Papers by Keyword: Calcium Carbonate

Abstract: To overcome the increased processing of eggshell waste in East Java, Indonesia, the important solution is to synthesize chicken eggshells into calcium carbonate. The process of synthesizing eggshells into calcium carbonate is carried out by a mechanochemical process using a ball milling machine for 10 h and the sintering time for 120 min at a temperature of 900, 1000, 1100, and 1200 °C. The results of the eggshell synthesis were characterized using X-ray Diffraction, SEM, Raman spectroscopy and FTIR. Those characterizations aimed to obtain the result of phase identification, morphology, physicochemical, and functional group of calcium carbonate. From the phase identification, calcium carbonate obtained from eggshell sintered 1000 °C shows the single-phase triangular structure with agglomeration and spherical morphology. The physicochemical results show that phonon interaction of calcium carbonate obtained from eggshell sintered at 1200 °C has the highest intensity at Raman shift 1083 cm^‒1 which indicates the C‒O symmetric stretching band. The functional group of calcium carbonate shows from FTIR results at 3642, 2987, 2508 cm^‒1 for O‒H bond, and 1790, 1507 cm^‒1 for C‒H bond, and 874, 712 cm^‒1 for calcite bonds respectively.

Abstract: A highly porous structure of a gypsum product creation is possible due to the porisation of gypsum mass, using new types of complex gas-forming components. At the same time, it is necessary to determine the technological conditions for the optimal formation of porous gypsum products structure and methods for increasing their strength. The article proposed to use dispersed calcium carbonate and aluminum sulphate, which interaction is the reaction with the release of СО₂ for the porisation of the gypsum cast mixture. Micro-reinforcing additives, such as polymeric, basalt and glass fibers were introduced into gypsum composition together with building gypsum and finely ground calcium carbonate to improve the physico-mechanical properties of gas-gypsum. The best results were shown by the gas-gypsum, which included fiberglass. Glass fiber was pre-ground to a specific surface of 190-240 m² / kg, in order to improve further the physico-mechanical properties of gas-gypsum.

Abstract: This paper presents the lime binding forced carbonate-hardening materials properties formation study and determins the stability of these properties during long-term storage and use under normal conditions. The tests showed these materials stability properties over time, confirming the strength and density growth of the test samples after long storage due to the calcium hydroxide recrystallization completion into calcium carbonate processes. Also, the results of the samples carbonate hardening study under natural conditions during 18 months are presented. An efficiency assessment of forced carbonate hardening as one of the methods of recycling technogenic CO₂ in order to reduce its emissions in the atmosphere, and, in the result, to obtain high-quality construction materials has been made.

Abstract: Resin transfer molding (RTM) is one technique that has been used to produce polymer composites, which consists in injecting a thermoset pre-catalysed resin into a closed mold containing a dry fiber preform. In this sense, this study aims to investigate the effect of the calcium carbonate content (CaCO₃) in the polyester resin during the RTM process. Several experiments were conducted using glass fiber mat molded in a RTM system with cavity dimensions 320 x 150 x 3.6 mm, at room temperature, and different injection pressure (0.75 bar) and CaCO₃content (0, 10, 20, 30 and 40%). Results of the physical parameters such as viscosity, permeability, and mobility, and flow front position of the resin into the mold along the RTM process are presented and analyzed. From the results was concluded that the higher the injection pressure and lower CaCO₃content into the resin, the lower filling time.

Abstract: The accelerated carbonation with different pressure steaming conditions was used to process the steel slag, so the slag could turn into a primary cementitious product with carbonation activity. XRD, FTIR, TG, N₂ absorption BET surface area analyzer and SEM were used to characterize the mineral and chemical compositions and microstructure of each sample before and after the carbonation. The results show that: the carbonation products with different morphologies are formed under different temperature conditions. The optimum temperature for the accelerated carbonation for processing the steel slag is selected to be 90 °C, which results in the compressive strength of 32.8 MPa. The BET specific surface area of the steel slag reduces after carbonation, the sample density increased after carbonation.

Abstract: Cotton-wool-like bioresorbable bone void fillers consisting of β-tricalcium phosphate (β-TCP), siloxane-containing vaterite (SiV) and poly (_L-lactic acid) (PLLA) was prepared by an electrospinning method. The fibers, which were 50 ~ 150 μm-width with 10 ~ 30 μm-thickness, were entwined. The resulting cotton-wool-like material showed mechanical flexibility and excellent shapability; it showed easy, excellent mechanical-fixation in defects. The in vivo performance of this material was examined in the distal femur in New Zealand white rabbits. It was evaluated using micro CT and histologic analyses at time points of 6 and 12 weeks. These analyses of the defect sites verified normal healing response and new bone formation. The in vivo testing with rabbits showed good biocompatibility and excellent osteogenic ability.

Abstract: The applicability of irreversible aggregation model for theoretical description of nanofiller particles aggregation processes in polymer nanocomposites has been shown. The correspondence of the indicated model and strength dispersive theory results was obtained. The main factors, influencing on nanoparticles aggregation process, were revealed.

Abstract: The article describes results of the determination of the interaction energy between particles of a hydrating binder and filler, a solution and base. It was found that in the case of particles having a diameter of 17 μm, a mineral suspension should be practically stable, since the energy barrier is much higher than the thermal motion energy of the particles and is 166 kT (100% gypsum), 125 kT (100% CaCO₃), 63 kT (gypsum-filler 90:10), and 41kT (gypsum-filler 80:20). A further increase in the amount of CaCO₃ particles leads to a significant reduction in the barrier, which at the gypsum-to-filler ratio of 70:30 is 6 kT, and at the ratio of 50:50 completely disappears. In the interaction of the smallest particles (5 μm), the energy barrier values are: 44 kT (100% gypsum), 28 kT (100% CaCO₃), 18 kT (gypsum-filler 90:10), 7 kT (80:20) and 2 kT (70:30). With the component ratio of 50:50, the energy barrier completely disappears, and the particles become denser in the first potential well.

Abstract: Because of its superior surface properties, nanocalcium carbonate can be applied to the adsorption of heavy metals in wastewater. However, because of the easy aggregation of nanocalcium carbonate, high surface energy and poor dispersibility in water, it is not conducive to the process of adsorption. Therefore, surface modification of nanocalcium carbonate is needed. In this paper, nanocalcium carbonate was prepared by liquid phase method. And the nanocalcium carbonate was surface modified by sodium dodecyl sulfate. The effects of modifier amount, modification temperature, and modification time on the activation and absorbance of nanocalcium carbonate were investigated. And the morphology and particle size of modified nanocalcium carbonate were tested by SEM and XRD patterns.The results show that the dispersion and surface activity of the modified nanocalcium carbonate have been improved remarkably. Moreover, the Cu²⁺ was adsorbed by sodium dodecyl sulfate modified nanocalcium carbonate and unmodified nanocalcium carbonate under the optimum modification conditions. And the effects of nanocalcium carbonate initial concentration on the adsorption performance were studied. The results show that the adsorption performance of modified calcium carbonate is better than that of the unmodified. Moreover, the adsorption process is studied by adsorption isotherm. By drawing the adsorption isotherms lines and by comparing the fitting result of the experimental data based on the Langmuir model and that of Freundlich model, it is found that the adsorption of Cu²⁺ by modified nanocalcium carbonate meets the Langmuir model.

Abstract: In this study, calcium carbonate was used to coat and link the surface of diatomite for the formation of a novel modified adsorbent (referred to as Ca–diatomite). Various analytical techniques were used to characterize structure and mechanisms of modification and adsorption process, like Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). Results showed that that Calcium carbonate had been successful grafted onto the surface of diatomite after modification, and Calcium carbonate modification improved the adsorption performance of diatomite for the removal of lead (II) ions from aqueous solution. Ca–diatomite adsorption isotherms and adsorption kinetics were also been studied. The adsorption isotherms and the kinetic data were best fitted with the Langmuir model and pseudo-second-order kinetics, respectively.