Talc Research Articles

Self-cleaning cellulose acetate/crystalline nanocellulose/polyvinylidene fluoride/Mg0.975Ni0.025SiO3 membrane for removal of diclofenac sodium and methylene blue dye in water

Recalcitrant pollutants present in wastewater, without an effective treatment, have several effects on aquatic ecosystems and human health due to their chemical structure and persistence. Therefore, it is crucial the development of efficient technologies to eliminate such pollutants in water. Nano-photocatalysts are considered a promising technology for water remediation; however, one common drawback is the difficulty of recovering it after water processing. One effective strategy to overcome such problem is its immobilization into substrates such as polymeric membranes. In this study, a polymeric membrane with embedded Mg0.975Ni0.025SiO3 is proposed to remove model pollutants diclofenac sodium and methylene blue dye by synergetic adsorption and photocatalytic processes. Mg0.975Ni0.025SiO3 was synthesized by the combustion method. The matrix polymeric blend consisting of a blend of cellulose acetate, crystalline nanocellulose and polyvinylidene fluoride was obtained by the phase inversion method. The composite membranes were characterized by FTIR, x-ray diffraction, and scanning electron microscopy. With pollutant solutions at pH 7, the pollutant adsorption capacity of the membranes reached up to 30% and 45% removal efficiencies for diclofenac sodium and methylene blue, respectively. Under simulated solar irradiation photocatalytic removal performances of 70% for diclofenac sodium pH 7, and of 97% for methylene blue dye at pH 13, were reached. The membrane photocatalytic activity allows the membrane to avoid pollutant accumulation on its surface, given a self-cleaning property that allows the reuse of at least three cycles under sunlight simulator irradiation. These results suggest the high potential of photocatalytic membranes using suitable and economical materials such as cellulosic compounds and magnesium silicates for water remediation.

MAGNEX and PILCCU in Finland: deployment of CO2 mineralisation in circular economies

Two ongoing projects in Finland, MAGNEX (Viable magnesium ecosystem: exploiting Mg from magnesium silicates with carbon capture and utilization) and PILCCU (Piloting of ÅA CCU) aim at using CO2 mineralisation technology for the overlapping purposes of large-scale CO2 emissions mitigation and bringing several valuable material streams into circular economies, including construction. Of central importance are magnesium-based materials, such as magnesium carbonate hydrate (MCH), besides (amorphous) silica and several metallic species. On top of revenues from these, CO2 emissions mitigation lowers the financial penalty from CO2 emission rights under for example the European ETS. The ÅA process routes are stepwise processes based on extraction of magnesium (and other species) from serpentinite-containing mining tailings from Finland, followed by precipitation of metallic species, carbonation using a CO2 containing gas-stream (no separate capture step needed) and recovery of solvent salt, respectively. Several separation steps involve (ion-selective) membrane electrodialysis. Besides ongoing mapping and characterisation of Finnish rock resources as tailings or other side-streams at metal and mineral mines in Finland, the projects address public acceptance, legislation and other non-technical issues related to large-scale roll-out of this type of CCU technology.For the use of the solids, magnesium-based cement binders and plaster-like recipes are investigated as well as applications for the (amorphous) silica and other residues, including the use of MCH for cyclic thermal energy storage (TES). Special focus is on accelerating the carbonation step and the final outcome of MCH production, considering pressure (including supercritical CO2 levels), and the role of recoverable catalysts and other additives. The work receives funding from the Academy of Finland (2022-2025) and from Business Finland plus industry partners (2022-2024), respectively.

Study on the Performance and Mechanism of Glass Fiber-Reinforced MgO-SiO2-H2O Cement.

The magnesium silicate hydrate system (MgO-SiO2-H2O) possesses issues such as susceptibility to cracking, brittleness, and poor volumetric stability, which hinder its development and practical use in engineering applications. This study aimed to enhance the properties of the MgO-SiO2-H2O system by incorporating glass fiber as a reinforcing material. The mechanical properties, shrinkage properties, and properties during accelerated aging were tested at different content levels of glass fiber. Additionally, the reaction mechanism and microscopic morphology were characterized using microscopic testing methods. The results revealed that the addition of glass fiber improved the mechanical properties of the MgO-SiO2-H2O system; meanwhile, with an increase in fiber content, the mechanical properties showed an initial increase followed by a decreasing trend. With a glass fiber content of 0.6%, the system exhibited a flexural strength of 7.9 MPa at 28 d, a compressive strength of 42.5 MPa at 28 d, and a 27.2% increase in splitting tensile strength compared to the control group. At a fiber content of 0.9%, the flexural toughness steadily increased, reaching a maximum value of 2.238 N·m, which is 5.41 times greater than that of the control group. Moreover, the incorporation of glass fiber effectively inhibited the shrinkage of the MgO-SiO2-H2O system. Accelerated aging experiments confirmed that the glass fiber in the MgO-SiO2-H2O system did not undergo significant deterioration or corrosion, thereby maintaining long-term stability. These findings have important theoretical and practical significance for the application and development of the MgO-SiO2-H2O system.

Systematic comparison of Mg K-edge XANES spectra of magnesium-bearing clay minerals and magnesium silicate hydrates: A promising tool for identifying magnesium silicate hydrate in natural samples

Magnesium silicate hydrate (MSH) is a low-crystalline material of recent interest in the fields of geoengineering, low-temperature geochemistry, and planetary science. Despite the potential importance of the phase in a wide range of research areas, methods for identifying MSH in natural samples are limited because of its low crystallinity and variable chemical composition. The use of Mg-XANES spectroscopy for identifying MSH and Mg-bearing clay minerals were examined in this study. The spectra of various MSHs synthesized under different conditions were systematically compared against the spectra of various other natural and synthetic clay mineral species (montmorillonite, Fe-montmorillonite, saponite, Fe-saponite, stevensite, talc, antigorite, chrysotile, and chlorite). The spectra for all the mineral species were similar, regardless of composition and crystallinity. Quantitative comparison of the spectral similarities revealed that species with the same structure had similar spectra, such that 2:1 dioctahedral smectites (montmorillonite), 2:1 trioctahedral smectites (saponite and stevensite), 2:1 trioctahedral talcs, and 1:1 trioctahedral serpentines all have unique Mg-XANES spectra. The spectra of six freshly prepared MSHs with Mg/Si ratios of 0.7–1.3 and synthesized under different pH conditions (pH = 10 or 12) were comparable. Two freshly prepared Fe-containing MSHs showed very similar Mg-XANES spectra to those of the MSHs. Spectral analysis revealed that the spectra of the freshly prepared MSHs could not be reconstructed by combining the spectra of the other Mg-bearing clay minerals, indicating that the coordination environment of Mg in freshly prepared MSH is unique and common regardless of the material's composition and reaction pH. The spectra of two MSHs (Mg/Si ratio, 0.8–1.3) aged for 12 months were slightly different from those of the freshly prepared MSHs due to partial transformation of the MSH to trioctahedral clay minerals. In summary, Mg-XANES spectroscopy can be used to identify MSHs and certain other clay minerals due to their unique spectra.

Nickel nanoparticles supported on magnesium silicate MWW molecular sieve as an efficient catalyst for dry reforming of methane

Magnesium silicate delaminated MWW layers (Mg-DMLs) with two-dimensional (2D) crystal morphology were synthesized by a single-step hydrothermal conversion of borosilicate MWW precursor using magnesium nitrate aqueous solution. As hydrothermal temperature increased from 100 to 180 °C, the crystal structures of Mg-DMLs were changed from crystalline three-dimensional (3D) tectosilicate to amorphous 2D phyllosilicate via delaminated MWW structure. Meanwhile, the substitution of framework B by Mg occurred resulting in the continuous increase of Mg content and basicity of Mg-DMLs as a function of hydrothermal temperature. The X-ray photoelectron spectroscopy study differentiated the framework Mg species on Mg-DML-x (x = 100–160 °C) and MgO on Mg-DML-180. Owing to the strong metal-support interaction originated from framework Mg species, the highest dispersion of Ni species was obtained on Ni/Mg-DML-160, resulting in the outstanding catalytic activity and stability. The present study suggests that the synergic effect of appropriate framework Mg species with Lewis basicity and the structural 2D MWW character can result in a promising catalyst for dry reforming of methane.

Limit of detection in qualitative analysis: Classification Analytical Signal approach

This paper presents a new methodology for the estimation of the limit of detection and other related parameters in qualitative analysis. Estimation of the detection limit is important in special cases when a small amount of an illegal ingredient can significantly affect the quality of the product or the presence of even a small amount of an extraneous analyte is significant. The approach is based on a recently introduced concept of an analytical signal in qualitative analysis, called the Classification Analytical Signal (CAS). A detailed algorithm to calculate the detection capability for a one-class classification method Data-Driven Soft Independent Modeling of Class Analogy (DD-SIMCA) is described and illustrated with two real-world examples. Both examples consider cases where the detection of low analyte concentrations is important and corresponding samples should be considered as non-compliant. The first case presents adulteration of wheat flour with talcum powder, where the samples were specially prepared with various concentrations of the analyte. The second case uses a publicly available dataset devoted to the estimation of tetracycline in blood serum. The latter case is used to compare the limits of detection estimated for multivariate calibration with those presented for qualitative analysis.

Highly stretchable, self-healing, self-adhesive and conductive nanocomposite hydrogels based on multi-reversible interactions as multifunctional strain sensors

Construction of highly stretchable and sensitive flexible strain sensors is of great significance for wide applications in human–computer interaction, wearable devices, and electronic skins. However, it turned out to be not effortless to integrate the two seemingly contrary features of high stretchability and sensitivity into a system. Herein, we designed a nanocomposite conductive hydrogel (NCCH) composed of zwitterionic poly(HEAA-co-SBMA) polymers and lithium magnesium silicate (XLG) by means of multi-reversible molecular interactions (MRMIs) including borate ester bonds between polyHEAA and borax, hydrogen bonds, and polySBMA-XLG-based electrostatic interaction, endowing the NCCH with enhanced mechanical, self-healing, adhesive, biocompatible, and sensing performances. The MRMI method enabled NCCHs to obtain an excellent stretchability (∼1080 %)/compressibility (∼98.5 %), a tensile strength of ∼ 0.06 MPa, a good self-healing with a fracture strain recovery of 90.5 %, and a strong adhesion on various hard and soft substrates (e.g. a adhesive shear force of 60 kPa to pigskin tissues). Besides, the integration of zwitterionic polySBMA and conductive XLG promoted charge transfer.by optimal ioinic channels. Based on these outstanding strengths, the NCCHs were farther rationally fabricated as multifunctional strain sensors with remarkable sensing stability for fast and accurately detecting strain/pressure-induced deformation, joint motions, and animal heartbeats. Notably, the excellent self-healing property of NCCH sensors can facilitate their long-period usage and complete recyclability for avoiding wastes. The new MRMI-based NCCH sensor without any conductive additives is deemed to provide a new strategy for broadening their multifunctional strain sensor and healthcare monitoring applications.

Biocontrol rhizobacteria enhances growth and yield of wheat (Triticum aestivum) under field conditions against Fusarium oxysporum

ABSTRACTThe current study aimed to identify the survival of bio-control bacteria with antifungal activity against Fusarium oxysporum and assess their growth promoting activity in wheat crop field conditions. To evaluate the fungicidal activities of isolated bacteria using the dual culture method, both qualitative and quantitative bioassays were performed. Plant Growth Promoting activities such as Indole 3-Acetic Acid (IAA), phosphate solubilization, Hydrogen cyanide (HCN), and Siderophore production were assessed for three biocontrol bacterial isolates (BCB 07, BCB16, and BCB 83) out of 180 with 70% antagonistic activity against Fusarium oxysporum. Chitinase, protease, and cellulase interaction in isolates was also tested. BCB16 was selected as it had 70% antagonist activity against F. oxysporum but also had the highest PGPR (Plant Growth Promoting Rhizobacteria) traits when compared to the other two isolates. BCB16 was also tested for survival in talc powder and in wheat crop field conditions. Even after 4 months in talc powder, the survival rate remained stable. In a wheat crop field, BCB16 reduced the disease incidence of Fusarium oxysporum by 54.38%. When compared to fungus alone treatment, BCB16 increased average yield by 57% alone and 32% in challenged conditions. BCB16 was identified molecularly using the 16s rRNA gene. Bacillus amyloliquefaciens shared 97% of the deduced sequence. The sequence was submitted to genbank and assigned the accession number OM333889. Bacillus amyloliquefaciens has the potential to be used in the field as an alternative to synthetic fungicides against Fusarium oxysporum.

Experimental investigation of Different types of Dust effect on the Grid-connected Rooftop Solar Power Plant

ABSTRACT The accumulation of dust and dirt not only reduces the power output of the solar power plant but also reduces the performance ratio, efficiency, and energy generation (kWh). In this paper, a 100-kWsolar power plant was selected for the experiment. Firstly, string identification and selection were done to find out the strings for the experiment. A total of 5 strings were selected for the experiment and there were 19 photovoltaic panels were connected to each string. Sand, Cement, Talcum powder, and dry leaves were deposited on string-1, string-2, string-3, string-6, and string-7 as reference strings. This paper investigates the performance of these materials on the operating voltage, DC current, power, energy (kWh), performance ratio, and efficiency. However, the impact of these materials on the photovoltaic panel temperature was also investigated. It was calculated that the output power of the photovoltaic panel string-2 (cement), string-3 (Talcum powder), string-1 (sand), and string-6 (Dry leaves) was reduced by 81.4%,53.4%, 9.8%, and 0.9% compared to the reference string and minimum photovoltaic panel temperature was observed in the case of Talcum powder. After completion of the experiment, the selected string was manually cleaned with water and it was observed that sand and trash of dry leaves were easily cleaned by water but Cement and talcum powder needs high-pressure water and wiping with a microfiber cloth to prevent these substances from the surface of the photovoltaic panels. Also, some future studies are suggested in the end section of the research paper.

Study on the application of two magnesium salts in low temperature adsorption refining of fragrant rapeseed oil

Magnesium silicate and basic magnesium carbonate were characterized and their application in the low temperature adsorption refining of fragrant rapeseed oil was investigated. The results showed that both materials had a loose porous structure, but their particle size distribution, active functional groups, crystallinity, specific surface area, pore volume, and pore size differed. Under the optimal adsorption refining conditions, magnesium silicate and basic magnesium carbonate reduced the phospholipid content from 4.18 to 0.83 and 1.57 mg/g, acid value from 1.67 to 0.88 and 0.90 mgKOH/g, yellow value from 38.2 to 32.1 and 36.2, and red value from 2.9 to 1.7 and 2.2, respectively. The use of these two magnesium salts did not significantly alter the composition of fatty acids and the content of tocopherol. The retention rates of total phytosterol by magnesium silicate and basic magnesium carbonate were 93.6% and 95.9%, respectively. The retention rates of total phenol were 88.9% and 93.9%, respectively. The adsorption refining process proved to be advantageous in purifying fragrant rapeseed oil while maintaining the dominant flavor components relatively unchanged (P < 0.05). As a result, these two magnesium salts have the potential to be used during the low temperature adsorption refining process of fragrant rapeseed oil.

Novel silanized colloidal silica-MgO self-flowing dispersions with improved hydroxylation resistance

MgO-containing and colloidal silica-bonded are important classes of refractory castables of, respectively, high refractoriness and straightforward processing. On the other hand, their combination is not synergetic. Although 0.1–1 wt% additions of MgO set and harden typical colloidal silica-bonded castables in a 1-hour time frame, greater amounts gel the system instantaneously. This paper addresses the combination of fine MgO sinter with a novel aqueous dispersion of colloidal silica whose particles’ surfaces were modified with an epoxysilane-based coupling agent. Their low reactivity produced self-flowing MgO-colloidal silica suspensions of excellent workability and, after curing, generated a packed magnesium silicate hydroxide hydrate (Mg5Si8O20(OH)2.8H2O) protective coating over MgO particles, hindering their hydroxylation and preventing volumetric expansion. The cast structures attained displayed safer drying and suitable strength. During thermal treatment, silica particles softened and promoted viscous flow, favoring grains densification. Therefore, after sintering, the microstructure comprised dense MgO grains surrounded by thin layers of forsterite (Mg2SiO4).

Bilyeli Değirmen ve Karıştırmalı Değirmen Kombinasyonu ile Çok İnce Talk Üretimi

In this study, it was investigated that talc ore could ground to very fine sizes using a combination of conventional ball mill and vertical stirred mill. Firstly, the conventional ball mill parameters such as mill speed (% of critical speed), material filling ratio (Jb), ball filling ratio (fc), ball size distribution (10-20-30-40 mm, %), grinding aid ratio (% of powder) and grinding time (min.) were optimized using classic experimental design. As a result of the optimization, fine talc product was obtained with d90=93.52 µm particle size. In the second stage, the ball mill product was re-milled using a stirred mill. As a result of study, a final ultra-fine talc powder was obtained after 60 minutes grinding time with d50=1.85 µm particle size and 14058 cm2/g total surface area. It has been seen that the conventional ball mill+stirred mill combination effective a process to obtain talc powder that suitable for industrial use.

Immobilization of Pb2+ and Cd2+ on the novel calcium/magnesium silicate and their transformation in the presence of phosphate

Adsorbent development is a key step toward the removal of heavy metals (HMs) from water. The transformation of fixed HMs in the environment is of the utmost importance for successful remediation treatments. Herein, novel calcium silicate (CS) and magnesium silicate (MS) adsorbents were prepared by a composite-hydroxide-mediated method, which were used to remove Pb2+ and Cd2+ from water, and the synthesis mechanism was studied in detail. Our results showed that CS/MS exhibited a high uptake of Pb2+ and Cd2+, which were 970.87/1594.81 and 334.45/448.43 mg g−1, respectively. Various characterization techniques confirmed the high adsorption capacities of the adsorbents for heavy metal ions, and the identified adsorption mechanisms were ion exchange, chemical precipitation, and surface-complexation. Afterward, the aging test of the heavy metal-adsorbent complex was conducted in a solution containing phosphate (P) to investigate the effect of P on the speciation of HMs fixed by CS and MS. The results revealed that the immobilized HMs transformed into a more stable phosphates phase to different degrees; in addition, the content of P significantly decreased in the aging process, which was beneficial for controlling the eutrophication of water bodies. In summary, CS and MS effectively immobilized HMs in the investigated aqueous system.

Transforming calcium carbonate–silicate wastes into steel protective coatings

This work focused on developing an innovative steel protective coating, in which calcium carbonate (CC) is the primary precursor. Mixing sodium silicate solution with CC-powder induced calcium silicate hydrate (CSH) formation binding phase via the cationic exchange reaction. Incorporating lead glass sludge and glass waste, as environmentally friendly silicate rich source alternative to sodium silicate, enhanced the creation of CSH binding phase, which is associated with an increase in the compaction of the resulted coating’s microstructure. Using prepared coatings on the surface of steel rebars improved their resistance to chloride-induced corrosion. The coated steel containing lead glass sludge was found to represent the higher affinity to mitigate chloride diffusion, as it recorded polarization resistance (Rp) (480 kΩ/cm2) higher than that reference steel reinforcement (39 kΩ/cm2) at 3 months of immersion in seawater. Utilizing nano magnesia (nM) as an additive to the protective coating with lead glass sludge results in a further improvement in the coated steel against chloride-induced-corrosion. An additional magnesium silicate hydrate (MSH) binder was formed, resulting in remarkable improvements in the compactness of the coating's microstructure. This innovative approach is different from traditional methods for producing reactive calcium oxide through thermal treatment of CC at higher temperatures. Reactive calcium is produced through the cationic exchange reaction at room temperature, reflecting a reduction in CO2 emissions, minimizing processing costs and energy demands. Unlike the alkali-activated aluminosilicate-based coatings, the prepared coatings represent high commercial viability and low cost. Additionally, due to the properties of calcium carbonate, which are independent of its source, these coatings can be globally standardized. However, before applying this coating to different surfaces, it is crucial to address its mechanical properties and durability against various aggressive media. These aspects will be the primary focus of our future work.

Research on predicting compressive strength of magnesium silicate hydrate cement based on machine learning

In this study, a machine learning approach was employed to establish a predictive model for the compressive strength of magnesium silicate hydrate cement (MSHC). Sensitivity analysis of the input parameters was conducted using Shapley Additive Explanations (SHAP). The results indicated that the Gradient Boosting Regression (GBR) and Extreme Gradient Boosting (XGB) models exhibited enhanced precision in forecasting the compressive strength of MSHC, with the XGB model showcasing superior prowess in generalization. Among the various feature parameters, the curing age (Age) was identified as the most significant factors influencing the compressive strength of MSHC. The compressive strength of MSHC was positively correlated with the content of Age, MgO (C-Mg), and SiO2 (C-Si), and negatively correlated with the water-cement ratio (W/C). It also had a nonlinear relationship with parameters such as the specific surface area of MgO (S-Mg) and the Mg/Si ratio. Finally, the optimal parameters for preparing MSHC were proposed, including an optimal S-Mg value of approximately 22 m2/g and an optimal Mg/Si ratio of 1:1. When potassium dihydrogen phosphate (K) was used as a dispersant, the optimal dosage was around 4.5%. On the other hand, when sodium hexametaphosphate (S) was used as a dispersant, a dosage greater than 2.5% resulted in a certain improvement in strength.

Water Consolidation Performance of Acrylic-Polymer-Modified Materials and Their Concrete Impermeability Repair Characteristics.

Acrylic materials exhibit favorable grouting repair performance. However, their curing products are easily inclined to drying shrinkage, and their concrete impermeability repair characteristics have seldom been investigated. To improve material properties, reveal the impermeability repair mechanism, and address drying shrinkage, this study proposed the addition of styrene-acrylate copolymer emulsion (styrene-acrylic emulsion) to the grouting material to prepare two-component acrylate grouting materials. Using orthogonal and single-factor tests combined with physical and mechanical properties, the mechanical properties and impermeability repair performance (physical and mechanical properties combined) of grouting materials were analyzed and studied, and the optimal ratio of each component of acrylate grouting materials was determined. Results show that (1) the hydrogel produced by the reaction of sodium methacrylate with hydroxyethyl acrylate has good physical and mechanical properties. (2) With the increase in the accelerator dosage, the setting time of slurry initially decreases and then increases; as the initiator dosage increases, the setting time of slurry decreases, which is negatively correlated with the initiator dosage. (3) Talcum powder can improve the physical and chemical properties of gel and enhance the reliability and durability of acrylate grouting materials, and the comprehensive performance is the best at a dosage of 3%. (4) Styrene-acrylic emulsion can increase the solid content and reduce the volume drying shrinkage when added to grouting materials. The fractured impermeable specimens were repaired by grouting with prepared acrylate grouting materials and cured for 24 h for the impermeability test, and the water pressure for the 24 h impermeability repair was 1.0 MPa. This study's results provide important reference and basis for revealing the impermeability principle of acrylate grouting materials and evaluating their impermeability.

Insight into the Corrosion Inhibition Mechanism of Sodium Silicate on the Magnesium Alloy Surface: Experimental and Theoretical Calculations.

The corrosion inhibition mechanism of sodium silicate (SS) for WE43 magnesium alloy in NaCl solution was investigated by in situ observation, electron probe microanalysis (EPMA), electrochemical test, and theoretical calculations. In situ observation showed that local corrosion was markedly inhibited after the addition of the SS inhibitor. Electrochemical data revealed that a protective layer was formed on the metal/solution interface and an optimum inhibition efficiency of 98.3% in the case of 2.5 g/L SS. A uniform magnesium silicate layer with a thickness of ∼2 μm formed on the uncorroded area was confirmed. Quantum chemical calculations revealed that SiO32- could absorb on the MgO (1 0 0) surface in a parallel orientation through the coordinate bonds between the O and Mg atoms. The distances of Mg-O bonds are 2.052 and 2.249 Å, suggesting that they are coordinated. The adsorption/interaction mechanisms of SiO32- were also analyzed through charge density distribution and atomic densities. Molecular dynamics simulations further confirmed that a uniform SiO32- layer was absorbed on the MgO surface. In the local corroded area, free SiO32- would react with Mg2+ and OH- produced by corrosion to form the insoluble magnesium silicate compound, which hindered the spread of corrosion.

Anisim Efremovich Malakhov (1899–1989) and former malakhovite (now khesinite)

Anisim Efremovich Malakhov, a prominent specialist in the fi eld of geology of ore, non-ore and rare metal deposits of the Urals. For about 30 years he headed the Department of Geology of Ore Deposits and Coal and Non-Metal Deposits of the Faculty of Exploration Geology at the Sverdlovsk Mining Institute. In honor of Anisim Efremovich, a new mineral was named – malakhovite, calcium, magnesium and iron silicate, which was discovered by B. V. Chesnokov in the burnt dumps of the Chelyabinsk coal basin. The International Mineralogical Association did not approve it as a new mineral species, and recently a natural analogue of malachovite, hesinite, was found in Israel.

Optimization of the rice husk ash production process for the manufacture of magnesium silicate hydrate cements

Different types of amorphous, silica-rich materials can be employed as supplemental cementitious materials (SCM) in Portland cement compositions that are more common. SCMs react with Ca(OH)2 in the presence of Portland cement and a water solution to create calcium silicate hydrate (C–S–H). When produced under specific circumstances, rice husk ash (RHA) contains a high concentration of amorphous silicon dioxide and is utilized as SCM in Portland cement formulations. Similar to this, materials high in amorphous silica, like RHA, encourage the production of hydrated magnesium silicate gels (M-S-H) in reactive magnesium aqueous solutions. Studies examining RHA's capacity to generate M-S-H under various temperature settings, however, are scarce. For the creation of cellulose-reinforced cementitious composites, M-S-H cements, which have superior mechanical qualities and reduced alkalinity (pH 9–10) as compared to Portland cement, are a suitable option. Because of this, the current study assesses the hydration reaction of magnesium oxide with silica produced from RHA and processed by various heat treatments (500, 550, 600, and 650 °C) to generate M-S-H. There were tests for mechanical stability, electrical conductivity, calorimetry, XRD, TG, pH, and more. As benchmarks, compositions containing MgO and commercially active silica (SF) were employed. The findings demonstrate that, in comparison to previous thermal treatments, RHA generated at 500 °C (RHA500) enabled the creation of an increased M-S-H concentration. The axial compressive strength of this composition (MgO/RHA500) in the initial phases is comparable to that of the reference composition (MgO/SF). Since the paste consisting of MgO/RHA500 had the lowest pH values at 30 days of curing, even when compared to the pH of the reference composition MgO/SF (pH 10.04), the calcination of RHA at 500 °C is also the best treatment to lower the alkalinity of the created system. The MgO/RHA500 composition's decreased alkalinity will enable the RHA generated at lower temperatures to be applied in a new way. The RHA, which is already a by-product of the agro-industrial sector with some added value, serves as a predecessor for the creation of M-S-H cement, which will promote both technical and environmental benefits for non-conventional cementitious materials.

Effect of Dehydroxylation on Tribological Performances of Synthetic Magnesium Silicate Hydroxide as Lubricant Additive

Abstract The heat-treated nanoparticle heat-treated magnesium silicate hydroxide (MSHH) was obtained based on the synthesis of lamellar nanoparticle magnesium silicate hydroxide (MSH) and analysis of thermal stability, and the morphology, phase composition, and chemical groups of nanoparticles were subsequently characterized. The heat treatment process induces partial dehydroxylation of MSHH, while preserving the layered structure. Compared with MSH, the tribological performances of MSHH as a lubricant additive have been greatly improved. The mechanical properties of MSH and MSHH are analyzed by calculation of elastic constants using density functional theory (DFT). The interactions among dispersant oleic acid (OA), nanoparticles (MSH and MSHH), and Fe tribopairs were investigated by simulations of classical molecular dynamics (CMD) from the views of adsorption energy and confined shear. The tribological mechanism of MSHH as a lubricant additive is proposed based on the decreased shear strength and weakened agglomeration.