Papers by Keyword: Calcium Carbonate

Abstract: To minimize the cost of production and enhancement pipe quality, this research aims to gain insights into the physical and mechanical characteristics of high-performance polypropylene random filled with rigid inorganic calcium carbonate particles at various content levels, with a specific focus on how the toughness of PPR changes. Virgin Polypropylene Random PPR, a new material extracted from a homopolymer polypropylene, is used as a matrix with 10, 20, 30, 40, and 50 wt. % of CaCO₃. The density, melt flow rate, tensile strength, tensile strain, modulus of elasticity, and hardness are used to evaluate the quality of the material. The results showed that the density, the modulus of elasticity, and the hardness increased with increasing the percentage of CaCO₃. As the percentage of CaCO₃ increased, the melt flow rate decreased. The tensile strength and strain increased to 28.7 MPa and 533.25%, respectively at 20 wt.% of CaCO₃, with 14.8% and 6.65% reaching gains compared to the virgin PPR (25 MPa and 500%). The enhancement of the mechanical properties is thanks to the presence of stiffer and rigid particles of CaCO₃ that act as a reinforcing agent. Moreover, when CaCO₃ is well dispersed, it forms a strong bond with the polypropylene matrix, and facilitates the transfer of stress from the matrix to the fillers, resulting in increased stiffness. The optimum percentage of CaCO₃ to add into the inner layer of extruded PPR pipes is at a composition of the filler of 20 wt. %.

Abstract: A rise in shipping activities, such as oil exploration, production, storage, and transportation, is a result of increasing demand and needs for oil among consumers worldwide. The risk of oil spills causing marine pollution has increased as a result of these activities. Adsorption is a cost-effective and straightforward method for removing contaminants from water. The use of residuals as adsorbents can improve the process's sustainability and cost-effectiveness. This study suggests using eggshells as an oil adsorbent. Eggshells were cleaned with water and dried in sunlight. Heated treatment in an oven at 70 °C for 1 hour followed by careful grinding. Overall, the specimen was filtered through a 60-200 mesh sieve (74-250 mm). X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) were utilized to characterize the eggshell. The results revealed that eggshell is composed of calcium (Ca) at a 98.46 atomic percent concentration. The highest palm oil adsorption capacity of 38.01 mL was achieved by optimizing the following parameters: adsorption time of 26.15 min, agitation speed of 357.62 rpm, and weight of adsorbent, which was 19.98 g. The findings demonstrated that eggshell is an effective biosorbent for the removal of oil from water. It will offer a low-cost method of cleaning the oily and contaminated water environment, thereby protecting both human health and the lives of aquatic organisms.

Abstract: The study presents mechanical performance metrics, especially, energy absorption, of aluminium foams fabricated by melt processing with CaCO₃ blowing agent without Ca additive. Relatively ductile Al1Mg0.6Si alloy and high strength Al6Zn2.3Mg alloy comprising brittle eutectic domains were employed for the foams manufacture and then examined in conditions of uniaxial quasi-static compression. It was recognized that mechanical response of the foams and energy absorption is radically defined by the mechanism of cell collapse which, in turn, depends on the nature of structural constituents of the cell wall material. In particular, the presence of brittle eutectic domains in the cell wall material of foam based on Al6Zn2.3Mg alloy results in reducing the compressive strength and energy absorption compared to those of foam processed with Al1Mg0.6Si alloy, both deviate markedly from the theoretical predictions. In spite of this experimental verification of foams cell collapse is considered to be strongly required before their engineering application.

Abstract: Continuous cockle shell dumping in open areas has become a global problem which generate major environmental issues. The conversion of the wastes into value-added products is highly desirable and economic. This work aimed to investigate the influence of sol-gel processing parameter on the properties of the synthesized calcium hydroxide (Ca(OH)₂). In this study, cockle shell waste was used as calcium carbonate (CaCO₃) precursor in the preparation of Ca(OH)₂ via sol-gel method and the processing parameter varied was hydrochloric acid (HCl) concentration (0.5, 1.0 and 2.0 M). The cockle shell based CaCO₃ and the prepared Ca(OH)₂ powders were characterized by X-ray diffraction (XRD), Fourier transform infra-Red (FTIR), field emission scanning electron microscopy with energy dispersive X-ray (FESEM-EDX), X-ray fluorescent (XRF) and particle size analyzer (PSA). The XRD analysis indicates that the calcium carbonate obtained from cockle shell was mainly in the form of aragonite polymorph. Upon sol-gel processing, the analysis of the sample shows the presence of portlandite and small traces of aragonite in all samples suggesting an incomplete reaction of the hydrolysis process. Ca(OH)₂ powder prepared using 1M HCl yields the smallest particle size.

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: Calcium carbonate (CC)-hydroxyapatite (HAP) porous microparticles have gained a lot of popularity as a promising material for clinical applications. The objective of this study is to evaluate the effects of CC-HAP microparticles on osteoblast-like cells to be used as a bone-regeneration biomaterial. In this study, the different concentrations of conditioned media were used to compare the effects of released ions from CC-HAP microparticles. The material’s characteristics demonstrated that the immersion in cell culture medium did not change the crystal phases of CC-HAP. The decrease of calcium ions in cell culture medium is due to the dissolution-precipitation reactions on the material surfaces, which made more crystalline surfaces. The atomic absorption spectroscopy measurement demonstrated that the dissolution-precipitation reactions on the material surfaces in cell culture medium happened in 3 days and were stable between 3 to 5 days. The conditioned media immersed in cell culture medium for 4 days were used for further experiments. Cell evaluations demonstrated that excessive adding of CC -HAP could inhibit cell behaviors such as cell adhesion, proliferation, and differentiation. The cell adhesion indicated by the number of vinculin-positive focal adhesions per cell decreased with the increase of the CC-HAP concentrations. The cells cultured with CC-HAP proliferated at a lower rate than the control without CC-HAP. One of the reasons for the inhibition of cell proliferation was thought to be less formation of focal adhesions with higher concentrations of CC-HAP. The excessive adding of CC-HAP had an inhibitory effect on osteoblast differentiation. The results of this study revealed that the conditioned media prepared by immersion of CC-HAP porous microparticles in cell culture media had effects on the behaviors of osteoblast-like cells such as cell adhesion, proliferation, and differentiation.

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: This research investigated the effect of reactant concentrations, reaction medium, urease enzyme source, and calcium source on the precipitation rate of calcium carbonate (CaCO₃). This project is aiming to develop a biochemical reaction by using Enzyme Induced Calcite Precipitation (EICP) technique. This new technique would help in replacing the traditional cementation for the dune sand stabilization and promise an environmentally friendly and sustainable approach in the field of construction materials. Jack beans and soybeans were employed as a substrate to catalyze the urea hydrolysis in the study. The sources of calcium used in the experiments were calcium chloride (CaCl₂), eggshell and sesame. In addition, both seawater and distilled water were used as a reaction medium to distinguish the effect on calcium carbonate precipitation. The experiments showed that using sesame at a concentration of 4.5 g, 5 g of urea and 6 g of jack bean at 60 mL of distilled water, is the best reaction conditions to precipitate 100.288 g of calcium carbonate. Further, the results indicated that the calcium carbonate precipitation enhanced by using 5 g of urea, 5 g of CaCl₂ and 5 g of soybean at 50 mL of seawater. The precipitation amount was 25.593 g. These results provide a useful way for the bio cementation by following the EICP technique to address the issues of environment friendly practice of ground improvement.

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: Calcium carbonate is so hard to be further developed in polymer applications because it is difficult to combine with other materials. Starch-coated calcium carbonate was prepared by using starch as the main modifier and sodium stearate and sodium hexametaphosphate as the auxiliary modifiers. Optimal modification conditions were tested by single factor experiment and orthogonal experiment optimization. Manifestation was evaluated with the help of Fourier infrared spectrometer (FT-IR) and laser particle size analyzer and other test instruments. Results showed that a starch film was successfully coated on the surface of calcium carbonate, and the edges and corners of the modified coated calcium carbonate were passivated, and the particles were rounded. The active interface calcium carbonate has a broad application prospect in the field of degradable biomaterials.