Synthesis Of Calcium Carbonate Research Articles

Biomimetic synthesis of calcium carbonate with different morphologies under the direction of different amino acids

Using three different amino acids (AAs) as organic matrices, including the highly nonpolar hydrophobic l-valine, the positively charged l-arginine and the less polar uncharged l-serine, calcium carbonate (CaCO3) with different morphologies and polymorphs were synthesized by a facile gas diffusion reaction based on biomimetic strategy. Compared with the control cubic calcite obtained in the absence of AAs, the product from l-valine was cubic calcite aggregates assembled by nano-platelets. The product from l-arginine was spherical vaterite aggregates assembled by spherical nanoparticles. The product from l-serine was the mixture of cubic calcite and spherical vaterite. The structures and properties of the side chains of the AAs exerted the significant effects on the nucleation and growth of the CaCO3. The formation mechanisms of the CaCO3 in the presence of AAs are preliminarily discussed. The results suggest that the polymorphs and morphologies of the inorganic nanomaterials might be easily adjusted through the careful selection of the organic matrices.

Synthesis of Calcium Carbonate Crystals by Using Bacteria

The synthesis of calcium carbonate (CaCO3) crystals in the presence of bacteria Escherichia coliform (E. coli) was investigated. The products were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray powder diffractometry. The results showed that calcite spherical superstructures constructed from small rhombohedral building units were formed with bacteria, and the particles are much larger than those formed without bacteria. The formation mechanism of CaCO3 crystals in the presence of E. coli is explored, suggesting that the bacterial biomolecules especially proteins may induce the nucleation, growth, and aggregation of CaCO3 crystals.

Biomimetic Synthesis of Aragonite Nanorod Aggregates with Unusual Morphologies Using a Novel Template of Natural Fibrous Proteins at Ambient Condition

Biomimetic synthesis of calcium carbonate has been studied for decades in order to understand the biomineralization process. However, to date, it is still difficult to obtain pure aragonite by transformation of amorphous calcium carbonate (ACC) at room temperature. Herein, we obtained almost pure aragonite nanorod aggregates (ANA) with unusual morphologies via transformation of ACC at ambient conditions using a novel fibrous protein K58 from bivalve Siliqua radiata ligament as the template. We found that nanorods are formed initially as ACC containing disordered aragonite nanocrystals, which then evolve into oriented attached nanocrystals coated with minor ACC, and finally into aragonite single crystals. Further analysis reveals K58 is homologous to type II cytoskeletal 1 and type I cytoskeletal 9, with many acidic amino acid residues. It should be the carboxyl groups of these residues, which have short-range order similar to aragonite lattice, control short–range order ACC formation, resulting in the preferential transformation of ACC into aragonite. This article provides some valuable information for better understanding of aragonite crystal growth and biomineralization process; it also highlights the role of biomacromolecule in the formation of aragonite fibers in bivalve ligaments.

Green Synthesis of Calcium Carbonate Uniform Microspheres Using Vegetables

AbstractWe report a novel strategy for the green synthesis of calcium carbonate (CaCO3) microspheres by using four vegetables: potato, cucumber, aubergine, and carrot. The products were characterized by scanning electron microscopy, X‐ray powder diffractometry and/or Fourier transform infrared spectroscopy. The results show that the spherical calcite crystals are obtained in the presence of potato, cucumber and aubergine extracts, while uniform vaterite and calcite mixed microspheres are produced with the extracts of carrot. The possible formation mechanism of the CaCO3 microspheres by using vegetables is also discussed, suggesting that the biomolecules especially proteins may induce and control the nucleation and growth of CaCO3 crystals. CaCO3 is an important biomineral and inorganic material. Uniform particles have numerous important applications in many areas. Therefore, this study is very significant not only for expanding the scope of crystal engineering, but also for biomineralization research and green synthesis of functional inorganic materials.

Synthesis of Calcium Carbonate by Semicontinuous Carbonation Method in the Presence of Dextrans

Precipitated calcium carbonate (PCC) was prepared by means of semicontinuous carbonation of Ca(OH)2 suspension, at 35 and 45 C and in the presence of non-ionic dextran and dextran sulfate. The carbonation process was regulated at different predetermined values of electrical conductivity, that corresponded to different concentrations of dissolved Ca(OH)2: 0.5 mS cm-1< 25 < 5.0 mS cm-1. The results of physical–chemical characterization of the product showed that calcite was the only polymorphic modification obtained in the whole range of experimental conditions investigated. In addition, it was found that morphology, crystal size distribution and specific surface area of PCC strongly depended on the electrical conductivity / concentration of dissolved Ca(OH)2, at which the process was performed: predominantly scalenohedral crystals of higher surface area (about 5 m2 g–1) were produced at higher electrical conductivity, while at lower electrical conductivity predominantly rhomohedral calcite crystals of relatively low specific surface area were obtained. In the system of the highest electrical conductivity, 25 = 5.0 mS cm-1, and at 35 C, the addition of non-ionic dextran significantly influenced the process by preventing the regulation. The crystals that appeared were in the form of irregular aggregates of high specific surface area, S ≈ 29 m2 g–1. FT-IR and TG analyses indicated that the non-ionic dextran was adsorbed onto the calcite surface, most probably by relatively strong and specific interactions between oxygen from the hydroxyl groups of dextran molecules and calcium ions from the crystal surface. On the contrary, the anionic dextran (dextran sulfate) exerted minor effects in the course of semicontinuous carbonation process and in the properties of the final product, PCC. However, the analysis of the precipitate indicated that dextran sulfate was adsorbed at the surfaces, most probably by the weak and non-specific electrostatic interactions.

Sonochemical Formation of CaCO3Nanoparticles with Controlled Particle Size Distribution

ABSTRACT The effect of operating parameters such as flow rate of CO2 and concentration of Ca(OH)2 on the particle size distribution, crystallite size, and induction period of nano calcium carbonate synthesis in a sonochemical carbonization process has been investigated. Synthesis of calcium carbonate was carried out by bubbling CO2 gas (40, 50, 60 L/h) through Ca(OH)2 slurry (4%, 5%, 6% by weight). Particle size was determined using a dynamic light scattering technique. It was found that average crystallite size was between 45 and 36 nm for 40 to 60 L/h at 4% concentration of Ca(OH)2 slurry, which was maintained constant. This indicates that ultrasound imparts the shear stress on the gas–solid interface that leads to a decrease in particle size. As the concentration of Ca(OH)2 increased from 4% to 6% (by weight), crystallite size was found to be increased from 45 to 72 nm. The pH and conductivity, induction time, and particle size distribution (PSD) data also indicate that an appropriate combination of sl...

Fast precipitation of uniform CaCO3 nanospheres and their transformation to hollow hydroxyapatite nanospheres

Shape-controlled synthesis of calcium carbonate with specific polymorphs can be achieved by the assistance of organic additives. In this study, highly uniform nanosized calcium carbonate spheres were synthesized by a fast precipitation method in the presence of a simple polymer, poly(styrene sulfonate) (PSS). The polymorph of the synthesized calcium carbonate products changes from pure calcite in PSS-free reactions to vaterite in PSS-containing (1-50 g/L) reactions. The effect of PSS on the formation of vaterite can be attributed to the two aspects: decrease of driving force by reducing the interfacial energy, and phase stabilization effect caused by the adsorbed PSS. A higher PSS concentration (50 g/L) results in highly uniform vaterite nanospheres of 400-500 nm in diameter. Furthermore, PSS is found more effective to induce the formation of vaterite in the Ca(2+)-rich reaction condition (Ca(2+):CO(3)(2-)=5:1) than in the CO(3)(2-)-rich conditions (Ca(2+):CO(3)(2-)=1:5). It has also been found that different mixing mode of the calcium and carbonate precursor solutions has a significant influence on the size distribution of the products. Finally, with a controlled anion-exchange method, the as-prepared vaterite nanospheres can be easily transformed to hollow hydroxyapatite spheres, which exhibit great potential to be used as the drug carriers due to their considerably high surface area and biocompatibility.

Biological synthesis of calcite crystals using Scindapsus aureum petioles

We report a novel strategy for the biological synthesis of calcite crystals using the petioles of the plant Scindapsus aureum. The resultant calcite crystals were characterized by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffractometry, and electron diffraction. The biomolecules of S. aureum petioles were confirmed by UV–Vis and FT-IR analysis. The results showed that the spherical or rhombohedral calcite crystals were obtained in the cells of S. aureum petioles. Biomimetic synthesis of calcium carbonate (CaCO3) in aqueous solution containing extracts of S. aureum petioles was also performed to investigate the soluble biomolecules’ influence on crystal growth of CaCO3. It was found that twinborn spherical calcite crystals were formed, suggesting that the soluble biomolecules of S. aureum play a crucial role in directing the formation of calcite spherical particles. The possible mechanism of formation of CaCO3 crystals using S. aureum is also discussed; the biomolecules of S. aureum may induce and control the nucleation and growth of CaCO3 crystals.

Controlled deposition and transformation of amorphous calcium carbonate thin films

AbstractControlled synthesis of amorphous calcium carbonate (ACC) films was realized by using the multiple templates, which are composed of a self‐assembled film (SAF, insoluble Poly (ε‐caprolactone) film) and a soluble modifier (poly allylamine), as modifiers. The formation of self‐assembled film was analyzed by monitoring the morphologies using atomic force microscopy. Even more noteworthy, using anhydrous ethanol as media, the ACC‐to‐vaterite‐to‐calcite transformation was also investigated, and the obtained products were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. The results demonstrated that organic solvent has profound influence on transformation of amorphous calcium carbonate thin films. In the air of anhydrous ethanol, the controlled synthesis of calcium carbonate films with different morphologies, such as planar films with a few sporadic particles, symmetric rhombohedral crystals, novel crystals with symmetrical terraced convexity formation of calcite, was obtained by the fine‐tuning of induction time. It provides a new and simple method to prepare polymorphic CaCO3 crystal films from the ACC films by controlling the crystallization process (© 2009 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Synthesis of calcium carbonate in ethanol-ethylene glycol solvent

Calcium carbonate has been synthesized from Ca(OH)2 in ethanol-ethylene glycol solvent by carbonation and aging process. Carbonation in organic solvent caused Ca(OH)2 to form a white gelatinous CaCO3 product, which was then destroyed by aging process. The calcium carbonate precipitated and agglomerated in these steps was composed of stable calcite, and meta-stable aragonite and vaterite. These meta-stable particles were shaped either peanut-like or sphere. When a little amount of distilled water was added to organic solvent, the meta-stable phases remarkably decreased, whereas stable calcite increased. When Ca(OH)2 was carbonated with water addition increased to 2 vol% of the total organic solvent and aged at 40°C, only rhombic calcite was synthesized.

Influence of the surfactant nature on the calcium carbonate synthesis in water-in-oil emulsion

Calcium carbonate has been precipitated from water-in-oil emulsions consisting of n-hexane/nonionic surfactant (Brij 30) and its mixture with cationic (DTAB) or anionic surfactant (SDS) to which calcium chloride and sodium carbonate were added. It was found that the surfactant kind and its amount can regulate the size, form and morphology of the precipitated particles. In case of nonionic surfactant the water/surfactant ratio is the most important parameter that allows to obtain small and regular calcium carbonate crystals. Addition of the DTAB results in different morphology of particles having the same crystal form, whereas addition of SDS changes the kind of emulsion from water-in-oil to oil-in-water. Moreover, light transmittance and backscattering light measurements have been used as a method to study the kinetics of calcium carbonate precipitation in emulsion systems.

PAA-assisted synthesis of CaCO 3 microcrystals and affecting factors under microwave irradiation

In the present paper, we described a polyacrylic acid (PAA)-assisted microwave irradiation route for synthesis of Calcium carbonate (CaCO 3) microcrystals. CaCl 2·2H 2O and NaHCO 3 were used as the starting reactants. Researches showed that the presence of PAA could strongly affect the phase and morphology of CaCO 3 crystals. X-ray powder diffraction (XRD) analyses showed that the product prepared from the system with/without PAA corresponded to Vaterite/Calcite, respectively. Scanning electron microscopy (SEM) observations showed that the hierarchical CaCO 3 microcrystals were obtained in the presence of PAA. Some factors influencing the morphology of the as-synthesized CaCO 3 crystals were systematically investigated.

Microwave-Assisted Synthesis of Calcium Carbonate (Vaterite) of Various Morphologies in Water−Ethylene Glycol Mixed Solvents

A fast microwave-assisted method is reported for the synthesis of CaCO3 (vaterite) with various morphologies in the water/ethylene glycol (EG) system with surfactants. Our experiments show that microwave heating, reaction time, surfactant, and the water-EG mixed solvents play important roles in the morphology of vaterite. Vaterite with dagger-like, bicone-like, shuttle-like morphology and microspheres self-assembled from nanoparticles have been obtained by adjusting the experimental parameters. The products were characterized by X-ray powder diffraction, transmission electron microscopy, and scanning electron microscopy.

Synthesis of vaterite CaCO 3 by direct precipitation using glycine and l-alanine as directing agents

We report room temperature synthesis of calcium carbonate (CaCO 3) vaterite phase by the reaction of calcium chloride and sodium carbonate with glycine or l-alanine as directing agents. The compound crystallize in the hexagonal symmetry, P6 3/ mmc with a = 4.1304(8) Å and c = 8.4770(2) Å.

Synthesis and Characterization of Monodispersed Spheres of Amorphous Calcium Carbonate and Calcite Spherules

The isotropic property of amorphous calcium carbonate (ACC) is useful for the controlled synthesis of calcium carbonate based biomaterials. A simple and efficient strategy for the synthesis of monodispersed microspheres of ACC is reported using a low-temperature precipitation of calcium carbonate in the presence of magnesium ions. The room-temperature aging of this amorphous phase yielded superstructures of self-assembled calcite crystals. The stability of the precipitated ACC is proportional to an increase in the concentration of the magnesium ions and the precipitation time. The ACC with high magnesium content was stable for a one month period at room temperature under dry conditions. The ACC aged in solution was stable for up to 48 h. It is believed that the low temperature and the presence of magnesium ions facilitated the formation of stable monodispersed spheres of ACC. The morphological studies and characterizations were carried out using SEM, FTIR, XRD, electron diffraction, and Raman spectroscopy...

Controlled synthesis of calcium carbonate in a mixed aqueous solution of PSMA and CTAB

A mixed system of poly (styrene-alt-maleic acid) (PSMA) and cetyltrimethylammonium bromide (CTAB) was used as a very effective crystal growth modifier to direct the controlled synthesis of CaCO 3 crystals with various morphologies and polymorphs. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. It was found that the concentrations and relative ratios of PSMA and CTAB in the mixed aqueous solution were turned out to be important parameters for the morphology and polymorph of CaCO 3 crystals. Various morphologies of CaCO 3 crystals, such as hollow microsphere, peanut and so on, were produced depending on the concentrations and relative ratios of PSMA and CTAB. Moreover, the formation mechanisms of CaCO 3 crystals with different morphologies were discussed.

Synthesis of calcium carbonate in a pure ethanol and aqueous ethanol solution as the solvent

The possibility of formation of precipitated calcium carbonate (PCC) in pure ethanol, not as small additives, but as the main solvent, was investigated by precipitating a variety of PCC via a carbonation reaction. During the carbonation in a slaked lime–pure ethanol suspension, three morphology types of CaCO 3 were also precipitated, including calcite, which was the only type of PCC precipitated in the pure water system, and aragonite and vaterite, which were also precipitated without leaving Ca(OH) 2 as the reactants. Their particle size was half of those from pure water. In a pure ethanol system, calcite was first precipitated from the carbonation in bulk solution as in the pure water system, while the aragonite and vaterite might be synthesized via other local carbonation routes occurring in the surface of the Ca(OH) 2 grain following the bulk carbonation in the solution. In this local carbonation, there was little variation of electrical conductivity and pH. In the aqueous solution of less than 40 mol% ethanol, the PCC is all calcite; therefore, water has dominant effect as the solvent. On the other hand, in the solution of more than 60 mol% ethanol, the solvent acts as the pure ethanol and calcite, aragonite and vaterite can be precipitated.

Effect of anionic surfactant–polymer complexes on the crystallization of calcium carbonate

The synthesis of calcium carbonate (CaCO 3) crystals from aqueous solutions containing anion surfactants (sodium dodecylsulfonate (DDS), sodium dodecylbenzenesulfonate (SDBS)) or anionic surfactant–poly( N-vinyl-1-pyrrolidone) (PVP) complexes has been performed by the method of rapid mixing of the solutions of calcium chloride (CaCl 2) and sodium carbonate (Na 2CO 3), followed by 10-h incubation under stirring. Polymorphism of CaCO 3 crystals was observed in different additive systems. In pure anionic surfactant systems, DDS induced the transformation of initially formed amorphous CaCO 3 to calcite, while SDBS favored the formation of vaterite as the final product. The addition of PVP into the above two anionic surfactant systems, promoting the formation of supermolecular complexes of surfactant/polymer, resulted in a distinct variation of the morphology of CaCO 3 crystals. The polymorphs of CaCO 3 are dependent not only on PVP but also on DDS or SDBS concentrations in the complex solution, i.e., anionic surfactants control the crystalline phase, but PVP only changes the crystal shape.

Microemulsion-based synthesis of stacked calcium carbonate (calcite) superstructures.

Synthesis of calcium carbonate in water-in-oil microemulsions results in the spontaneous formation of stacked superstructures of 20 nm-thick pseudo-hexagonal calcite plates in crystallographic register.

Crystallization habit of calcium carbonate in presence of sodium dodecyl sulfate and/or polypyrrolidone

The synthesis of calcium carbonate (CaCO 3) crystals from aqueous solutions containing sodium dodecyl sulfate (SDS), poly( N-vinyl-1-pyrrolidone) (PVP) or SDS/PVP complexes has been performed through a slow titration method. It was found that aragonite and calcite coexisted in the prepared crystals. The formation of aragonite in the precipitation systems without magnesium ions indicates that at ambient temperature ca. 26.0°C, initially formed amorphous CaCO 3 could also transfer into aragonite in the sedimentary phase, which indicates the controlling factor of organic additives in the nucleation and growth process of CaCO 3 crystals. The appearance of hexagonal crystals in the suspensible phase confirmed the hexagonal crystallization cell of vaterite, and revealed the colloidal-dispersion function of the SDS/PVP complex in the crystallization process of CaCO 3.