Showing papers on "Calcium oxide published in 2018"
TL;DR: In this article, the authors investigated the mechanical and hydration properties of CaO/Na2CO3-activated slag binders by measuring the compressive strength, pH value of pore solution and non-evaporable water content up to 28 days.
116 citations
TL;DR: In this article, the optical properties of desert dune sand are investigated to evaluate its performance as a direct solar absorber, and it is shown that the samples appear to be thermally stable between approximately 650°C to 1000°C following an initial mass loss occurring during the first heating cycle.
83 citations
TL;DR: In this paper, the effect of calcium-rich compounds on setting time and compressive strength development of fly ash (FA) pastes was investigated, and it was shown that adding three calcium compounds, namely, Portland cement (PC), calcium hydroxide (CH) and calcium oxide (CaO), resulted in an acceleration in the setting time.
66 citations
TL;DR: In this paper, the potential of chicken eggshell waste to produce calcitic lime was explored, and the results showed that the most reactive class of calcium oxides from eggshells was R5-60°C within 10min, the same as that of calcium oxide from limestone.
Abstract: Eggshells wastes are produced in huge amounts worldwide. The recycling or valorization of this waste, which otherwise is usually disposed in landfills, represents an opportunity within a circular economy perspective. In the present work, the potential of chicken eggshell waste to produce calcitic lime was explored. After collection from an industry supplier, the waste was thoroughly characterized for its mineralogical, chemical, and thermal properties. The material was calcined at 1000 °C, and the obtained calcium oxide was evaluated for its reactivity in wet slaking tests. Comparison was made with commercial limestone used as reference. It was found that the calcium oxide from eggshell waste belonged to the most reactive class (R5—60 °C within 10 min), the same of the calcium oxide from limestone. However, different times were obtained to reach 60 °C (25 s and 4:37 min:s) and for 80% of the reaction (28 s and 5 min) for calcium oxide from limestone and eggshell waste, respectively. The lower reactivity of calcium oxide from eggshell waste was related to its larger size particles with smoother surfaces and lower specific surface area in comparison to limestone calcium oxide. Industrial, environmental and economic implications concerning the use of this waste to produce lime were also evaluated. The eggshell waste could be all consumed at an industrial scale in Portugal allowing for approximately 2.6% partial substitution of limestone in a lime factory.
47 citations
TL;DR: Kinetic studies showed that iron and aluminium anodes obey pseudo-second order kinetic, and this hybridisation is effective for sulfate removal, and that a bipolar configuration showed better results than the monopolar configuration.
43 citations
TL;DR: In this article, a carbonated alumina doped by calcium oxide was successfully synthesized by a simple, cost effective and rapid microwave combustion method (MCM) and the effect of fuel type on the structural and performance of the sample in the microwave-assisted transesterification reaction were examined.
43 citations
TL;DR: In this paper, the role of calcium oxide on ash fusion properties was investigated by molecular dynamics simulations and thermodynamics calculations, which was compared with the liquidus temperature calculated by the FactSage codes.
35 citations
TL;DR: In this article, the effect of calcination conditions on the formation of the metal oxide phases and the catalytic activity of the resulting dolomite-derived mixed metal compounds was studied.
31 citations
TL;DR: In this article, a carbon arrestor process was used to produce a functionalized biochar product for use as an agronomic soil amendment, and the addition of lime to the pyrolysis process resulted in a significant reduction in CO2 evolution via the carbonation reaction of CaO and the formation of H2 and CH4.
Abstract: This study forms the fundamental foundation for the development of a novel carbon arrestor process to produce a functionalized biochar. In this study, an experimental investigation was carried out on the production and characterization of biochar produced using a novel carbon arrestor process, which operates under the principle of in situ pyrolysis of biomass with lime (CaO) to produce a functionalized biochar product for use as an agronomic soil amendment. Two biomass sources were used, a woody biomass, Eucalyptus pilularis (or blackbutt) sawdust, and a herbaceous biomass, wheat stem. Characterization of the biochars produced as well as the gaseous products was completed via thermogravimetric analysis, micro gas chromatography, solid-state Fourier transform infrared (FTIR) spectroscopy, nitrogen adsorption, and scanning electron microscopy. The addition of CaO to the pyrolysis process resulted in a significant reduction in CO2 evolution via the carbonation reaction of CaO and the formation of H2 and CH4 ...
26 citations
TL;DR: In this paper, a calcium-based sorbent was synthesized from calcium acetate and mesoporous silica through chemical impregnation method, and the results showed that the sorbent possessed a good surface structure as the calcium salt decomposed to calcium oxide (CaO) through multiple calcination steps.
23 citations
TL;DR: In this article, a sustainable hydraulic cement was developed based primarily upon the alkali aluminosilicate chemistry, which employed coal fly ash, granulated ground blast furnace slag and natural feldspar as sources of alkalis and soluble silica.
TL;DR: In this article, the authors proposed the synthesis of nanocrystalline calcium oxide by sonication assisted reverse emulsion technique, which possesses 153 times higher specific surface area compared to commercial calcium oxide due to its smaller crystallite size and particle size.
Abstract: The present work proposes the synthesis of nanocrystalline calcium oxide by sonication assisted reverse emulsion technique The synthesized and the commercially available calcium oxide were characterized by various techniques The prepared material possesses 153 times higher specific surface area as compared to commercial calcium oxide due its smaller crystallite size and particle size The performance of both the calcium oxide as a catalyst were investigated for the transesterification reaction of soybean oil under ultrasound irradiation with identical reaction conditions of power and frequency The influence of different operating parameters on the conversion of soybean oil were studied for the synthesized catalyst Under the optimal operating conditions viz nanocrystalline catalyst loading of 4 wt% of oil, methanol to oil molar ratio of 6:1, temperature of 60 °C and ultrasonic power of 21289 kW/m2, the conversion of oil was 8989% in 80 min of reaction time The synthesized catalyst shows 1881% enhanced conversion of oil as compared to commercial catalyst at the same operating conditions Finally, the activation energy of reaction was also determined at the optimized operating conditions for the synthesized catalyst and was found to be 5426 kJ/mol
TL;DR: In this article, the effect of the material factors, i.e., type and the particle size of cement, the calcium oxide content in the fly ash, the fineness modulus of fine aggregate, the types and the dosages of superplasticizers (SPs), on the carbonation properties of the concrete was studied.
Abstract: The carbonation is one of the main factors to cause the degradation of the properties in the reinforcement concrete structures In this study, the effect of the material factors, ie the type and the particle size of cement, the calcium oxide content in the fly ash, the fineness modulus of fine aggregate, the types and the dosages of superplasticizers (SPs), on the carbonation properties of the concrete was studied The carbonation coefficient (K) values of the concrete mixtures with various material factors were obtained The control indexes of the material to resist against carbonation of the reinforced concrete were proposed The test results show that the type and the particle size of cement, the calcium oxide content in the fly ash and the types of SPs have the significant influence on the carbonation coefficient (K) The concrete mixture with the excellent resistance against carbonation can be prepared by using cement with the fine particle size and the high-calcium fly ash and the PCA SP of lower dosage in the concrete
TL;DR: Tantalum-doped hydroxyapatite (Ta-Doped HA) nanopowders with different Ta contents were synthesized by a wet-chemical precipitation route as mentioned in this paper.
TL;DR: Different composition of composite material of zirconium dioxide co-doped with magnesium oxide [MgO(x)] and calcium oxide [CaO(y)] according to the general molecular formula {1 ǫ−ǫ(x+ǫ) +ǫ+ǔ)} were prepared by co-precipitation method and characterized by different techniques, such as XRD, FTIR, TG-DTA and SEM as discussed by the authors.
TL;DR: Except for Butere, where maize did not respond to fertilizer alone, the other sites are not sufficiently acid to permit the solubility of Al to toxic levels for maize, so more attention should be focused on N and P replenishment at these sites than liming.
Abstract: Many soils in Western Kenya are acidic and deficient in nitrogen and phosphorus. Acidity hinders crop responses to fertilizers applied to remedy nutrient deficiencies. The common liming materials used to ameliorate acidity are Calcium Oxide (CaO) and Calcium Carbonate (CaCO3) in powdery formulations. Broadcasting these materials by hand followed by incorporation is recommended on smallholder farms to enhance their effectiveness but this is laborious. Granular lime which is easier to handle was recently introduced but there is little information on its effectiveness. This study therefore tested the effects of CaCO3, CaO and granulated lime, applied alone or in combination with fertilizer (Diammonium phosphate (DAP) + calcium ammonium nitrate (CAN)), on maize yield for three seasons, 2015 long rains (LR), 2015 short rains (SR) and 2016 LR at four sites: Butere, Emuhaya, Mumias and Kakamega North in Western Kenya. CaCO3 and CaO were applied at 2 t ha-1 once in the 2015 LR while granular lime was applied at a ratio of 1:1 with DAP per season. There was no significant effect of lime type on maize yields. Maize did not respond to lime without fertilizer. Application of lime, irrespective of the type, with fertilizer, did not give yields that were significantly different from those of fertilizers alone except at Butere in the 2015 LR when application of CaO and CaCO3 with fertilizer significantly out yielded those with fertilizer applied alone. Similar results were obtained with granular lime in the 2015 SR at Emuhaya. It was concluded that except for Butere, where maize did not respond to fertilizer alone, the other sites are not sufficiently acid to permit the solubility of Al to toxic levels for maize. More attention should therefore be focused on N and P replenishment at these sites than liming. At Butere, soil acidity is a problem and lime should be applied together with fertilizers.
Key words: Aluminum toxicity, lime, maize, nitrogen, phosphorus.
24 Apr 2018-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a steel-inclusion kinetic model is used for mass transfer to the inclusion interface and diffusion within the calcium aluminate phases formed on the inclusion, which is then coupled with a previously developed steel-slag kinetic model.
Abstract: Calcium treatment of steel is typically employed to modify alumina inclusions to liquid calcium aluminates. However, injected calcium also reacts with the dissolved sulfur to form calcium sulfide. The current work aims to develop a kinetic model for the evolution of oxide and sulfide inclusions in Al-killed alloyed steel during Ca treatment in the ladle refining process. The model considers dissolution of the calcium from the calcium bubbles into the steel and reduction of calcium oxide in the slag to dissolved calcium. A steel–inclusion kinetic model is used for mass transfer to the inclusion interface and diffusion within the calcium aluminate phases formed on the inclusion. The inclusion–steel kinetic model is then coupled with a previously developed steel–slag kinetic model. The coupled inclusion–steel–slag kinetic model is applied to the chemical composition changes in molten steel, slag, and evolution of inclusions in the ladle. The result of calculations is found to agree well with an industrial heat for species in the steel as well as inclusions during Ca treatment.
TL;DR: In this paper, the authors report an experiment intended as a tool to introduce chemistry and materials science students to several chemical concepts through the determination of the best experimental conditions for the formation of calcium oxide (lime) from a source of high content of calcium carbonate (eggshells).
Abstract: In this paper, we report an experiment intended as a tool to introduce chemistry and materials science students to several chemical concepts through the determination of the best experimental conditions for the formation of calcium oxide (lime) from a source of high content of calcium carbonate (eggshells). Thermal gravimetric analysis (TGA), infrared spectroscopy (FTIR), and qualitative tests were used to optimize the experimental conditions of calcination temperature and time for the formation of calcium oxide.
TL;DR: In this article, the effects of CaO and Fe2O3 on the Na2CO3 activation-acid leaching process were studied systematically using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Inductively Coupled Plasma (ICP).
TL;DR: In this article, a series of calcium-based sorbents were chosen to evaluate the selective adsorption performance of mercury, these sarsbents included a calcium oxide adsorbent, a KCl-doped calcium oxide adorbent and a K2CO3-decompositioned calcined calcium oxide (C-SiO2), which all supported by mesoporous silica.
TL;DR: The results suggest that the dry mechanochemical process is a robust method to produce metallic nanoparticles and nanocomposites.
Abstract: We report an environmentally benign and cost-effective method to produce Fe and Co magnetic metal nanoparticles as well as the Fe/Cao and Co/CaO nanocomposites by using a novel, dry mechanochemical process. Mechanochemical milling of metal oxides with a suitable reducing agent resulted in the production of magnetic metal nanoparticles. The process involved grinding and consequent reduction of low-costing oxide powders, unlike conventional processing techniques involving metal salts or metal complexes. Calcium granules were used as the reducing agent. Magnetometry measurements were performed over a large range of temperatures, from 10 to 1273 K, to evaluate the Curie temperature, blocking temperature, irreversibility temperature, saturation magnetization, and coercivity. The saturation magnetizations of the iron and cobalt nanoparticles were found to be 191 and 102 emu g-1, respectively. The heating abilities of these nanoparticles suspended in several liquids under alternating magnetic fields were measured and the specific loss power was determined. Our results suggest that the dry mechanochemical process is a robust method to produce metallic nanoparticles and nanocomposites.
TL;DR: In this article, the roles of calcium oxide on fluorapatite crystal morphology, crystallization kinetics behavior and mechanical property of functional glass-ceramics in the SiO 2 -Al 2 O 3 -K 2 O-CaO-P 2 O 5 system were investigated.
TL;DR: In this article, the performance of glycerol-enriched calcium oxide in catalyzing the methanolysis of crude Jatropha curcas oil containing high free fatty acids content was systematically researched by examining the effects of glyacerol dose, temperature, time, methanol-to-oil molar ratio and calcium oxide (CaO) amount on the process.
Abstract: The present article demonstrates a superior catalytic performance of glycerol-enriched calcium oxide for biodiesel production than other calcium-based counterparts. The proficiency of glycerol-enriched calcium oxide in catalyzing the methanolysis of crude Jatropha curcas oil containing high free fatty acids content was systematically researched by examining the effects of glycerol dose, temperature, time, methanol-to-oil molar ratio and calcium oxide (CaO) amount on the process. Acid value of oil was lowered by 49 times and the maximum oil conversion of 96.1% was reported after the methanolysis reaction that indicated the improved performance of calcium oxide, after its treatment with glycerol, in accelerating biodiesel production from crude oil with very high free fatty acids amount. An interaction between the reaction variables, their influence on the methanolysis and optimum conditions affecting the process were moreover determined by means of the regression analysis (response surface methodology). The statistical analysis suggested that both CaO amount and mole ratio of methanol-to-oil had a significant impact on the current biodiesel production process.
01 Mar 2018
TL;DR: In this article, the physical, chemical, mineralogical, and morphological properties of ground limestone using X-ray fluorescence (X-RF), X-RD, Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy / energy dispersive x-ray spectroscopic (SEM-EDS) respectively are investigated.
Abstract: In Malaysia, limestone is essentially important for the economic growth as raw materials in the industry sector. Nevertheless, a little attention was paid to the physical, chemical, mineralogical, and morphological properties of the limestone using X-ray fluorescence (X-RF), X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy / energy dispersive x-ray spectroscopy (SEM-EDS) respectively. Raw materials (limestone rocks) were collected from Bukit Keteri area, Chuping, Kangar, Perlis, Malaysia. Lab crusher and lab sieved were utilized to prepare five different size of ground limestone at (75 µm, 150 µm, 225 µm, 300, and 425 µm) respectively. It is found that the main chemical composition of bulk limestone was Calcium oxide (CaO) at 97.58 wt.% and trace amount of MnO, Al2 O3 , and Fe2 O3 at 0.02%, 0.35%, and 0.396% respectively. XRD diffractograms showed characteristic peaks of calcite and quartz. Furthermore, main FTIR absorption bands at 1,419, 874.08 and 712.20 cm-1 indicated the presence of calcite. The micrographs showed clearly the difference of samples particle size. Furthermore, EDS peaks of Ca, O, and C elements confirmed the presence of CaCO3 in the samples.
01 Jan 2018
TL;DR: In this paper, two CaO nanoparticles were synthesized by chemical coprecipitation and thermal decomposition of chicken egg shells and the obtained powdered particles were characterised using Fourier transform infrared spectroscopy, SEM and X-ray diffraction techniques.
Abstract: Calcium oxide nanoparticles and its potential towards purification of vehicle gas exhaust were investigated in this work. Calcium oxide nanoparticles were synthesised and its efficiency in absorbing constituents of vehicle gas exhaust has been estimated. Calcium oxide nanoparticles were synthesised by chemical coprecipitation and thermal decomposition of chicken egg shells. The obtained powdered particles were characterised using Fourier transform infrared spectroscopy, SEM and X-ray diffraction techniques. The powdered products on the addition of polyvinyl alcohol (PVA) have been fabricated into a nanoporous membrane using electrospinning technique. The thin film was made with varying weight per cent of CaO particles. The efficiency of these membranes was estimated by passing exhaust gas through it using exhaust gas analyser/smoke metre. The FT-IR analysis confirms the presence of CaO particles. The SEM and XRD of the obtained samples showed the crystalline nature of CaO nanoparticles, and the size of the powdered CaO was found to be ~15–20 nm. The nanoporous electrospun membrane has low filtration capacity. The other two CaO nanoparticles with varying weight percentage showed great potential towards purifying vehicle gas exhaust. It reduces the quantity of HC, CO, CO2 in high rates. It is also proved that increase in the concentration of CaO increased the efficiency of filtration.
TL;DR: In this article, an enhanced carbon dioxide mineral sequestration with steelmaking slag in dilute alkali solution was analyzed through experiments and process evaluation, and the material and energy balance of the entire process was calculated and the net carbon dioxide sequestration efficiency at different reaction times was evaluated.
Abstract: Carbon dioxide mineral sequestration with steelmaking slag is a promising method for reducing carbon dioxide in a large-scale setting. Existing calcium oxide or calcium hydroxide in steelmaking slag can be easily leached by water, and the formed calcium carbonate can be easily wrapped on the surface of unreacted steelmaking slag particles. Thus, further increase in the carbonation reaction rate can be prevented. Enhanced carbon dioxide mineral sequestration with steelmaking slag in dilute alkali solution was analysed in this study through experiments and process evaluation. Operating conditions, namely alkali concentration, reaction temperature and time, and liquid-to-solid ratio, were initially investigated. Then, the material and energy balance of the entire process was calculated, and the net carbon dioxide sequestration efficiency at different reaction times was evaluated. Results showed that dilute alkali solution participated in slowing down the leaching of active calcium in the steelmaking slag and in significantly improving carbonation conversion rate. The highest carbonation conversion rate of approximately 50% can be obtained at the optimal conditions of 20 g/L alkali concentration, 2 mL/L liquid-to-solid ratio, and 70 °C reaction temperature. Carbonation reaction time significantly influences the net carbon dioxide sequestration efficiency. According to calculation, carbon dioxide emission of 52.6 kg/t-slag was avoided at a relatively long time of 120 min.
TL;DR: In this article, metal oxide (calcium oxide, zinc oxide, magnesium oxide) powders were used to provide antibacterial functionality to coated materials and the results indicated that the antibacterial effect of used metal oxides was strongly arisen from radical oxygen species.
Abstract: The main aim of this study was to produce PVC coated textile based antibacterial textile material and to investigate the antibacterial mechanism with detailed analyzes. Metal oxide (calcium oxide, zinc oxide, magnesium oxide) powders were used to provide antibacterial functionality to coated materials. Metal oxide concentrations were varied between 5–35 %. Antibacterial tests were performed according to ISO 22196–2011 standard. Antibacterial efficiency of the samples was tested for each metal oxide type and concentration with L. innocua species. The antibacterial mechanism was investigated with ESR technique, fluorescent microscobe and microplate reader using DCFH-DA probe, UV-vis spectrometer using fluorescein probe. The results indicated that the antibacterial effect of used metal oxides was strongly arisen from radical oxygen species. The morphology of coatings was investigated with SEM and the distribution of metal oxide particles on the surface was examined with EDX analysis and EDX mapping. The changes on the molecular basis of the coating due to the metal oxide addition was analyzed with FT-IR spectroscopy. High antibacterial efficiencies (up to 100 %) were detected. It is suggested that the non-toxic metal oxides can be used as an effective and economically feasible alternative to conventional antibacterial additives for industrial applications such as conveyor belts.
02 May 2018
TL;DR: In this article, the authors used X-ray fluorescence (XRF) and FTIR test to determine the characteristics of CaO calcined limestone from Ambunten Sumenep.
Abstract: Calcium oxide (CaO) and calcium carbonate (CaCO3) are widely used in industry. CaO and CaCO3 can be synthesized or derived from limestone. The purpose of this study to determine the characteristics of CaO calcined limestone from Ambunten Sumenep. Lime in calcined at 850 ° C for 6 hours. Characterization of X-ray fluorescence (XRF) was conducted to determine the chemical composition of limestone, X-ray diffraction test (XRD) to find the lime crystalline phase and FTIR test to determine the absorption of wave number. XRF test results showed that the limestone chemical composition consisted of Ca of 95.37% as the dominant element, Mg of 4.1%, Fe 0.17% and Y by 0.39%. The XRD test results showed that the limestone crystal phase is ankerite (Ca [Fe, Mg] [CO3] 2) and after the calcined phase calcination is vaterite (Ca [OH] 2), calcite (CaO) and calcite (CaCO3). While the FTIR test results show that the CaO spectra are seen at 3741.24, 1417.12 and 874.14 cm -1 .
TL;DR: In this paper, a quail eggshell was decomposed at 600-1100 o C to form calcium oxide and it was characterized by X-Ray measurement, FTIR and SEM spectroscopy to analyze the functional groups and the surface morphology, followed by N 2 adsorption desorption methods to determine the surface area.
Abstract: Calcium oxide decomposed from quail eggshell was used as catalyst for biodiesel synthesis from waste palm oil. Prior to being used, the quail eggshell was decomposed at 600-1100 o C to form calcium oxide and it was characterized by X-Ray measurement, FTIR and SEM spectroscopy to analyze the functional groups and the surface morphology, followed by N 2 adsorption desorption methods to determine the surface area. The results of X-Ray analysis powder pattern show that the decomposition of quail eggshell at 900 o C gave calcium oxide that has similar characteristic to the standard CaO from Joint Committee of Powder Diffraction Standard (JCPDS). The FTIR spectrum indicated vibration of calcium oxide from quail eggshell have a similar pattern with the calcium oxide of the standard. The SEM analysis showed that morphology of quail eggshell was changed after decomposition at 900 o C and it have the mesoporous structure. The biodiesel from waste palm oil was synthesized using CaO catalyst from quail eggshell decomposed at 900 o C. The biodiesel product has density of 0.86 g/cm 3 , viscosity of 5.50 mm 2 /s, free fatty acid of 0.56 mg/KOH, and iodine number of 60.49 g I 2 /100g, respectively. All those biodiesel characteristics meet to the biodiesel standard by the Indonesian National Standard (SNI).