Search Results (74)

Fluoride contamination in groundwater is a pressing environmental and public health issue, with chronic exposure linked to skeletal and dental fluorosis. Here, we report the synthesis of magnesium oxide nanoparticles via a controlled co-precipitation method employing dimethylformamide (DMF) as solvent and either ammonium hydroxide (MgO-1) or ammonium carbonate (MgO-2) as precipitating agents. The resulting materials were comprehensively characterized using thermogravimetric analysis (TGA/DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). Additionally, BET surface area and porosity analyses revealed mesoporous structures, with MgO-1 showing a slightly higher surface area (14.12 m² g⁻¹) than MgO-2 (13.87 m² g⁻¹). Both MgO-1 and MgO-2 exhibited high crystallinity, nanoscale particle sizes (81.6 nm and 128.1 nm, respectively), and distinct morphological features. Batch adsorption studies revealed maximum fluoride uptake capacities of 117.6 mg/g (MgO-1) and 94.5 mg/g (MgO-2) at neutral pH, with MgO-1 exhibiting superior performance due to its smaller particle size and higher specific surface area. Fluoride removal remained above 98% between pH 3–9, confirming stability across a wide pH range, with a minor decline at pH 11 due to OH⁻ competition. Adsorption equilibrium data were best described by the Temkin isotherm model, suggesting heterogeneous surface interactions and an exothermic process, while kinetic analyses indicated pseudo-second-order behavior for MgO-1 and pseudo-first-order for MgO-2. Both materials maintained high fluoride selectivity in the presence of competing anions and successfully reduced fluoride in tap water from 2.11 mg/L to below the WHO limits without altering water hardness. These findings underscore the potential of engineered MgO nanomaterials as efficient, selective, and sustainable adsorbents for water defluoridation, offering a promising pathway toward scalable remediation technologies in fluoride-affected regions. Full article

The Global Cement and Concrete Association (GCCA) estimated that by 2050, 36% industry-wide sustainable value will be created, which includes sequestering CO₂ into the cement and concrete industry to produce commercially feasible high-value products. Direct utilization of CO₂ in the cement and concrete industry, which utilizes natural and sustainable materials, is gaining momentum. Naturally occurring mixtures of hydro magnesite and huntite are important industrial minerals which, upon endothermic decomposition over a specific temperature range, will release water and CO₂. This unique chemistry has led to such mixtures being successfully utilized as fire retardants, replacing aluminum hydroxide or Alumina Tri-Hydrate (ATH). Despite the developed marketplace for magnesium-based fire-retardant products, there is little mention of CO₂ mineral carbonation methods, which attempt to recover and convert magnesium from natural seawater or industrial waste into oxides or carbonates as part of the carbon sequestration initiative. The hypothesis to be proven in this work states that if the process of seawater mineral carbonation is prematurely quenched, Mg²⁺ ionic species in seawater adsorbed on the calcite lattice formation will be trapped and therefore recovered in various oxidized forms, such as magnesium oxides, magnesium hydro magnesite, and magnesium carbonate precipitates. A novel method to recover magnesium Mg²⁺ ions from seawater was successfully explored and documented; as such, from an initial concentration of 1250 ppm Mg²⁺ in raw seawater, the average concentration of spent Mg²⁺ ions after the reaction was as low as 20 ppm. A very efficient near-total recovery of Mg²⁺ from the seawater into the solid precipitates was recorded. Subsequently, the process for continuous seawater mineral carbonation for the production of magnesium/brucite/huntite products was successfully proven and optimized to operate with a 30 s reaction time, a dynamic feedstock concentration, [CaO] at 1 gpl in seawater and a room temperature reaction temperature (30 °C), where the average yield of the fire-retardant magnesium-based compounds was 26% of the synthesized precipitates. Approximately 5000 g of the hydro magnesite materials was molded into a fire-retardant brick or concrete wall, which was subjected to an accredited fire performance and durability testing procedure BS476-22:1987. There were encouraging results from the fire resistance testing, where the fire-retardant material passed BS476-22:1987, with performance criteria such as physical integrity failure, the maximum allowable face temperature, and a minimum duration before failure, which was up to 104 min, evaluated. Full article

The work is focused on the study of the influence of different types of inorganic fillers, in combination with modifiers, on the rheological, thermal, and mechanical properties of a biodegradable mixture based on PLA/PHB. Ten types of inorganic fillers based on talc, magnesium hydroxide, aluminum hydroxide, calcium carbonate, and silicon dioxide were used in the study, along with three types of modifiers. It was concluded that fillers containing reactive OH groups on their surface act as strong pro-degradants in PLA/PHB blends, and their degrading effect can be suppressed by the addition of reactive modifiers. Each modifier acts specifically with different types of fillers. Therefore, it is necessary to select a suitable filler/modifier combination not only for fillers with different chemical compositions but also for fillers with different morphologies within the same chemical type. Moreover, the preparation of PLA/PHB/magnesium hydroxide blends with suitable processing and application properties opens the possibility of developing environmentally friendly polymeric materials with a reduced flammability. The addition of talc, which has a platelet structure, can increase the barrier properties of the mixture. Full article

Magnesium is a valuable industrial metal prized for its strength and reactivity. Traditionally, magnesium was extracted from seawater and brines. However, to meet the rising global demand, it is now primarily sourced from mineral deposits. This shift has sparked renewed interest in extracting magnesium from non-saline sources, including carbonates, silicates, halides, oxides, and hydroxides. This review examines the extraction technologies currently used for these mineral-based resources, including pyrometallurgical, hydrometallurgical, and electrometallurgical methods. Each method is assessed based on the reactions involved in the transformation, operational principles, efficiency, and energy requirements. The review emphasizes the importance of mineral pretreatment—thermal, mechanical, and chemical—in improving magnesium recovery, especially from refractory silicates. By summarizing recent advancements and process innovations, the review aims to inform future research and industrial practices, and support the development of sustainable, cost-effective, and scalable magnesium extraction strategies. Full article

Basic magnesium sulfate cement (BMSC) has attracted increasing attention as a low-carbon alternative to traditional Portland cement. Therefore, this study investigates the feasibility of using carbonated boron mud (CBM), an industrial solid waste, as a partial substitute for magnesium oxide (MgO) in BMSC. Prior to its incorporation into the cementitious matrix, boron mud (BM) underwent rapid carbonation treatment to improve its reactivity, microstructure compatibility, and CO₂ sequestration potential. Experimental results from macroscopic and microscopic analyses confirmed the effectiveness of the carbonation process, showing that the carbonate ions carried by the CBM were successfully incorporated into the cementitious system. These carbonate ions reacted with MgO to form stable magnesium carbonate phases, effectively suppressing the formation of magnesium hydroxide (Mg(OH)₂), which typically detracts from strength and stability. Compared to BMSC specimens containing untreated BM, the CBM-modified BMSC exhibited significantly improved mechanical performance and excellent volume stability. Furthermore, the carbonation pre-treatment effectively mitigated volumetric instabilities associated with rapid MgO hydration, thereby promoting a more favorable environment for the formation of the crucial 5·1·7 phase (5Mg(OH)₂·MgSO₄·7H₂O). Overall, this research presents a promising strategy for producing CBM-BMSC, offering a sustainable approach to CO₂ utilization and enhancing the volume stability of magnesium-based cements, providing a new direction for improving the sustainability of the concrete industry and advancing the development of magnesium cements. Full article

This study investigates the effectiveness of calcined magnesium–aluminium layered double hydroxide (CLDH) as a functional additive for mitigating carbonation-induced corrosion in alkali-activated slag concrete (AASC). Mixtures incorporating different CLDH contents (0%, 2%, 4%, 6%, and 8%) were evaluated under accelerated CO₂ exposure (3%, 65% RH, 25 °C) for 90 days. Mechanical characterisation was carried out through 28-day compressive strength tests to assess the potential impact of CLDH on the structural performance of the material. Performance characterisation included electrochemical impedance spectroscopy (EIS) to assess the corrosion of embedded steel, phenolphthalein spraying to determine the carbonation depth, and complementary techniques such as X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM/EDX) for assessments of the microstructural evolution. The results demonstrate that CLDH significantly enhances resistance to CO₂ ingress, increasing the polarisation resistance (Rp) to over 55 kΩ·cm² (at 6% CLDH) and reducing the carbonation depth by more than 50% compared to the reference mix. These improvements are attributed to the memory effect-induced regeneration of LDH-type lamellar phases, controlled release of OH⁻ and CO₃²⁻ anions, and progressive densification of the microstructure, thereby limiting the ingress of aggressive agents. The optimal dosage was identified as 6%, as higher contents offered no further improvement and evidenced the formation of residual phases such as MgO. This work highlights the potential of CLDH as an effective and sustainable strategy to enhance the durability of alkali-activated cementitious materials against degradation processes driven by carbonation and corrosion. Full article

Zinc-aluminum-magnesium (ZAM) steel, with its superior corrosion resistance and mechanical properties, is progressively supplanting traditional galvanized steel and zinc-aluminum steel. In this study, a solution containing sodium carbonate-only was employed as the treatment medium to form a vertically grown layered double hydroxide (LDH) pretreatment layer on the surface of ZAM steel via a simple immersion process at 50 °C. The temperature and salt solution not only provide the conditions for the dissolution of metal ions but also facilitate the formation of LDH products. The resulting LDH pretreatment layer exhibits excellent adhesion to the metal surface and enhances the adhesion of the top epoxy coatings. Furthermore, the “LDH/corrosion inhibitor/epoxy” coating system ensures ZAM steel remains rust-free in a 3.5 wt.% NaCl solution for a minimum of 120 days. This innovative approach offers a promising avenue for extending the durability and service life of ZAM steel in corrosive environments. Full article

Agriculture is one of the most important sectors of the global economy, but it increasingly faces sustainability challenges in meeting rising food demands. The intensive use of mineral fertilizers not only improves yields, but also causes negative environmental impacts such as increasing greenhouse gas emissions, water eutrophication, and soil degradation. To develop more sustainable solutions, the focus is on organic fertilizers, which are produced using waste and biostimulants such as amino acids. The aim of this study was to develop and characterize liquid nitrogen–calcium–magnesium fertilizers produced by decomposing dolomite with nitric acid followed by further processing and to enrich them with a powdered amino acid concentrate Naturamin-WSP and liquid extracts from digestate, a by-product of biogas production. Nutrient-rich extracts were obtained using water and potassium hydroxide solutions, with the latter proving more effective by yielding a higher organic carbon content (4495 ± 0.52 mg/L) and humic substances, which can improve soil structure. The produced fertilizers demonstrated favourable physical properties, including appropriate viscosity and density, as well as low crystallization temperatures (eutectic points from –3 to –34 °C), which are essential for storage and application in cold climates. These properties were achieved by adjusting the content of nitrogenous compounds and bioactive extracts. The results of the study show that liquid fertilizers enriched with organic matter can be an effective and more environmentally friendly alternative to mineral fertilizers, contributing to the development of the circular economy and sustainable agriculture. Full article

Background: The antidiabetic drug gliclazide is often taken with antacids due to its gastrointestinal side effects. However, patients rarely report antacid use, making drug–drug interactions a potential cause of therapy failure. Therefore, this study aimed to investigate the in vitro effects of various antacids on gliclazide permeability and to explore the underlying mechanisms. Methods: The permeability of gliclazide alone and in the presence of antacids (sodium bicarbonate, calcium carbonate, aluminum hydroxide, hydrotalcite and calcium carbonate/magnesium carbonate) was investigated using the parallel artificial membrane permeability assay (PAMPA) in four media (buffers pH 1.2, pH 4.5, pH 6.8 and water). The permeability coefficients were calculated, and the effect of pH on gliclazide permeability was also evaluated. Results: At simulated fasting gastric conditions (pH 1.2), groups with calcium carbonate, hydrotalcite and the combination of calcium carbonate/magnesium carbonate showed significantly higher permeability of gliclazide than the control group. At fed-state gastric conditions (pH 4.5), only hydrotalcite did not significantly change the permeability of gliclazide. Sodium bicarbonate, aluminum hydroxide and hydrotalcite significantly reduced the gliclazide permeability in comparison to the control group at pH 6.8 as a representative of fasted-state intestinal fluid. Conclusions: Antacids significantly impact the permeability of gliclazide at different pH values, potentially influencing its bioavailability. Gliclazide permeability is mainly influenced by pH-dependent ionization, though complex or salt formation may also play a role. Since both gliclazide and antacids are taken with food, and gliclazide is primarily absorbed in the small intestine, calcium- and magnesium-based antacids can be considered the most suitable choice. Full article

This study employs a wet precipitation–carbonation method to recycle and utilize purification slag from the calcium carbide industry, extracting high-value-added magnesium hydroxide (Mg(OH)₂) and aragonite nanoparticles. Experimental results demonstrate that the reaction temperature significantly influences the yield, morphology, and crystallinity parameters of the products. The optimal preparation temperatures for Mg(OH)₂ and aragonite are 60 °C and 80 °C, respectively. Analysis via X-ray diffraction (XRD) combined with the Williamson–Hall method reveals that within the temperature range of 60–90 °C, the crystallite sizes of Mg(OH)₂ and aragonite are 40.07–59.25 nm and 70.03–109.18 nm, respectively. As the temperature increases, the crystallite size, strain, lattice stress, and energy density of Mg(OH)₂ exhibit a decreasing trend, whereas the corresponding crystallographic parameters of aragonite gradually increase. Full article

A facile method was employed to impregnate activated carbon, a commonly used water treatment medium, with nanostructured magnesium oxide for fluoride removal. Batch adsorption tests were conducted to evaluate the adsorption performance of the nanostructured magnesia-impregnated activated carbon (nMgO@AC) for fluoride removal. The results demonstrated that this composite material exhibited a good adsorption capacity, with a maximum equilibrium uptake of approximately 121.1 mg/g for fluoride. Kinetic studies revealed that the adsorption process followed the pseudo-second-order adsorption kinetic model, reaching equilibrium in about 100 min. Within the initial pH range of 3 to 11, the adsorption efficiency of nMgO@AC for fluoride remained above 95%, indicating that the initial solution pH had a minimal effect on the material’s fluoride removal capability. The adsorption mechanism was elucidated by characterizing the material properties before and after adsorption using SEM, TEM, XRD and XPS. Initially, magnesium oxide reacted with water and rapidly transformed into magnesium hydroxide. Subsequently, a ligand exchange occurred between the hydroxide groups in magnesium hydroxide and fluoride ions in the aqueous solution, resulting in the effective removal of fluoride. The findings of this study suggest that nanostructured magnesia-impregnated activated carbon holds significant potential for the treatment of fluoride-containing wastewater, particularly for highly alkaline wastewater. Full article

This study evaluates the influence of multiwall carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and magnesium oxide (MgO) on the thermal conductivity of alkali-activated engineered composites (AAECs). Thirty-two ambient-cured AAECs consisting of two types of powdered-form reagents/activators (type 1—calcium hydroxide: sodium meta silicate = 1:2.5; type 2—calcium hydroxide: sodium sulfate 2.5:1), two dosages of MgO (0 and 0.5%) of MgO, three percentages (0, 0.3%, and 0.6%) of MWCNTs/rGO, and binary (45% ground granulated blast furnace slag ‘GGBFS’ and 55% Class C fly ash ‘FA-C’) and ternary combinations (40% GGBFS, 25% FA-C and 35% class F fly ash ‘FA-F’) of industrial-waste-based source materials, silica sand, and polyvinyl alcohol (PVA) fiber were developed using the ‘one-part dry mix’ technique. Problems associated with the dispersion and agglomeration of nanomaterials during production were avoided through the use of defined ultra-sonication with a high-shear mixing protocol. The impact of the combination of source materials, activators, and MgO/MWCNT/rGO dosages and their combinations on the thermal properties of AAECs is evaluated and discussed based on temperature–time history and thermal conductivity/diffusivity properties along with micro-structural characteristics. It was found that the change in temperature of the AAECs decreased during testing with the addition of MWCNTs/rGO/MgO. The thermal conductivity and diffusivity of AAECs increased with the increase in MWCNT/rGO/MgO contents due to the formation of additional crystalline reaction products, improved matrix connectivity, and high conductivity of nanomaterials. MWCNT AAECs showed the highest thermal conductivity of 0.91–1.26 W/mK with 49% enhancement compared to control AAECs followed by rGO AAECs. The study confirmed the viability of producing MgO/MWCNT/rGO-incorporated AAECs with enhanced thermal properties. Full article

In the present work, carbonate minerals are added in non-polar and polar polymer matrices to develop halogen-free flame-retardant composites. The examined fillers of calcium carbonate and magnesium carbonate delivered improved rheological performance in both non-polar (PE) and polar (EVA/PE) polymer compounds compared to the natural magnesium hydroxide and huntite/hydromagnesite mineral fillers. The presence of EVA in the matrix enhanced the mechanical behavior of all compounds in tensile testing. The thermal stability of the composites was particularly improved for the polar systems with the incorporation of the carbonate minerals, as this was evidenced under thermogravimetric analysis. The dielectric behavior of the fabricated systems was examined via broadband dielectric spectroscopy. The HFFR compounds attained higher values of the real part of dielectric permittivity from the unreinforced systems in the whole frequency and temperature range of the conducted tests. This behavior is ascribed to the higher permittivity values of the fillers with respect to the polymer matrices and the occurrence of interfacial polarization. All minerals improved the flame retardancy of the compounds in terms of LOI values, while the addition of EVA yielded further improvements, especially for the magnesium carbonate and the magnesium hydroxide minerals. Full article

Famotidine is a histamine H2 receptor antagonist used in the treatment of gastrointestinal disorders. It is available in multiple formulations, including film-coated tablets, chewable tablets, oral suspension, and injections. The purpose of this study was to develop and evaluate the film-coated tablet (FT) containing famotidine, magnesium hydroxide, and precipitated calcium carbonate, designed to be pharmaceutically equivalent to the marketed chewable tablet (CT). To achieve the pharmaceutical equivalence of two tablets, the dissolution profiles of FT should be similar to those of CT. However, since CT is intended to be chewed before swallowing, testing it in its intact form would not provide accurate results. Therefore, pulverized chewable tablets (PCT) were used as the reference product. The dissolution, performed by the paddle method at 50 rpm, was analyzed by the validated UV method. Similarity factor (f₂) and difference factor (f₁) were calculated to assess the equivalence of the dissolution profiles. The results demonstrated that the dissolution profiles of the FT and CT were similar. Additionally, the acid-neutralizing capacity test confirmed the equivalence of the two antacids. This study is one of the first to propose that dissolution tests for pharmaceutical equivalence should be conducted on pulverized CTs when developing generic equivalents to CTs. Full article

This study investigates a novel method of utilizing Direct Air Capture (DAC) technology for fertilizer production. Unlike traditional Direct Air Carbon Capture and Utilization (DACCU) technologies, Direct Air Carbon Capture for Fertilizers (FDAC) has the potential to produce fertilizers directly. This study aims to assess the feasibility of FDAC-based fertilizer production by examining the current state of traditional DAC technologies, evaluating the CO₂ fixation potential of FDAC, and analyzing the decarbonization effect of producing fertilizers using FDAC. Our evaluation results indicate that CO₂ emissions from producing 1 ton of conventional chemical fertilizer, FDAC fertilizer (current status), FDAC fertilizer with ingredient adjustment (sodium hydroxide), and FDAC fertilizer with ingredient adjustment (magnesium hydroxide) are 1.69, 1.12, 1.04, and 1.06 tons of CO₂, respectively. The FDAC fertilizer (current status) emits 0.57 tons of CO₂ per ton less than commercial fertilizers. FDAC fertilizers also have the potential to reduce CO₂ emissions further when the fertilizer composition is adjusted, offering a promising solution for lowering the environmental impact of fertilizer production. Significant CO₂ reduction can be expected by replacing conventional low-intensity chemical fertilizers with FDAC-produced fertilizers. Full article