CaCO3 Crystals Research Articles

Influence of the electromagnetic field on the corrosion of low-carbon steel in aqueous mineralized media and on the crystallization of calcium carbonate in the presence of iron(II) ions

The influence of the electromagnetic field (EMF) on the corrosion of structural carbon steel in a 3% aqueous solution of sodium chloride in the presence of CO2 was studied. It is shown that the EMF increases the corrosion rate of steel by 1.13 times in a 3% aqueous solution of NaCl in the presence of CO2. When Ca2+ ions are added to the solution, the corrosion rate of steel decreases under the influence of an electromagnetic field. It is assumed that the formation of CaCO3 in the near-surface layer of the solution and its adsorption on the metal surface prevents the development of corrosion. The influence of the electromagnetic field generated in the frequency range from 100 to 200 kHz on the crystallization of CaCO3 from supersaturated aqueous solutions on the model system CaCl2 – NaHCO3 – FeSO4 is studied. It was found that Fe2+, rather than EMF, has a more significant effect on salt deposition. The efficiency of the effect of Fe2+ on the inhibition of salt deposition in the model of mineralized water CaCl2-NaHCO3 is 11.5% higher than when exposed to EMF. During the crystallization of CaCO3, the predominant formation of aragonite is observed. In the presence of iron ions and under the influence of EMF, there was a decrease in the formation of aragonite and an increase in the formation of calcite and vaterite. Keywords: electromagnetic field; corrosion; carbon steel; iron ions; scale deposition; crystallization; calcium carbonate.

Enzyme-induced mineralization of hydrogels with amorphous calcium carbonate for fast synthesis of ultrastiff, strong and tough organic\u2013inorganic double networks

Hydrogels with good mechanical properties have great importance in biological and medical applications. Double-network (DN) hydrogels were found to be very tough materials. If one of the two network phases is an inorganic material, the DN hydrogels also become very stiff without losing their toughness. So far, the only example of such an organic–inorganic DN hydrogel is based on calcium phosphate, which takes about a week to be formed as an amorphous inorganic phase by enzyme-induced mineralization. An alternative organic–inorganic DN hydrogel, based on amorphous CaCO3, which can be formed as inorganic phase within hours, was designed in this study. The precipitation of CaCO3 within a hydrogel was induced by urease and a urea/CaCl2 calcification medium. The amorphous character of the CaCO3 was retained by using the previously reported crystallization inhibiting effects of N-(phosphonomethyl)glycine (PMGly). The connection between organic and inorganic phases via reversible bonds was realized by the introduction of ionic groups. The best results were obtained by copolymerization of acrylamide (AAm) and sodium acrylate (SA), which led to water-swollen organic–inorganic DN hydrogels with a high Young’s modulus (455 ± 80 MPa), remarkable tensile strength (3.4 ± 0.7 MPa) and fracture toughness (1.1 ± 0.2 kJ m−2).Graphical The present manuscript describes the method of enzymatic mineralization of hydrogels for the production of ultrastiff and strong composite hydrogels. By forming a double-network structure based on an organic and an inorganic phase, it is possible to improve the mechanical properties of a hydrogel, such as stiffness and strength, by several orders of magnitude. The key to this is the formation of a percolating, amorphous inorganic phase, which is achieved by inhibiting crystallization of precipitated amorphous CaCO3 with N-(phosphonomethyl)glycine and controlling the nanostructure with co polymerized sodium acrylate. This creates ultrastiff, strong and tough organic–inorganic double-network hydrogels.

Shear Strength and Wind Erosion Potential of Biologically Improved Sand

In the current study, Microbial-Induced Carbonate Precipitation (MICP) is used for the improvement of silty sand to mitigate wind erosion by spray-treating the soil surface layer with bacterial cell solutions. Wind tunnel, soil pocket penetrometer, and Torvane shear tests were carried out on the biologically treated and untreated samples. The bacteria were sprayed at bacterial concentrations of 0.05, 0.1, and 0.5 g/m2 and the samples were exposed to wind speeds of 20.57, 26.18, and 31.79 m/s. The results showed that the effect of wind speed was more pronounced in the untreated samples than the treated samples. A marked decrease in wind erosion potential was observed in the treated samples which was dependent on the bacterial concentration. An increase in the bacterial concentration from 0.05 to 0.5 g/m2 and in the curing time from 2 to 28 days decreased the wind erosion of the treated samples. Pocket penetrometer values were primarily affected by curing time and were almost independent of the bacterial concentration. The pocket penetrometer values of the treated samples were generally less than 2 MPa, which indicates the possibility of root growth. The results of the Torvane shear tests indicate that bio-cementation through MICP also increased the shear strength development of loose sand deposits. Scanning electron microscopy images of the structure of the treated samples revealed that MICP bound the sand particles together through CaCO3 crystal formation in the voids between the particles.

Morphology and organization of the internal shell of Ariolimax californicus (Gastropoda; Stylommatophora), an asymmetric two-face biomineralized matrix

A slug is a shell-less terrestrial gastropod mollusk. During evolution, slugs have lost their mineralized external shell but some of them have retained an internal shell (IS). Unlike external shells, which have been widely investigated, the ISs have been poorly studied. We report for the first time the compositional and complete morphological characterization of Ariolimax californicus’ IS. According to literature, this shell calcifies and decalcifies depending on the animal’s needs. Its composition is mostly organic, consisting of proteins and β-chitin. The internal shell is organized in layers and membranes in which CaCO3 crystal formation occurs in specific areas. In the two faces of the IS we observed different morphologies and aggregations of calcite bio-crystals along with a different organization of the organic matrix. Dorsally, the mineral forms a thick layer composed of misaligned crystal aggregates of large dimensions, separated by thin organic layers. This suggests a protective purpose and the use of this layer as a long-term calcium storage system. Ventrally, the mineral phase is organized in small crystal aggregates of comparable size, separated by thin organic layers, and quite aligned one to the other. The whole ventral mineral layer is covered by a membrane, identified as the hypostracum. This face is proposed to be a short-term calcium storage system. In vitro crystallization experiments suggest massive calcium ions sequestration from the solution for the precipitation of calcite crystals inside the organic matrix. In conclusion, this research provides new information on the dynamic of biomineralization on mollusk evolved in calcium-poor environments.

Effects of Tryptophan on the Polymorphic Transformation of Calcium Carbonate: Central Composite Design, Characterization, Kinetics, and Thermodynamics

The objectives of this study were to: (i) determine the effects of tryptophan on the polymorphic phase transformation of CaCO3, (ii) investigate the thermal degradation characteristics of CaCO3 in terms of kinetics and thermodynamics using the Coats-Redfern method, and (iii) assess the influence of the experimental conditions on the vaterite composition of CaCO3 using response surface methodology based on central composite design. First, the CaCO3 crystals were prepared and analyzed using XRD, FTIR, SEM, BET, AFM, and zeta potential analysis. Based on the characterization results, the shape of the CaCO3 crystals changed from smooth cubic calcite crystals to porous irregular spherical-like vaterite crystals with increasing tryptophan concentration. Meanwhile, the kinetic results showed that the thermal degradation of CaCO3 followed the shrinkage geometrical spherical mechanism, R3 and the average activation energy was 224.6 kJ/mol. According to the results of the experimental design, the tryptophan concentration was the most influential variable affecting the relative fraction of vaterite in the produced crystals. It can be concluded that tryptophan is important for better understanding and controlling the polymorph, size, and morphology of CaCO3 crystals.

Amino acids as performance-controlling additives in carbonation-activated cementitious materials

This article presents an investigation on the application of amino acids to control the CaCO3 crystallization in carbonation cured wollastonite composites. It was observed that wollastonite carbonated without any amino acid formed calcite as the primary polymorph of CaCO3. In contrast, the use of amino acids as admixtures resulted in the formation of stable amorphous calcium carbonate (ACC), vaterite, and aragonite during the carbonation of wollastonite. The carbonated composites produced with amino acids were observed to have a lower critical pore size, but a higher total porosity, compared to the control batch. Additionally, the utilization of amino acids was observed to increase the flexural strength and compressive strength of the composites up to 106% and 48%, respectively, compared to the control batch. Such performance enhancement of the carbonated composites in the presence of amino acids was attributed to the reduced critical pore size and the formation of organic-inorganic hybrid phases in the matrix.

Bio-cementation improvement via CaCO3 cementation pattern and crystal polymorph: A review

Due to environmental and sustainable concerns, the green bio-cementation technique has received growing attentions from both the academic world and engineering field. One of its essential applications is ground improvement, since the precipitated CaCO3 crystals in bio-cementation process could act as the solid bridges to cement separated particles together and enhance the mechanical behaviors of soils. Although researchers have realized the significance of the precipitated CaCO3 bondings and microstructures of bio-cemented materials, only few studies focus on improving the bio-cementation efficiency from a microscopic perspective. Consequently, in this paper, an integrative review is adopted to collect, review, and analyze the published studies and literature, indicating that the CaCO3 cementation pattern and crystal polymorph are the two principal aspects that reflect the bio-cementation efficiency to a certain extent. Subsequently, the major factors affecting the CaCO3 cementation pattern and crystal polymorph are comprehensively discussed. In a nutshell, the conducted discussions in this paper attempt to provide noteworthy insights into bio-cementation improvement, which may potentially inspire future studies.

Effects of Enzyme and Microbially Induced Carbonate Precipitation Treatments on the Response of Axially Loaded Pervious Concrete Piles

EICP (enzyme induced carbonate precipitation) and MICP (microbially induced carbonate precipitation) treatments were applied through pervious concrete model piles to cement soil around the piles and enhance soil-pile interaction and pile capacity. The behaviors of the pervious concrete piles treated by EICP and MICP when subjected to axial compression loading were compared with each other and with an untreated pervious concrete pile. These tests were performed on 1/10th-scale model piles in the soil-structure interaction (SSI) testing facility at Lehigh University. The piles and surrounding soil were instrumented with strain gauges, bender elements, in-soil null pressure sensors, and a tactile pressure sheet. The responses of the pervious concrete piles and surrounding soil were compared through analysis of shear wave (S-wave) velocities in the treated and untreated soil zones, load transfer along the piles at the ultimate load condition, soil moisture content, calcium carbonate (CaCO3) content and ammonium (NH4+) concentration in soil, and the characteristics of the precipitated CaCO3 crystals along the soil-pile interface. In addition, comparisons with consolidated drained (CD) triaxial test results were made among sand without treatment and with EICP and MICP treatments. The results presented in this paper demonstrated that both EICP and MICP treatments can create a cemented soil zone surrounding the pervious concrete pile and improve the pile capacity and load transfer under compression loading.

Characterization of a Novel CaCO3-Forming Alkali-Tolerant Rhodococcus erythreus S26 as a Filling Agent for Repairing Concrete Cracks.

Biomineralization, a well-known natural phenomenon associated with various microbial species, is being studied to protect and strengthen building materials such as concrete. We characterized Rhodococcus erythreus S26, a novel urease-producing bacterium exhibiting CaCO3-forming activity, and investigated its ability in repairing concrete cracks for the development of environment-friendly sealants. Strain S26 grown in solid medium formed spherical and polygonal CaCO3 crystals. The S26 cells grown in a urea-containing liquid medium caused culture fluid alkalinization and increased CaCO3 levels, indicating that ureolysis was responsible for CaCO3 formation. Urease activity and CaCO3 formation increased with incubation time, reaching a maximum of 2054 U/min/mL and 3.83 g/L, respectively, at day four. The maximum CaCO3 formation was achieved when calcium lactate was used as the calcium source, followed by calcium gluconate. Although cell growth was observed after the induction period at pH 10.5, strain S26 could grow at a wide range of pH 4–10.5, showing its high alkali tolerance. FESEM showed rhombohedral crystals of 20–60 µm in size. EDX analysis indicated the presence of calcium, carbon, and oxygen in the crystals. XRD confirmed these crystals as CaCO3 containing calcite and vaterite. Furthermore, R. erythreus S26 successfully repaired the artificially induced large cracks of 0.4–0.6 mm width.

Halogenation for improvement of seed yield and quality in chilli (Capsicum annuum L.)

Freshly harvested seeds of chilli variety Anugraha were treated with halogens namely Calcium oxy chloride (CaOCl2) and Iodine crystal (I2) indirectly through a carrier Calcium carbonate (CaCO3). The treatments included Control (Untreated), CaOCl2 + CaCO3 (2g each/kg seed), CaOCl2 + CaCO3 (4g each/kg seed), Iodine crystal + CaCO3 (50mg each/kg seed) and Iodine crystal + CaCO3 (100mg each/kg seed). Seed treatment with CaOCl2 + CaCO3 @2g each/kg seed registered significantly higher values for fruits per plant, fruit weight, seed yield per plant and hundred seed weight followed by CaOCl2 + CaCO3 @4g each/kg seed. The treatments, CaOCl2 + CaCO3 @2 g each/kg seed and Iodine crystal + CaCO3 @100mg each/kg seed performed superior in seed quality with higher seedling vigour and lower electrical conductivity of seed leachates over other treatments, while untreated control recorded least seedling vigour indices and highest electrical conductivity.

Effects of Bacterial Density on Growth Rate and Characteristics of Microbial-Induced CaCO3 Precipitates: Particle-Scale Experimental Study

Microbial-induced carbonate precipitation (MICP) has been explored for more than a decade as a promising soil improvement technique. However, it is still challenging to predict and control the growth rate and characteristics of CaCO3 precipitates, which directly affect the engineering performance of MICP-treated soils. In this study, we employ a microfluidics-based pore-scale model to observe the effect of bacterial density on the growth rate and characteristics of CaCO3 precipitates during MICP processes occurring at the sand particle scale. Results show that the precipitation rate of CaCO3 increases with bacterial density in the range between 0.6×108 and 5.2×108 cells/mL. Bacterial density also affects both the size and number of CaCO3 crystals. A low bacterial density of 0.6×108 cells/mL produced 1.1×106 crystals/mL with an average crystal volume of 8,000 μm3, whereas a high bacterial density of 5.2×108 cells/mL resulted in more crystals (2.0×107crystals/mL), but with a smaller average crystal volume of 450 μm3. The produced CaCO3 crystals were stable when the bacterial density was 0.6×108 cells/mL. When the bacterial density was 4–10 times higher, the crystals were first unstable and then transformed into more stable CaCO3 crystals. This suggests that bacterial density should be an important consideration in the design of MICP protocols.

Controllable crystallization of pure vaterite using CO2-storage material and different Ca2+ sources

The controllable synthesis of pure vaterite with the good properties and broad application prospects is considered as an important, yet a challenging task because the product properties are greatly affected by reaction conditions. In the present work, the controllable synthesis of pure vaterite crystals was explored with four different Ca2+ sources including CaCl2, Ca(NO3)2, CaBr2 and Ca(Ac)2 using an CO2-storage material (CO2SM) prepared by an indirect CO2 utilization approach as the CO32− source. The effects of five major reaction conditions including reaction medium, hydrothermal reaction temperature, hydrothermal reaction time, Ca2+ concentration and sources, and pH and conductivity on the crystallization of CaCO3 were systemically investigated. It is found that the amounts of CO2SM required for the formation of pure vaterite phase are in the order of CaBr2 (20 g/L CO2SM) > Ca(NO3)2 (16 g/L CO2SM) > Ca(Ac)2 (8 g/L CO2SM) due to the effects of ethylenediamine (EDA), diethylene glycol (DEG) and their anions. Especially, vaterite was not found in CaCl2 system. The effects of Ca2+ sources on the crystal phase composition of CaCO3 are revealed for the controllable synthesis of CaCO3 crystals. Our work not only provides a controllable synthesis method of pure vaterite, but also an indirect CO2 utilization strategy.

Facile synthesis of pure vaterite using steamed ammonia liquid waste and ammonium carbonate without additives via simple mechanical mixing

This paper describes a simple, low-cost, and fast method for synthesizing high-purity porous vaterite calcium carbonate (CaCO3) without any additives using steamed ammonia liquid waste and (NH4)2CO3. The obtained vaterite samples were characterized using various techniques such as powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and laser particle size analysis (LPSA). The XRD and FTIR analyses indicate that the prepared product is high-purity vaterite CaCO3. The SEM analysis shows obtained micro/nanosized spherical and porous vaterites. The effects of stirring mode and stirring speed on the morphology, particle size, and stability of vaterite were studied systematically. The stirring speed and stirring mode were found to play an important role in the crystallization of vaterite CaCO3 with different purities, morphologies, particle sizes, and particle size distributions. Based on the analysis of vaterite CaCO3 particles obtained under different stirring modes and stirring speeds, a possible mechanism for obtaining smaller vaterite CaCO3 particles at high stirring speed is proposed. The possible mechanism underlying the properties of ammonia-distilled waste liquid during vaterite formation is also discussed.

Surface versus bulk CaCO3 crystals with ethylene vinyl alcohol co-polymers and polyamide thin-film composite membranes

We conducted experiments to study the influence of material surface chemistry and morphology on the crystallization of calcium carbonate from supersaturated solution containing mixed electrolytes. The study evaluated ethylene vinyl alcohol (EVOH) co-polymers and fluorinated and non-fluorinated polyamide thin film composite membranes to evaluate how surface functional groups impact partitioning of salt crystals between the surface and the bulk fluid. Our methodology and results can aid in developing scaling-resistant thin film composite membranes and in selecting materials for engineered structures exposed to supersaturated solutions. We analyzed turbidity, surface scale deposition, bulk crystal yield, and overall Ca balance to quantify salt crystal adhesion (aka scaling) during exposure to the supersaturated stream and subsequent desupersaturation. Through our studies, we found polyethylene was much more prone to scaling as compared to EVOH. We also show that EVOH containing 56% vinyl alcohol monomer appears to have higher scaling resistance as compared to an EVOH containing 68% vinyl alcohol monomer. These two grades of EVOH were analyzed using atomic force microscopy to elucidate if differences in co-polymer morphology existed; it appears so and this may underlie the measured differences in the salt crystal's surface adhesion. Also, the studies found that the incorporation of fluorine in the polyamide thin film composite membrane surface by means of a novel mono-fluorinated trimesoyl chloride derivative does not impact salt scaling or the total solution de-supersaturation. Our studies provide new insight that not only -OH functional group quantity but also polymer chain configuration and conformation need to be optimized for surfaces that are resistant to calcium carbonate scale buildup.

Formation and Phase Selection of CaCO3 in the Intervention of Lignin Monomer Model Compounds

AbstractThe single crystal form and uncontrollable topography of CaCO3 in nature severely restrict its product grade and application. Meanwhile, lignin is still not utilized efficiently. In order to improve this, three types of lignin monomer model compounds as p‐coumaric acid (PCA), ferulic acid (FA), and sinapic acid (SA) are employed to induce the growth of CaCO3 to investigate the relationship between lignin structure and CaCO3 crystallization. The synthesized PCA and CaCO3 composite crystals (PC‐ACCs), FA and CaCO3 composite crystals (F‐ACCs), and SA and CaCO3 composite crystals (S‐ACCs) are characterized by field emission scanning electron microscope (FESEM), X‐ray diffraction (XRD), and Fourier transmission infrared spectroscopy (FTIR) to ascertain their molecular structures and crystal information. The growth rule of the acid and CaCO3 composite crystals (ACCs) induced by the three units is also explored. The results show that the vaterite and calcite of ACCs can be formed selectively. In the presence of PCA, FA, and SA, pH is the key factor on the phase selection of ACCs. The temperature and organic acid type also play important roles on the formation of CaCO3. The ACCs present distinguishing surface topographies at different temperatures. The number of methoxyl in the PCA, FA, and SA decides the phase ratio of vaterite and calcite in the ACCs.

Polymorphic Phase Change of Calcium Carbonate with Glutamic Acid as an Additive

The calcium carbonate (CaCO3) crystals were successfully synthesized in the presence of glutamic acid used as an additive at 30 °C and at a pH of 8.5. The synthesized product was characterized in detailed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrometry and scanning electron microscopy (SEM) to identify the structure and habit of the crystals. Moreover, the size and surface charge of the crystals were measured by particle size and zeta potential analyzer. XRD and FTIR results showed that both calcite and vaterite in forms of apparently CaCO3 crystals were obtained in the presence of 50 ppm additive concentration at t=30 min. When increasing the glutamic acid concentration in the suspension, the formed CaCO3 were only in the vaterite form. The SEM analysis results pointed out that the addition of the glutamic acid significantly changed the shape of the CaCO3. At t=30 min the resulting product sample was found to contain two types of polymorphs; larger cubic shaped calcite crystals and smaller spherical-like vaterite crystals. Further addition of high concentrations of the additive enhanced the adsorption of the glutamic acid, resulting in the smaller spherical-like ellipsoidal vaterite crystals. Investigation of the zeta potential analysis indicated that higher additive concentration (100 ppm) resulted in a positive surface charge of the crystals, whereas lower concentration (50 ppm) gave negative electrical charge. Moreover, filtration analysis pointed out that adding glutamic acid additive resulted in a less specific cake resistance value (5.01 × 1011 m/kg) than that in pure media, which was 1.03 × 1012 m/kg.

Histological description of Saxifraga paniculata leaves with special focus on structures that release CaCO3

Saxifraga paniculata is a subalpine succulent perennial plant arranged in a rosette that is usually found in shallow soil among limestone rocks. Stereoscopic, light and scanning electron microscopy were used to describe the anatomical structure of S. paniculata leaves, paying special attention to structures related to CaCO3 (calcium carbonate) release. Anomocytic stomata are unevenly distributed on each leaf face, being absent in the lower third. The basal leaf margin presents translucent pluricellular trichomes of variable length and width. Towards the apical margin, trichomes become teeth. Both trichomes and teeth are completely covered with whitish CaCO3 crystals. Each tooth has a circular cavity connected to a single hydathode through pores. Clearing treatment revealed camptodromous leaf venation. Anatomical structure shows a bifacial cross-section with spongy mesophyll cells at basal part, becoming heterogeneous at the apex with palisade mesophyll on the adaxial face. Hydathodes are epithematic and connected to outer cavities via two kidney-shaped guard cells showing large substomatal cavity. The epithem is surrounded by a thickened sheath and is formed of highly packed elongated cells with interspersed tracheary elements. CaCO3 deposits consist of microscopic crystals with varying geometries, of which the rhombus is the basic unit.

Individual and synergetic effect of EDTA and NTA on polymorphism and morphology of CaCO3 crystallization process in presence of barium

The effect of different chelating agents on the crystallization of CaCO3, polymorphism and morphology of CaCO3 in the presence of barium were studied at 100 °C. The samples were characterized using FTIR, Raman spectroscopy, XRD and FESEM techniques. The study revealed that without any chelating agents, in the presence of different volumes of 0.1 M Ba2+ ion solution, stabilization of a binary mixture of rhombohedral calcite and flower-like vateritewas facilitated. In the presence of EDTA, the phenomenal transformation of calcite to vateritewas observed. Pure calcite has resulted in the presence of Nitrilotriacetic acid (NTA) in the presence of Ba2+ ions. Blending EDTA with NTA favored a binary mixture of spherical vaterite and calcite. The probable mechanism for stabilization of various polymorphs by the additives and effect of blending of additives for better scale inhibition efficiency has been discussed.

CO2 introduced the coagulation-flocculation of oil acidized wastewater: pollutant removal and cost analysis.

It is difficult to adjust the pH of oil acidized wastewater rich in Ca2+, thus hindering the polyacrylamide (PAM) flocculation. This study aims at accelerating the flocculation process by introducing CO2 into the water to induce the formation of CaCO3 nuclei. The order in which CO2 and NaOH were added affected the floc structures. Compared with CO2-NaOH-PAM, the flocs of NaOH-CO2-PAM were more compact and more CaCO3 crystals were formed. The aqueous Ca2+ involved in the reaction reached 20%, and CO2 utilization was enhanced. The settling time was shortened by half (from 20 to 3 min), and NaOH consumption was reduced by one-tenth (from 0.03 to 0.003 mol), hence significantly reducing the costs. Due to the higher settling rate and shorter contact time, the NaOH-CO2-PAM flocs adsorbed less so that the residual oil was 124 mg·L-1, while in the case of CO2-NaOH-PAM it was 88 mg·L-1. As a promising coagulation aid, CO2 can also be used to mineralize pollutants in wastewater.

Curcumin and quercetin as templates in the in vitro biomineralization of CaCO3: A comparative study on phase modulation

Biomineralization of calcium-based biominerals is influenced by organic molecules containing oxygen donor atoms. In this work, we were able to synthesize and stabilize the least stable crystalline phase of CaCO3, vaterite, using the biologically useful organic molecule curcumin as the template. The vaterite phase formed was stable in solution at least for 18 h. A comparative study with chemically similar molecule quercetin, a flavonoid, was performed. Though quercetin as a template could not stabilize the vaterite phase, an interesting observation was made in terms of the morphology of the calcite particles obtained. A dumbbell-shaped morphology, different from the usual rhombohedral morphology of the calcite crystals was obtained under ambient conditions. The maturation of the CaCO3 crystals in solution with time was studied to observe the changes in terms of phase and morphology of the particles. Additionally, extended studies were performed to investigate the influence of the change in parameters such as; template concentration, the sequence of addition, temperature and ionic strength on the phase, morphology and size of the particles in the presence of both the templates.