Preparation Of CaCO3 Research Articles

Additive application for modulating physicochemical properties and antitumor effects of CaCO3 nanodelivery systems

Calcium carbonate (CaCO3) nanoparticles are highly regarded for their excellent biocompatibility and distinctive pH responsiveness, making them an ideal nanocarrier system for anti-tumor therapy. The incorporation of additives during the preparation of CaCO3 can significantly influence its morphology, particle size, and tumor inhibitory effects, necessitating a systematic study of these impacts. This study utilized the gas diffusion method to prepare CaCO3 nanoparticles, introducing various additives such as hyaluronic acid, polyacrylic acid, polyvinyl pyrrolidone, fucoidan, and polyethyleneimine. Different additives were found to have diverse effects on the morphology, particle size, zeta potential, and pH responsiveness of CaCO3. Methotrexate was employed as a model drug to evaluate the cytotoxicity of CaCO3 nanoparticles with different additives. Among them, hyaluronic acid-modified CaCO3 nanoparticles exhibited ideal morphology, particle size, significant pH responsiveness, and tumor-targeting capabilities. In vitro and in vivo experiments demonstrated their remarkable antitumor effects.

Calcium recovery from waste carbide slag via ammonium sulfate leaching system

Waste carbide slag (WCS) is a typical industrial solid waste with high calcium content, which shows highly potential in preparation of CaCO3 by CO2 mineralization technology. This study demonstrated the feasibility of efficient calcium leaching from WCS using ammonium sulfate ((NH4)2SO4) under mild conditions (≤40 °C，0.1 MPa). Nearly 90% calcium was converted into calcium sulfate dihydrate (CaSO4·2H2O) in about 15 min, and after impurity separation the CaSO4·2H2O with about 90% whiteness and 94% purity was effectively collected. In addition, a surface coverage kinetics model suitable for this leaching system was proposed. It was found that, kinetics behavior followed the chemical reaction control mechanism within the first minutes and then switched to the product islands diffusion-control along with CaSO4·2H2O crystallization. Accordingly, calcium leaching in (NH4)2SO4 system could be reinforced by readjusting S/L after reaching equilibrium. This process provides a potential path for the resource treatment of industrial solid wastes such as calcium carbide slag and desulfurization gypsum.

Recycling of Industrial Waste Gypsum Using Mineral Carbonation

Direct mineral carbonation (MC) is used to mitigate carbon dioxide (CO2) emissions. This method has the great advantages of reducing the amount of industrial residues and creating valuable materials by incorporating CO2. Waste gypsum, industrial waste including flue gas desulfurization (FGD) gypsum (25.27–53.40 wt% of CaO), and phosphogypsum (30.50–39.06 wt% of CaO) can be used for direct MC (conversion rate up to 96%). Mineral carbonation converts waste gypsum into calcium carbonate (CaCO3), which can be recycled during desulfurization. Furthermore, ammonium sulfate ((NH4)2SO4), which is used as a fertilizer, can be prepared as a by-product when the carbonation reaction is performed using ammonia (NH3) as a base. In this study, recent progress in the carbonation kinetics and preparation of CaCO3 using FGD gypsum and phosphogypsum with NH3 was investigated. Temperature, CO2 partial pressure, CO2 flow rate, and NH3 concentration were reviewed as factors affecting carbonation kinetics and efficiency. The factors influencing the polymorphs of the prepared CaCO3 were also reviewed and summarized. A state-of-the-art bench-scale plant study was also proposed. In addition, economic feasibility was investigated based on a bench-scale study to analyze the future applicability of this technology.

Preparation of CaCO3:Eu3+@SiO2 and its application on adsorption of Tb3+

Rare earth elements (REEs) are widely used in modern technologies while their constant consumption made it urgent to find an efficient method to recover the REEs for the sustainable development. Owing to the porous structure and various active sites, the core-shell materials turned into the focus of adsorption researches. Herein, we synthesized a porous core-cell material CaCO3:Eu3+@SiO2 and applied it into the adsorption of Tb3+ for the first time. CaCO3:Eu3+@SiO2 was characterized by XRD, FTIR, SEM, TEM and Zeta potential measurements. The adsorption data fitted best with the pseudo-second-order model while the Weber and Morris described the rate-controlling steps. The material exhibited a maximum adsorption capacity of 188.26 mg·g-1 at 323 K and pH 5.83. Besides, it showed different adsorption capacities among the competing adsorption of La3+, Nd3+ and Tm3+. This work presented a promising and economical adsorbent for the efficient removal of REEs for environmental remediation applications.

Synthesis and Characterization of Spherical Calcium Carbonate Nanoparticles Derived from Cockle Shells

Cockle shells are a natural reservoir of calcium carbonate (CaCO3), which is widely used in bone repair, tissue scaffolds, and the development of advanced drug delivery systems. Although many studies report on the preparation of CaCO3, the development of a nanosized spherical CaCO3 precursor for calcium oxide (CaO) that is suitable to be incorporated in dental material was scarce. Therefore, this study aimed to synthesize a nanosized spherical CaCO3 precursor for CaO derived from cockle shells using a sol–gel method. Cockle shells were crushed to powder form and mixed with hydrochloric acid, forming calcium chloride (CaCl2). Potassium carbonate (K2CO3) was then fed to the diluted CaCl2 to obtain CaCO3. The effect of experimental parameters on the morphology of CaCO3, such as volume of water, type of solvents, feeding rate of K2CO3, and drying method, were investigated using field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffractometry (XRD), Brunauer–Emmett–Teller surface area analysis, and thermogravimetric analysis. Optimized CaCO3 was then calcined to form CaO. XRD analysis of CaCO3 nanoparticles was indicative of the formation of a calcite phase. The well-structured spherical shape of CaCO3 was obtained by the optimum condition of the addition of 50 mL of water into CaCl2 in ethanolic solution with a 1 h feeding rate of K2CO3. Less agglomeration of CaCO3 was obtained using a freeze-drying technique with the surface area of 26 m2/g and average particle size of 39 nm. Spherical shaped nanosized CaO (22–70 nm) was also synthesized. The reproducibility, low cost, and simplicity of the method suggest its potential applications in the large-scale synthesis of the nanoparticles, with spherical morphology in an industrial setting.

Effect of pH and temperatures on the fast precipitation vaterite particle size and polymorph stability without additives by steamed ammonia liquid waste

This paper reports on the effect of pH and temperature on size and polymorph stability of calcium carbonate (vaterite) formed without use of additives by Steamed ammonia liquid waste. The effect of the reaction temperature (20–80 °C), the initial Steamed ammonia liquid waste pH (1.5–12.1) and the stirring speed (800 and 1200 rpm/min) on the preparation of CaCO3 with respect to the particle size and polymorph stability of final product were investigated. The obtained different CaCO3 size and polymorphs were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and a Laser particle size analyzer (LPSA). The phase of vaterite transformed to calcite with increasing temperature 20 to 80 °C. The SEM and LPSA show that the CaCO3 particle size increased from nano to several micron with the increase of temperature. When the initial CaCl2 aqueous solution in low pH (1.5 and 2.6), nano-micro porous spherical vaterite can be obtained. When the initial CaCl2 aqueous solution in high pH (11.7 and 12.1), preparation of CaCO3 is mainly for the vaterite contains a small amount of calcite and the size particle increased. The possible mechanisms for the porous vaterite CaCO3 formation have also been discussed. Since requirements for the physical properties of CaCO3 particles are diverse for industrial and medical applications, it is important to understand CaCO3 crystallization behavior for tailored particle synthesis.

Investigating the effect of ultrasonic irradiation on synthesis of calcium carbonate using Box-Behnken experimental design

In this study, CaCO3 crystals were synthesized in the presence of the water-soluble polymers carboxymethyl inulin (CMI) and poly(vinyl sulfonic acid) (PVS) by means of ultrasonic irradiation method. The synthesized CaCO3 crystals were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), BET (Brunauer, Emmett and Teller), thermal analysis (TGA-DTA) and particle sizer. The pure phase of vaterite was obtained in the presence of PVS, meanwhile, the mixed phases of calcite and vaterite were observed in the presence of CMI.·The effects of the amplitude of sonicator (Amp), polymer concentration (PC) and the application time of ultrasound (AT) on the preparation of CaCO3 with respect to the specific surface area (SSA) and particle size of the final product were investigated by applying the Box-Behnken experimental design based on three levels. The experimental values were 0.25g/L, 0.50g/L and 0.75g/L for polymer concentration; 25%, 38% and 50% for sonicator amplitude; 1min, 3min and 5min for an application time of the ultrasound. The polymer concentration and application time of the ultrasound were found to be main controlling variables on both surface area and particle size of the crystals. The experimental values agreed with the values predicted by Box-Behnken response surface design under our experimental conditions.

Box-Behnken experimental design for the production of precipitated calcium carbonate

Abstract Calcium carbonate (CaCO3) was synthesized by means of ultrasonic process in the presence of the water-soluble polymer carboxymethyl inulin (CMI). Synthesized CaCO3 crystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET (Brunauer, Emmett and Teller) isotherm. Applying Box-Behnken experimental design, the effects of the amplitude of sonicator (Amp), biopolymer concentration (BC) and the application time of ultrasound (AT) on the preparation of CaCO3 with respect to specific surface area (SSA) of final product was investigated. The experimental design was studied at three levels. The range of the amplitude of sonicator, polymer concentration and the application time of ultrasound were 25%–50%, 0.25–0.75 g/L and 1–5 min, respectively. The model equation representing specific surface area (SSA) of calcium carbonate was expressed as functions of three operating parameters namely the application time of the ultrasound, the amplitude of sonicator and polymer concentration. The results showed that the application time of ultrasound was the most significant variable that influenced the surface area of the crystals among three variables and the experimental results were in good agreement with those predicted by the proposed regression model. The highest value of specific surface area was obtained at the maximum application time of ultrasound.