust removal process may lead to inconsistent local color on the iron relics. To address this, mending materials are applied to treat the surface, ensuring consistent local color. In the surface treatment of iron cultural relics, a significant challenge lies in modulating the color of these mending materials. The corrosion products of Yuquan Iron Pagoda are mainly Fe3O4, γ-FeO(OH), α-FeO(OH) and α-Fe2O3, with contents of 13.1, 16.1, 40.2 and 30.6%, respectively. Due to their structural stability and suitable color characteristics, Fe3O4 and α-Fe2O3 are selected as the primary raw materials for the repair material. This study employs machine learning methods to predict the color of mending materials corresponding to varying contents of α-Fe2O3, Fe3O4, and epoxy resin. The Artificial Neural Network (ANN), eXtreme Gradient Boosting (XGBoost), and Light Gradient Boost Machine (LightGBM) algorithms are utilized to develop the model, and the predictive performance of these three algorithms is compared. XGBoost exhibits the best prediction performance, achieving a square correlation coefficient (R2) of 0.94238 and a mean absolute error (MAE) of 0.68485. Additionally, the SHapley Additive exPlanations (SHAP) method is employed to analyze the most crucial raw material affecting the color of mending materials, which is identified as Fe3O4. The study illustrates the specific process of employing this model by applying it to the surface treatment of the Yuquan Iron Pagoda, demonstrating the practicality of the model. This model can be applied to assist in the surface treatment of other iron cultural relics.

Promoted production of aromatic hydrocarbons in biomass catalytic pyrolysis over the coupled catalysts of carbon-reduced waste lithium battery cathode materials and HZSM-5

Inexpensive catalyst sources are of great importance in the conversion of biomass to economically valuable monocyclic aromatic hydrocarbons, and transition metals (Co, Ni, Fe and Mn) rich in catalytic effects in massive waste lithium battery cathode materials are not effectively reutilized currently. For this reason, the feasibility of employing the valuable metal oxides in the carbon-reduced waste lithium battery cathode materials (waste LiFePO4 batteries, LFP, and waste LiNixCoyMn1–x–yO2 batteries, NCM) with HZSM-5 as coupled catalysts in the rape straw catalytic pyrolysis to produce aromatic hydrocarbons was explored. The carbon-reduced waste lithium battery cathode materials performed well at 5 wt% carbon loading, and the content of active components Fe2O3 (SLFPC-5) and NiO (SNCMC-5) used for the reduction of large molecular oxygenates in biomass pyrolysis gas was increased by water leaching treatment. SLFPC-5 demonstrated superior bond-cutting performance, while SNCMC-5 exhibited strong deoxygenation performance. The selectivity of monocyclic aromatic hydrocarbons (MAHs) catalyzed by SLFPC-5/HZSM-5 and SNCMC-5/HZSM-5 was as high as 63.69 % and 79.19 %, with BTX yields of 14.58 wt% and 16.68 wt% respectively. This coupled catalytic system offers a low-cost source of catalysts for biomass catalytic pyrolysis and broadens the possibility of high-value recycling of wasted lithium batteries.

Identification of working conditions and prediction of FeO content in sintering process of iron ore fines

Identification of working conditions and prediction of FeO content in sintering process of iron ore fines

OPTIMIZING VANADIUM CONVERTER SLAG UTILIZATION: TARGETED ENRICHMENT AND STABILIZATION OF VANADIUM THROUGH NON-EQUILIBRIUM SOLIDIFICATION

The objective of this research was to optimize the comprehensive utilization of vanadium converter slag through targeted enrichment and stabilization of heavy metal vanadium. Employing the non-equilibrium solidification theory and FactSage software, we investigated the potential of modifying vanadium converter slag. When the original slag failed to generate vanadium-rich spinel with usable V elements, introducing modifying agents Fe and Al proved effective. Fe facilitated the enrichment of Cr within spinel, while Al significantly promoted the V enrichment. Expanding on this, we systematically examined the influence of Fe2O3, Al2O3 and MgO contents on spinel phase precipitation during vanadium slag solidification. The addition of Al resulted in the precipitation of corundum, hematite, spinel, olivine and diopside phases. With an increase in the Fe2O3 content, the precipitation of FeV2O4 and MgV2O4 initially increased, peaking at 9.67 % before subsequently decreasing. Maintaining the Fe2O3 content within a range of 25–30 % proved optimal for enhancing vanadium precipitation and enrichment. In contrast, variations in the Al2O3 content had minor impacts on SP-V phase precipitation, with slight effects on FeV2O4 reaching 10.34 %. Furthermore, the incorporation of MgO facilitated the precipitation of MgV2O4 while concurrently suppressing the FeV2O4 precipitation. By judiciously controlling the MgO content at approximately 20 %, vanadium enrichment in the form of FeV2O4 and MgV2O4 spinel phases reached a remarkable 94.46 %.

Characterization, Dielectric Analysis and Thermal Properties of Novel Flexible Polymer Composite Films

In this work, mixtures of polypyrrole (PPy) and iron oxide (Fe2O3) are synthesized using oxidative chemical polymerization process to create a novel flexible PET/(PPy-Fe2O3) composite films. The films were characterized by different methods as FTIR, SEM, XRD and TGA to prove the efficient manufacturing of the composite. The dielectric performance measurements were done at frequency of 20 Hz to 6 MHz for the polymer PET and the composite (PPy-Fe2O3)/PET with varying concentrations of Fe2O3. Moreover, to reveal the characteristics of the fabricated composite, the contact angle, the work of adhesion, surface energy of the composite PET/(PPy-Fe2O3) films were considerably determined. The SEM results support the deposition of PPy-Fe2O3 composite on the PET surface. The water contact angle drops from 78.32° for PET to 40.11° for PET/6%(PPy-Fe2O3), while the dispersive free energy raised from 23.9 mJ m−2 to 43.7 mJ m−2and the polar free energy rises from 8.9 mJ m−2 to 22.3 mJ m−2. The concentration of Fe2O3 increased the surface features of the samples, according to the obtained results. At frequency of 100 Hz, the dielectric constant enhanced from 18 for PET to 923 for the PET/6%(PPy-Fe2O3), and the dielectric loss improved from 24 to 9231, while the energy density improved fromm 7.9 × 10−5 J/m3 for PET to 408 × 10−5 J m−3. The TGA results show marginal modifications in thermal stability after deposition the PPy/Fe2O3 on the PET film. The obtained data showed the dielectric characteristics of the PET/(PPy-Fe2O3) were improved respect to polymer PET, to can be applied the fabricated composite in storage devices and capacitors.

Investigation of structural, physical and optical properties of sodium boro-tellurite glasses doped with iron oxide

In this work, we demonstrate systematic studies on the influence of Fe2O3 on the structural and optical properties of transparent B2O3–TeO2–Na2O glasses containing the different concentrations of Fe2O3. The glasses were prepared via the standard melt quenching method, and the prepared glasses were characterized using, XRD, electron paramagnetic resonance (EPR), FTIR, and UV–visible spectroscopic techniques. Furthermore, we evaluated several physical properties of the glasses, including densities, molar volume, boron-boron separation, and oxygen packing density, with respect to the concentration of Fe2O3 in the host glass matrix. It is observed that the density of the glasses and the average boron-boron distance found increase with Fe2O3 concentration due to the modification in the glass network induced by the dopant ions. EPR spectra reveals the presence resonance signals at g ∼2.04 and g ∼4.26, hence it proves the existence of Fe3+ in distorted octahedral coordination and supported by UV–Vis absorption bands. The FTIR spectra revealed an increase in spectral intensity with the concentration of Fe2O3. This was attributed to the formation of non-bridging oxygens through converting BO4 units into BO3 units, which Fe2O3 mediated. The UV–visible spectral analysis showed a decreased energy band gap from 2.26 to 1.51 eV with increased Fe2O3 concentration. Additionally, we determined the Urbach energy, refractive index, optical basicity, and electronegativity, which are presented in detail.

Microstructure and magnetic properties of the FeSiBCuNb nanocrystalline soft magnetic composites coated with oil-phase single Fe3O4 nanoparticles by thermal decomposition method

Here, the core-shell structured FeSiBCuNb/Fe3O4 soft magnetic composites (SMCs) were successfully designed and fabricated by coating Fe3O4 magnetic nanoparticles on the surface of phosphorylated FeSiBCuNb powder. The effects of Fe3O4 and Polyvinylpyrrolidone (PVP) contents on the micromorphology, interface structure, and soft magnetic properties of SMCs were systematically investigated. The results demonstrate that the Fe3O4 magnetic nanoparticles are uniformly distributed on the surface of magnetic powders, which fill up the air gap in-between the magnetic powder and increase the resistivity. It shows that the permeability gradually decreases with the increase of Fe3O4 from 0 wt% to 1 wt%, while the loss decreases first and then increases. The loss separation of SMCs indicates that the Fe3O4 nanoparticles effectively reduce the hysteresis loss and eddy current loss. Furthermore, the FeSiBCuNb/Fe3O4 SMCs with the addition of PVP as a binder enhance the binding force between Fe3O4 nanoparticles and the powder matrix, which facilitates the formation of a uniform and dense interface structure. When adding 0.3 wt% PVP + Fe3O4 nanoparticles, the FeSiBCuNb/Fe3O4 SMCs exhibit excellent soft magnetic properties with ultra-low loss of 138.5 kW/m3 (100 mT/50 kHz), high permeability of 54, and good frequency stability. The presented results provide a new strategy for synthesizing ultra-low core loss and frequency stability of core-shell structured SMCs, which has great potential for applications at high frequencies.

Geologic History of the Amundsen Crater Region Near the Lunar South Pole: Basis for Future Exploration

We provide the first detailed 1:100,000 scale geomorphologic map of the ∼100 km Amundsen crater region, which is of high scientific relevance for future exploration, e.g., NASA’s VIPER mission, the Artemis program, and the Chinese International Lunar Research Station. We investigated the complex geological history of the region before and after the formation of Amundsen crater on the rims of the South Pole–Aitken (SPA) and Amundsen–Ganswindt basins. We present a new Amundsen crater formation age of ∼4.04 Ga, which, in contrast to previously derived ages, is based on non-light-plains terrain. The estimated maximum excavation depth for Amundsen crater is ∼8 km, and elevated concentrations of FeO near the crater suggest that Amundsen may have redistributed SPA-derived materials. Plains materials of various kinds were observed both inside and outside Amundsen crater and are estimated to be up to 350 m thick and ∼3.8 Ga old. A less cratered, tens of meters thick mantling unit indicates a resurfacing event ∼3.7 Ga ago. We highlight five potential exploration sites that satisfy technical constraints (such as shallow slopes, solar illumination, and Earth visibility), provide materials that can be sampled, and are capable of addressing multiple science objectives. Due to its accessibility and traversability, combined with its geologic diversity, proximity of permanently shadowed regions for studying volatile processes, and ability to address multiple science objectives, we confirm and reinforce the Amundsen crater region as a high-priority landing and exploration site.

Physico-chemical, technological and radiological characteristics of kaolinized granite from northwestern Serbia

In the ceramic industry, the quality of the final ceramic tile as well as the possibility of its use depends on the quality and characteristics of the starting raw materials. One of the potential raw materials that can be used in the production of ceramic tiles is kaolinized granite, and it is necessary to examine its characteristics. In this research, the kaolinized granite of the Jadar block, northwestern Serbia, from the Beli Majdan surface mine, Jadranska Lešnica, was examined. Chemical analysis, X-ray diffraction analysis (XRD), and differential thermal analysis (DTA) were carried out. Ignition tests of the prepared composites were also conducted at three selected temperatures (1000, 1100, and 1250 °C), where total linear shrinkage and water absorption were determined. The activity concentrations of natural radionuclides and the artificial radionuclide 137Cs were determined using the gamma spectrometry method, and then the radiation risk for the external exposure of workers when working with this raw material was assessed. For the samples with the highest content of 226Ra, radon exhalation measurements were performed with the RAD7 device, and the values of the radon emanation coefficient were determined, as well as the values of alpha dose equivalents, which quantified the potential internal exposure of workers. The results of the chemical analysis showed that the content of Al2O3 in the examined composites ranged from 19.11 to 21.00%, and the content of Fe2O3 from 1.53 to 1.72%. Additionally, the K2O content in the tested composites ranges from 4.01 to 5.46%, which indicates the presence of K-feldspar and muscovite, and the Na2O content from 1.82 to 2.61%. Based on XRD analysis, it was established that the mineral composition of kaolinized granite includes quartz, feldspar, mica, calcite/dolomite, and kaolinite minerals. DTA analysis indicates the occurrence of minor endothermic processes at 488.05 °C and 558.12 °C, as well as an exothermic process at 980.8 °C. The color of the ignition is brick red to dark brown red. A trend of increasing linear shrinkage and decreasing water absorption with increasing ignition temperature was observed with the normal appearance of the samples. The average activity concentration of natural radionuclides are around and below the average values for building materials, expect for 40K. The values for 137Cs are below the values measured in soil. Annual effective doses estimated for external exposure are below 1 mSv y−1, which indicates that there is no increased radiation risk when working with this raw material. The values of the radon mass exhalation rate are in the range of 61–113 mBq kg−1 h−1, and the values of the radon emanation coefficient are 6.3–8.4%. The average value of the alpha dose equivalent is 1mSvy−1, which indicates a potential exposure to radon below 100 Bq m−3. Based on the obtained results, it can be concluded that kaolinized granite is a high-quality and radiologically safe raw material for making ceramic composites in the production of ceramic tiles. It has all the necessary characteristics to partially or completely replace feldspar in ceramic composites.

Structural, radiation shielding, thermal and dynamic mechanical analysis for waste rubber/EPDM rubber composite loaded with Fe2O3 for green environment

Increasing waste rubber recycling produces a specious range of products for many valuable applications. Waste Rubber/EPDM composite with different concentrations was prepared. Infrared spectroscopy (FTIR) is used to identify the chemical composition. A water absorption test, Dynamic mechanical analysis (DMA), and Thermal Gravimetric Analysis (TGA) were performed. The (75/25) WR/EPDM rubber composite exhibited the best behavior with the highest mechanical performance. Fe2O3 was added to (75/25) WR/EPDM rubber composite. Water absorption, FTIR, TGA, and DMA were investigated. The composite performance was improved with increasing Fe2O3 content. The linear attenuation coefficients (μ) were also measured as a function of the concentrations of Fe2O3 for γ-ray energy 662 keV by using 137Cs point source; the radiation shielding can be denoted by numbers of parameters like mass attenuation coefficient (μm), half value layer (HVL), Tenth value layer TVL and radiation protection efficiency (RPE%), radiation protection efficiency increased as Fe2O3 increased.

Generation and persistency of combustion-derived environmentally persistent free radicals from phenolic compounds over a Fe2O3/SiO2 surface

Combustion of organic solid wastes releases phenolic compounds which can act as precursors in the formation of environmentally persistent free radicals (EPFRs) in the post-flame, cooling zone of waste combustion. The study investigated the generation mechanism of EPFRs from phenolic compounds catalyzed by transition metals in air atmosphere under simulated combustion conditions. Representative combustion-derived phenolic compounds were used, and SiO2 particulates containing different mass ratio of Fe2O3 were synthesized as carriers. EPFRs formed had g-factors between 1.9998 and 2.0066, indicating phenoxyl-, cyclopentadienyl-, and semiquinone-type radicals, along with paramagnetic F-centers. The promotion effect of phenolic compounds on EPFR formation during heating decreased as catechol > hydroquinone > phenol > p-cresol. This trend is related to hydroxyl groups and activation energy. In particular, catechol chemically adsorbed on Fe2O3 at 600 K led to the formation of EPFRs with relatively high spin concentrations (up to 1.28 × 1017 spin/g). Higher Fe2O3 concentrations promoted the transformation of phenoxyl-type radicals into cyclopentadienyl-type and paramagnetic F-centers. However, as the Fe2O3 loading increased from 1.25% to 5%, the density of EPFRs decreased. The findings related to the influence of various precursors and Fe2O3 concentration on EPFR formation provide valuable insights for estimating EPFR generation and associated risk during combustion processes.

Growth and characteristics of bicolor Fe-doped MgAl2O4 crystals

Bicolor Fe-doped MgAl2O4 crystals were successfully grown using the floating zone technique. These bicolor crystals were grown with composition ratios of MgO to Al2O3 (x) ranging from 0.3 to 1.0 and Fe2O3 concentrations of 0.1 mol%–2.0 mol%. Their growth process involved changing the O2 concentrations in the growth atmospheres: 0 vol% O2–100 vol% Ar, 50 vol% O2–50 vol% Ar, and 100 vol% O2–0 vol% Ar. The color of the resultant crystals changes with the growth conditions employed. Crystals manifested in six colors: pink, green, purple, violet, blue, yellow, and brown, based on the combination of Fe2O3 concentrations, O2 concentrations, and x. Additionally, bicolor crystals could be grown by suddenly changing the O2 concentration in the growth atmosphere, while tri-color crystals could be achieved through gradual alterations in the O2 concentration in the growth atmosphere. The color change of the bicolor crystals is considered to be caused by the change in the optical absorption ratio at λ = 455 (blue light) and λ = 550 nm (green light) due to the change in the concentration ratio of Fe2+ and Fe3+ in the crystal.