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Background and Objectives: Diffusion of hydroxide (OH)− and calcium (Ca)++ ions through dentin may cease external root resorption. Calcium hydroxide (Ca(OH)2), mineral trioxide aggregate (MTA), and calcium‐enriched mixture (CEM) cement are the choices for this purpose due to their optimal properties. This study sought to analyze the effects of ultrasonic activation (UA) on pH and the release of calcium ions from Ca(OH)2, MTA, and CEM cement in external root resorption artificial defects. Materials and Methods: This in vitro research involved the instrumentation and shaping of the root canals of 150 single‐rooted teeth (#F4). External defects were intentionally made on the middle one‐third of the root surface. Teeth were randomly assigned to a negative control group (n = 10), one positive control group (n = 20), and six experimental groups (each n = 20) according to the root canal filling material (Ca(OH)2 paste, MTA, CEM, gutta‐percha, Ca(OH)2 paste+ultrasonic, MTA + ultrasonic, and CEM + ultrasonic). Ultrasonic energy was transferred to the test materials using a #25 spreader. Ca++ concentration and pH were measured after 1, 7, 15, and 30 days in all groups. Statistical analysis involved the use of repeated measure analysis of variance (ANOVA) and paired‐sample T‐test (P ≤ 0.05). Results: The levels of calcium ions and pH increased significantly over time in all groups (P < 0.001). There were significant differences between the experimental groups in terms of pH and the concentration of released calcium ions at different times (P < 0.001). The Ca(OH)2 plus ultrasonic energy group ranked first, while the gutta‐percha group ranked last in terms of release of calcium ions and pH. Conclusion: The Ca(OH)2, MTA, and CEM cement groups showed an increase in pH and the release of calcium ions at the external root resorption defects. Additionally, the application of ultrasonic energy increased the release of calcium ions at these sites. [ABSTRACT FROM AUTHOR]

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Seven experiments exploring the reaction of titanite with various hydrothermal solutions have been carried out at 700 °C and 200 MPa for a run duration of 16 days. In experiments involving fluids consisting of NaCl+H2O, KCl+H2O, CaCl2+H2O, 2M NaOH, or 2M KOH, no reaction of the titanite with the fluid was observed other than a slight dissolution of the titanite. Experiments involving NaF+H2O and Ca(OH)2+H2O resulted in visible alteration of the titanite in texture and composition, coupled with the formation of perovskite. In the NaF+H2O experiment, perovskite, enriched with rare earth elements (REE), formed as euhedral to subhedral crystals on the surface of the recrystallized titanite. In the Ca(OH)2+H2O experiment perovskite took in minor amounts of REE, and formed as a reaction rim partially replacing the titanite via a coupled dissolution-reprecipitation reaction. Wollastonite, along with minor calcite, and grossular garnet, formed as an outer rim on the perovskite. In the NaF+H2O experiment major and trace elements were leached from the titanite, whereas in the Ca(OH)2+H2O experiment no leaching of major or trace elements was observed. Nb/Ta, Th/U, and Y/Ho were investigated as potential indicators of hydrothermal processes. While the Nb/Ta ratio was altered in the experimentally metasomatised titanite, the degree of alteration was the same for both fluids. In contrast, only small changes in the Th/U and Y/Ho ratios between the altered and original titanite were seen for either experiment. The formation of perovskite at the expense of titanite in NaF+H2O or Ca(OH)2+H2O fluids demonstrates how titanite reacts with these fluids in simple, low silica activity systems under mid to upper crustal P-T conditions. [ABSTRACT FROM AUTHOR]

The saggar plays a crucial role as a carrier during the solid‐state sintering process of Li‐ion battery cathode materials. In order to enhance its resistance against alkali erosion, the study utilized hibonite, cordierite, α‐Al2O3, and zirconia as primary raw materials, along with Ca(OH)2 as an additive, to fabricate a composite‐layered hibonite–cordierite saggar. Our investigation delves into the sintering bond formation between the composite layer and the saggar matrix and, more crucially, scrutinizes the saggar's erosion resistance against Li‐ion battery cathode materials. The outcome underscores the groundbreaking impact of a 3% Ca(OH)2 infusion on in situ anorthite formation within the composite layer, ushering in a robust integration between the composite layer and the saggar matrix. Moreover, this unique anorthite formation establishes a dense isolating shield along the periphery of hibonite particles, effectively impeding the corrosive reaction between the cathode material and the saggar, thus enhancing the saggar's resistance to corrosion. [ABSTRACT FROM AUTHOR]

Bimetallic AuCu/SiO2 nanosized catalysts were prepared using the wet chemical reduction technique. From among Au0.1–1.5Cu10/SiO2 catalysts, the Au0.5Cu10/SiO2 catalyst gave the highest yield of calcium lactate of 87% at a glycerol conversion of 96% when the reaction of glycerol with calcium hydroxide at a mole ratio of calcium hydroxide to glycerol of 0.8:1 was conducted under an anaerobic atmosphere at 200 °C for 2 h. The interactions between metallic Au0 and Cu0 nanoparticles facilitate calcium lactate formation. The simulation of glycerol consumption rate with an empirical power-function reaction kinetics equation yielded a reaction activation energy of 44.3 kJ∙mol−1, revealing that the catalytic reaction of glycerol with calcium hydroxide to calcium lactate can be conducted by overcoming a mild energy barrier. The synthesis of calcium lactate through the catalytic reaction of glycerol with calcium hydroxide on a bimetallic AuCu/SiO2 nanosized catalyst under a safe anaerobic atmosphere is an alternative to the conventional calcium lactate production technique through the reaction of expensive lactic acid with calcium hydroxide. [ABSTRACT FROM AUTHOR]

Calcium hydroxide (Ca(OH)2) finds widespread use in the petrochemical industry, particularly in flue gas desulfurization applications. However, its conventional usage is limited by its inherently low specific surface area, hampering its efficiency. To address this limitation, this study aims to develop a simple and industrially scalable preparation process for Ca(OH)2 with a high specific surface area, thereby enhancing its effectiveness in various applications. This study aimed to develop a preparation process for making Ca(OH)2 with a high specific surface area, suitable for industry and easy to make. Ca(OH)2 with a specific surface area of 41.555 m2/g was successfully synthesized by incorporating polyols during lime digestion. The prepared high specific surface area Ca(OH)2 is more than five times the specific surface area of ordinary Ca(OH)2. Incorporation of polyols within the lime digestion process induces a reduction in both Ca(OH)2 grain size and particle dimensions, concurrently amplifying the specific surface area and optimizing mass transfer efficiency. Specifically, the desulfurization breakthrough time for Ca(OH)2 subject to a 15% triethanolamine modification was notably extended to 879 s, surpassing the desulfurization breakthrough time of unaltered Ca(OH)2 by more than tenfold. Moreover, the modified Ca(OH)2 exhibited remarkable efficacy in neutralizing acidic wastewater. A new approach for the preparation of high-performance Ca(OH)2 is proposed in this study, which could facilitate the industrial production of Ca(OH)2 with high specific surface area. [ABSTRACT FROM AUTHOR]

Recycling of wasted phosphate slag (PS) into useful mineral additives shows great significance not only in carbon reduction but also contributes to the availability of green additives to cement-based materials. This work aims to explore a feasible way of disclose the mechanism of PS added cement-based materials. It was found that compressive strengths of pastes were all declined with increasing addition of PS both at early age of 2 d and long age of 28 d, increased the curing temperatures from 20 °C to 40 °C helped to improve the above situation. A remarkable increase of compressive strength in 10SF+20PS sample with the value of 55.48 MPa was obtained at 28 d. The enhanced mechanical property was related with the generation of large amount of hydration products such as C–S–H, Ca(OH)2 and AFt.

Objective: To investigate the effect of the use of Calcium Hydroxide (Ca(OH)2), Triple Antibiotic Paste (TAP), and Double Antibiotic Paste (DAP) as intra-canal medicaments on the development of antibiotic resistance by evaluating tetracycline genes. Methods: Forty five patients were randomly assigned into 3 groups according to the intracanal medication using a web program (www.randomizer.org), (Ca(OH)2, TAP and DAP). Root canal bacteriological samples were collected before root canal treatment (S1) and after chemo-mechanical procedures (S2). Following root canal shaping procedures, intra-canal medication of the root canals was performed with selected intra-canal medicament. A second appointment was planned for the patients 15 days later. At the second appointment, the medication was removed mechanically and after irrigation of the root canals, the post medication samples (S3) were collected. Bacteriological samples were then investigated for bacterial counts and antibioticresistant genes [Tet Repressor proteins (TetR), Tetracycline resistance gene W (TetW) and Tetracycline resistance gene Q (TetQ)] using polymerase chain reaction (PCR), and the data were statistically analyzed. The Friedman, Kruskall-Wallis and chi-square tests were used. These genes were selected as the difference between TAP and DAP is that TAP contains tetracycline and tetracycline resistance is governed by tet genes. Results: There was no statistically significant difference among the samples (S1, S2, and S3) in terms of the number of root canals positive for antibiotic resistance genes in both the Ca(OH)2 and DAP groups. However, the number of root canals positive for TetR gene increased significantly (6 [40%] to 12 [86%]) following intra-canal medication with TAP. Conclusion: It can be concluded that 15 of days intra-canal medication with TAP causes tetracycline resistance. In contrast, DAP does not cause tetracycline resistance and it has similar antibacterial effectiveness to TAP. The DAP would be the choice of medicament rather than TAP in clinical practice. [ABSTRACT FROM AUTHOR]

In this paper, Ca(OH)2 nanoparticles are prepared by impinging stream co‐precipitation method. The process of preparing nanoparticles by impinging stream is optimized. The influence of process variable, such as dispersant type, dispersant dosage, circulating flow rate, reactant concentration ratio of OH− and Ca2+, reaction temperature and circulation time, on the particle size of Ca(OH)2 nanoparticle are investigated. The results show that the concentration ratio of reactants has a significant effect on the size of Ca(OH)2 nanoparticles. The optimal process conditions are obtained by single factor experiment, PEG6000, 3.3% dispersant dosage, Q = 1000 L · h−1, C = 1.88, T = 46.68°C and t = 60 min. The average particle size of Ca(OH)2 nanoparticles prepared under these conditions is 107.67 nm. According to the microstructure analysis, the prepared Ca(OH)2 nanoparticles samples have high purity and a good crystal structure. The powder dispersed with a marked hexagonal crystal shape and good thermal decomposition. [ABSTRACT FROM AUTHOR]

Stone mastic asphalt is a type of hot mix asphalt that requires much coarse aggregate, so substitution waste aggregate, such as steel slag, will be an economic reason. The problem is that there are still many things that have not been consistent in various studies related to the moisture resistance of steel slag. The study aimed to compare the effect of CA(OH)2 on the moisture resistance of the steel-slag stone mastic asphalt mixture and to determine the optimal CA(OH)2 dosage for improving the mixture resistance. This study employs basalt aggregate, steel slag from Krakatau Steel Company, 60/70 penetration asphalt, a stabilizing substance made of bamboo fiber, and CA(OH)2. The Texas boiling and the static immersed methods are used to test the adhesion on a loose mixture. The retained Marshall stability and indirect tensile strength are used to test the adhesion on the compacted mix. Testing result of Krakatau steel slag shows that steel slag has a much higher Fe2O3 content than steel slag in general and has low water absorption; a poor affinity for asphalt results from this. The result of the Texas boiling method showed a decrease in the percentage adhesion value between steel slag and asphalt compared to natural basalt aggregates and asphalt. Marshall Stability Ratio and Tensile Strength Ratio increased after mixing the asphalt with CA(OH)2. Marshall test results show decreased stability in mixtures with steel slag substitution. Adding CA(OH)2 increased stability and resistance to moisture significantly. This indicated that CA(OH)2 enhances moisture resistance on stone mastic asphalt with modified steel slag. Stability, Marshall stability ratio, indirect tensile strength ratio, particle loss, and Texas boiling test significantly improved with adding CA(OH)2. [ABSTRACT FROM AUTHOR]

Calcium Hydroxide Ca(OH)2 has been used since years ago as pulp capping material in inducing reparative dentin for pulp complex preservation. Calcium Hydroxide has effect by stimulating mineralization and inhibiting bacterial growth. However, Ca(OH)2 also has shortcomings which theoretically could be boosted by high polyphenol level in extract of green tea and extract of cacao pod shell which is effective as antibacterial, anti-inflammation and antioxidant. The addition of green tea extract and cacao pod shell extract with Ca(OH)2 are supposed to improve physical properties of Ca(OH)2. This study expected to compare the reduction of malondialdehyde and odontoblast apoptosis expressions as the effects of addition green tea extract and cacao pod shell extract with Ca(OH)2 on exposed dental pulp. Thirty six rats were divided to 3 groups: The positive control group was given Ca(OH)2 and aquadest, group II was given cacao pod shell with Ca(OH)2, groups III was given extract of green tea with Ca(OH)2. On the third and seventh day an incision was made and examined to check the malondialdehyde and odontoblast cells apoptosis expressions. Data analysis result using Tukey HSD test, the Data showed there were significant differences between each groups. [ABSTRACT FROM AUTHOR]

Legacy brominated flame retardants (BFRs) in printed circuit boards are gradually being replaced by novel BFRs (NBFRs). Safe disposal and recycling of polymeric constituents in the polymeric fractions of e-waste necessitate the removal of their toxic and corrosive bromine content. This is currently acquired through thermal recycling operations involving the pyrolysis of BFRs-containing materials with metal oxides. Nonetheless, the debromination capacity toward NBFRs is yet to be established. Thus, this study aims to address these two crucial gaps in the current knowledge pertaining to the plausible formation of brominated toxicants from the thermal decomposition of NBFRs and their thermal recycling potential. Herein, we investigate the pyrolysis of a mixture of 2,4,6-tribromophenol (TBP), allyl 2,4,6-tribromophenyl ether (ATE) and Tetrabromobisphenol A-bis (2,3-dibromo propyl ether) (TBBPA-DBPE) in the presence of acrylonitrile butadiene styrene (ABS) polymers at various loads. To demonstrate a viable debromination route, pyrolysis of NBFRs-ABS mixture with Ca(OH)2 was also investigated. The latter is a potent debromination agent for legacy BFRs. Upon pyrolysis with Ca(OH)2, the bromine content in the collected oil was reduced up to 80.49% between 25–500 °C. Products of the co-pyrolysis process generally feature non-brominated aromatic and aliphatic compounds; a finding that indicates an effective thermal recycling approach. As evident by IC measurements, no HBr emission could be detected when Ca(OH)2 is added to the mixture. As XRD patterns show, Ca(OH)2 is partially converted into CaBr2. DFT calculations provide pathways for the observed surface debromination characterized by surface-assisted fission of aromatic C–Br bonds and the formation of CaBr sites. Outcomes reported herein are instrumental to designing and operating a thermal recycling facility of polymeric materials contaminated with high loads of bromine, i.e., most notably during scenarios encountered in the thermal recycling of e-waste. [ABSTRACT FROM AUTHOR]

The process of anaerobic digestion used for methane production can be enhanced by dosing various additive materials. The effects of these materials are dependent on various factors, including the processed substrate, process conditions, and the type and amount of the additive material. As part of the study, three different materials—iron powder, lime, and milled porous ceramic—were added to the 30-day anaerobic digestion of the brewer's spent grain to improve its performance. Different doses ranging from 0.2 to 2.3 gTS × L−1 were tested, and methane production kinetics were determined using the first-order model. The results showed that the methane yield ranged from 281.4 ± 8.0 to 326.1 ± 9.3 mL × gVS−1, while substrate biodegradation ranged from 56.0 ± 1.6 to 68.1 ± 0.7%. The addition of lime reduced the methane yield at almost all doses by −6.7% to −3.3%, while the addition of iron powder increased the methane yield from 0.8% to 9.8%. The addition of ceramic powder resulted in a methane yield change ranging from −2.6% to 4.6%. These findings suggest that the use of additive materials should be approached with caution, as even slight changes in the amount used can impact methane production. [ABSTRACT FROM AUTHOR]

The influence of chemical nature of polyvinyl alcohol (PVA) on the microstructure of cement hydration products was investigated. Thermal analysis, X-ray diffraction, Si29 nuclear magnetic resonance (NMR), and scanning electron microscope were used to explore the microstructure and content of cement hydration products. The pore structure of the matrix was measured by a mercury intrusion porosimeter. Ca(OH)2 in PVA-modified cement composites showed multidirectional growth, and its platelike structure was distorted due to the intersection of different growth orientations. The decomposition temperature of Ca(OH)2 in PVA-modified cement composites was lower than in unmodified cement composites, which was greatly affected by degrees of polymerization of PVA. Besides, the mean chain length of calcium silicate hydrate (C-S-H) gels showed an increasing trend with the increase of degrees of hydrolysis and polymerization of PVA, but it was less than that of unmodified cement composites. The incorporation of PVA increased the porosity, but refined the pore-size distribution of the matrix. PVA film between layered Ca(OH)2 and on the surface of cement hydration products acted as an additional bond and increased the internal cohesion of the matrix. [ABSTRACT FROM AUTHOR]

The biodiesel production from the used cooking oils from the frying of different food items (French fries, chicken breasts, or pork steaks) and methanol in the presence of slaked lime as a catalyst and the triethanolamine:menthol (1:2 mol/mol) deep eutectic solvent as a cosolvent was studied. This deep eutectic solvent accelerated the transesterification reaction. The transesterification reaction involves only the chemical reaction controlled region from its beginning and follows the pseudo‐first‐order reaction rate law. A good agreement between the model and the experimental data was confirmed by a low mean relative percent deviation between the predicted and observed values of triacylglycerol conversion degree (<3.5%). The highest apparent reaction rate constant of 0.421 min−1 was achieved with the used cooking oil from frying pork steaks at 60°C. The activation energy increases in the following order of the used cooking oils from frying the food items:French fries (23.1 kJ/mol) → chicken breasts (30.7 kJ/mol) → pork steaks (41.6 kJ/mol). A methyl esters content higher than 97.5% was achieved within 40 min of the transesterification of the used cooking oils over slaked lime combined with the triethanolamine:menthol deep eutectic solvent. [ABSTRACT FROM AUTHOR]

It is believed that many historic mortars were made using hot-lime mixing techniques. They are back in use today, and their good qualities are often praised, including being more compatible and a better match with historic fabrics. This paper studies the methods of producing hot-lime mortars and putties. It discusses the variables that determine the properties of the resultant mortars such as slaking and calcination, and compares hot-lime mortars with their equivalent putties, and with factory-produced calcium lime and hydraulic lime mortars. The paper concludes that the most important variable that governs the properties of hot-lime mixed mortars is the quantity of water used for slaking, because it determines the temperature reached during slaking which makes the resultant Ca(OH)2 vary from a fairly large size to extremely small, hence producing mortars with different properties. Based on scientific and historic evidence, it is concluded that the best method for hot-lime mixing is dry-slaking (sand-slaking) with long storage, because it combines a high slaking temperature (that reduces particle size and increases the surface area of the hydrate), with gradual slaking (that lowers volume expansion and crack development) and long storage (to ensure complete slaking hence no expansion cracks). Many historic mortars were probably hot-lime mixed. However, it is practically impossible to recreate them today due to the different limestones, kilns, calcination regimes and slaking/storage methods used in the past. Hydraulic and magnesian quicklimes were used historically for hot-mixing. In contrast, most of the factory quicklimes used today are purer limes with higher free lime content and a greater reactivity. Therefore, a hot-lime mix made with a factory-produced quicklime may not be more authentic or compatible than a natural hydraulic lime –NHL– mortar designed to suit a specific fabric and application. To ensure quality mortars that can be consistently repeated, a hot-lime mixing specification should contain both the process and the materials including: type of slaking (dry/wet); amount of water used; mixing details and the time at which it takes place; storage time and at what stage does it occur. To control the slaking temperature, the right amount of water should be established (according to free lime content) by trial which will also inform on the amount of yield and hence allow proportioning. With careful site work and specification, high-quality, compatible mortars can be made with both NHLs and hot-lime mixing. However hot-lime mixing requires more time and logistics, closer care and a more complicated specification. [ABSTRACT FROM AUTHOR]

Thermal energy storage is an essential technology for improving the utilization rate of solar energy and the energy efficiency of industrial processes. Heat storage and release by the dehydration and rehydration of Ca(OH)2 are hot topics in thermochemical heat storage. Previous studies have described different methods for improving the thermodynamic, kinetic, and structural stability of Ca(OH)2 to improve energy storage density, energy storage rate, and cycle stability, respectively. Here, the mechanisms and effects of different techniques on the performance improvement of Ca(OH)2 and some common problems were reviewed. Specific problems were also clarified based on the characteristics of different technologies. Finally, suggestions for the future development of Ca(OH)2 heat storage materials were provided. [ABSTRACT FROM AUTHOR]

Compared with Portland cement, geopolymers have poor carbonization resistance, which will greatly limit the application their application. To improve the carbonization resistance of geopolymers, firstly, the carbonization behavior of the fly ash-metakaolin-based geopolymer was studied through accelerated carbonization tests. Secondly, different amounts of Ca(OH)2 were introduced into the composite system, and the modification effect of the carbonization resistance of the modified geopolymer was studied. Finally, the modification effect of Ca(OH)2 on the fly ash-metakaolin-based geopolymers was analyzed, and the modification mechanism was explored. It was found that adding Ca(OH)2 to the fly ash-metakaolin-based geopolymer could significantly improve its initial compressive strength, but its strength after carbonization remained basically unchanged; meanwhile, the compressive strength of the terpolymer after carbonization clearly decreased after adding Ca(OH)2. Compared with ordinary Portland cement, the carbonization rate of fly ash-metakaolin-based geopolymer is faster, and the addition of Ca(OH)2 can inhibit the development of its carbonization depth. With increased carbonization age, the alkalinity of the geopolymer decreased, and the addition of Ca(OH)2 inhibited the decrease in the alkalinity of the geopolymer. The addition of Ca(OH)2 improved the microstructure of the geopolymers, the pore structure became denser, and the pore size became smaller size after carbonization. The hydration products of fly ash-metakaolin-based geopolymer are mainly amorphous silicaluminate gel and C–S–H gel, and Ca(OH)2 forms in the hydration products of terpolymer with the incorporation of Ca(OH)2, which is conducive to improving the carbonization resistance. In summary, Ca(OH)2 can play a good role in modifying the carbonization resistance of fly ash-metakaolin-based geopolymers. [ABSTRACT FROM AUTHOR]

The present study proposes the one‐step synthesis of Zn/Ca hybrid nano‐oxides combining an electrochemical route to ZnO nanostructures (NSs) with the wet chemical production of Ca(OH)2 NSs. ZnO is a known antimicrobial and Ca(OH)2 has consolidating properties, both appealing for stone artwork preservation in the field of cultural heritage. Two concentrations of the electrolytic bath (NaOH 0.1 and 0.4 M) were studied resulting in distinct final nanomaterials (Zn−Ca0.1 and Zn−Ca0.4). Fourier transform infrared, X‐ray photoelectron spectroscopies, and transmission electron microscopy demonstrated that Zn−Ca0.1 consisted of lamellar calcium hydroxyzincate NSs, whereas Zn−Ca0.4 showed hexagonal Ca(OH)2 (∼500 nm) and ZnO (∼50 nm) NSs. Nanocoatings prepared with Zn−Ca0.1 exhibited a Zn2+ release increasing up to 1 μmol cm−2 in 24 h. Instead, Zn−Ca0.4‐based nanocoatings released a constant value of about 0.35 μmol/cm2. Both types of nanocoatings showed good antimicrobial activity against Bacillus subtilis after 48 h and hydrophilic behavior over 28 days. [ABSTRACT FROM AUTHOR]

Ca(OH)2 nanoparticles are effective materials for cultural heritage restoration, hazardous substance absorption and photocatalyst. However, many methods are complex, and the particle sizes are usually above 80–100 nm, involving mediocre efficacy for application in the stone restoration field. In this work, Nano Ca(OH)2 with diameters less than 70 nm and composited with Graphene Quantum Dots (GQDs) were successfully synthesized in aqueous media. The morphology and structure of the nanoparticles were investigated with TEM, HRTEM, XRD, Raman and FTIR. The particle size distribution and relative kinetic stability of the Ca(OH)2 in ethanol were performed using a laser particle size analyzer and spectrophotometer. Firstprinciple calculations based on the spin-polarized density functional theory (DFT) were carried out to study the reaction process and combination model. The nanoparticles, as prepared, are composed of primary hexagonal crystals and high ammoniated precursors, which have a positive effect on reducing the grain size, and interacted with the GQDs hybrid process. According to the First-principle calculations results, the energy variation of the whole reaction process and the bonding mode between Ca(OH)2 and GQDs can be understood better. [ABSTRACT FROM AUTHOR]

Vanadium tailings from vanadium extraction by a sodium roasting process are solid waste and cannot be used in sintering and ironmaking due to their high sodium content. In this paper, a calcification and reduction roasting process was proposed to remove sodium from vanadium tailings. The effects of Ca(OH)2 addition, reduction temperature, and roasting time on the sodium removal behavior and compression strength of pellets were studied. The addition of Ca(OH)2 and the reduction of iron oxides promoted the sodium-containing phases to transform to be simpler, which could enhance sodium removal. The sodium removal rate was up to 93.47% and the compression strength of the reduced products was 4497 N/P, and the metallized ratio of the product was higher than 70% under the optimal conditions: roasting at 1200 °C for 2 h with the Ca(OH)2 addition of 35%. The treated product after removing sodium can be recycled in the ironmaking process in a steel company. [ABSTRACT FROM AUTHOR]

Background: Dental caries is a very common non-communicablae disease found in all age groups and found in 3.5 billion people in the world. Caries that harm the pulp tissue can be treated by direct or indirect pulp capping. One of the physical properties possessed by pulp capping is the porosity of material. The material most often used for pulp capping treatment of pulp perforations is calcium hydroxide (Ca(OH)2). However, Ca(OH)2 has a high pH that caused the porosity to be low. High porosity can facilitate cell development and ion exchange. Thus, additional materials with a lower pH are needed to increase porosity such as Epigallocatechin-3-gallate (EGCG). However, the porosity of the combination of EGCG with Ca(OH)2 is still unclear, so it needs to be researched. Purpose: To explain the differences of Ca(OH)2 porosity after the addition of EGCG. Methods: This study used a laboratory experimental study with a post test only control group design. This research using 16 samples for each control (Ca(OH)2 -- aquadest) and treatment (Ca(OH)2--EGCG) group. Samples from each group were subjected to freeze drying, observed with SEM, analyzed with ImageJ software, and tested with independent T-test. Results: There was a significant difference (p<0.05) in the percentage of porosity between the addition of EGCG to Ca(OH)2 namely 32,61% compared to Ca(OH)2 with aquadest namely 23,38%. Conclusion: The porosity of the combination of calcium hydroxide with EGCG has a higher percentage compared to calcium hydroxide with aquadest [ABSTRACT FROM AUTHOR]

Groundwater nitrate contamination poses a threat to both the ecological environment and human health. This study investigated the potential of using saturated Ca(OH) 2 to pretreat wheat straw and woodchips, aiming to enhance their efficacy as carbon sources for denitrification. The optimization of pretreatment conditions, and the elucidation of underlying mechanisms were explored. The pretreatment process involved the dissolution of lignin and hemicellulose, exposure of the cellulose structure, reduction of hydrogen bonds within cellulose, hydrolysis of polymerized cellulose, and the formation of cracks and hierarchical structures on the surface of the carbon source. These alterations improved the attachment and utilization of microorganisms. The maximum enzymatic reducing sugar yields for wheat straw and woodchips were achieved at solid-liquid ratios of 1:40 and soaking times of 5 and 2 days, respectively. The response surface predicted the optimal pretreatment conditions for wheat straw to be a solid-liquid ratio of 1:88.1 and a soaking time of 8.2 h. Alkaline treatment increased the denitrification rate of woodchips by fivefold and prevented the initial organic matter leaching rate of wheat straw, thereby reducing the risk of secondary pollution. The predominant microbial communities in all samples exhibited functions related to lignocellulose degradation and denitrification. The community composition of solid-phase carbon sources was found to be richer than that of liquid-phase carbon sources, and the pretreatment increased the abundance of lignocellulose degradation and denitrification functional microorganisms. The pretreatment liquid of wheat straw achieved the highest denitrification rate constant (0.43 h−1). Our result validated the feasibility of using the pretreatment liquid as a denitrification carbon source and presenting a novel approach for waste resource utilization. [Display omitted] • Alkali pre-treatment boosts wood-based denitrification rate by 5 times. • Wheat straw leachate from alkali treatment achieves highest denitrification rate. • Alkaline treatment reduces organic pollution risk in agricultural and forestry waste. • Lignin-utilizing and denitrifying microbes enriched under alkaline treatment conditions. [ABSTRACT FROM AUTHOR]

Tartary buckwheat is rich in starch and rutin, with Ca(OH) 2 often used to improve the quality of buckwheat-extruded noodles. This study investigated the properties of a system combining tartary buckwheat starch (TBS), fixed Ca(OH) 2 (0.6 %), and varying rutin addition (R, 2–10 %) to understand their interactions. Rutin addition in the presence of Ca(OH) 2 significantly affected the structural and physicochemical properties of TBS in a dose-dependent manner. Microscopy showed that rutin particles precipitated on the gel walls of the TBS-R-Ca complexes at high rutin doses, more noticeably without Ca(OH) 2. Rutin decreased gelatinization viscosity, whereas Ca(OH) 2 alleviated this reduction in viscosity and gel structure. Ca(OH) 2 and 2 % rutin significantly reduced the gelatinization and retrogradation enthalpies, relative crystallinity, short-range order degree, and TBS digestion rate. 1H NMR spectroscopy revealed interaction sites between rutin and TBS. Molecular dynamics results indicated that rutin and TBS can form effective hydrogen bonds and hydrophobic interactions, with Ca(OH) 2 helping to maintain system stability. • More rutin particles precipitated on the TBS gel wall without Ca(OH) 2. • Ca(OH)₂ mitigates the decrease in viscosity and gel structure caused by rutin. • Rutin and Ca(OH)₂ collaboratively decrease the enthalpy, crystallinity and digestion rate of TBS. • Hydrogen bond and hydrophobic interaction serve as key driving forces in the formation of complex. [ABSTRACT FROM AUTHOR]

Heavy metal (HM) pollution remains a pressing global concern, affecting soil regarding food safety, and negatively influencing the UN Sustainable Development Goals (SDGs). We investigated the efficacy of untreated cypress biochar (UCB) and Ca-modified cypress biochar (MCB) in mitigating HM contamination and enhancing growth across native and contaminated soils (40 mg/kg) in carrot pot experiments. Both biochar types were pyrolyzed at 900 °C and applied at rates of 3 %, 6 %, and 9 %. We found that carrot growth parameters significantly improved, particularly with 6 % UCB also for the contaminated soil. X-ray fluorescence (XRF) analysis showed that both UCB and MCB reduced HM concentrations in the edible part of carrots grown in native and contaminated soils. Pb concentration declined from 1.3 mg/kg to below the detection limit (< 0.3 mg/kg), Zn concentrations decreased from 50.3 mg/kg to 39.8 mg/kg (9 % UCB) and to 36.8 mg/kg (9 % MCB), while Cu concentrations reduced from 35.3 mg/kg to 25.9 mg/kg (9 % UCB) and to 22.6 mg/kg (9 % MCB). MCB, characterized by high pH (9.7) and active nano-sized CaCO 3 particles, demonstrated superior HM immobilization compared to UCB. Statistical analysis supported the superior efficacy of MCB in reducing HM bioavailability and uptake. Understanding the specific responses of different plant species to biochar amendments is essential for recommending broader applications of MCB for soil remediation and sustainable agriculture. [Display omitted] • Ca-impregnated cypress biochar (MCB) was used to immobilize Pb, Zn, and Cu in contaminated soil. • XRF analyzer was used to determine heavy metals in soil, biochar and carrot parts. • MCB enhanced immobilization through elevated pH and highly active nano sized CaCO 3 particles. • MCB decline the BF, TF and HRI values associated with HM exposure. • Statistical analysis revealed MCB showed superior performance compared to UCB. [ABSTRACT FROM AUTHOR]

Colloidal nanosilica is a byproduct of the etching process used in silica wafer production. This study assessed the effect of nanosilica incorporation on the performance of cement mortar and analyzed the influence of nanosilica based on mineralogical and microstructural characteristics. Tests regarding the flow, isothermal calorimetry, and compressive strength of cement mortars, and X-ray diffraction, Fourier transform infrared spectroscopy, mercury intrusion porosimetry, and compressive strength of cement pastes were performed at 3 and 28 days. The nanosilica-incorporated samples exhibited higher compressive strengths than the control sample. They did not exhibit pozzolanic reactivity but provided a pore-filling effect. At an early hydration age, the nanosilica particles refined the pore size and contributed to a reduction in the total porosity, leading to an enhancement in the compressive strength. Among the hydration products, the difference in Ca(OH) 2 between the nanosilica-incorporated samples and control samples was confirmed. During hydration, the difference in Ca(OH) 2 is assumed to be due to the blocking of the growth of Ca(OH) 2 by the nanosilica particles. • Colloidal nanosilica byproducts generated from silicon wafer processing were used. • Compressive strengths increased with the addition of the nanosilica byproducts. • Difference in Ca(OH) 2 between samples was confirmed resulting in pore refinement. • Growth of Ca(OH) 2 during hydration may have been blocked by nanosilica particles. [ABSTRACT FROM AUTHOR]

The present investigation provides a cost-effective approach to the development of nanostructured g-C3N4 coated eggshell waste-derived Ca(OH)2 nanoparticles as a photocatalyst for the degradation of Eriochrome cyanin R (ECR), and disinfection of pathogenic bacteria. The g-C3N4/Ca(OH)2 nanocomposite was characterized via XRD, SEM, EDX, and TEM. XRD patterns and TEM images revealed the successful synthesis of the samples in nanoscale range. The efficacy of the g-C3N4/Ca(OH)2 nanocomposite was assessed with different parameters, including solution pH, initial concentration of a targeted contaminant, and loading of the g-C3N4/Ca(OH)2 nanocomposite. Notably, 0.01 g of the g-C3N4/Ca(OH)2 nanocomposite achieved an impressive 90.0% removal efficiency of ECR at the solution pH of 3.0. When isopropanol was added, the photodegradation of ECR dye by the g-C3N4/Ca(OH)2 nanocomposite was decreased (42%), suggesting that the OH⋅ radical was the primary species responsible for degradation. The tested samples are effective against various bacteria, including Eschericia coli (E. coli) and Staphylococcus aureus (S. aureus). Specifically, the g-C3N4/Ca(OH)2 nanocomposite was the most effective combination against S. aureus (13.9 mm ZOI and 12.5 µg/mL MIC), and E. coli (12.4 mm ZOI and 12.5 µg/mL MIC). In reaction mechanism determination, the amount of the synthesized nanomaterials is directly correlated with the quantity of E. coli protein removed, and they were accounted as 22.23, 55.10, and 101.44 µg/mL following incubation with g-C3N4, Ca(OH)2 NPs, and g-C3N4/Ca(OH)2 nanocomposite, respectively. [ABSTRACT FROM AUTHOR]

The economic challenges arising from resource depletion and uneven distribution of Mg in land reserves have spurred interest in technologies for Mg extraction from seawater. Thus, this study introduces a novel method to recover high-purity magnesium carbonate, specifically hydromagnesite, from seawater through carbonation using Ca(OH)₂ as an alkali source. A significant achievement of this method is the production of high-purity hydromagnesite despite the presence of large amounts of Ca, realized only through carbonation without the need for expensive additives such as NaOH. Experimental results reveal that the Ca(OH)₂ content predominantly influences the Mg dissolution efficiency during carbonation and the overall Mg recovery rate. Maximizing the efficiency of this technology relies on using an appropriate amount of Ca(OH)₂. Notably, the appropriate amount of OH− supply enhances CO₂ dissolution, facilitating Mg dissolution. Conversely, an excess of Ca(OH)₂ impedes Mg dissolution. The overall Mg recovery rate reaches a peak of 67 %, enabling the recovery of 3.4 kg of hydromagnesite from one ton of seawater. The findings highlight the effectiveness of the proposed technology as a promising and cost-effective method for extracting high-purity Mg from seawater, utilizing Ca(OH) 2 , previously considered an impurity, as a cost-effective alkali source. • Recovered high-purity hydromagnesite from seawater via carbonation using Ca(OH) 2 • Used Ca(OH)₂, previously deemed an impurity, as a cost-effective alkali • Optimal amounts of Ca(OH)₂ enhanced Mg dissolution but excess content inhibited it • Mg recovery peaked at 67 %, yielding 3.4 kg hydromagnesite per ton of seawater [ABSTRACT FROM AUTHOR]

Utilizing soluble alkalis such as KOH and NaOH, hydrothermal humification technology (HTH) facilitates the conversion of biomass into artificial humic acid-like substances. However, the impact of less soluble bases like Ca(OH) 2 has been underexplored. In this study, we investigates the use of Ca(OH) 2 as an alternative to KOH in converting waste litchi wood into artificial humic acid (AHA) under hydrothermal conditions, and examined the potential of residual hydrochar in the field of electrochemistry. Under optimal conditions (20 % Ca(OH) 2 addition, 225 ℃, and 4 h), 16.77 ± 0.49 % AHA was produced, with a yield and structure comparable to those obtained with KOH. During the hydrothermal process, Ca(OH) 2 promotes the formation of small molecules that contribute to AHA formation, which then complex with Ca2+ and incorporate into the solid phase. This process significantly reduces carbon gas emissions by decreasing the loss of soluble sugars and absorbing CO 2 (5.22 % with Ca(OH) 2 vs. 18.24 % with KOH). Additionally, after simple pyrolysis, the hydrochar exhibited a specific capacitance of 88.15 F−1 at 0.5 A g−1 and maintained over 97 % of its capacitance at 10 A g−1 after 10,000 cycles. This study highlights the potential of Ca(OH) 2 in the hydrothermal humification and offers a novel approach for the sustainable utilization and high-value application of litchi wood and other biomass. [Display omitted] • Ca(OH) 2 -assisted hydrothermal humification resulted in an artificial humic acid yield of 16.77 ± 0.49 %. • Compared with KOH, the artificial humic acid prepared by Ca(OH) 2 has a similar structure. • Ca(OH) 2 can effectively promote the production of small molecule polysaccharide derivatives to produce AHA. • Ca(OH) 2 significantly reduces carbon emissions from hydrothermal humification processes. • Carbon materials prepared from hydrochar exhibit good electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract The present study proposes the one‐step synthesis of Zn/Ca hybrid nano‐oxides combining an electrochemical route to ZnO nanostructures (NSs) with the wet chemical production of Ca(OH)2 NSs. ZnO is a known antimicrobial and Ca(OH)2 has consolidating properties, both appealing for stone artwork preservation in the field of cultural heritage. Two concentrations of the electrolytic bath (NaOH 0.1 and 0.4 M) were studied resulting in distinct final nanomaterials (Zn−Ca0.1 and Zn−Ca0.4). Fourier transform infrared, X‐ray photoelectron spectroscopies, and transmission electron microscopy demonstrated that Zn−Ca0.1 consisted of lamellar calcium hydroxyzincate NSs, whereas Zn−Ca0.4 showed hexagonal Ca(OH)2 (∼500 nm) and ZnO (∼50 nm) NSs. Nanocoatings prepared with Zn−Ca0.1 exhibited a Zn2+ release increasing up to 1 μmol cm−2 in 24 h. Instead, Zn−Ca0.4‐based nanocoatings released a constant value of about 0.35 μmol/cm2. Both types of nanocoatings showed good antimicrobial activity against Bacillus subtilis after 48 h and hydrophilic behavior over 28 days.

For decades, distiller waste and CO2 were not the first choice for production of high valued products. Here, CaCO3 hollow microspheres, a high-value product was synthesized from such a reaction system. The synthetic methods, the formation mechanism and operational cost were discussed. When 2.5 L·min−1·L−1 CO2 was flowed into distiller waste (pH = 11.4), spheres with 4–13 diameters and about 2 shell thickness were obtained. It is found that there is a transformation of CaCO3 particles from solid-cubic nuclei to hollow spheres. Firstly, the Ca(OH)2 in the distiller waste stimulated the nucleation of calcite with a non-template effect and further maintained the calcite form and prevented the formation of vaterite. Therefore, in absence of auxiliaries, the formation of hollow structures mainly depended on the growth and aging of CaCO3. Studies on the crystal morphology and its changes during the growth process point to the inside-out Ostwald effect in the formation of hollow spheres. Change in chemical properties of the bulk solution caused changes in interfacial tension and interfacial energy, which promoted the morphological transformation of CaCO3 particles from cubic calcite to spherical clusters. Finally, the flow process for absorption of CO2 by distiller waste was designed and found profitable. [ABSTRACT FROM AUTHOR]

Calcium hydroxide nanoparticles (Ca(OH)2 NPs) are of great interest in the development of new products due to their antibacterial properties. Chemical precipitation process was used for synthesizing Ca(OH)2 NPs. The synthesized Ca(OH)2 NPs were characterized by using X‐ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transmission Infrared Spectroscopy (FTIR), UV‐Visible spectroscopy, DLS (Dynamic Light Scattering) techniques. Ca(OH)2 NPs were assessed for antibacterial activity against gram‐positive bacteria (Bacillus subtilis, Staphylococcus aureus) and gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa). The results showed reasonable bactericidal activity and flash out that the antibacterial activity of Ca(OH)2 had an important inhibitory activity against B. subtilis and P. aeruginosa which are gram‐positive and gram‐negative bacteria respectively. Reactive oxygen species (ROS) generation of Ca(OH)2 NPs were also studied and shows significant results against both gram negative and gram positive bacteria. From the analysis of the results, it was observed that Ca(OH)2 shows the best antibacterial activity against gram‐positive bacteria B. subtilis. Further, the possible mechanisms of antibacterial behaviour of Ca(OH)2 against each bacteria were suggested. These outcomes indicate that Ca(OH)2 could be utilized as a functional antibacterial material. [ABSTRACT FROM AUTHOR]

Background and Objectives: Diffusion of hydroxide (OH) - and calcium (Ca) ++ ions through dentin may cease external root resorption. Calcium hydroxide (Ca(OH) 2 ), mineral trioxide aggregate (MTA), and calcium-enriched mixture (CEM) cement are the choices for this purpose due to their optimal properties. This study sought to analyze the effects of ultrasonic activation (UA) on pH and the release of calcium ions from Ca(OH) 2 , MTA, and CEM cement in external root resorption artificial defects. Materials and Methods: This in vitro research involved the instrumentation and shaping of the root canals of 150 single-rooted teeth (#F4). External defects were intentionally made on the middle one-third of the root surface. Teeth were randomly assigned to a negative control group ( n  = 10), one positive control group ( n  = 20), and six experimental groups (each n  = 20) according to the root canal filling material (Ca(OH) 2 paste, MTA, CEM, gutta-percha, Ca(OH) 2 paste+ultrasonic, MTA + ultrasonic, and CEM + ultrasonic). Ultrasonic energy was transferred to the test materials using a #25 spreader. Ca ++ concentration and pH were measured after 1, 7, 15, and 30 days in all groups. Statistical analysis involved the use of repeated measure analysis of variance (ANOVA) and paired-sample T -test ( P ≤ 0.05). Results: The levels of calcium ions and pH increased significantly over time in all groups ( P < 0.001). There were significant differences between the experimental groups in terms of pH and the concentration of released calcium ions at different times ( P < 0.001). The Ca(OH) 2 plus ultrasonic energy group ranked first, while the gutta-percha group ranked last in terms of release of calcium ions and pH. Conclusion: The Ca(OH) 2 , MTA, and CEM cement groups showed an increase in pH and the release of calcium ions at the external root resorption defects. Additionally, the application of ultrasonic energy increased the release of calcium ions at these sites., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Azadeh Kheradyar et al.)

Due to its notable low carbon footprint, calcium sulfoaluminate (CSA) cement has become a research hotspot for cement chemists in recent years. Relevant studies have shown that supplementary cementitious materials (SCMs) can greatly improve the properties of CSA cement pastes, but the utility of SCMs in CSA cement has not yet been fully exploited due to their low alkalinity. To stimulate the activity of pozzolanic materials, the effect of different alkalies on the hydration of CSA-fly ash (CSA-FA) was systematically investigated, and the results indicate that after calcium hydroxide (Ca(OH)2) is incorporated into the CSA-FA paste, it first forms a saturated solution and then rapidly hydrates to form ettringite. The initial pH value of the suspension is approximately 12.65, which then slumps to a level lower than that without Ca(OH)2. The initial pH value of the CSA-FA suspension mixed with 1 M sodium hydroxide (NaOH) solution is 13.0, which is then rapidly decreased to a stable value of approximately 11.3. Ca(OH)2 can promote the hydration of CSA to form ettringite and improve the compressive strength of the paste, and the larger the Ca(OH)2 content, the more obvious this effect. NaOH inhibits the hydration of CSA. With increasing NaOH concentration, the compressive strength of the paste first increases and then decreases, and the effect of inhibiting the hydration of CSA becomes stronger. The CSA-FA paste blended with 1 % Ca(OH)2 and 1 M NaOH shows collapsing and cracking behavior, for which a large number of well-developed flaky aluminum hydroxide crystals are formed, and strong diffraction peaks for unhydrated CSA are observed.

This work examined the effects of seawater (SW) on the hydration of tricalcium aluminate (C3A) in C3A–gypsum and C3A–gypsum–Ca(OH)2 systems through the characterization of hydration heat release, the evolution of aqueous phase composition and hydration products with the hydration time. It was found that SW increased the dissolution driving force of C3A and solubility of gypsum, which accelerated the early hydration of C3A and the formation of ettringite (AFt), leading to a higher hydration degree of C3A at an early age compared with the deionized (DI) water–mixed pastes. After gypsum depletion to form AFt, and in the absence of Ca(OH)2, the formation of chloroaluminate hydrates was slower due to the insufficient Ca resulted in an accumulation of Al in solution. This would delay the subsequent transformation of AFt to monosulfate (SO4–AFm) and the formation of hydrogarnet (C3AH6), which would further reduce the hydration degree of the C3A at the later ages. However, in the presence of Ca(OH)2, the hydration degree of C3A–gypsum–Ca(OH)2 at later ages was increased, which was similar to that of the corresponding DI pastes. This can be inferred that the amount of Ca available in SW‐mixed cement concrete can affect the hydration degree of C3A in cement. [ABSTRACT FROM AUTHOR]

Betel quid (BQ) containing Piper betle leaf (L), green unripe Areca catechu nut (AN) and slaked lime (Ca(OH) 2) is an addictive carcinogenic stimulant, with no pharmacotherapy, chewed by millions of people in Asia. We measured the effect of the constituents of slaked lime, NaOH and Ca(OH) 2 , on the levels of endogenous alkaloids in aqueous extracts of AN alone and L+AN (LAN) using UHPLC-MS/MS. Alkaloid levels in AN and LAN extracts were arecoline> >guvacoline>arecaidine>guvacine. In vitro hydrolyzation of extracts of AN and LAN by NaOH or Ca(OH) 2 , as occurs in vivo when BQ is chewed, dose-dependently decreased levels of muscarinic esters, arecoline (maximum 65%↓) and guvacoline (maximum 69%↓), and increased carboxylic acid GABA uptake inhibitors, arecaidine (maximum 275%↑) and guvacine (maximum 18%↑). In five volunteers, chewing BQ but not LAN, increased heart rate (maximum 19b/min), forehead temperature (maximum 1 °C), facial flushing and sweating, all symptoms of BQ stimulation. Hydrolysis of compounds in LAN is necessary to induce stimulant effects. Levels of arecoline, considered to mediate stimulant and addictive properties of BQ, negatively correlate with the physiological stimulant effects while levels of GABA uptake inhibitors positively correlate. Unripe, green AN warrants investigation as replacement therapy in the treatment of BQ substance use disorder. [Display omitted] • Areca nut chewed with slaked lime (SL) is an addictive stimulant. • Endogenous muscarinic esters are thought to mediate intoxication and addiction. • SL decreases amount of esters by hydrolization forming other neuroactive compounds. • Physiological stimulation requires hydrolysis of compounds in areca nut. • Chewing areca nut alone may be a suitable replacement therapy for addiction. [ABSTRACT FROM AUTHOR]

The long-term energy storage and high-efficiency Carnot battery system are imperative to developing the future carbon-neutral energy system. This paper proposes a Carnot battery system integrating the CaO/Ca(OH) 2 thermochemical energy storage, supercritical CO 2 Brayton power and heat pump cycles, and some industrial waste heat. By effectively converting thermal, chemical, and electrical energy, the system not only harnesses excess electricity but also provides residential heating while enabling on-demand regeneration of electricity to the grid. According to the differential evolution algorithm and the HEATSEP framework, a multi-level optimization workflow is constructed to optimize heat transfer processes and operating conditions for deriving the most favorable system configuration in the energy aspect. The optimized system showcases impressive metrics, achieving an energy efficiency of 49.19 %, an exergy efficiency of 40.48 %, and a round-trip efficiency of 71.52 %. The key to further enhancing system efficiency lies in reducing heat loss from the regenerators and minimizing exergy destruction in the heat exchangers. Effects of the temperature of flue gas and the effective mass fraction of Ca(OH) 2 in fluidized particles on the thermodynamic performance of the system are also investigated. It is recommended to leverage flue gas temperatures exceeding 250 °C for preferable energy cascade utilization. However, mechanically enhanced Ca(OH) 2 -rich fluidized particles with only 40 wt% of Ca(OH) 2 show no significant impact on system efficiency. This research provides promising insights for advancing the efficiency and effectiveness of Carnot battery systems. [Display omitted] • A Carnot battery based on Ca(OH) 2 /CaO thermochemical energy storage is proposed. • Supercritical CO 2 power and heat pump cycles are integrated. • Waste flue gas and residential heat are considered for energy cascade utilization. • The system configuration is optimized, providing a round-trip efficiency of 71.52 %. • The influences of flue gas temperature and Ca(OH) 2 fraction are discussed. [ABSTRACT FROM AUTHOR]

In this article, the results of sorbitol hydrogenolysis (15% aq. solution), done in an autoclave reactor, over Ru, Pt and Ni loaded on SBA15, carbon coated SBA15 (SBA15C), activated carbon (AcC), Na–Y, Fly Ash (FA) and hydroxyapatite (HAP) catalysts by our group, were compared to find the best metal-support combinations. The metal loading was 1 wt% for Ru and Pt, 6 wt% for Ni and the catalysts' preparations were carried out by impregnation of respective salts. The catalysts were characterized with nitrogen and hydrogen adsorption measurements and X-ray diffraction. Addition of a base (Calcium hydroxide) to the reactants' mixture increased the overall conversion and selectivities of the glycols, ethylene glycol (EG) and 1,2-propylene glycol (PG). The catalysts’ performance at 60 bar and 220 °C with the presence of base (B), evaluated by the yield of glycols (PG + EG), showed the following order:Ni/Na–Y > Ru/AcC ∼ Ru/SBA15C > Ni/HAP ∼ Ru/SBA15 > Ni/SBA15 > Ru/Na–Y > Ni/FA ∼ Ni/AcC and the yields were 57, 40, 39, 33, 31, 29, 26, 22 and 21 wt%, respectively.Na–Y appeared to be the best support, especially for Ni metal; AcC and SBA15C were good supports for Ru and Pt respectively. Reusability studies revealed that Ni on HAP was the best catalyst and exhibited only a small deactivation during four runs of loading it.

The design on expansive soils can easily change in volume due to the influence of water content. This makes it necessary to consider soil improvement methods in the planning process to maintain the variation in the water content. One of these methods includes chemical stabilization, which is carried out by adding materials such as cement or lime. In expansive soils, stabilization efforts aim to reduce the plasticity index and increase the shear strength parameters. Therefore, this study focused on the addition of slaked lime (Ca(OH)2) to expansive soil in Lakarsantri, Surabaya. The stabilizing materials used contain calcium to form pozzolan in the clay and increase the bearing capacity parameter, which is variation in shear strength. The soil was taken at 2 points A and B with a different moisture content of 48.57% and 35.12%, as well as a high plasticity index value > 50% using a percentage (Ca(OH)2) of 6%-24% at a certain curing time. Based on the results, the plasticity index in the soil changed from very high to moderate with an optimum percentage value of 6% at 30 days of curing time. The optimum value of soil shear strength is (Ca(OH)2) 6% at 30 days of age in soil A, the cohesion value is 0.02 kg/cm2, and an internal shear angle of 36°. In soil B, the optimum shear strength obtained (Ca(OH)2) was 6% at the age of 10 days with a cohesion value of 0.14 kg/cm2 and an internal shear angle of 23.80°. Therefore, the results of this study show that the parameter of shear strength of the soil from the cohesion value showed that the cohesion value decreased with the addition of Ca(OH)2, while the internal shear angle increased.

• Effect of Ca conversion on syngas production during sludge gasification. • Investigation on quantitative analysis of syngas and chemical structure of chars. • Ca(OH) 2 addition promoted the conversion of aromatic C H into aliphatic C H. • Ca(OH) 2 promoted ring-opening and steam reforming reaction of tar. Gasification shows great potential as an alternative method for energy utilization from sewage sludge. Lime (CaO) is a cheap and commonly used dewatering conditioner for sewage sludge. The calcium hydroxide (Ca(OH) 2) generated during the drying process with lime can enhance the pH level of the sludge, thereby providing disinfection properties. This paper investigated enhancement mechanism of Ca(OH) 2 on hydrogen gas generation and the effect on gas product yield during the steam gasification process of lime-dried sludge. The experiments were conducted in an electrically heated reactor at 500–800 °C. The forms of calcium present in the gasified sludge char samples were analyzed using X-ray diffraction (XRD) analysis to investigate their transformation process. Fourier transform infrared spectroscopy (FTIR) was utilized to obtain information regarding the chemical structure in the gasified sludge char samples, with the aim of exploring the mechanism behind hydrogen production from lime-dried sludge. The results indicate that the CaO generated from Ca(OH) 2 dehydration acts both CO 2 adsorbent and catalyst during the gasification process. The addition of Ca(OH) 2 during the sewage sludge gasification process leads to a reduction in the aromatic C H content in the organic matter, while significantly increasing the content of reactive CH 3 -chains. It also promotes the ring-opening and rearrangement reactions of aromatic hydrocarbons and nitrogen-containing heterocycles and steam reforming reaction of tar. The combined effects of these factors contribute to an overall increase in hydrogen gas yield. [ABSTRACT FROM AUTHOR]

Losses of soil organic carbon (C) following liming have been proposed to result from stimulated C mineralization, which could occur through a variety of mechanisms including soil enzymes. Given the pH-sensitivity of enzyme activities, liming could impact catalysis of C mineralization by extracellular enzymes independently of microbial response. To this end, we evaluated the responses of C mineralization as CO 2 flux, permanganate-oxidizable C (POXC), and the activities of C-hydrolytic enzymes to liming of a Haplic Ferralsol (Typic Kandiudox) in western Kenya under three differing 11-year soil fertility managements: unfertilized (UNF), mineral fertilized (MIN), and organic fertilized (ORG). Five rates of Ca(OH) 2 (1.5, 3.0, 4.5, 6.0, and 7.5 t ha−1) and an unlimed control were used to establish a pH gradient of 4.6–6.4. Soil C mineralization rates assessed as CO 2 production peaked within 5 d for high liming rates, and converged to a similar rate as unlimed soils after 21 d. At 28 d, activities of β-glucosidase and cellobiohydrolase decreased with increasing pH, increased for β-glucosaminidase, and were unaffected for β-galactosidase. POXC generally increased with liming rate for fertilized soils, more so in ORG and less in MIN soils, with relative increases of 18%, 5%, and 1% for ORG, MIN and UNF soils, respectively, at 7.5 relative to 0 t ha−1 liming. This study identifies potentially rapid albeit short-lived stimulation of C mineralization following addition of a highly soluble liming agent. Notably, decreases in activities of soil enzymes that catalyze the first and last step of the cellulosic C depolymerization suggests that short-term losses of soil C were not driven by enzyme activities, and may occur in spite of lowered C-hydrolytic enzyme activity. The enhanced C mineralization observed could reflect augmentation of labile C pools via non-enzymatic processes (e.g., desorption) in the short-term. • Ca(OH) 2 liming of Ferralsol/Kandiudox (Kenya) impacted soil carbon (C) cycling. • Liming stimulated C mineralization and increased POXC. • Soil C mineralization differed by each of three fertility management histories. • C mineralization response to liming was not explained by C-enzyme activity changes. • Lime-stimulated C mineralization in acidic soils due to non-enzymatic mechanisms. [ABSTRACT FROM AUTHOR]

Natrium Hydroxide (NaOH) and Calcium Hydroxide (Ca(OH)2) as an absorbent was used in the filtration system of the mobile anaerobic digester (AD) to improve the quality of biogas from dairy cattle manure. Twelve pilots insulated of mobile AD used in this study. The average temperature inside the digester was 28.37 °C, and in the outer digester 27.16 °C. The average biogas temperature before filtration was 28.37 °C, and after filtration 31.09 °C. The biogas filtration using adsorbent was a very significantly effect (P 0.05). The average biogas production using NaOH was 717.50 mL h−1, Ca(OH)2 715.63 mL h−1, and control 676.25 mL h−1. The adsorbent treatments were very significantly effects (P 0.05) among the type of adsorbent. The NaOH could increase the percentage of methane (CH4) (14.26 %) and oxygen (O2) (22.06 %) content, and reduced carbon dioxide (CO2) (30.86 %) compared with control. However, Ca(OH)2 adsorbent could increase CH4 (7.77 %) and O2(11.22 %) and reduced CO2 (17.88 %). The mobile anaerobic digester is suitable for smallholder farmer because more simple and cheaper.

In this study, CO2 removal efficiency from flue gas was investigated in a fluidized bed reactor under semi-dry conditions. A lab-scale fluidized bed reactor, filled with inert glass beads, was used to investigate the effect of operating parameters on the CO2 removal efficiency using calcium hydroxide slurry as the absorbent. The Taguchi design method was used to design the experiments. The maximum inlet concentration of CO2 was 3 vol%. The most important factors were the reaction surface area, inlet gas velocity, inlet CO2 concentration, absorbent solution flow rate, inlet gas temperature and calcium hydroxide slurry concentration. The experimental results indicated that the CO2 removal efficiency increased when increasing the effective surface area of the reaction. Moreover, the removal efficiency increased by decreasing the input gas flow rate and inlet CO2 concentration. By performing experiments under optimum conditions, the maximum obtained CO2 removal efficiency was 79%. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Background: Calcium hydroxide [Ca(OH)2] is a material used during pulp capping treatment, despite being readily soluble in both water and acid. In contrast, propolis constitutes a nontoxic resin which is not easily dissolved in water. Therefore, a combination of Ca(OH)2and propolis is assumed to be capable of increasing the mechanical properties of Ca(OH)2and to diffuse into the dentinal tubules. Objective: This research aimed to reveal the solubility and water sorption ability of a combination of Ca(OH)2and propolis as pulp capping material. Materials and Method: The samples comprised 18 Ca(OH)2and Ca(OH)2-propolis chips, 15 mm × 1 mm in dimension, all of which were stored in an incubator for 24 h at 37°C. Each sample was then divided into two groups: one dissolved in 50 mL of artificial saliva for 24 h at 37°C and another for 7 days before being weighed, dried, incubated, and weighed for a second time. The result of the reduction in mass divided by the volume of the samples was considered to constitute the level of solubility and water sorption. The difference between the solubility and water sorption ability was analyzed using an independent t-test with significant difference

Thermal energy storage is an essential technology for improving the utilization rate of solar energy and the energy efficiency of industrial processes. Heat storage and release by the dehydration and rehydration of Ca(OH)2 are hot topics in thermochemical heat storage. Previous studies have described different methods for improving the thermodynamic, kinetic, and structural stability of Ca(OH)2 to improve energy storage density, energy storage rate, and cycle stability, respectively. Here, the mechanisms and effects of different techniques on the performance improvement of Ca(OH)2 and some common problems were reviewed. Specific problems were also clarified based on the characteristics of different technologies. Finally, suggestions for the future development of Ca(OH)2 heat storage materials were provided.

The assessment of the discoloration caused by calcium hydroxide, triple antibiotic paste, and chlorhexidine gel when used as intra-canal medicaments in teeth undergoing root canal treatment is of interest. The study measured the discoloration over seven and fourteen days using a spectrophotometer. After obtaining ethical clearance, ninety anterior teeth requiring root canal therapy were selected based on eligibility criteria. Using basic randomization, participants were split up into three groups, each consisting of thirty patients. The colorimeter was used to measure preoperative, one and two weeks following the medication's removal. All groups showed significant discoloration, with 2% chlorhexidine gel (p≤0.03) and triple antibiotic paste (p≤0.02) causing the highest discoloration in the central region of teeth. The discoloration was inversely correlated with the remaining dentin thickness. Thus, intracanal medicaments used for endodontic treatment cause tooth discolouration., (© 2024 Biomedical Informatics.)

The catalytic ozonation, combining ozone with solid catalysts technology, was adopted to dispose of the reverse osmosis concentrate (ROC) produced from landfill leachate. To explore an effective and economically sustainable process, three different combined processes were investigated in a microbubble reactor. The considered catalytic oxidation processes were Ca(OH)2/O3+ AC/O3, Ca(OH)2+ AC/O3, and AC/O3. The results indicated the combined Ca(OH)2+ AC/O3 process was able to reduce obviously the economic requirements and have higher degrading efficiency. In particular, the final removal fraction of COD and CN reached 92.88%, 91.84%, respectively, and the value of BOD5/COD was 6.4 times higher than the original leachate. Meanwhile, the operational cost was 5.36 $/t through economic evaluation. The maximum removal fraction of COD reached 96.25% under the option condition of inlet ozone concentration of 65 mg/L, the ozone feed rate of 195 mg/min, reactor pressure of 0.2 MPa, the reaction time of 3 h, Ca(OH)2 dosage of 12 g/L, and AC dosage of 60 g/L. Furthermore, the mechanism of organic degradation in the ROC was explored through analysis of the macromolecular organics present by UV-vis, 3D-EEM, and GC-MS. The results demonstrated that the combination of Ca(OH)2 flocculation and AC-catalyzed ozonation can enhance the degradation efficiency of the organic pollutants. Results indicated that the new-proposed integrating process was an efficient and economically sustainable ozonation process for ROC treatment. [ABSTRACT FROM AUTHOR]