Papers by Keyword: Calcium Oxide

Abstract: The article provides information about the initial elements in the waste and tailings of the copper processing plant of the Almalyk Mining and Metallurgical Combine and theoretical solutions for the extraction of metals. According to chemical data, the amount of iron in the waste is high (52.6%), and the most effective solution for extracting iron from the waste is the reduction process. An increase in the amount of iron to 88.9% was formed using coal and lime as reducing agents.

Abstract: This study aims to produce and characterize CaO (calcium oxide) from limestone, a natural product of Lobong Village. Calcination is the thermal decomposition of limestone to remove carbon so that it can produce calcium oxide. One of the functions of CaO is as an eco-friendly catalyst that does not produce toxic or hazardous waste and can be reused. CaO resulting from the calcination process at a temperature of 900°C for 1.5 h was characterized using XRD, SEM, FTIR, and EDS. XRD analysis of calcined limestone produced 2θ (h k l) diffraction peaks, namely 32.228^o (1 1 1), 37.389^o (2 0 0), 53.864^o (2 2 0), 64.169^o (3 1 1), and 67.404^o (2 2 2) which indicates the dominance of CaO. SEM analysis shows that the morphological structure of Lobong limestone after calcination is more porous than before. Studies by FTIR show that the chemical bonds of carbonate groups in the calcined limestone are decreasing. EDS analysis also shows that the mapping of carbon, which forms carbonates in calcined limestone, is decreasing.

Abstract: Calcium carbonate (CaCO₃) has been taken from sea urchin (Diadema setosum) shell and calcinated at several temperatures to obtain calcium oxide (CaO). X-Ray Fluorescence Spectroscopy (XRF) revealed that the powder from this shell had a high Ca level, which increased at a higher temperature. Fourier Transform Infrared Spectroscopy (FTIR) spectra agreed to an increase in Ca level that showed the presence of CaO at 900 °C and 1100 °C; otherwise, CaCO₃ disappeared. Using Scanning Electron Microscopy (SEM), the powder morphology was more homogeneous at 900 °C and 1100 °C than at lower temperatures. This morphology was encouraged by decreasing particle size, indicating compound decomposition in the powder and Ca leaved. This decomposition was confirmed by an Energy Dispersive X-ray Spectroscopy (EDS) analysis that showed increased Ca content with higher mass and atomic level at a higher temperature.

Abstract: The increment of pilot plant waste at UniKL MICET and eggshell waste cause disposal problems, such as the water and soil pollution, human health concerns, and disruption to aquatic ecosystems. Thus, to reduce the effect of disposal problem to the environment, pilot plant waste is converted into biodiesel, while eggshell is converted into catalyst in this study. This paper reports on the effect of catalyst preparation method and reaction temperature on biodiesel yield and quality. Transesterification process of pilot plant waste (olein and stearin) was conducted by using Ni/CaO (eggshell) catalyst from different preparation methods at different reaction temperatures (328 K, 333 K, 338 K and constant reaction time (5 hours), methanol-to-oil ratio (15:1), and weight of catalyst (8 wt%). The catalysts were synthesized via wet impregnation and sol–gel method and its physicochemical properties were subsequently characterized by TGA and FTIR analysis. Biodiesel analysis was done using GCMS and FTIR, while the physical properties (density, flash point, and kinematic viscosity) of biodiesel were measured according to ASTM D6751. Kissinger-Akahira-Sunose (KAS) kinetic model shows that the catalyst prepared by wet impregnation method has the lowest activation energy, which was 81.48 kJ mol^–1. In addition, GCMS analysis shows that reaction temperature at 338 K produced the highest yield of biodiesel (88.26%). In conclusion, the best catalyst preparation method was wet impregnation method and the best reaction temperature was 338 K. In addition, the physical properties of the produced biodiesel corresponded to ASTM standard, thereby indicating high quality of biodiesel and can be used as petroleum-diesel substitute.

Abstract: This article is focused to investigate the corrosion resistance of LCC, ULCC and NCC. Castables microstructure is one of the key factors influencing corrosion resistance, therefore new fine matrix was designed. Potassium carbonate was used as a corrosive medium using static crucible method for tested castables. The corrosion mechanism was evaluated by Scanning Electron Microscopy (SEM) with EDX probe. The experimental results disclosed that corrosion resistance was improved with decreasing calcium oxide content of tested castables.

Abstract: This paper highlights the study on effect of sintering temperature on the morphologies and compressive strength of zirconia ceramics doped with calcium oxide (CaO) as stabiliser to enhance the zirconia structure undergo sudden phase transformation. CaO reportedly has good stability in cubic phase at all temperature, which open up a new possibility for new material to evolve for zirconia ceramic dental application. CaO synthesis from calcium nitrate tetrahydrate (Ca(NO₃)₂.4H₂O) is used as metal precursor to produce Calcia-Sabilized Zirconia (Ca-SZ). 8 wt. % of Ca(NO₃)₂.4H₂O and 92 wt. % of zirconium oxide (ZrO₂) mixed and stirred together with ethanol as solvent and sintered at temperatures 1200, 1300 and 1400°C. Surface morphologies are investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) element analysis, X-ray Diffraction (XRD) for composition studies, as well as compressive strength to figure out the mechanical properties of Ca-SZ sample. Increment in sintering temperature enhance the surface morphologies, the phase of Ca-SZ become intensified and transformed from monoclinic to tetragonal ZrO₂ also flexural strength increases as well. The compressive strength recorded the highest value of 4537 MPa for Ca-SZ at temperature of 1400°C. The optimal temperature of Ca-SZ suitable for dental application was 1400°C due to the good morphologies and mechanical properties suitable for teeth restoration. The development of Ca-SZ can establish a pathway as an alternative material for dental applications.

Abstract: The aim of this study was to upscale the production of calcium oxide (CaO) derived from cockle shells using an improved protocol and determine its purity, as well as to study the hardness of the new, improved calcia stabilized zirconia (Ca-SZ). A mixture of diluted cockle shells powder with hydrochloric acid solutions (HCl) was stirred to obtain calcium chloride (CaCl₂). The homogenous CaCO₃ solutions were obtained by mixing CaCl₂ solution with potassium carbonate (KCO₃) using upscaled mechanochemical synthesis process. Then, CaCO₃ powder underwent calcination process at a temperature in range of 300°C – 550°C to obtain CaO powders. CaO showed the result under FESEM analysis as a spherical shape with crystal-like structure as well dispersed with no visible agglomeration. The yield production of CaO obtained was approximately about 5.0g which was upgraded from a previous study. The morphologies of Ca-SZ were observed at three different sintering temperatures at 1200°C, 1300°C and 1400°C were selected in order to understand the morphological and mechanical properties of Ca-SZ after incorporating 8wt% of CaO powders derived from cockle shells. The Ca-SZ pellets were then characterized using Field Emission Scanning Electron Microscopy (FESEM) and Vickers Hardness Test to ensure the effectiveness of CaO powder in fabricating Calcia-Stabilized Zirconia (Ca-SZ). As a result, sintered Ca-SZ at 1400°C showed the most promising performance for nano-CaO act as a stabilizer as it has the highest hardness at 590.03MPa with significantly difference (p<0.05) among all sintered Ca-SZ specimens. Therefore, these findings revealed that by adjusting the previous protocol, upscaling of a pure CaO may be synthesized using natural Ca source from cockle shells. The fabricated Ca-SZ showed a significantly lower hardness when sintered at 1400°C, which may be easier for machining.

Abstract: The eggs are not only a good source of nutrients but their shells are rich in various minerals of which CaCO₃ is the most prominent. Egg shell contains about 90% CaCO₃ of the total weight. The interest in clean technology has attracted the use of eggshell waste as a focus of research. The objective of this work is to extract calcium oxide (CaO) from calcium carbonate (CaCO₃) available in chicken eggshells. CaO is white in colour possessing high porosity with narrow particle size distribution. CaO have very high percentage of ceramic yield. This CaO can be used as precursor for synthesis of calcium phosphate that can be further used in biomaterial synthesis. The uncalcined eggshell waste (ESW) and calcined ESW powders were characterized by using X-ray diffraction (XRD), Scanning electron microscope (SEM) and Fourier transform infra-red (FTIR) analyses. The calcination temperatures were varied from 700 ^oC to 1100 °C. XRD and FTIR results suggested that CaCO₃ is converted into calcium oxide at 900 °C and SEM micrographs also compliment these results. The calcination method can be used to extract calcium oxide from ESW being eco-friendly as well as low cost.

Abstract: Quick lime or calcium oxide has attracted significant attention as a sustainable material to be used as fillers and catalysts in a broad range of industries. The quick lime derived from calcination of eggshell waste in a laboratory-scale rotary furnace is reported in this study. The eggshell waste was prepared by washing several times, drying in the sun, grinding and sieving through a 250 micrometers sieve size. Calcination of the sieved eggshells waste was conducted in a single zone rotary tube furnace at 800 °C with 5 degree slope and at 1 rpm. Both physical and chemical properties of the calcium oxide derived from the calcination of eggshell waste were systematically investigated by various scientific instruments. The results from powder X-Ray Diffraction (PXRD) and X-Ray Fluorescence: (XRF) showed that most of the calcium carbonate in the eggshell waste was thermally transformed to nano-calcium oxide with mean crystallite size of 47.5 nm and with a purity of 97.8%. The results from this study indicated the optimum conditions and the possibility for mass production of nano-calcium oxide via rotary furnace and have shown that the obtained nano-calcium oxide is comparable to the commercial chemical.

Abstract: The results of the development of the flux CaO-Li₂CO₃-B₂O₃, operating in the oxidizing environment of the furnace, are shown. Flux is used to protect the melt from oxidation and removal of oxides from the coated sample surface. The use of this flux in open furnaces made it possible to apply high-quality nickel coatings with a thickness of 18 μm, which is comparable to the thickness of coatings obtained in vacuum furnaces in argon atmosphere. The negative effect of flux components on the sample surface was noted during prolonged contact under the conditions of the oxidizing environment of the furnace. Practical application of the research results will provide high-quality diffusion coatings on metal products. In addition, economic efficiency is maintained through accessibility of the equipment and flux components.