Showing papers on "Calcium oxide published in 2022"
TL;DR: Wang et al. as mentioned in this paper synthesized a sorbent with resistance to sintering via citric acid and calcine method, which was innovatively employed to the adsorption of As2O3 combining experiment and theoretical analysis.
20 citations
TL;DR: In this paper , a systematic understanding of fundamental aspects of the CaCO3 calcination is reviewed, and the effects of calcination reaction conditions on the sintering of CaO grains and the resulting decline in CO2 capture performance during the cyclic operation were discussed.
20 citations
TL;DR: In this paper , the use of clay/CaO heterogeneous catalyst for the production of biodiesel from waste cooking oil was investigated, where the catalyst was synthesized from clay and calcined using calcium oxide under controlled conditions.
19 citations
TL;DR: Wang et al. as discussed by the authors synthesized a sorbent with resistance to sintering via citric acid and calcine method, which was innovatively employed to the adsorption of As2O3 combining experiment and theoretical analysis.
19 citations
TL;DR: In this paper , a series of N-doped hierarchical porous carbons were successfully prepared from the direct pyrolysis process of three food waste components, and the porous biochar that derived from bone showed a high specific surface area (1405.06 m2/g) and sizable total pore volume (0.97 cm3/g).
17 citations
TL;DR: In this paper, the influence of macro-element calcium in coal on the spontaneous combustion of coal was investigated using In-situ infrared spectroscopy, and the results showed that CaO, CaCO3 and Ca(Ac)2 have a catalytic effect on the oxidation of organic matter in coal.
16 citations
TL;DR: In this article , the influence of macro-element calcium in coal on the spontaneous combustion of coal was investigated using In-situ infrared spectroscopy, and the results showed that CaO, CaCO3 and Ca(Ac)2 have a catalytic effect on the oxidation of organic matter in coal.
16 citations
TL;DR: In this article , the upgrading of simulated biogas with an equal mole ratio of methane and carbon dioxide through dry reforming over calcium promoted on cobalt-based catalysts was investigated.
15 citations
TL;DR: In this paper , the effect of two major chemical compositions in the CKD and FA on the long-term compressive strength of cement mortar, especially their Calcium Oxide (CaO) and Silicon Dioxide (SiO 2 ) contents, was investigated.
Abstract: Environmental issues are raised from the global warming due to raised Carbon Dioxide (CO 2 ) emissions of factories worldwide. Cement manufacturing is highly energy- and emissions-intensive because of the extreme heat required to produce it. Producing a ton of cement requires 4.7 million British Thermal Units (BTU) of energy, equivalent to about 400 pounds of coal, and generates nearly a ton of CO 2 . Therefore, it is necessary to reduce cement production; as a result, it contributes to solving those issues. This study investigates the effect of two major chemical compositions in the CKD and FA on the long-term compressive strength of cement mortar, especially their Calcium Oxide (CaO) and Silicon Dioxide (SiO 2 ) contents; furthermore, their chemical, mineralogical, and microstructure are compared. In addition, 228 data for FA-modified cement mortar and 167 data for CKD-modified cement mortar were collected from previous literature and used to develop predictive models to forecast the compressive strength of cement mortar modified with CKD and FA. The dataset contained different mix proportions of the cement mortar, such as curing times, various SiO 2 (%), CaO (%), water/cement ratio (w/c), and curing times up to 90 days. The result of the Multi expression programming (MEP), full quadratic (FQ), Nonlinear regression (NLR), and artificial neural network (ANN) models were used to quantify the effect of CaO and SiO 2 . The short-term compressive strength of cement mortar modified with fly ash (from 1 to 28 days) decreases with increasing the fly ash content, while the long-term compressive strength (from 28 to 90 days) increases by up to 15% replacement of cement with fly ash. However, the compressive strength of the cement kiln dust modified-cement mortar decreases with increasing the cement kiln dust content. The sensitivity evaluation discovered that the most influential parameter for predicting compressive of the cement mortar modified with CKD and modified with FA is the curing time.
14 citations
TL;DR: In this paper , the physical and chemical properties of the synthesized catalysts were characterized, and the effect of different experimental factors on the biodiesel yield was studied, revealing that the CaO-TiO2 nano-catalyst displayed bifunctional properties, has both basic and acid phases, and leads to various effects on the catalyst activity in the transesterification process.
12 citations
TL;DR: In this article , the effect of mechanical, chemical, and thermal activation methods on the properties of recycled concrete powder (RCP) were investigated, and the most feasible and effective activation method is thermal activation (800 °C), followed by chemical activation (Ca(OH)2+CaSO4), and mechanical activation (75 min).
Abstract: Recycled concrete powder (RCP) poses a considerable challenge with respect to effective utilisation of construction and demolition waste (CDW) resources due to its low activity, high water demand, and potential to cause dust pollution during storage. A suitable activation method is necessary for stimulating the potential activity of RCP and enhancing its utilisation. Therefore, the effect of mechanical, chemical, and thermal activation methods on the properties of RCP were investigated in this study. Mechanical and thermal activation were helpful for the activity of RCP due to the modification of particle size and distributions. RCP exhibits a higher content of SiO2 and a lower content of CaO as well as the main crystal phases of quartz, calcite, gismondine, and dolomite. After 400–800 °C thermal activation, dolomite is not observed while the RCP shows new active components (such as larnite, calcium silicate, and calcium oxide). The chemical activation test highlights that CaO (3%) is the most optimal, followed by CaSO4 (1%) and Na2SO4 (2%), while Ca(OH)2 (4%) has the least optimal activation effect on the strength activity index (SAI) of RCP mortar. For combined activation, Ca(OH)2 and CaSO4 with 1:1 ratio has the most optimal activation effect, and the SAI reaches 80.27%. Based on the mechanical performance, SAI, and micro-characteristics, the most feasible and effective activation method is thermal activation (800 °C), followed by chemical activation (Ca(OH)2+CaSO4), and mechanical activation (75 min). This study proposes a useful combined activation method for RCP that verifiably contributes to the application of CDW.
TL;DR: In this paper, coal-related model compounds with representative O-containing functional groups [1,4-naphthalenedicarboxylic acid, poly (4-vinylphenol) and poly (2,6-dimethyl-1, 4-phenylene oxide)] were chosen to study the primary pyrolysis product distribution and composition over calcium components.
TL;DR: In this paper , the structural characterization of CaO NPs obtained by using UV-Vis, FTIR, XRD, and SEM-EDS indicates the presence of purity and primarily aggregated spherical nanosized material with an average size of 32.08 nm observed.
Abstract: Calcium oxide nanoparticles (CaO NPs) have unique catalytic and biological properties; their activities are highly influenced by their morphology; as a result, these characteristics are most needed for various applications in several fields, including material science, environmental science, and medicinal science. The primary motivation for synthesizing CaO NPs using a biological method is to suppress the usage of hazardous chemicals used in making its process, which will be more cost-effective and ecologically profitable. However, due to the complexity of the biological extracts employed in chemical processes, large-scale manufacturing of nanoparticles via the green synthesis approach remains a significant problem. As a result, the production of CaO NPs utilizing Moringa oleifera plant leaves aqueous extract as an alternative biological agent for capping, stabilizing, and reducing agents due to rich phytochemical parameters in synthesis was investigated in this study. The structural characterization of the CaO NPs obtained by using UV-Vis, FTIR, XRD, and SEM-EDS indicates the presence of purity and primarily aggregated spherical nanosized material with an average size of 32.08 nm observed. The XRD study revealed that heat annealing increased the size of the crystallites, favoring monocrystalline. Finally, these findings, together with the cheap cost of synthesizing the plant-mediated CaO NPs produced, show good antimicrobial (gram-positive) activities.
TL;DR: In this article , the preparation of CaO nanoparticles (NPs) was reported by a precipitation method, using CaCl 2 and NaOH as starting raw materials, and the produced NPs were characterized for chemical composition, phase composition, particle size distribution, morphological features, specific surface area, and crystallite sizes.
Abstract: Abstract In this paper, the preparation of calcium oxide (CaO) nanoparticles (NPs) is reported by a precipitation method, using CaCl 2 and NaOH as starting raw materials. The produced NPs were characterized for chemical composition, phase composition, particle size distribution, morphological features, specific surface area, and crystallite sizes. It is shown that calcination of Ca(OH) 2 in vacuum takes place faster/at a lower temperature compared to the calcination in air due to the higher entropy of the gaseous product of calcination. It is also shown that when these CaO nanoparticles are kept at room temperature in air, they fully and spontaneously transform into CaCO 3 within 3 weeks. Therefore, if this material is disposed in open fields (not necessarily in industrial conditions), it is able to capture carbon dioxide from normal air slowly, but surely. However, when the CaO nanoparticles are kept in the air at 100–200 °C, they mostly capture water vapor from the air instead of carbon dioxide, and the resulting calcium hydroxide blocks the carbon dioxide capture by CaO nanoparticles.
TL;DR: In this article , the adsorption isotherm of naphthalene on calcium oxide nanoparticles was described by Langmuir, Freundlich, Temkin and Dubinin Radushkevich and theoretical maximum monolayer adaption capacity was found to be 63.81 mg/g at 303 K.
Abstract: The adsorptive nature of calcium oxide nanoparticles in aqueous sample of naphthalene in presence of Ca2+ ions was estimated. Enhanced efficiency of calcium oxide regeneration (90%) with the aid of calcium chloride in the solution concentration of 0.002-0.1 M was depicted. The less degree of toxic naphthalene desorption merged with SEM, FTIR and XRD characterization data portrays the importance of naphthalene adsorption onto calcium oxide using calcium chloride for regeneration. Batch adsorption studies were performed to evaluate the operating parameters such as pH, naphthalene concentration, contact time and impact of Ca2+ on naphthalene study. The adsorption isotherm of naphthalene on calcium oxide nanoparticle was described by Langmuir, Freundlich, Temkin and Dubinin Radushkevich and theoretical maximum monolayer adsorption capacity was found to be 63.81 mg/g at 303 K. The adsorption kinetic best fitted with pseudo second order kinetic model. The positive influence of making the addition of Ca2+ ions into naphthalene solution for its rapid adsorption was elucidated which is leaded by a probable increase in sorption capacity for naphthalene molecules at lower concentrations. The stable nature of crystallinity of calcium oxide and a less degree of naphthalene molecules leaching during consecutive cycles of adsorptive process and nanoparticle regeneration was also scrutinized.
TL;DR: In this article , the effects of calcination temperatures (550 °C, 700 °C and 900 °C) on characteristics and elemental composition of calcium oxide derived from shells of four marine species collected in Thailand: oyster ( Saccostrea cucullata), green mussel ( Perna viridis), blue swimming crab ( Portunus pelagicus ), and cuttlefish ( Sepia brevimana ).
TL;DR: In this paper, the adsorption isotherm of naphthalene on calcium oxide nanoparticles was described by Langmuir, Freundlich, Temkin and Dubinin Radushkevich and theoretical maximum monolayer adaption capacity was found to be 63.81% at 303 K.
TL;DR: In this paper , the application of synthesized calcium oxide nanoparticles by sol-gel process from a waste resource of hen eggshells for the adsorption of lead ion from aqueous solutions was investigated.
TL;DR: In this paper , coal-related model compounds with representative O-containing functional groups [1,4-naphthalenedicarboxylic acid, poly (4-vinylphenol) and poly (2,6-dimethyl-1, 4-phenylene oxide)] were chosen to study the primary pyrolysis product distribution and composition over calcium components.
TL;DR: In this article , the pyrolysis mechanism of Spirulina platensis with calcium oxide was investigated using a thermogravimetric analyzer and a fixed bed reactor, respectively.
TL;DR: In this paper , a green titanium doped HAP photocatalyst (WMPHAP-Ti) was used to degrade Congo Red dye in aqueous solution and process variables such as pH, reaction time, dose of catalyst and concentration were optimised by one factor at a time analysis.
TL;DR: In this paper , the effects of three phosphorus impurities (Ca3(PO4)2, CaHPO4, Ca(H2PO42)2) on the decomposition of CaSO4, formation of minerals, microstructure of the clinker, and the hydration and mechanical properties of the cement were studied.
TL;DR: In this article, the suitability of low-calcium fly ash (FA) for stabilizing expansive soil (ES) using the in-situ deep soil mixing (DSM) technique was investigated.
Abstract: This study investigates the suitability of low-calcium fly ash (FA) for stabilizing expansive soil (ES) using the in-situ deep soil mixing (DSM) technique. The primary objective of the stud...
TL;DR: In this paper , the use of methane, an abundant fuel, is investigated as the reductant in chemical looping syngas production, and the looping materials became more active with cycling using methane as the fuel.
Abstract: Previous work on calcium ferrites showed they were able to convert syngas to hydrogen via chemical looping. The mixture of iron and calcium and their oxides has different thermodynamic properties than iron oxide alone. Here, the use of methane, an abundant fuel, is investigated as the reductant in chemical looping syngas production. In contrast to syngas-fueled cycles, the looping materials became more active with cycling using methane as the fuel. When reduced by methane, the looping material often showed a significant induction period, indicating that products of reduction (in particular metallic Fe) acted as a catalyst for further reduction. The behavior in a thermogravimetric analyzer (TGA) and a fluidized bed was comparable, i.e., no degradation with cycling. The reduced C2F appeared to be easily reformed when oxidized with CO2, and there was little evidence of bulk phase segregation. The improved kinetics on cycling was likely due to the separation of metallic Fe onto the surface. Using hydrogen to partially reduce C2F promotes the catalytic pyrolysis of methane.
TL;DR: In this paper , the suitability of low-calcium fly ash (FA) for stabilizing expansive soil (ES) using the in-situ deep soil mixing (DSM) technique was investigated.
Abstract: This study investigates the suitability of low-calcium fly ash (FA) for stabilizing expansive soil (ES) using the in-situ deep soil mixing (DSM) technique. The primary objective of the study was to control the swell-shrink behavior of ES and achieve higher strength characteristics. Owing to the presence of a low amount of calcium oxide (CaO) in Class-F fly ash (FA), an alkali environment is required to produce pozzolanic reactions involving silica and alumina. In this study, the alkali environment in the FA was created by adding a 50:50 ratio of sodium hydroxide (NaOH) and liquid sodium silicate (Na2SiO3) solution, referred to as liquid alkali activator (LAA). The properties of stabilized ES were investigated through Atterberg limits, one-dimensional swell tests, linear shrinkage tests, consolidation tests, and unconfined compressive strength tests. Further, scanning electron microscopy images and X-ray diffraction tests were performed on stabilized samples to understand the microstructural and physicochemical reaction mechanisms. The tests were conducted by varying the binder ratio (LAA/FA) from 0 to 1.5 for curing periods of 7, 14, and 28 days. The results showed that the binder ratio LAA/FA=1.5 effectively controlled the swell-shrink behavior of ES. A 10-fold improvement in UCS was observed for LAA/FA=1.50 at a 28-day curing period. Linear shrinkage strains and swell potential of the ES were reduced by 97% and 83%, respectively, with LAA/FA=1.5 at 28 days of curing. Overall, LAA/FA=1.5 is considered an optimum binder ratio to prepare DSM columns.
TL;DR: In this article , a procedure for the synthesis of calcium oxide has been developed, which consists in heat treatment of an aqueous solution of calcium acetate and d-glucose at 350 and then at 700 °C.
TL;DR: In this paper , the authors investigated an innovative and improved method for stabilization/solidification (S/S) of MSWI FA with coal gangue based geopolymer by the addition of active calcium content.
TL;DR: In this paper , non-edible Ceiba pentandra seed oil (CPSO) was used to produce biodiesel, which yielded an oil content of 18.6% after extraction.
TL;DR: In this paper , three distinct mathematical models, including β, rational, and Vipulanandan p-q models, were proposed to predict stress-strain relationships of the lime-based plasters.