Oxide Silicate Research Articles

Unlocking High Capacity and Reversible Alkaline Iron Redox Using Silicate-Sodium Hydroxide Hybrid Electrolytes.

Alkaline iron (Fe) batteries are attractive due to the high abundance, low cost, and multiple valent states of Fe but show limited columbic efficiency and storage capacity when forming electrochemically inert Fe3O4 on discharging and parasitic H2 on charging. Herein, sodium silicate is found to promote Fe(OH)2/FeOOH against Fe(OH)2/Fe3O4 conversions. Electrochemical experiments, operando X-ray characterization, and atomistic simulations reveal that improved Fe(OH)2/FeOOH conversion originates from (i) strong interaction between sodium silicate and iron oxide and (ii) silicate-induced strengthening of hydrogen-bond networks in electrolytes that inhibits water transport. Furthermore, the silicate additive suppresses hydrogen evolution by impairing energetics of water dissociation and hydroxyl de-sorption on iron surfaces. This new silicate-assisted redox chemistry mitigates H2 and Fe3O4 formation, improving storage capacity (199 mAh g-1 in half-cells) and coulombic efficiency (94 % after 400 full-cell cycles), paving a path to realizing green battery systems built from earth-abundant materials.

Enhanced Water Resistance of TiO2-GO-SMS-Modified Soil Composite for Use as a Repair Material in Earthen Sites.

Most earthen sites are located in open environments eroded by wind and rain, resulting in spalling and cracking caused by shrinkage due to constant water absorption and loss. Together, these issues seriously affect the stability of such sites. Gypsum-lime-modified soil offers relatively strong mechanical properties but poor water resistance. If such soil becomes damp or immersed in water, its strength is significantly reduced, making it unviable for use as a material in the preparation of earthen sites. In this study, we achieved the composite addition of a certain amount of sodium methyl silicate (SMS), titanium dioxide (TiO2), and graphene oxide (GO) into gypsum-lime-modified soil and analyzed the microstructural evolution of the composite-modified soil using characterization methods such as XRD, SEM, and EDS. A comparative study was conducted on changes in the mechanical properties of the composite-modified soil and original soil before and after immersion using water erosion, unconfined compression (UCS), and unconsolidated undrained (UU) triaxial compression tests. These analyses revealed the micro-mechanisms for improving the waterproof performance of the composite-modified soil. The results showed that the addition of SMS, TiO2, and GO did not change the crystal structure or composition of the original soil. In addition, TiO2 and GO were evenly distributed between the modified soil particles, playing a positive role in filling and stabilizing the structure of the modified soil. After being immersed in water for one hour, the original soil experienced structural instability leading to collapse. While the water absorption rate of the composite-modified soil was only 0.84%, its unconfined compressive strength was 4.88 MPa (the strength retention rate before and after immersion was as high as 93.1%), and the shear strength was 614 kPa (the strength retention rate before and after immersion was as high as 96.7%).

The Development of Polylactide Nanocomposites: A Review

Polylactide materials present a promising alternative to petroleum-based polymers due to their sustainability and biodegradability, although they have certain limitations in physical and mechanical properties for specific applications. The incorporation of nanoparticles, such as layered silicate (clay), carbon nanotubes, metal or metal oxide, cellulose nanowhiskers, can address these limitations by enhancing the thermal, mechanicals, barriers, and some other properties of polylactide. However, the distinct characteristics of these nanoparticles can affect the compatibility and processing of polylactide blends. In the polylactide nanocomposites, well-dispersed nanoparticles within the polylactide matrix result in excellent mechanical and thermal properties of the materials. Surface modification is required to improve compatibility and the crystallization process in the blended materials. This article reviews the development of polylactide nanocomposites and their applications. It discusses the general aspect of polylactides and nanomaterials as nanofillers, followed by the discussion of the processing and characterization of polylactide nanocomposites, including their applications. The final section summarizes and discusses the future challenges of polylactide nanocomposites concerning the future material’s requirements and economic considerations. As eco-friendly materials, polylactide nanocomposites offer significant potential to replace petroleum-based polymers.

OnComparing Rhombus Oxide and Silicate Networks via Zagreb Connection Indices

A topological index (TI) is a number that describes the topology of a chemical structure. TIs can describe numerous chemical and physical properties of chemical compounds, such as melting and freezing points, strain energy, stability, temperature, volume, density, and pressure. TIs are classified into several categories, including degree-based TIs, distance-based TIs, and connection number-based TIs. Wiener developed the first distancebased TI. After that, he developed the first degree-based TI for calculating the π-electron energy of molecules. These indices are regarded as the most important TIs for preserving the psychochemical features of chemical compounds. Recently, connection number-based TIs have been researched, which are more efficient than distance and degree-based TIs. Connection-based TIs can predict the physical and chemical properties of molecular structures more efficiently than degree or distance-based descriptors. In this paper, we compute the connection number-based TIs for the two most significant types of chemical structures: rhombus silicate and rhombus oxide. In the end, to evaluate the effectiveness of these structures in predicting psycho-chemical attributes, we compare them based on their computed results. These findings are novel and make significant contributions to providing knowledge to understand the deep topology of these critical structures.

On the Comparative Analysis among Topological Indices for Rhombus Silicate and Oxide Structures

A topological index (TI) is a numeric digit that signalizes the whole chemical structure of a molecular network. TIs are helpful in predicting the bioactivity of molecular substances in investigations of quantitative structure-activity relationship (QSAR) and quantitative structure-property relationship (QSPR). TIs correlate various chemical and physical attributes of chemical substances such as melting and freezing point, strain energy, stability, temperature, volume, density, and pressure. There are several distance-based descriptors available in the literature, but connection-based TIs are considered more effective than degree-based TIs in measuring the chemical characteristics of molecular compounds. The present study focuses on computing the connection-based TIs for the most significant type of chemical structures, namely, rhombus silicate and rhombus oxide networks. At the end, we compare these structures on the basis of their computed result.

Production of novel Zr–Mg nanoceramics based on kaolinite clay with strong antibacterial activity

Gram-negative bacteria Pseudomonas putida, Gram-positive Bacillus subtilis, and Staphylococcus aureus were utilized as test samples to evaluate the antibacterial characteristics of DD3-clay/MgO and DD3+38 wt% ZrO2-clay/MgO nanoparticles. The ceramic powders prepared by a thermal autoclave method are characterized before and after Mg addition by SEM, EDX, XRD, IR, UV–visible, and TEM in order to investigate microstructure, phase, and surface morphology. The results showed that after adding Mg, it led to the deformation of the crystal lattices of (mullite, zirconium silicate, and zirconium oxide) together with a decrease in particle size (75–103 nm) and a complete change in its shape from nanotube to nanospherical, as observed by SEM and TEM analyses. It also confirmed by UV–visible spectroscopy that the addition of Mg increases the absorbance accompanying a decrease in the energy gap of 1.91, 1.74, 1.73, and 1.43 eV corresponding to DD3, DD3Z, DD3/30 wt% Mg and DD3Z/30 wt% Mg respectively. The antibacterial mechanism is related to the size of the particles, the solvent used for powder dissolution, the nanoparticle's size when they come into touch with bacteria, and the generation of reactive oxygen species (ROS: ˙O2−, ˙OH, and H2O2). It was observed that the anti-bacterial activity is enhanced with 10 wt% and 30 wt% of Mg added to a modified ceramic powder. Also, more O2− is formed on the surface of the prepared powder, which penetrates the bacterial cell and destroys it. The nanocomposite particles showed remarkable antibacterial activity when they were dissolved in DMSO compared to methanol and chloroform as organic solvents. The aim is to enrich knowledge on the antibacterial activities of metal nanoparticles (ZrSiO4 and MgO) on three bacterial strains with different Grams due to their extensive involvement in the phenomena of contamination and infection encountered in the medical field. The synthesized nanoparticles have good antimicrobial activity against all strains tested. A maximum inhibition zone of 35 ± 0.2 mm was obtained with S. aureus, a zone of 23 ± 0.46 mm with P. putida and a zone of 27 ± 0.46 nm with B. subtilis for DD3/30 wt% Mg and an inhibition zone of 38 ± 0.93 mm, 26 ± 0.24 nm and 17 ± 0.33 nm was obtained with same strains for DD3Z/30 wt% Mg, respectively.

Green Synthesis of Aluminum Silicate and Aluminum Iron Oxide Nanocomposites for Industrial Applications

Nano chemistry is revolutionizing the chemical industry. This research targets the green synthesis of Al-Si and Al-Fe nanocomposites and their application in the cement industry to produce durable cement coating. The nanocomposites were prepared by incorporating the green ingredients as reducing and stabilizing agents followed by the direct heating and calcination of the samples. The X-ray diffraction analysis and SEM were performed to confirm crystallinity and the nano-dimensional structure of the prepared nanocomposites. The SEM micrographs of Al-Si and Al-Fe nanocomposites provided the sizes as 15-37 nm and 17-61 nm, respectively. BET analysis revealed the surface area as 1.084 m2/g and 0.884 m2/g respectively, for Al-Si and Al-Fe nanocomposites. These were applied in cement mortar and stability was checked for 07 and 28 days. The samples with 07 days of stability time showed an increase while the samples with 28 days showed a decrease in compressive strength.

Solidification and stabilization of heavy metals in medical waste ash through alkali activation

In the present work, medical waste ash was used as an aluminosilicate precursor to produce a geopolymer binder with stabilised heavy metals. The ash was initially calcined at a temperature of 800 °C for two hours to reduce the organic content. Calcined kaolin and medical waste ash were used as precursors to produce the geopolymer binder and sodium silicate and calcium oxides were used as alkaline activators. The effect of curing temperature (23, 60, and 100 °C) and the calcium oxide addition (0, 5, and 10%) on the geopolymer properties were evaluated. Eighteen geopolymer samples were prepared and evaluated for immobilizing heavy metals through the Toxicity Characteristic Leaching Procedure (TCLP). When compared to raw materials, TCLP results indicated that geopolymerization can significantly reduce the concentration of heavy metals in the medical waste ash leachate. The metal fixation percentages of the geopolymers ranged from 70 to 100%. The sequential extraction test results showed that geopolymerization (stabilization/solidification) is very beneficial in reducing the bioavailable fraction in the solid waste and maximizing the difficulty of fraction extraction.

Absorption dispersion below boson peak frequency in oxide glasses studied by THz-time domain spectroscopy

The dispersion properties of the absorption coefficients [α(ν)] of different multi-component silicate oxide glasses have been studied in the frequency region below the boson peak by using THz-time-domain spectroscopy. The value of α(ν)/ν2 has been shown to exhibit a minimum level (R) at low frequency and subsequently a linear increase in the form of r(ν/νBP + E) with increasing frequency, where νBP is the boson peak frequency and R, r, and E are material-specific constants. It has also been found that R ∝ r and E is a constant common to most glasses. This α(ν)/ν2 behavior is ascribed to the dispersion property of the light-vibration coupling coefficient under the reasonable vibrational density of state function. The minimum (constant) and linear terms of the α(ν)/ν2 spectrum are originated from the physical/chemical disorder-induced charge fluctuations in the long-range scale (constant term) and short-range scale (linear term), respectively. The fluctuating charge (σ1) caused by uncorrelated, long-range disorders has primary significance for determining the sub-THz absorption dispersion properties, and its value has been determined for each glass material.

Facile Synthesis of Sodium Iron Silicate/Sodium Iron Oxide Silicate Nanostructures from Canned Beans and Rice Husk Wastes for Efficient Removal of Cd(II) Ions from Aqueous Media

Facile Synthesis of Sodium Iron Silicate/Sodium Iron Oxide Silicate Nanostructures from Canned Beans and Rice Husk Wastes for Efficient Removal of Cd(II) Ions from Aqueous Media

EFFECT OF MIXING METHODS PRIOR THE DECOMPOSITION PROCESS ON THE DECOMPOSED FERRONICKEL SLAG

Ferronickel slag is a by-product that was obtained from ferronickel production and contains Si and Mg as the main elements. Decomposition process using alkali could decrease energy consumption to process ferronickel slag by decreasing its melting point. The mixing methods prior to the decomposition process could significantly affect interaction between reactants over the process, therefore it is essential to study. The aim of this study is to determine the effect of mixing methods of ferronickel slag and NaOH prior decomposition process on the chemical composition, phase, and microstructure of decomposed ferronickel slag. Two different mixing methods, physical mixing, and impregnation, followed by roasting process at 350 ℃ for 60 minutes were performed, characterized, and analyzed. Thermodynamic analysis was calculated and shows having a good agreement with the characterization results which formation of sodium silicate, magnesium hydroxide and iron oxide were identified. Distribution of product layer of RI can be determined, while spotty decomposition was clearly identified. The effectiveness of impregnation over physical mixing was investigated.

Screening of Filler Material for a Packed‐Bed Thermocline Energy Storage Test Facility with Lead–Bismuth Eutectic as the Heat Transfer Fluid

Suitable solid filler materials are investigated for use in a packed‐bed heat storage test facility for high temperatures with lead–bismuth eutectic (LBE) as the heat transfer fluid. Accordingly, first, the thermophysical properties of six different candidate materials, two glasses and four ceramics, are determined. The density and heat capacity are measured experimentally and the thermal conductivity is discussed based on literature data. Subsequently, a static corrosion test is performed at 500 °C for 1 and 4 weeks in LBE under reducing conditions. The glasses are found to be unsuitable due to corrosion attack. Among the ceramics, zirconium silicate and zirconium oxide are identified to be highly resistant to corrosion. Zirconium silicate is subsequently also successfully tested as a storage material in a laboratory experiment under cyclic conditions.

Acidithiobacillus species drive the formation of ferric-silica cemented microstructure: Insights into early hardpan development for mine site rehabilitation

Hardpan-based profiles naturally formed under semi-arid climatic conditions have substantial potential in rehabilitating sulfidic tailings, resulting from their aggregation microstructure regulated by Fe-Si cements. Nevertheless, eco-engineered approaches for accelerating the formation of complex cementation structure remain unclear. The present study aims to investigate the microbial functions of extremophiles on mineral dissolution, oxidation, and aggregation (cementation) through a microcosm experiment containing pyrites and polysilicates, of which are dominant components in typical sulfidic tailings. Microspectroscopic analysis revealed that pyrite was rapidly dissolved and massive microbial corrosion pits were displayed on pyrite surfaces. Synchrotron-based X-ray absorption spectroscopy demonstrated that approximately 30 % pyrites were oxidized to jarosite-like (ca. 14 %) and ferrihydrite-like minerals (ca. 16 %) in talc group, leading to the formation of secondary Fe precipitates. The Si ions co-dissolved from polysilicates may be embedded into secondary Fe precipitates, while these clustered Fe-Si precipitates displayed distinct morphology (e.g., “circular” shaped in the talc group, “fine-grained” shaped in the chlorite group, and “donut” shaped in the muscovite group). Moreover, the precipitates could join together and act as cementing agents aggregating mineral particles together, forming macroaggregates in talc and chlorite groups. The present findings revealed critical microbial functions on accelerating mineral dissolution, oxidation, and aggregation of pyrite and various silicates, which provided the eco-engineered feasibility of hardpan-based technology for mine site rehabilitation.

Radiation attenuation of SiO2–MgO glass system for shielding applications

Silicate glasses are an essential material in many industries due to their unique properties. In this study, we aim to investigate the potential of (100-x) SiO2-xMgO (x = 5, 20, 35, and 55 mol%) glass system to use for medical and nuclear applications. The silicate oxide is reduced and the MgO is added accordingly with different concentrations of 5, 20, 35, and 55 mol%, with sample codes of SM1, SM2, SM3, and SM4, respectively. The goal of such change is to develop glasses with optimum radiation attenuation properties. The Mass attenuation coefficient (MAC) of the glasses, for different photon energies, is calculated using the Geant4 Monte Carlo simulations and the XCOM photon cross section database. The simulation results provide vital data on the shielding effectiveness of the glass compositions against photon radiation. The obtained findings showed that the radiation attenuation properties can be tailored by adjusting the relative concentrations of the constituting glass oxides, such as SiO2 and MgO. For example, the best shielding performance is observed for the SM1 sample, with the highest concentration of SiO2, among the studied glasses. Furthermore, the shielding performance of the studied glasses is compared with some famous materials previously considered in recent publications. Therefore, the present glasses show promising shielding performance, with high effective and low-cost, for potential use in real radiation sources for experimental validation.

Leaching behavior and occurrence of metal elements in copper slag: The key to recycling metals in copper slag

Recovering of metals from Copper Slag (CS) is important to alleviate the resource shortage of metals and eliminate environmental pollution. Thus, this study aimed to propose information on leaching behavior and a full image of CS's main element occurrence phases in order to further improve the efficiency of metal recovery. The pH-dependent leaching experiments with the help of geochemical modeling showed that 99.66 % undissolved Fe exists in fayalite, magnetite, and calcium-iron silicates, and 97.14 % undissolved Zn exists in fayalite and sphalerite. The mineral liberation analysis (MLA) results confirm that 80.92 % Fe and 83.75 % Zn are present in fayalite. It was found that 52.71 % calcium-iron silicate and 65.60 % iron oxide were associated with fayalite, so in the future, the recovery of Fe and Zn should not only target fayalite but also pay attention to the influence of calcium-iron silicate and iron oxide on the recovery. At the same time, when leaching elements such as Fe and Zn from fayalite in CS, the environmental risks associated with the subsequent leaching of Pb should be considered. Overall, the results of this study provide comprehensive information on the leaching behavior of significant metal elements and the associated mineral characterization of CS and thus, provide the basis for the metal recovery of CS in the future.

Recent advances of SiO x -based anodes for sustainable lithium-ion batteries

The world is facing an ever-growing global energy crisis with unprecedented depth and complexity. The sustainable development of high energy density lithium-ion batteries for electric vehicles and portable electric devices has become a feasible way to deal with this problem. Silicon suboxides (SiO_<i>x</i>) have been deemed as one of the most promising anode materials because of their ultrahigh theoretical lithium storage capacity, proper working potential, natural abundance, and environmental friendliness. However, the mass utilization of SiO_<i>x</i>-based anodes is severely obstructed by their low electrical conductivity and inevitable volume expansion. While lithium silicate and lithium oxide formed in the first lithiation process act as buffer layers to some extent, it is urgent to address the accompanying low initial Coulombic efficiency and unsatisfactory cycling stability. In this review, we summarized recent advances in the synthesis methods of SiO_<i>x</i>-based materials. Besides, the benefits and shortcomings of the various methods are briefly concluded. Then, we discussed the effective combination of SiO_<i>x</i> with carbon materials and designs of porous structure, which could considerably enhance the electrochemical performance in detail. Furthermore, progresses on the modified strategies, advanced characteristics and industrial applications for SiO_<i>x</i>-based anodes are also mentioned. Finally, the remaining challenges encountered and future perspectives on SiO_<i>x</i>-based anodes are highlighted.

Hydrogeological controls on chromium enrichment along the groundwater flow path in the Baiyangdian Catchment, North China Plain

Although the natural occurrence of high chromium (Cr) groundwater has been intensively investigated in bedrock or sedimentary aquifers, the impacts of hydrogeological conditions on dissolved Cr distribution are poorly understood. In this study, groundwater samples from recharge mountain area (Zone I) through runoff area (Zone II) to discharge area (Zone III) were taken from bedrock and sedimentary aquifers approximately along the flow path in Baiyangdian (BYD) catchment, China, to reveal how hydrogeological conditions and hydrochemical evolution contributed to Cr enrichment in groundwater. Results showed that dissolved Cr was dominated by Cr(VI) species (>99 %). Around 20 % of studied samples had Cr(VI) exceeding 10 μg/L. Groundwater Cr(VI) was of natural origin, which generally increased along the flow path, and high concentrations (up to 80.0 μg/L) were observed in deep groundwater of Zone III. At the local scales, geochemical processes including silicate weathering, oxidation, and desorption under weakly alkaline pH, predominately contributed to Cr(VI) enrichment. Principal component analysis showed that oxic conditions were the principal control of Cr(VI) in Zone I, and geochemical processes (especially Cr(III) oxidation and Cr(VI) desorption) predominantly enhanced groundwater Cr(VI) enrichment in Zones II and III. However, at the regional scale, Cr(VI) enrichment was dominantly facilitated by the low flow rate and recharge of paleo-meteoric water due to the long-term water-rock interaction in the BYD catchment.

Novel Samarium Cobaltate/Silicon Carbide Composite Catalyst for Dry Reforming of Methane into Synthesis Gas

The paper describes a specifically developed novel samarium cobaltate/silicon carbide composite that transforms into a high-performance carbon-resistant catalyst for dry reforming of methane into syngas (DRM). This 30%SmCoO3/70%SiC composite without hydrogen prereduction was tested in DRM at atmospheric pressure and GHSV 15 L g–1 h–1 (of an equimolar CH4–CO2 mixture). During the test, the yields of hydrogen and carbon monoxide reached 92 and 91 mol %, respectively, at 900°C, and 20 and 28 mol % at 700°C. Using XRD, TGA, and SEM examination, zero carbonization of the catalyst surface was demonstrated. It was found that, in the course of DRM, the initial composite transformed into a material that contained silicon carbide, samarium silicate, and samarium oxide, as well as metallic cobalt nanoparticles (20 nm).

The Possible Role of Anoxic Alkaline High Subcritical Water in the Formation of Ferric Minerals, Methane and Disordered Graphitic Carbon in a BARB3 Drilled Sample of the 3.4Ga Buck Reef Chert.

The present article reports Raman spectroscopic observations of siderite, hematite, disordered graphitic carbon and possibly greenalite inside the quartz matrix of a banded iron sample from the BARB3 core drilled inside the 3.4Ga Buck Reef Chert of the Barberton Greenstone Belt in South Africa. The article also reports Raman spectroscopic observations of quartz cavities, concluding in the presence of water, methane and sodium hydroxide at high concentration leading to pH ~ 15 inside the inclusion, suggesting an Archean water which was strongly basic. FeIII-greenalite may also be present inside the inclusion. The possible role of anoxic alkaline high subcritical water in the formation of ferric minerals and the CO required for the synthesis of molecules of biological interest has been demonstrated theoretically since 2013 and summarized in the concept of Geobiotropy. The present article experimentally confirms the importance of considering water in its anoxic strongly alkaline high subcritical domain for the formation of quartz, hematite, FeIII-greenalite, methane and disordered graphitic carbon. Methane is proposed to form locally when the carbon dioxide that is dissolved in the Archean anoxic alkaline high subcritical water, interacts with the molecular hydrogen that is emitted during the anoxic alkaline oxidation of ferrous silicates. The carbon matter is proposed to form as deposition from the anoxic methane-rich fluid. A detailed study of carbon matter from diverse origins is presented in a supplementary file. The study shows that the BARB3_23B sample has been submitted to ~ 335°C, a temperature of the high subcritical domain, and that the graphitic structure contains very low amounts of oxygen and no hydroxyl functional groups. The importance of considering the structure of water is applied to the constructions of the Neoproterozoic and Archean banded iron formations. It is proposed that their minerals are produced inside chemical reaction chambers containing ferrous silicates, and ejected from the Earth's oceanic crust or upper mantle, during processes involving subduction events or not.

Novel Samarium Cobaltate/Silicon Carbide Composite Catalyst for Dry Reforming of Methane into Synthesis Gas

The paper describes a specifically developed novel samarium cobaltate/silicon carbide composite that transforms into a high-performance carbon-resistant catalyst for dry reforming of methane into syngas (DRM). This 30%SmCoO3/70%SiC composite without hydrogen prereduction was tested in DRM at atmospheric pressure and GHSV 15 L g–1 h–1 (of an equimolar CH4–CO2 mixture). During the test, the yields of hydrogen and carbon monoxide reached 92 and 91 mol %, respectively, at 900°C, and 20 and 28 mol % at 700°C. Using XRD, TGA, and SEM examination, zero carbonization of the catalyst surface was demonstrated. It was found that, in the course of DRM, the initial composite transformed into a material that contained silicon carbide, samarium silicate, and samarium oxide, as well as metallic cobalt nanoparticles (<20 nm).