Fayalite Research Articles

A novel sodium Iron silicate composite with chitosan for efficient removal of Cd(II) ions from water

Cadmium ions constitute a major threat to human health and the environment owing to their toxicity, bioaccumulation, and persistence in water bodies, causing renal dysfunction, cancer, and cardiovascular diseases. Hence, this study reports the facile fabrication of a novel sodium iron oxide silicate@amorphous sodium iron silicate product (S1) and its chitosan composite (S1@chitosan) for the high-performance separation of Cd(II) ions from aquatic environments. The Brunauer-Emmett-Teller surface area, total pore volume, and mean pore diameter of S1 were 94.97 m2/g, 0.5853 cm3/g, and 25.65 nm, respectively, while those for S1@chitosan were 30.94 m2/g, 0.09518 cm3/g, and 12.31 nm, respectively. The reduction in pore diameter, pore volume, and surface area confirms the successful functionalization of S1 with chitosan, as the chitosan coating partially blocks and fills the pores, reducing the available surface area and porosity. Also, scanning electron microscope (SEM) images revealed an uneven surface morphology for S1 and a more textured and rougher surface for S1@chitosan, supporting the incorporation of chitosan. Besides, energy-dispersive X-ray spectroscopy (EDX) and CHN analyses affirmed the existence of chitosan in the composite through the detection of carbon and nitrogen elements, characteristic of chitosan. The optimum conditions for the removal of Cd(II) ions were determined to be a contact time of 70 min for S1 and 50 min for S1@chitosan, a pH of 7.50, and a temperature of 298 K. The maximum sorption capacities were 284.09 mg/g for S1 and 389.11 mg/g for S1@chitosa. The removal mechanism for S1 primarily involves ion exchange, while S1@chitosan utilizes both ion exchange and complexation through the amino and hydroxyl groups of chitosan. Regeneration using HCl confirmed the effective reusability of both adsorbents over five successive cycles. The adsorption process was found to be chemical, exothermic, and best described by the pseudo-second-order kinetic model and Langmuir isotherm.

A Sustainable Way to Produce Mn-Sinter with Charcoal

Biocarbon is a suitable replacement to traditional coke because it is a promising approach to reduce CO2 emissions and it is compatible with current metallurgical processes, where solid materials are favored. The industrial-scale use of biocarbon in manganese ore sintering remains rare or largely unexplored. In this study, manganese sinters were produced using charcoal in a sintering pot, with particular emphasis on its impact on the physical properties and phase composition of sinters. The results demonstrate that substituting coke with charcoal can produce sinters of comparable/higher quality and productivity than those made exclusively using coke breeze, provided the charcoal content does not exceed 30%. It is considered that the manganese oxides are existing in the forms of Mn3O4 and MnO in the sinter. Three distinct phases were identified based on their different morphological features from phase characterization. The first phase consists of (Mn,Fe)O and (Mn,Fe)3O4, and the second phase is an Al2O3-rich phase containing Mn-oxides, while the third phase is a manganese-containing silicate ((Mn,Fe)2SiO4). The strength of sinter was also discussed; the results show that the strength first decreases and then increases with increasing charcoal content. When the charcoal content is between 40 and 60%, the sinters exhibit a lower strength.Graphical

Phase transformation of ferric-iron-rich silicate in Earth’s mid-mantle

Abstract The incorporation of ferric iron in mantle silicates stabilizes different crystal structures and changes phase transition conditions, thus impacting seismic wave speeds and discontinuities. Recent experiments of MgSiO3-Fe2O3 mixtures indicate the coexistence of fully oxidized iron-rich (Mg0.5Fe0.53+)(Fe0.53+Si0.5)O3 with Fe-poor silicate (wadsleyite or bridgmanite) and stishovite at 15 to 27 GPa and 1773 to 2000 K, conditions relevant to subducted lithosphere in the Earth’s transition zone and uppermost lower mantle. X-ray diffraction (XRD) shows that (Mg0.5Fe0.53+)(Fe0.53+Si0.5)O3 recovered from these conditions adopts the R3c LiNbO3-type structure, which transforms to the bridgmanite structure again between 18.3 and 24.7 GPa at 300 K. XRD data are used to obtain the equation of state of the LiNbO3-type phase up to 18.3 GPa. Combined with multi-anvil experiments, these observations suggest that the stable phase of (Mg0.5Fe0.53+)(Fe0.53+Si0.5)O3 is bridgmanite at 15–27 GPa, which transforms on decompression to LiNbO3-type structure. Our calculation revealed that ordering of the ferric ion reduces the kinetic energy barrier of the transition between (Mg0.5Fe0.53+)(Fe0.53+Si0.5)O3 LiNbO3 structure and bridgmanite relative to the MgSiO3 akimotoite-bridgmanite system. A dense Fe3+-rich bridgmanite structure is thus stable at substantially shallower depths than MgSiO3 bridgmanite and would promote subduction.

The Role of FeO/SiO2 Ratio in Valorizing Iron Silicate Slags as Supplementary Cementitious Materials

Pyrometallurgical copper production is associated with high slag rates, typically ranging from 2.2 to 3.0 tons of slag per ton produced copper. Therefore, slag valorization is necessary to maintain a resource-efficient operation. An attractive application for these iron silicate slags is as supplementary cementitious materials (SCMs), which effectively lowers the CO2 emissions per ton of concrete. Although utilizing iron silicate slags as SCMs has been studied in previous work, the scientific literature has limited data on the isolated effect of composition on the inherent reactivity in cementitious systems. In particular, no reports on the impact of the FeO/SiO2 ratio have been presented in previous publications. Therefore, the present study aimed to isolate this parameter in a synthetic FeO–SiO2–Al2O3–CaO–MgO–Cr2O3 system. Since the amorphous content is a pertinent parameter for SCMs, a hot-stage confocal laser scanning microscope was utilized to assess the crystallization behavior at continuous cooling conditions. Furthermore, high-temperature rheological experiments were conducted to measure the viscosities of the slags in relation to the crystallization behavior. The experiments highlighted that depolymerizing the slag by increasing the FeO/SiO2 ratio poses increased demands on the cooling rate to avoid crystallization, which was consistent with the rheological data on the impact of temperature on structural changes in the slags. Furthermore, Rapid Reliable Relevant (R3) isothermal calorimeter experiments, assessing the inherent reactivity as an SCM, showed that increasing FeO/SiO2 ratios improves early reactivity at the expense of seven-day reactivity, i.e., a balance between the degree of polymerization and contribution of silicon to the reactions.Graphical

Sulfate-Resistant Clinker Base Cement with New Secondary Main Constituents: A Technical, Economic, and Environmental Analysis

The Spanish cement sector must adapt its production model to a green economy model. This study focuses on the use of new secondary main constituents (SMCs) suitable for a cement plant that specializes in sulfate-resistant (SR) cement production, defining a framework of technical conditions for their usage and their economic and environmental feasibility. Low-calcium-carbonate-content albero, steel slags, and iron silicate were the tested SMCs; however, they are not currently permitted in cement manufacture. CEM I 42.5 R-SR 3 (type I-SR) was mixed with 5%, 20%, and 30% of these new SMCs. XRF, XRD, leaching and other chemical tests, setting, and hardening tests were performed with no significant issues. Albero is the best option, on the whole, because of the following characteristics: availability, >100 Mt; proximity, 3 km; and acceptable compressive strength level. However, black slag cement with 30% SMC after 28 days shows the best performance, with a compressive strength of 41.3 MPa compared to 35.3 MPa for albero cement and 56.5 MPa for the type I-SR reference. Albero and steel slag at 30% content are the best option according to the cost savings of 32% (−31.5 EUR/t and −31.6 EUR/t, respectively) compared to the type I-SR reference. Regarding the carbon footprint, albero and steel slag at 30% content have the least impact, showing a 31% reduction (−254.8 kg CO2/t and −255.2 kg CO2/t, respectively) compared to the type I-SR reference. The studied SMCs meet the analytical conditions and—with the corresponding regulatory changes—offer potential cost savings for SR cement production, exhibiting a competitive advantage.

Thermoelastic Properties of Iron‐Rich Ringwoodite and the Deep Mantle Aerotherm of Mars

AbstractThe Martian mantle is considered to have a higher Fe/Mg ratio than the Earth's mantle. Ringwoodite, γ‐(Mg,Fe)2SiO4, is likely the dominant polymorph of olivine in the core‐mantle boundary (CMB) region of Mars. We synthesized anhydrous iron‐rich ringwoodite with molar Mg/(Mg + Fe) = 0.44 and determined its thermal equation of state up to 35 GPa and 750 K by synchrotron X‐ray diffraction. Using a third order Birch‐Murnaghan equation of state, we obtain KT0 = 182 (3) GPa, K′ = 4.6 (2), and α0 = 3.18 (6) × 10−5 K−1. Using these results and an updated mineralogical model with an iron‐rich composition of Mg/(Mg + Fe) = 0.75 for the Martian mantle, we estimate ∼1900 K for the temperature of the D1000 seismic discontinuity inside Mars. The resulting adiabat predicts a warm aerotherm, which could explain the presence of partial melt at the CMB of Mars recently detected with seismic data from the 2019 InSight mission.

Optimizing the Dealkalization Process of Red Mud: Controlling Calcium Compounds to Improve Solid–Liquid Separation Performance

The acid neutralization process is widely recognized for its effectiveness in the dealkalization of red mud, and it faces challenges in solid–liquid separation due to the formation of numerous colloidal components. This study investigated the impact of calcium-containing compounds (CaO, CaCl2, CaCO3, and CaSO4) on the solid–liquid separation and the dealkalization efficiency of red mud during the dealkalization process. The sodium leaching efficiency of the red mud reached 95.6% when the red mud was reacted with 8% of sulfuric acid for 10 min with a stirring speed and liquid to solid ratio of 700 r/min and 5:1, respectively. The replacement of sulfuric acid using simulated waste acid reached similar sodium leaching efficiency. However, the filtration rate of red mud becomes exceedingly sluggish using sulfuric acid or simulated waste acid. Adding calcium-containing compounds significantly augments the efficacy of solid–liquid separation in red mud. With a mass content of 2% for CaO or 8% for CaCl2, the filtration speed experienced a remarkable fivefold and ninefold increase, respectively. Furthermore, a simplification in the composition was observed within the leaching solution derived from red mud, thereby creating favorable conditions for the extraction of sodium. The influence mechanism was investigated with X-ray diffraction, inductively coupled plasma analysis, and scanning electron microscopy. The addition of calcium compounds led to the formation of calcium silicate and iron silicate in the leaching residue, inhibiting the generation of colloidal substances, such as silica gel. Additionally, these compounds increased the size of red mud particles, facilitating the solid–liquid separation process. This study provides valuable technical insights for the dealkalization of red mud.

Solubility of Gold in FeOx-SiO2-Al2O3 Slags at 1300°C

ABSTRACT Solubility of gold in copper-free alumina iron silicate slags in equilibrium with iron alumina spinel was studied using equilibration-quenching technique under controlled p(O 2) gas atmosphere at 1300°C. The gold concentration in slag was analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), which allowed elimination of the mechanical metal dispersion from the slag analyses. Thus, the data represent purely the chemically dissolved gold, and the dissolution in slag was shown to occur as AuO0.5 species at high oxygen partial pressures ≥10−7 atm. Contrary to earlier observations in (basaltic) iron-lean high-silica melts, the results indicate that gold solubility at low oxygen partial pressures, <10−7 atm, was no more decreasing but maintained at a minimum (log10LAu/s(Au) = 5.6–5.7). Even at the highest partial pressure of oxygen (=10−5 atm), the distribution coefficient was above log10LAu/s(Au) = 5.2, which suggests that mechanical dispersion containing gold causes by far the major source of gold loss in the copper and nickel matte smelting as well as in the secondary copper (‘black copper’) smelting operations.

Study of Environmental and Geochemical Effects on The Distribution and Transformations of Iron Oxides in Some Soils

This study was conducted to determine the content, distribution and transformation of iron oxides in the soils of the Middle Euphrates regions in Iraq. The study included four sites: Tuwairij area in Karbala Governorate, College of Agriculture at the University of Kufa in Najaf Governorate, College of Agriculture at the University of Qadisiyah in Diwaniyah Governorate, and the Nile District in Babylon Governorate. The results showed that the soils of Najaf and Qadisiyah were superior in terms of their content of total free iron oxides (Fet) compared to the soils of Karbala and Babylon. The relative distribution of free iron oxides was generally close among the studied sites, with a homogeneous pattern in the distribution of these oxides within the soil horizons. As for silicate iron oxides (Fes), a homogeneous pattern was observed in the soil of Babylon with its content increasing with depth, while these patterns varied in the soils of Karbala, Najaf and Qadisiyah. Regarding the ratios of crystalline iron oxides (Fed/Fet), the study showed that the Babylon and Qadisiyah soils recorded the highest values, while these values were lower in the Najaf and Karbala soils. On the other hand, amorphous iron oxides (FeO) showed similar values in the Najaf and Qadisiyah soils. In general, these results clearly showed the effect of environmental and geochemical factors of the study areas on the distribution and transformations of iron oxides in the soil of the Middle Euphrates regions.

Effect of Soil pH, added C/N on Denitrification in Different Soil Properties Using Silicate Iron

Effect of Soil pH, added C/N on Denitrification in Different Soil Properties Using Silicate Iron

Most High-density Exoplanets Are Unlikely to Be Remnant Giant Planet's Cores

Some exoplanets have much higher densities than expected from stellar abundances of planet-forming elements. There are two theories—metal-rich formation hypothesis and naked core hypothesis—that explain how formation and evolution can alter the compositions and structures of rocky planets to diverge from their primordial building blocks. Here we revisit the naked core hypothesis, which states that high-density planets are remnant cores of giant planets that remain in a fossil-compressed state, even after envelope loss. Using a planetary interior model and assuming energy-limited atmospheric escape, we show that a large fraction, if not all, of the iron–silicate core of a giant planet is molten during the planet's early evolution. Upon envelope loss, the molten part of the planets can rapidly rebound owing to low viscosity, resulting in a decrease in radius by at most 0.06%, if they had hydrogen/helium envelopes, or by at most 7%, if they had H2O envelopes, compared to self-compressed counterparts with the same core mass fraction. Based on our findings, we reject the hypothesis that all high-density exoplanets are naked cores with Kolmogorov–Smirnov p-value ≪0.05 for both envelope compositions. We find that some high-density exoplanets can still possibly be naked cores, but the probabilities are lower than ∼1/2 and ∼1/3 for the ice giant and gas giant scenario, respectively, in 95% of the cases. We conclude that most high-density exoplanets are unlikely to be remnant giant planet cores.

Methodology Development of Electrical Conductivity Measurements for Iron Silicate Slags

Methodology Development of Electrical Conductivity Measurements for Iron Silicate Slags

Synergized Effects of Amino Acids and NaCl to Enhance Silicate Mineral Dissolution in Aqueous Environments for Efficient Atmospheric CO2 Removal.

Enhanced weathering of silicate minerals is a promising approach for reducing atmospheric CO2 levels by increasing the aquatic pH and facilitating CO2 dissolution. However, the slow and unsustainable dissolution of silicate minerals in natural environments remains a challenge. This study proposed a new CO2 capture system that uses the combined effect of amino acids and NaCl to promote mineral dissolution, and its characteristics were investigated experimentally. The results showed that amino acids are promising for enhancing the near-congruent dissolution of silicate minerals, specifically at weakly alkaline pHs (i.e., 8), implying the long-term effectiveness of the system. Comprehensive findings revealed a 13-fold increase in the level of Ca extraction from wollastonite (CaSiO3) in the presence of 0.1 mol/L glutamic acid (Glu) over 72 h at 35 °C and a 22-fold increase in the level of CO2 capture efficiency. However, Fe-bearing minerals, such as olivine ((Mg,Fe)2SiO4), are unsuitable for application, because the enhanced Fe extraction results in the generation of Fe hydroxide, which lowers pH and consequently reduces CO2 capture efficiency. Moreover, NaCl facilitates the release of the Ca-Glu complex from mineral surfaces into the solution, synergizing amino acids to promote mineral dissolution. A semiclosed application system is proposed, with future studies needed to assess ecological impacts and ensure long-term sustainability.

Simple synthesis and excellent coagulation performance of a novel red soil-based coagulant

Simple synthesis and excellent coagulation performance of a novel red soil-based coagulant

Growth and Structure of Ultrathin Iron Silicate and Iron Germanate Films.

The growth and structure of two-dimensional iron silicate and iron germanate films on Ru(0001) are studied. We investigate in detail the temperature-dependent film formation of ultrathin layers of iron silicate and iron germanate. These two-dimensional films can be seen as model systems for more complex catalytically active structures, such as zeolites, which can be used as selective catalysts or molecular sieves. The experimental methods of XPS, LEED, LEEM, LEEM-IV, and XPEEM are applied for correlated chemical and physical characterization in situ and in real time, and DFT is applied for theoretical consideration. We show that both systems can be considered as two-layered systems, with a monolayer of iron oxide at the Ru interface and a monolayer of silica or germania on top, respectively. The Fe-Fe distance in the iron oxide layer is influenced by the Si-O-Si or Ge-O-Ge bond length, in agreement with those of unstrained silicates or germanates. Moreover, iron silicate can be prepared using different preparation methods. The actual loading of Fe atoms is three per unit cell for FeGeOx and only two for FeSiOx.

Effective remediation of toxic metal ions (Cd(II), Pb(II), Hg(II), and Ba(II)) using mesoporous glauconite-based iron silicate nanorods: Experimental and theoretical studies

Effective remediation of toxic metal ions (Cd(II), Pb(II), Hg(II), and Ba(II)) using mesoporous glauconite-based iron silicate nanorods: Experimental and theoretical studies

Peroxidase-Mimetic Iron Silicate Nanosheets Coordinated with Indocyanine Green for Enhanced Anti-Tumor Therapy.

The versatile element composition and multifunctional properties of biodegradable silicates have attracted significant attention in cancer therapeutics. However, their application as nanozymes is often limited by suboptimal catalytic efficiency and insufficient intratumoral retention. In this study, the hydrothermal synthesis of iron silicate (FeSi) nanosheets are reported exhibiting exceptional peroxidase (POD)-like activity (136.7Umg-1), outperforming most reported iron-based nanozymes. Density functional theory calculations revealed that the introduction of Si into the catalyst enhances H2O2 adsorption and dissociation of Fe sites, leading to superior POD performance. Furthermore, the FeSi nanosheets are modified with Indocyanine Green (ICG) to facilitate targeted aggregation-potentiated therapy. The integration of ICG improved tumor penetration and retention of the FeSi nanosheets, significantly increasing their reactive oxygen species production and bolstering therapeutic efficacy.

Study of slag formation behavior in iron ore pellets based on thermodynamic calculations and experiments

Study of slag formation behavior in iron ore pellets based on thermodynamic calculations and experiments

Precision Remediation of Mining Soils through On-Site Investigation and Large-Scale Synthesized Ferrosilicate

To seek a restoration plan for the safe use of agricultural land around mining areas, this study focuses on the regions around a mining plant in Huidong County, western Sichuan Province, affected by lead–zinc mining, and the precise remediation of heavy metal pollution through large-scale synthesis of iron silicate. In this study, we investigated heavy metal pollution in the vicinity of the mining area and proposed a treatment strategy using large-scale synthesis of iron silicate to mitigate this pollution. According to field investigation and sampling analysis, the collected soil samples contained excessive Cd, Pb, and Zn. Cd is a heavy metal related to lead–zinc mining. The planting of crops such as loquats and garlic with a high accumulation coefficient for Cd was found inappropriate for the research area. Instead, it was recommended to plant economically important crops like mangoes and peaches which had lower heavy metal accumulation. On the basis of field investigation, the study area was seriously polluted by heavy metals, among which Cd was 4.0 times higher than the standard of agricultural land. In order to accurately passivate excessive Cd, Zn, and Pb, iron silicate material was put into mass production. In situ passivation experiments showed that when the soil water content was between 25% and 20%, adding 4% silicate material could rapidly reduce the content of effective heavy metals in the soil and the heavy metal content of garlic and other cash crops in the research area by about 8%. After conducting a field investigation, it has been determined that the large-scale preparation of iron silicate can accurately repair soil contaminated by heavy metals in the vicinity of mining areas. In conclusion, iron silicate is capable of effectively reducing the pollution of heavy metals on agricultural land and facilitating the safe utilization of such land.

Sustainable Modification of Naturally Available Resources for Metal-Ion Storage Applications

The adoption of naturally abundant resources for energy storage applications represents a pivotal strategy in advancing large-scale sustainable green energy solutions across diverse sectors. This presentation provides an overview of E2MC's approaches to the green modification of naturally occurring materials at a low cost, focusing on their metal-ion energy storage capabilities. Key natural materials discussed include molybdenum disulfides (MoS2), ilmenite and natural graphite minerals, as well as corn waste. (a) The thermal oxidation of MoS2 is explored as a straightforward and effective method to produce layer-structured molybdenum trioxide (α-MoO3) with crystalline defects, showing enhanced Li-ion storage kinetics. The molten salt treatment of MoS2 produces sodium dimolybdate with improved Li-ion and Na-ion storage performances. Additionally, a hybrid nanostructure comprising metastable monoclinic molybdenum trioxide (β-MoO3), hexagonal MoS2 secondary crystals and graphene nanosheets is produced through mechanochemical-molten salt treatment. This hybrid structure exhibits an interesting Li-ion storage performance. (b) Carbonization of largely available corn lignocellulosic waste in the presence of molten salt is discussed as a facile approach for the preparation of biocarbons with appropriate specific surface area, pore volume, and elemental carbon purity. The partial dissolution of biomass impurities into the molten salt enhances the Li-ion and Na-ion storage performance of the biocarbon. Additionally, the treatment of corn-derived silica with Fe2O3 and graphite-derived graphene nanosheets, leads to the preparation of a nanostructure in which ferric oxide particles are coated with iron silicate, and these hybrid nanostructures are integrated with graphene nanosheets, showcasing an interesting Li-ion storage performance. (c) Efficient exfoliation of naturally available graphite minerals in molten salt is introduced leading to the formation of carbon nanostructures with promising applications in both Li-ion and Na-ion storage. The economic and strategic advantages associated with utilizing such naturally available resources for energy storage applications are also discussed. References W. Zhu, A.R. Kamali*, J. Alloy Compd. 932 (2023) 167724W. Zhu, A.R. Kamali*, J Alloy Compd. 968 (2023) 171823A.R. Kamali*, H. Zhao, J. Alloy Compd. 949 (2023) 169819W. Zhu, A.R. Kamali*, J. Alloy Compd. 831(2020) 154781H. Zhao, A. Rezaei, A.R. Kamali*, J. Electrochem. Soc. 169 (2022) 054512A.R. Kamali*, J. Ye, Miner. Eng. 172 (2021) 107175S. Li, A.R. Kamali*, Chem. Eng. Sci. 265 (2023) 118222S. Li, A.R. Kamali*, Gels 9 (2023) 701S. Li, A.R. Kamali*, Colloids Surf. A 656 (2023) 130275H. Fu, A.R. Kamali* et al, Chem. Eng. J. (2023) 146936W. Zhu, A.R. Kamali*, J. Electrochem. Soc. 168 (2021) 046517