BaCO3 Research Articles

Enhanced performance of Sr2Fe1.5Mo0.5O6-δ electrode by infiltrating dual functional barium carbonate nanoparticles in symmetrical SOFCs

Enhanced performance of Sr2Fe1.5Mo0.5O6-δ electrode by infiltrating dual functional barium carbonate nanoparticles in symmetrical SOFCs

Conversion of barium sulfate into barium carbonate in rare earth acid insoluble slag using low-temperature roasting with sodium hydroxide

Conversion of barium sulfate into barium carbonate in rare earth acid insoluble slag using low-temperature roasting with sodium hydroxide

First full-scale application of barium carbonate as an effective dispersed alkaline substrate for sulfate removal from acid mine drainage

A full-scale passive treatment plant using barium carbonate (BaCO3), the mineral witherite, as a Dispersed Alkaline Substrate (DAS) for strongly contaminated acid mine drainage was implemented for the first time globally at Mina Concepción, located in the Iberian Pyrite Belt (SW Spain). The plant was monitored over a 105-day period, covering the wettest months of the hydrological year and with a mean flow around 4 L s−1. The AMD treated in the plant exhibits a high strength, with an average sulfate concentration around 1500 mg L−1 and net acidity close to 1000 mg L−1 as CaCO₃ equivalent. According to the above, the loading rate for SO4 and Fe was around 400 and 80 kg day−1, respectively. The treatment process produced an alkaline effluent with low metal content. Nearly complete removal of most metal(loid)s was achieved, with significant sulfate decrease to below 500 mg L−1 in the alkaline outflow of the barium carbonate tank. Barium carbonate demonstrated superior performance compared to magnesia, particularly in enhancing alkalinity and lowering net acidity and concentrations of sulfate and manganese. The high efficiency attained by the plant after the barium carbonate treatment is evidenced by compliance with environmental water quality standards for most contaminants.

Influences of additives on the properties of geopolymer matrix composites (GMCS) for high-temperature applications (1150 °C)

In this study, the influence of different additives on a geopolymer matrix composite (GMC) was explored as an alternative to a ceramic matrix composite (CMC) for thermostructural applications. Different GMCs using an N610 textile (10 × 10 cm2) and various additives (SrCO3, BaCO3, BaSO4, MgO and Al2O3 and mullite-rich powder) were cured under 6 MPa at 120 °C for 2 h. The mechanical, microstructural and structural data of the composites were compared with those of the geopolymer matrix after thermal treatment at 1150 °C. The results showed that the addition of alkali-earth barium carbonate or sulfate to the geopolymer matrix facilitated the formation of alkali-earth aluminosilicate crystalline phases and a higher viscous flow apparition temperature (990 °C), which did not enhance its mechanical properties (50 MPa) due to poor impregnation of the textile. Refractory additives such as MgO and Al2O3 in the geopolymer matrix support fiber impregnation with a low-viscous-flow apparition temperature (865 °C) and the formation of crystalline phases such as forsterite, spinel and sapphirine, which act as reinforcements, allowing a flexural strength up to 80 MPa. The addition of a refractory compound, such as mullite, leads to better embedding of fibers and a flexural strength reaching 100 MPa. To conclude, mixing the geopolymer matrix with refractory compounds results in a successful thermo-structural geopolymer composite.

Raman Evidence for Pressure-Induced Phase Transition in Barium Carbonate

Raman Evidence for Pressure-Induced Phase Transition in Barium Carbonate

A Facile Route to Catalytic Degradation of Polystyrene over Zeolite and Barium Carbonate

A Facile Route to Catalytic Degradation of Polystyrene over Zeolite and Barium Carbonate

A comparative study between aqueous and methanol solutions of barium hydroxide: implications for applying barium protectants in gypsification calcareous relics

Gypsification is a common problem in weathered calcareous relics. In previous studies, the solutions of barium hydroxide in water and methanol were used as protectants for gypsification calcareous relics and showed significant differences in permeability. In this study, the underlying reasons for permeability differences between these two solutions were investigated using optical microscopy, ultraviolet–visible spectrophotometry, X-ray diffractometry, Fourier transform infrared spectroscopy, the phenolphthalein test and physical property characterizations. The results indicated that the permeability differences were primarily caused by the solutions’ reactivity. Specifically, owing to the high reactivity of barium hydroxide in water, it reacted rapidly with atmospheric CO2 and gypsum (the weathering product) to generate barium carbonate, barium sulfate and calcium hydroxide precipitates. These precipitates hindered the penetration of solution into weathered relics. In contrast, barium hydroxide in methanol did not react with atmospheric CO2 or weathered relics, which also kept the solution in a liquid state during the infiltration process. Therefore, the solution of barium hydroxide in methanol exhibited high permeability. Based on the above findings, this study is meaningful for applying barium protectants in the conservation of gypsification calcareous relics.

Effect of lithium, strontium and barium carbonates on the belite phase formed at 1200°C

Effect of lithium, strontium and barium carbonates on the belite phase formed at 1200°C

Dielectric Properties of Materials Used for Microwave-Based NOx Gas Dosimeters.

Nitrogen oxides (NOx), primarily generated from combustion processes, pose significant health and environmental risks. To improve the coordination of measures against excessive NOx emissions, it is necessary to effectively monitor ambient NOx concentrations, which requires the development of precise and cost-efficient detection methods. This study focuses on developing a microwave- or radio frequency (RF)-based gas dosimeter for NOx detection and addresses the optimization of the dosimeter design by examining the dielectric properties of LTCC-based (Low-Temperature Co-fired Ceramics) sensor substrates and barium-based NOx storage materials. The measurements taken utilizing the Microwave Cavity Perturbation (MCP) method revealed that these materials exhibit more pronounced changes in dielectric losses when storing NOx at elevated temperatures. Consequently, operating such a dosimeter at high temperatures (above 300 °C) is recommended to maximize the sensor signal. To evaluate their high-temperature applicability, LTCC substrates were analyzed by measuring their dielectric losses at temperatures up to 600 °C. In terms of NOx storage materials, coating barium on high-surface-area alumina resolved issues related to limited NOx adsorption in pure barium carbonate powders. Additionally, the adsorption of both NO and NO2 was enabled by the application of a platinum catalyst. The change in dielectric losses, which provides the main signal for an RF-based gas dosimeter, only depends on the stored amount of NOx and not on the specific type of nitrogen oxide. Although the change in dielectric losses increases with the temperature, the maximum storage capacity of the material decreases significantly. In addition, at temperatures above 350 °C, NOx is mostly weakly bound, so it will desorb in the absence of NOx. Therefore, in the future development of a reliable RF-based NOx dosimeter, the trade-off between the sensor signal strength and adsorption behavior must be addressed.

Low-carbon steel fatigue behavior after pack carburizing with buffalo bone charcoal and barium carbonate media

The pack carburizing method is a technique that can be employed to enhance the surface hardness of Low-Carbon Steel (LCS). This method can potentially improve the hardness of the material while maintaining its strength. This study aims to investigate how different carburizing media, specifically varying percentages of Buffalo Bone Charcoal (BBC) powder as a carbon source, impact the mechanical properties of LCS. The temperature in the carburizing process ranges from 850°C and 950°C while maintaining a holding time of 2 hours. The carbon derived from buffalo bone charcoal is finely ground and mixed with barium carbonate (BaCO3) as the energizer during this process. This study used different ratios of BBC powder and BaCO3 as carburizing mediums. The ratios tested were 60% BBC + 40% BaCO3, 70% BBC + 30% BaCO3, and 80% BBC + 20% BaCO3, based on the weight of the BBC powder used in the carburizing process. The steel will be combined with BaCO3 and powdered BBC for this research. Next, the fatigue test was examined. BBC in the pack carburizing process increases LCS carbon content by 0.735% from 0.268%. This change alters the steel's microstructure, possibly increasing its hardness and wear resistance. The direct link between BBC concentration and LCS carbon enrichment shows the process's efficiency. Pack carburizing also improves LCS fatigue strength. This improvement is due to higher BBC concentration, smaller carburizing medium particles, and higher processing temperatures. After carburizing, the LCS can resist 36,625 to 61,435 cycles.

Enhanced electrode reaction for La0.8Sr0.2FeO3-δ-Sm0.2Ce0.8O1.9 composite cathode by barium carbonate nanoparticles as a synergistic catalyst

Enhanced electrode reaction for La0.8Sr0.2FeO3-δ-Sm0.2Ce0.8O1.9 composite cathode by barium carbonate nanoparticles as a synergistic catalyst

Study on flame retardant properties and thermal stability of synergistically modified polyurethane foam with ammonium polyphosphate and barium phytate

Abstract Barium phytate (Pa–Ba) was prepared by phytic acid and barium carbonate, and then the flame-retardant modified polyurethane foam (PUF) was synergized with Pa–Ba and ammonium polyphosphate (APP). The flame retardant properties and thermal stability of the modified PUFs were investigated by thermogravimetric analysis, cone calorimetry (CONE) and smoke density (Ds). The results showed the modified PUF with the addition of 5 % Pa–Ba and 10 % APP (PUF-A10-PB5) had the highest integral programmed decomposition temperature and the activation energy, indicating that its thermal stability was better compared with other samples. In addition, PUF-A10-PB5 had the lowest total heat release under different radiation intensities, and it had the smallest Ds and the highest light transmittance under the flame and flameless condition. The current results indicated that PUF-A10-PB5 had better flame-retardant properties and thermal stability, which can provide a useful reference for future experimental studies on the flame retardant properties of phytate-modified PUF.

Compose and Convert: Controlling Shape and Chemical Composition of Self‐Organizing Nanocomposites

AbstractOrganizing the right material at the right place has the potential to revolutionize bottom‐up assembly of functional architectures. Despite tremendous progress, this is still difficult in particular because control over chemical composition and morphology are typically inherently entangled. Here a two‐step strategy is introduced based on self‐organization and conversion reactions to shape a wide selection of chemical compositions into user‐defined designs. First, photogeneration of CO2 induces precipitation of nanocomposites of barium carbonate nanocrystals and amorphous silica (BaCO3/SiO2) with control over shape and location following arbitrary illumination patterns. Second, the resulting nanocrystals are converted by sequential ion exchange into a palette of chemical compositions, while the original shape is preserved. By considering thermodynamic stability and chemical reactivity, orthogonal conversion reactions are designed for sequentially positioning nanocomposites of different metal chalcogenide semiconductors next to each other. Based on these strategies, different compositions are integrated into the same hybrid architecture, and the functionality potential is demonstrated by forming a light‐emitting perovskite semiconductor that is embedded into an optical waveguide. Combining light‐controlled self‐organization and shape‐preserving ion‐exchange reactions offers exciting opportunities for shaping up materials.

Light-controlled morphological development of self-organizing bioinspired nanocomposites.

Nature's intricate biominerals inspire fundamental questions on self-organization and guide innovations towards functional materials. While advances in synthetic self-organization have enabled many levels of control, generating complex shapes remains difficult. Specifically, controlling morphologies during formation at the single micro/nanostructure level is the key challenge. Here, we steer the self-organization of barium carbonate nanocrystals and amorphous silica into complex nanocomposite morphologies by photogeneration of carbon dioxide (CO2) under ultraviolet (UV) light. Using modulations in the UV light intensity, we select the growth mode of the self-organization process inwards or outwards to form helical and coral-like morphologies respectively. The spatiotemporal control over CO2 photogeneration allows formation of different morphologies on pre-assigned locations, switching between different growth modes-to form for instance a coral on top of a helix or vice versa, and subtle sculpting and patterning of the nanocomposites during formation. These findings advance the understanding of these versatile self-organization processes and offer new prospects for tailored designs of functional materials using photochemically driven self-organization.

Controllable synthesis of barium carbonate nano- and microparticles for SPECT and CT imaging.

The design and synthesis of nano- and microcarriers for preclinical and clinical imaging are highly attractive due to their unique features, for example, multimodal properties. However, broad translation of these carriers into clinical practice is postponed due to the unknown biological reactivity of the new components used for their synthesis. Here, we have developed microcarriers (∼2-3 μm) and nanocarriers (<200 nm) made of barium carbonate (BaCO3) for multiple imaging applications in vivo. In general, barium in the developed carriers can be used for X-ray computed tomography, and the introduction of a diagnostic isotope (99mTc) into the BaCO3 structure enables in vivo visualization using single-photon emission computed tomography. The bioimaging has shown that the radiolabeled BaCO3 nano- and microcarriers had different biodistribution profiles and tumor accumulation efficiencies after intratumoral and intravenous injections. In particular, in the case of intratumoral injection, all the types of used carriers mostly remained in the tumors (>97%). For intravenous injection, BaCO3 microcarriers were mainly localized in the lung tissues. However, BaCO3 NPs were mainly accumulated in the liver. These results were supported by ex vivo fluorescence imaging, direct radiometry, and histological analysis. The BaCO3-based micro- and nanocarriers showed negligible in vivo toxicity towards major organs such as the heart, lungs, liver, kidneys, and spleen. This study provides a simple strategy for the design and fabrication of the BaCO3-based carriers for the development of dual bioimaging.

The Effect of the Environment on the Case Hardening Characteristics of AISI 1018 Steel during Cassava Leaf Pack Cyaniding

As part of a comprehensive study on eco-friendly processing techniques, the influence of the heat treatment environment on the case hardening of AISI 1018 steel using pulverized cassava leaf was studied. The process was carried out at two different temperatures (850 °C and 950 °C) and under three environmental conditions: Process 1, the control experiment, was carried out in air only; in Process 2, the medium comprised pulverized cassava leaves; and in Process 3 a combination of pulverized cassava leaves plus barium carbonate (BaCO3) was used as an energizer (CBC mixture). Vickers microhardness testing and scanning electron microscopy were used to evaluate the effect of the processing environment on the case hardening of the steel. As expected, regardless of the processing temperature, Process 1 resulted in little or no hardening of the steel surface. However, notable case hardening occurred when the steel specimens were subjected to either Process 2 or Process 3. Furthermore, the inclusion of barium carbonate in Process 3 significantly enhanced the case hardening effectiveness of the cassava leaf in terms of the rate of and maximum hardness achieved. A maximum enhancement was observed at 950 °C. After 1 h, the increase in hardness was 160% and 280% for Process 2 and Process 3, respectively. Upon increasing the processing time to 5 h, the increase in hardness due to Process 2 was raised to 254%, while that of Process 3 remained at approximately 280%. The diffusivity of AISI 1018 was calculated using the microhardness data. The diffusivity was highest in Process 2 samples with values of 1.568 × 10−9 m2/s at 850 °C and 1.893 × 10−9 m2/s at 950 °C. Effective case hardening of AISI 1018 steel was carried out using the medium of cassava leaf, without the addition of barium carbonate (BaCO3) as an energizer.

Effects of surface hardening on hardness and tensile strength of locally manufactured feed mill hammers

Animal feed is a major production cost of raising livestock and accounts for about 65 - 68 % of the total production cost, mainly ingredients and processing costs. During feed manufacturing, a hammermill is required for the grinding process to produce quality feed. However, the absence of durable hammers on the local market in Ghana and the high cost of imported hammers compels feed producers to resort to locally manufactured hammers which wear fast due to poor quality of the material. This study considers the application of two surface hardening techniques: (i) carburizing (charcoal and Barium Carbonate (BaCO3) as activator) and (ii) carbonitriding (charcoal, NPK fertilizer as a nitrogen source and Barium Chloride (BaCl2) as activator) in combination with three different quenching media (water, air and oil), to improve the material properties of locally produced hammermill hammers. The surface hardening experiments were performed at 900 oC for 3 h after which the samples were quenched. Tempering was performed afterwards at 160 oC for 1 h. Carbonitriding and water quenching treatment had the best effect on hardness and tensile strength of all the treatments. It yielded the highest surface hardness and tensile strength of 410.06 HV and 768.79 MPa, respectively, representing about a 218 % increase in hardness and a 47 % increase in tensile strength compared to the control sample, which were 128.92 HV and 522.41 MPa, respectively. The result implies hammers produced with this carbonitriding surface hardening and water quenched technique would have improved hardness and wear resistance compared to untreated hammers.

Disordered Crystal Structure and Anomalously High Solubility of Radium Carbonate.

Radium-226 carbonate was synthesized from radium-barium sulfate (226Ra0.76Ba0.24SO4) at room temperature and characterized by X-ray powder diffraction (XRPD) and extended X-ray absorption fine structure (EXAFS) techniques. XRPD revealed that fractional crystallization occurred and that two phases were formed─the major Ra-rich phase, Ra(Ba)CO3, and a minor Ba-rich phase, Ba(Ra)CO3, crystallizing in the orthorhombic space group Pnma (no. 62) that is isostructural with witherite (BaCO3) but with slightly larger unit cell dimensions. Direct-space ab initio modeling shows that the carbonate oxygens in the major Ra(Ba)CO3 phase are highly disordered. The solubility of the synthesized major Ra(Ba)CO3 phase was studied from under- and oversaturation at 25.1 °C as a function of ionic strength using NaCl as the supporting electrolyte. It was found that the decimal logarithm of the solubility product of Ra(Ba)CO3 at zero ionic strength (log10 Ksp0) is -7.5(1) (2σ) (s = 0.05 g·L-1). This is significantly higher than the log10 Ksp0 of witherite of -8.56 (s = 0.01 g·L-1), supporting the disordered nature of the major Ra(Ba)CO3 phase. The limited co-precipitation of Ra2+ within witherite, the significantly higher solubility of pure RaCO3 compared to witherite, and thermodynamic modeling show that the results obtained in this work for the major Ra(Ba)CO3 phase are also applicable to pure RaCO3. The refinement of the EXAFS data reveals that radium is coordinated by nine oxygens in a broad bond distance distribution with a mean Ra-O bond distance of 2.885(3) Å (1σ). The Ra-O bond distance gives an ionic radius of Ra2+ in a 9-fold coordination of 1.545(6) Å (1σ).

A Simple Preparation of Electrolyte Powder for Stoichiometric Electrolyte in Protonic Ceramic Cells

Most candidate proton conducting electrolytes are multi-elements perovskite consisting of barium in A site, thus substantially have challenges associated with high volatility of barium during high-temperature sintering process. Here, we describe a simple strategy to fabricate protonic ceramic cells (PCCs) with highly conductive proton electrolyte by minimizing barium volatilization through a low-temperature (1100oC) calcination process. The PCC is fabricated using low-temperature calcined electrolyte powder at which the minimum temperature to remove the barium carbonate phase. While the calcined powder consists of two phases, it becomes perfectly single phase with full density after final cosintering process (1400oC). This result implies that the status of initial electrolyte powder can significantly influence the overall cell characteristics.

Bacterial communities shift and influence in an acid mine drainage treatment using barium carbonate disperse alkaline substrate system

Chemical passive treatment systems used to remediate acid mine drainage has been evaluated based mainly on the reactivity of the chemical alkaline reagents, overlooking the activity of the microorganisms that proliferate in these artificial ecosystems. In this study, the bacterial communities of a unique passive treatment system known as BDAS (Barium carbonate Dispersed Alkaline Substrate) were investigated using 16S rRNA gene metagenomic sequencing combined with hydrochemical characterization of the AMD and phenotypic characterization of biogenic precipitates. According to the hydrochemical characterization, the water quality improved as the water progressed through the system, with a drastic increase in the pH (up to alkaline conditions) and total organic carbon, as well as the removal of main contaminants such as Ca2+, SO42−, Fe3+, Al3+, and Mn2+. These environmental changes resulted in an increase in bacterial diversity (richness) after the inlet and in the shift of the bacterial communities from chemoautotrophs (e.g., Ferrovum and Acidiphilum) to chemoheterotrophs (e.g., Brevundimonas and Geobacter). Some of these taxa harbour potential to immobilize metals, aiding in the treatment of the water. One of the mechanisms involved in the immobilization of metals is microbially induced calcium carbonate precipitation, which seems to occur spontaneously in BDAS. The production of biofilm was also observed in most parts of the system, except in the inlet, helping with the removal of metals. However, in the long run, the build-up of biofilm and precipitation of metals could clog (i.e., biofouling) the pores of the matrix, reducing the treatment efficiency. Potential human pathogens (e.g. Legionella) were also detected in BDAS indicating the need for a treatment step at the end of the system to remove pathogenic microorganisms. These findings present a new perspective of the bacterial communities and their effects (both positively and negatively) in a chemical passive treatment system.