Showing papers on "Calcium oxide published in 2019"
TL;DR: In this article, the temperature dependence of composition, unit cell parameters, thermal expansion coefficients and microstructure during complete thermal decomposition of calcite has been investigated by in-situ high-temperature X-ray powder diffraction.
188 citations
TL;DR: In this paper, the synthesis of calcium oxide nanoparticles from raw eggshell has been described using the sol-gel method, where raw egg shells were dissolved by HCl to form CaCl2 solution, adding NaOH to the solution dropwise to agitate Ca (OH)2 gel and finally drying the gel at 900 °C for 1 h.
Abstract: The sol-gel technique has many advantages over the other mechanism for synthesizing metal oxide nanoparticles such as being simple, cheap and having low temperature and pressure. Utilization of waste materials as a precursor for synthesis makes the whole process cheaper, green and sustainable. Calcium Oxide nanoparticles have been synthesized from eggshell through the sol-gel method. Raw eggshell was dissolved by HCl to form CaCl2 solution, adding NaOH to the solution dropwise to agitate Ca (OH)2 gel and finally drying the gel at 900 °C for 1 h. The synthesized nanoparticle was characterized by scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray fluorescence (XRF) and X-ray diffraction (XRD). The FTIR and XRD results have clearly depicted the synthesis of calcium oxide from eggshell, which is mainly composed of calcium carbonate. The FE-SEM images of calcium oxide nanoparticles showed that the particles were almost spherical in morphology. The particle size of the nanoparticles was in the range 50 nm–198 nm. Therefore, waste eggshell can be considered as a promising resource of calcium for application of versatile fields.
120 citations
TL;DR: In this paper, the feasibility of utilizing low-quality desulfurization ash from semi-dry flue gas desulurization by mixing with α-hemihydrate gypsum was investigated.
116 citations
TL;DR: In this article, a review of lime preparation factors that influence the reagent performance properties, mechanisms of lime interaction with collector chemicals and mineral surfaces, its role in promoting selective separation between different sulphide minerals, and the effect on pulp and froth properties are discussed.
67 citations
TL;DR: In this article, solid synthetic C-S-H made at room temperature from easily obtainable calcium sources (calcium oxide, calcium hydroxide) and nanosilica (w/s = 2) with a 2 minute mixing time.
59 citations
TL;DR: High-temperature heat treatment (500 °C) is an effective measure for decomposing the organic binder polyvinylidene fluoride (PVDF) in the cathode electrode of spent lithium-ion batteries as discussed by the authors.
Abstract: High-temperature heat treatment (500 °C) is an effective measure for decomposing the organic binder polyvinylidene fluoride (PVDF) in the cathode electrode of spent lithium-ion batteries (LIBs). Ho...
58 citations
TL;DR: In this paper, the authors investigated how silica particle size influences the rate and extent of formation of calcium silicate hydrate (C-S-H) at room temperature by isothermal calorimetry, thermal analysis, Raman spectroscopy and X-ray diffraction.
56 citations
TL;DR: In this article, a new hybrid calcium oxide (CaO)/L-aspartic (Asp) inhibitor was proposed for AA5052 aluminum alloy anode of alkaline aluminum air batteries.
56 citations
TL;DR: In this paper, a mixture of industrial solid waste was calcined under different calcination conditions to study the decomposition behavior of FGD gypsum and properties of CSA cement made from the FGD Gypsum.
52 citations
TL;DR: Calcium oxide is an efficient adsorbent for high-temperature CO2 capture process, however, it suffers from rapid deactivation and capacity loss after a few cycles as a result of particle sintering as discussed by the authors.
Abstract: Calcium oxide is an efficient adsorbent for high-temperature CO2 capture process, however, it suffers from rapid deactivation and capacity loss after a few cycles as a result of particle sintering....
43 citations
TL;DR: In this article, the authors proposed a direct integrated approach in which amine-bearing solvents, such as monoethanolamine (MEA), and alkaline Ca-bearing carbonates, are reacted in a slurry reaction system in two modes to facilitate the capture of CO2 using MEA and the release of CO 2 into the aqueous phase to produce higher conversions.
Abstract: One of the critical and emerging needs for sustainable energy production is the development of novel integrated approaches for the capture, conversion, and storage of CO2. In this context, carbon mineralization, which is a thermodynamically downhill route for the accelerated conversion of CO2 to water-insoluble and stable calcium and magnesium carbonates, is a sustainable approach for permanently storing CO2. However, one of the challenges with carbon mineralization has been the need for higher concentrations of CO2 to accelerate the formation of calcium and magnesium carbonates. In this study, we propose a direct integrated approach in which amine-bearing solvents, such as monoethanolamine (MEA), and alkaline Ca-bearing solids, such as calcium oxide and calcium silicate, are reacted in a slurry reaction system in two modes. These two modes involve in situ changes in the aqueous chemistry to facilitate the capture of CO2 using MEA and the release of CO2 into the aqueous phase to produce higher conversions...
TL;DR: Considering the fresh and hardened properties of cement mortar, the incorporation of calcined oyster shell powder of approximately 3% by weight of cement is recommended to enhance the properties of concrete mortar in terms of compressive strength and autogenous shrinkage.
Abstract: The present study prepared calcined oyster shell powder having chemical composition and crystal structure of calcium oxide and lime, respectively, and investigated the fresh and hardened properties of cement mortar incorporating calcined oyster shell powder as an additive. The test results indicated that the hydration of calcined oyster shell powder promoted the additional formation of Ca(OH)2 at the initial reaction stage, thereby increasing the heat of hydration. In particular, the volumetric increase of calcined oyster shell powder during hydration compensated the autogenous shrinkage of mortar at early ages, ultimately leading to a clear difference in the shrinkage values at final readings. However, an excessive incorporation of calcined oyster shell powder affected the rate of C–S–H formation in the acceleratory period of hydration, resulting in a decrease in the compressive strength development. Meanwhile, the degree of flow loss was inconsequential and rapid flow loss was not observed in the specimens with calcined oyster shell powder. Therefore, considering the fresh and hardened properties of cement mortar, the incorporation of calcined oyster shell powder of approximately 3% by weight of cement is recommended to enhance the properties of cement mortar in terms of compressive strength and autogenous shrinkage.
TL;DR: In this paper, the effect of steam on the decomposition of the carbonate is investigated and a clear rateenhancing effect up to a factor of 4 is observed when steam concentrations up to 1.25% are applied during isothermal reactions at temperatures between 590 and 650°C.
Abstract: The search for cheap solutions for carbon dioxide capture in order to prevent global warming is still challenging. Calcium oxide may be a suitable sorbent, but the regeneration process from calcium carbonate requires too high temperatures, causing sintering and decreasing sorption capacity. In this study the effect of steam on the decomposition of the carbonate is investigated. A clear rate-enhancing effect up to a factor of 4 is observed when steam concentrations up to 1.25% are applied during isothermal reactions at temperatures between 590 and 650 °C. This results in a decrease of the apparent activation barrier from 201 to 140 kJ mol−1, caused by the opening of a new reaction pathway. The kinetics of steam catalyzed decomposition of CaCO3 is discussed and a simple reaction scheme is proposed, including estimation of kinetic constants. The new pathway proceeds via formation of a stable surface bicarbonate followed by decomposition to surface OH groups, which then decompose by desorbing H2O.
TL;DR: In this paper, the influence of chemical composition of aggregate on emulsified asphalt demulsification speed was examined, and the results indicated that mixing ratio of chemical components has a significant effect on asphalt emulsion.
TL;DR: In this paper, the authors take a fresh look at the decomposition of calcium oxalate and warn users of thermogravimetric analysis against the hasty interpretation of results obtained.
Abstract: The goal of this study is twofold: to take a fresh look at the decomposition of calcium oxalate and to warn users of thermogravimetric analysis against the hasty interpretation of results obtained. Since the pioneer work of Duval 70 years ago, the scientific community has agreed unanimously as to the decomposition of anhydrous calcium oxalate (CaC2O4) into calcium carbonate (CaCO3) and CO gas, and that of the calcium carbonate into calcium oxide (CaO), and CO2 gas. We will demonstrate how these reactions, simple in appearance, in fact result from a succession of reactive phenomena involving numerous constituents both solid (CaCO3, free carbon) and gaseous (CO2 and CO) produced by intermediary reactions. The mass losses evaluated in the two distinct domains correspond closely to the molar masses of CO and CO2, respectively. The simple mathematical calculation of that mass loss has simply concealed the existence of other reactions, and, most particularly the Boudouard reaction and that of solid phases between CaCO3 and C. It just goes to show that appearances can be deceiving.
TL;DR: In this article, the effect of calcium content on catalytic activity and syngas formation in perovskite systems was investigated in steam reforming of acetic acid under steady state conditions.
TL;DR: Two main correlations are observed between the porosity and the heating rate, and between the formation of crystalline structure in intermediate temperatures and the CaCl2 concentration in the gelation step.
TL;DR: The results show that the steel slag asphalt permeable mixture had good permeability, water stability, and Marshall stability, as well as good high-temperature stability and a low expansion rate.
Abstract: Steel slag is an industrial solid waste with the largest output in the world. It has the characteristics of wear resistance, good particle shape, large porosity, etc. At the same time, it has good adhesion characteristics with asphalt. If steel slag is used in asphalt pavement, it not only solves the problem of insufficient quality aggregates in asphalt concrete, but can also give full play to the high hardness and high wear resistance of steel slag to improve the performance of asphalt pavement. In this study, a steel slag aggregate was mixed with road petroleum asphalt to prepare a permeable steel slag–asphalt mixture, which was then compared with the permeable limestone–asphalt mixture. According to the Technical Regulations for Permeable Asphalt Pavement (CJJT 190-2012), the permeability, water stability, and Marshall stability of the prepared asphalt mixtures were tested and analyzed. In addition, the high-temperature stability and expansibility were analyzed according to the Experimental Regulations for Highway Engineering Asphalt and Asphalt Mixture (JTG E20-2011). The chemical composition of the steel slag was tested and analyzed by X-ray fluorescence spectrometer (XRF). The mineral composition of the steel slag was tested and analyzed by X-ray diffractometer (XRD). The asphalt was analyzed by Fourier transform infrared spectroscopy (FTIR). The results show that the steel slag asphalt permeable mixture had good permeability, water stability, and Marshall stability, as well as good high-temperature stability and a low expansion rate. The main mineral composition was ferroferric oxide, the RO phase (RO phase is a broad solid solution formed by melting FeO, MgO, and other divalent metal oxides such as MnO), dicalcium silicate, and tricalcium silicate. In the main chemical composition of steel slag, there was no chemical reaction between aluminum oxide, calcium oxide, silicon dioxide, and asphalt, while ferric oxide chemically reacted with asphalt and formed new organosilicon compounds. The main mineral composition of the steel slag (i.e., triiron tetroxide, dicalcium silicate, and tricalcium silicate) reacted chemically with the asphalt and produced new substances. There was no chemical reaction between the RO phase and asphalt.
TL;DR: In this article, the integrated sorptionenhanced chemical looping reforming and water splitting (SECLR-WS) process was proposed for hydrogen (H2) production from biogas using iron oxide as an oxygen carrier and calcium oxide (CaO) as a carbon dioxide (CO2) adsorbent.
TL;DR: In this paper, the authors investigated the deoxygenation abilities of composite basic catalysts during the thermochemical conversion process and showed that using calcium oxide as a catalyst reduced activation energy from 260kJ/mol to 185kJ /mol, leading to a reduction in the reaction temperature of approximately 20-40°C.
TL;DR: In this paper, marine bivalve shells were thoroughly characterised for their mineralogical, chemical and thermal properties and the obtained calcium oxide was subjected to wet slaking test to evaluate its reactivity in the production of hydrated lime.
Abstract: The present work aimed at valorizing marine bivalve shells. First, clam, mussel, edible cockle, wedge, razor, oyster, dog cockle and scallop shells wastes were thoroughly characterised for their mineralogical, chemical and thermal properties. Then, the materials were calcined at 1000 °C, milled and sieved to lower than 0.250 mm. The obtained calcium oxide was subjected to wet slaking test to evaluate its reactivity in the production of hydrated lime. The reactivity results of the calcined materials showed that, dog cockle (60 °C in 7:54 min:s) and edible cockle (60 °C in 9:20 min:s) can be classified in the most reactive class (R5) in which 60 °C is reached in less than 10 min. The remaining species were classified in the R4 class, reaching 60 °C between 10 and 25 min, with the lowest reactivity being found for oyster shell (60 °C in 19:09 min:s). Interestingly, the hydrated limes from seashells typically presented a white tonality superior that of the lime from commercial limestone used as reference. Overall, seashell wastes can be used in the production of lime, with several benefits, including, the inexistence of environmental impacts related to the exploitation of limestone on quarry, lesser energy spent in the comminution process, or, inexistence of disposal costs related with landfill tariff. These wastes could thus be used as raw materials in other industrial sector.
TL;DR: Among the catalysts, CaO showed the most favorable effects in terms of reducing the acidity of the bio-oil and anhydrosugar and thermal stability of bio-oils produced in the presence of CaO was studied.
TL;DR: In this article, the role of different flux agents on coal ash viscosity temperature properties was investigated by a combination of molecular dynamics simulations and thermodynamic calculations, and the results from the current work are expected to provide new clues to find strategies controlling the fusion behaviour of coal ash systems.
TL;DR: In this paper, the potential and innovative utilization of Rice Husk Ash (RHA) and Eggshells as partial cement replacement to develop green concrete is discussed, which can reduce CO 2 gas emissions as well as resolve the environmental issues that the inhabitants face during the disposal of such waste materials.
Abstract: Concrete which is widely used material in the construction industry, has a carbon footprint. Approximately 10% of global Carbon Dioxide (CO 2 ) gas is emitted during the production of cement which is vital ingredient of concrete. The increase in production of cement affects global warming and climate change. Therefore, many have attempts have been made to develop green and sustainable concrete by utilizing different waste materials. With the utilization of waste materials as cement replacement, the CO 2 gas emissions can be reduced as well as resolve the environmental issues that the inhabitants face during the disposal of such waste materials. This paper reviews the potential and innovative utilization of Rice Husk Ash (RHA) and Eggshells as partial cement replacement to develop green concrete. RHA which is rich in silica and eggshells contain identical amount of calcium oxide as cement, when finely grinded and used together as partial cement replacement, can trigger a pozzolanic reaction, in which silica reacts with calcium oxide resulting in the formation of calcium silicates which are responsible for achieving higher strengths.
TL;DR: In this article, the formation kinetics of hydroxyapatite Ca10(PO4)6(OH)2 during ball milling of mixtures of calcium phosphates with calcium oxide or calcium hydroxide were studied.
TL;DR: In this article, micro-structured calcium oxide obtained from the calcination (850 °C for 3 h) of Gallus gallus domesticus (chicken) eggshells was used as a catalyst in the transesterification of soybean oil.
Abstract: In this study, micro-structured calcium oxide obtained from the calcination (850 °C for 3 h) of Gallus gallus domesticus (chicken) eggshells was used as a catalyst in the transesterification of soybean oil. This catalyst was characterized by Scanning Electron Spectroscopy (SEM) methods. The structure of the obtained CaO showed several agglomerates of white granular solids with a non-regular and unsymmetrical shape. In terms of calcium oxide catalytic activity, three different catalyst loadings (1%wt, 3%wt, and 5%wt) were tested for the same reaction conditions, resulting in transesterification yields of 77.27%wt, 84.53%wt, and 85.83%wt respectively. The results were compared to the current literature, and whilst they were lower, they were promising, allowing us to conclude that the tendency of yield improvement for this reaction, when the size range of catalyst particles is to be reduced to a nano scale, can be verified.
TL;DR: In this paper, four incineration bottom ashes (IBA) and coal fly ash (CFA) were directly treated in hydrothermal conditions in autoclave, and the modification of calcium oxide/silica (C/S) molar ratio of the initial mixtures to the value of 0.83 would enhance the properties of such products.
TL;DR: The findings in this work highlight the application potential of CaO-AcS for gaseous Hg2+ sampling and measurement from coal-fired flue gas.
TL;DR: In this paper, the properties of preserved salted eggs from Chaiya, Suratthani, Thailand and their abilities to remove phosphorus from a low phosphorus-containing wastewater (4 g L−1) were compared to those from duck eggshells.
Abstract: Eggshells represent a large volume of unused calcium carbonate-rich material which can be valorized into adsorbents for wastewater treatment through a calcination process which converts calcium carbonate into calcium oxide. In this work, the properties of preserved salted eggs from Chaiya, Suratthani, Thailand and their abilities to remove phosphorus from a low phosphorus-containing wastewater (4 g L−1) were compared to those from duck eggshells. Different calcination temperatures (500 and 700 °C), calcination periods (2 and 4 h) and adsorbent dosages were tested. Chemical composition, functional groups, surface area, porosity, particle size, and morphology were determined for all samples. The specific surface area was in the range of 0.44–0.92 m2 g−1. The maximum experimental phosphorus removal from salted eggshells was equal to 96.2%. It was obtained from calcined samples at 700 °C for 4 h at adsorbed phosphorus of 3.32 ± 0.06 mg g−1 after 240 min. This study suggests that the egg preservation process enhanced the adsorption ability of eggshells at high calcination temperature. Lower calcination temperature did not result in good phosphorus removal (
TL;DR: In this paper, the authors investigated the feasibility of roasting waste calcium arsenate with charcoal powder, serving the purpose of minimizing and/or reclaiming the waste by obtaining elemental arsenic of commercial value while regenerating recyclable CaO.