Nucleation Of Calcium Carbonate Research Articles

Nanostructured Surfaces Enhance Nucleation Rate of Calcium Carbonate.

Nucleation and growth of calcium carbonate on surfaces is of broad importance in nature and technology, being essential to the calcification of organisms, while negatively impacting energy conversion through crystallization fouling, also called scale formation. Previous work studied how confinements, surface energies, and functionalizations affect nucleation and polymorph formation, with surface-water interactions and ion mobility playing important roles. However, the influence of surface nanostructures with nanocurvature-through pit and bump morphologies-on scale formation is unknown, limiting the development of scalephobic surfaces. Here, it is shown that nanoengineered surfaces enhance the nucleation rate by orders of magnitude, despite expected inhibition through effects like induced lattice strain through surface nanocurvature. Interfacial and holographic microscopy is used to quantify crystallite growth and find that nanoengineered interfaces experience slower individual growth rates while collectively the surface has 18% more deposited mass. Reconstructions through nanoscale cross-section imaging of surfaces coupled with classical nucleation theory-utilizing local nanocurvature effects-show the collective enhancement of nano-pits.

Simulation of calcium carbonate nucleation processes in confined C-S-H nanopores with different calcium-silicon ratios

Carbonation curing technology plays an important role in carbon cycling and improving the properties of cement-based materials, while the nucleation and growth mechanism of calcium carbonate (CaCO3) is still unclear. Based on molecular dynamics simulation, the formation process and nucleation mechanism of CaCO3 in confined C-S-H nanopores with different calcium-silicon ratios were studied. The results show that the clustering behavior of CaCO3 in C-S-H nanopores filled with saturated CaCO3 solution can be divided into three phases, rapid agglomeration stage, slow cluster stage, and stable cluster stage. The aggregation is mainly dependent on ionic bonding for nucleation growth and is consistent with the prenucleation mechanism. The Ca/Si ratio of C-S-H has a direct influence on the clustering of CaCO3. The anchoring mechanism of CaCO3 clusters is determined by ionic bonds and hydrogen bonds, and large clusters are preferentially adsorbed at the C-S-H interface through ionic bonds. The Ca/Si ratio of 1.5 can provide more nucleation sites by ionic bonds and hydrogen bonds for the formation of CaCO3, which is more conducive to the growth of clusters. And the calcium source from C-S-H in cluster bodies can be as high as 33 %. This study helps to understand the early formation process of CaCO3 in cement-based materials and lays a theoretical foundation for the development of carbonization curing technology.

Effects of temperature and CO2 concentration on the early stage nucleation of calcium carbonate by reactive molecular dynamics simulations.

It is significant to investigate the calcium carbonate (CaCO3) precipitation mechanism during the carbon capture process; nevertheless, CaCO3 precipitation is not clearly understood yet. Understanding the carbonation mechanism at the atomic level can contribute to the mineralization capture and utilization of carbon dioxide, as well as the development of new cementitious materials with high-performance. There are many factors, such as temperature and CO2 concentration, that can influence the carbonation reaction. In order to achieve better carbonation efficiency, the reaction conditions of carbonation should be fully verified. Therefore, based on molecular dynamics simulations, this paper investigates the atomic-scale mechanism of carbonation. We investigate the effect of carbonation factors, including temperature and concentration, on the kinetics of carbonation (polymerization rate and activation energy), the early nucleation of calcium carbonate, etc. Then, we analyze the local stresses of atoms to reveal the driving force of early stage carbonate nucleation and the reasons for the evolution of polymerization rate and activation energy. Results show that the higher the calcium concentration or temperature, the higher the polymerization rate of calcium carbonate. In addition, the activation energies of the carbonation reaction increase with the decrease in calcium concentrations.

Directing polymorph specific calcium carbonate formation with de novo protein templates

Biomolecules modulate inorganic crystallization to generate hierarchically structured biominerals, but the atomic structure of the organic-inorganic interfaces that regulate mineralization remain largely unknown. We hypothesized that heterogeneous nucleation of calcium carbonate could be achieved by a structured flat molecular template that pre-organizes calcium ions on its surface. To test this hypothesis, we design helical repeat proteins (DHRs) displaying regularly spaced carboxylate arrays on their surfaces and find that both protein monomers and protein-Ca2+ supramolecular assemblies directly nucleate nano-calcite with non-natural {110} or {202} faces while vaterite, which forms first in the absence of the proteins, is bypassed. These protein-stabilized nanocrystals then assemble by oriented attachment into calcite mesocrystals. We find further that nanocrystal size and polymorph can be tuned by varying the length and surface chemistry of the designed protein templates. Thus, bio-mineralization can be programmed using de novo protein design, providing a route to next-generation hybrid materials.

Inhibition of calcium carbonate nucleation and crystallization by carboxymethyl dextran: Experiments and molecular dynamics simulations

Fouling causes huge economic losses for industrial process. In this work, experimental and molecular dynamics simulation approaches were used to carefully examine the scale inhibitory effects of carboxymethyl dextran (CMD) on the nucleation and crystallization process of calcium carbonate. The findings of the experiment demonstrated that CMD could significantly inhibit calcium carbonate's crystallization and nucleation processes. Moreover, an increase in the CMD concentration prolonged the induction period of calcium carbonate nucleation, and led to an increase in the critical conductivity value, inhibition effect on the nucleation process, and scale inhibition efficiency. The simulation results demonstrated the presence of strong interactions between the calcium ions in solution and the carboxyl groups of CMD. The probability and strength of calcium and carbonate ions adsorbing to the solution's surface decreased as the CMD concentration rose. Adsorption probability and strength of calcium and carbonate ions in the solution declined as CMD concentration rose, tightly agglomerated calcium carbonate gradually dispersed into small clusters and ions, and scale inhibition effectiveness improved. The experimental results were found to be in good agreement with the simulation results.

Investigation on coal dust prevention by biomimetic mineralized dust suppressant with polyacrylic acid modifier

Coal dust prevention is crucial for the environment and the safety of coal miners. This study proposed a biomimetic mineralized dust suppressant (BMDS) with polyacrylic acid (PAA) modifier, based on calcium carbonate precipitation technology. The consolidation effect of BMDS on coal dust was evaluated through wind erosion resistance tests, unconfined compressive strength tests, and microscopic characterizations. The results show that the consolidation effect of the BMDS on coal dust heavily depends on the PAA concentration. When the PAA concentration is 4 g/L and the concentration of calcium chloride and sodium carbonate is 0.5 mol/L, the BMDS presents the best dust suppression effect and could realize the practical application requirements. The generated calcium carbonate is mainly calcite type, and the efficiency of cementing coal dust particles is the highest. Moreover, similar to bacteria in biological dust suppressants, it confirms that PAA could effectively modify the nucleation and growth of calcium carbonate, promote the adhesion of calcium carbonate to the surface of coal dust particles, and enable the generated calcium carbonate to effectively bond coal dust particles. Accordingly, the BMDS with PAA modifier can be effectively used in the prevention of secondary coal dust pollution.

Apatite-coated outer layer eggshell membrane: A novel osteoinductive biohybrid composite for guided bone/tissue regeneration

Hybrid biomimetic materials aim to replicate the organic-inorganic constructs of mineralized tissues. During eggshell formation, the outer surface of the eggshell membrane (ESM) promotes calcium carbonate nucleation, while the inner one prevents mineralization toward the egg white and yolk. In the current study, the outer surface of the ESM acted as a heteronucleant in calcium phosphate precipitation by the vapor diffusion sitting drop method, while the inner one remained unmineralized. The aim was to fabricate a 2D biomaterial with dual functions, osteoinductive on one side and protective against cell invasion on the other side. The microstructural, physicochemical, morphological, and mechanical properties of the mineralized ESM were characterized by XRD, TGA, XPS, FTIR/Raman, HR-SEM, and mechanical testing techniques. The cytocompatibility and osteoinductive ability were assessed by biological assays of cell viability, proliferation, and osteogenic differentiation on human mesenchymal stromal cells (hMSCs). Results indicate that the outer surface of the ESM induces the heterogeneous precipitation of carbonate-apatite phase depicting biomimetic features. In addition, the apatite/ESM shows a much higher cytocompatibility than the pristine ESM and promotes the osteogenic differentiation of hMSCs more efficiently. Overall, the apatite/ESM composite exhibits compositional, crystalline, mechanical, and biological properties that resemble those of mineralized tissues, rendering it an approachable and novel material especially useful in guided tissue/bone regeneration.

Investigating the Effect of Leucine on Calcium Carbonate Nucleation Mechanisms in the View of a Circular Economy

Investigating the Effect of Leucine on Calcium Carbonate Nucleation Mechanisms in the View of a Circular Economy

Accelerated curing of cement mortar: In-situ carbonation utilising CO2-impregnated faujasite

This study explores the use of in-situ carbonation using CO2-impregnated faujasite (FAU) for accelerating the curing of cement mortar. Results indicate that adding 3–12 wt% CO2-impregnated FAU reduces the setting time of the mortars by 2–11% and significantly enhances the compressive strength of the mortars at 1, 7, and 28 days, compared to plain FAU. Microstructural analyses reveal that the in-situ carbonation promotes the hydration of cement by providing additional calcium carbonate nucleation sites for the C-S-H precipitation. This increases the formation of hydration products, which leads to the refinement of the pore structure. Additionally, the in-situ carbonation results in the formation of calcium carbonate crystals with a particle size of 150–200 nm at 28 days, with the calcium carbonate content increased by 1.9 wt% at an addition level of 12 wt% CO2-impregnated FAU. Overall, the in-situ carbonation technique shows great promise as an alternative method for accelerating the curing of cement-based materials, particularly for cast-in-place concrete.

Investigation on mechanical properties of biomimetic mineralized mortar incorporated with boric acid modifier

Microbially induced carbonate precipitation (MICP) has been intensively studied as a potential method to improve engineering properties of soil. However, MICP has limitations due to the introduction of microorganisms and the difficulty of controlling the calcium carbonate crystal precipitation model. This study proposed biomimetic mineralized mortar based on the biomimetic-chemically induced carbonate precipitation (BCICP) method with boric acid as a crystal modifier. Similar to the bacteria in MICP, boric acid can promote the nucleation of calcium carbonate and the adsorption of calcium carbonate on the surface of sand particles. Besides, the boric acid concentration can effectively change the precipitation mode of calcium carbonate. Unconfined compression strength (UCS) test and microscopic characterization were conducted to investigate the mechanism of boric acid modifying calcium carbonate crystal growth and precipitation morphology. The results show that with the increase of boric acid concentration, the reinforcement efficiency of calcium carbonate increased. With the increase of boric acid concentration, the crystalline calcium carbonate changed from a cube-shaped calcite with a smooth surface to a spherical calcite with a rough surface and the coating pattern of calcium carbonate distribution on the surface of sand particles was weakened, while the bonding-filling pattern was enhanced. Besides, the cementing fluid concentration can also affect the reinforcement efficiency of calcium carbonate and with the participation of boric acid, biomimetic mineralized mortar can use the high concentration cementing fluid to achieve effective strength enhancement. This study confirms that boric acid could effectively modify the form and distribution of calcium carbonate between sand particles, and enhance the cementation between calcium carbonate and sand particles.

Earthworm granules: A model of non-classical biogenic calcium carbonate phase transformations.

Different non-classical crystallization mechanisms have been invoked to explain structural and compositional properties of biocrystals. The identification of precursor amorphous nanoparticle aggregation as an onset process in the formation of numerous biominerals (crystallization via particle attachment) constituted a most important breakthrough for understanding biologically mediated mineralization. A comprehensive understanding about how the attached amorphous particles transform into more stable, crystalline grains has yet to be elucidated. Here, we document structural, biogeochemical, and crystallographic aspects of the formation as well as the further phase transformations of the amorphous calcium carbonate particles formed by cultured specimens of earthworm Lumbricus terrestris. In-situ observations evidence the formation of proto-vaterite after dehydration of earthworm-produced ACC, which is subsequently followed by proto-vaterite transformation into calcite through nanoparticle attachment within the organic framework. In culture medium spiked with trace amounts of Mn2+, the cauliflower-like proto-vaterite structures become longer-lived than in the absence of Mn2+. We propose that the formation of calcite crystals takes place through a non-classical recrystallization path that involves migration of proto-vaterite nanoparticles to the crystallization site, and then, their transformation into calcite via a dissolution-recrystallization reaction. The latter is complemented by ion-by-ion crystal growth and associated with impurity release. These observations are integrated into a new model of the biocrystallization of earthworm-produced carbonate granules which highlights the sensibility of this process to environmental chemical changes, its potential impact on the bioavailability of contaminants as well as the threat that chemical pollution poses to the normal development of its early stages. STATEMENT OF SIGNIFICANCE: Understanding the mechanisms of nucleation, stabilization and aggregation of amorphous calcium carbonate (ACC) and factors controlling its further transformation into crystalline phases is fundamental for elucidation of biogenic mineralization. Some species of earthworms are natural workbench to understand the biogenic ACC, stabilization and the transformation mechanisms, because they create millimeter-sized calcareous granules from amorphous calcium carbonate, which crystallize to a more stable mineral phase (mostly calcite). This study undergoes into the mechanisms of ACC stabilization by the incorporation of trace elements, as manganese, and the ulterior precipitation of calcareous granules by a coupled process of amorphous particle attachment and ion-by-ion growth. The study points to sensibility of this process to environmental chemical changes.

Calcification of cell membranes: From ions to minerals

The whole process of cell membrane calcification of Bacillus licheniformis DB1–9 was studied by molecular dynamics (MD) and microbially-induced carbonate precipitation (MICP) laboratory experiments. Typical metabolitic products of Bacillus licheniformis DB1–9 were used as the calcium carbonate nucleation template to establish the organic constituents and a water‑calcium carbonate two-phase system model for MD simulation, and to characterize the early stages of calcium carbonate nucleation on the surfaces of extracellular polymeric substances (EPS). The surface minerals of calcified bacteria obtained by MICP were prepared by focused ion-beam (FIB) and further analyzed using high-resolution transmission electron microscopy-selected area electron diffraction (HRTEM-SAED). We propose that the evolution process of cell membrane calcification is: ions → ion-pairs → multi-ion complexes (MIC) of large-size topological structures → pre-nucleated clusters (PNC) → amorphous calcium carbonate (ACC) → carbonate minerals (monohydrocalcite, vaterite, aragonite). In addition, ACC and the state before ACC were adsorbed on to the surface of the cell membrane after self-assembly in the aqueous solution; the ACC then underwent maturation and crystallized into ordered carbonate minerals with a crystal structure. Our study reveals the processes of microbial calcification, which has implications for the calcification of microorganisms in modern aqueous environments and for the formation of microbialites throughout the geological record.

Inhibition of Mg corrosion in physiological fluids by carbonate coating

Corrosion protective coatings were grown on pure magnesium in naturally carbonated mineral water containing Ca2+ using a simple, green conversion method. Dissolution of the native corrosion product, Mg(OH)2, mediates the surface nucleation of hydroxycarbonates. The pH increase due to CO2 degassing to atmospheric pressure leads to calcium carbonate nucleation and lateral growth by the incorporation of nanoparticles in a continuous layer of calcite -Ca(Mg)CO3- microcrystals. The coated surfaces have a much improved corrosion resistance in physiological fluids, measured by EIS, weight loss, corrosion rates and hydrogen release. Cell viability/morphology assessment demonstrates that the coating is non-toxic and promotes the proliferation of osteoblastic cells.

Different carbon treatments for steel slag powder and their subsequent effects on properties of cement-based materials

In order to fill the research gap of CO 2 -fixing cementitious materials, and to deal with China's dual-carbon goal, first to use bacteria and steel slag powder to fix CO 2 . The paper using untreated steel slag powder as control group, different CO 2 -fixing steel slag powder are compared, they are CO 2 treated steel slag and bacteria-CO 2 treated steel slag. The XRF and XRD results shows that the physicochemical properties of steel slag powder with different treatments are significantly different. Because the chemical composition and particle surface properties of steel slag powder are changed in the CO 2 fixing process due to the reactions. There are calcium carbonates formed in steel slag powder when cured by CO 2 from cement kiln tail gas. The SEM images show that the surface of steel slag powder has defects. Steel slag with bacteria will produce more calcium carbonates and its surface has more defects. Therefore, it will have an impact on the cement-based material fresh paste workability and hardened paste properties. The results of the fresh paste workability show that, the surface defects of steel slag powder have an adverse impact on the workability, because the defects increase the internal friction between particles. The results of hardened paste strength show that the cement-based materials mixed with SSLP-BC has the better mechanical properties. The XRD, FTIR , SEM, 1 H NMR and X-CT results of hardened paste show that, the microstructure of cement-based materials mixed with SSLP-BC is denser. This may be caused by the nucleation of bacteria and calcium carbonate. Moreover, calcium carbonate may play an important role in hydration process , there is carboaluminates formed in the hardened paste that containing calcium carbonate, and it is beneficial for mechanical properties. Therefore, steel slag after bacteria-CO 2 treated can used as SCM , it has better social and environmental benefits.

Scaling inhibition by sol-gel phosphosilicate hybrid films: Influence of doping Cu2+ and Zn2+ cations

In this work, the scaling protection performance of Zn2+ and Cu2+, added to a phosphosilicate hybrid sol-gel coating and applied on both carbon and stainless steel surface, was evaluated for the first time in a solution containing initially 200 mg.L−1 of Ca2+ (corresponding to a water hardness of 50 °F) at 30 °C. Inhibition efficiency was estimated using chronoamperometry (CA) and quartz crystal microbalance (QCM). Results showed that these smart coatings were efficient to protect steel surface against scaling phenomenon. The coatings containing the Cu2+ inhibitor was the most effective of the systems tested. Moreover, CA and QCM measurements showed that the formation of calcium carbonate deposition on carbon steel decreased when the amount of zinc and copper ions added to the sol-gel film increased. Scanning electronic microscopy and X-ray diffraction results indicated that both cations included in the sol-gel film affected calcium carbonate nucleation by changing the morphology of CaCO3 crystals.

The role of diffusion in the nucleation of calcium carbonate

Both simulation and experimental results confirmed the significance of chemical diffusion in the nucleation of calcium carbonate, which was ascribed to the enhancement of unit collision driven by diffusion. Nucleation widely exists in nature, from cloud formation to haze generation. The classical nucleation theory (CNT) was created to describe the nucleation process, but it fails to predict many experimental phenomena due to the short consideration of nanoscale phenomena and macroscale dynamics. Although the attachment and detachment of monomers are considered in the developed model of nucleation, the diffusion of chemicals in the bulk is not valued as supersaturation in the nucleation process so far. Here we employ simulation and experimental approaches to investigate how the diffusion of ions affects the nucleation of calcium carbonate. The diffusion of ions is regulated by the viscosity of solvents and the sonication imposed on the solution. It is found that the nucleation rates increased exponentially with the diffusion coefficient of ions, which is beyond the prediction of CNT. This abnormal finding might be ascribed to the involvement of cluster aggregation in the nucleation of calcium carbonate. This study highlights the significance of chemical diffusion in the nucleation process, which may help to revise the nucleation theory and develop solutions for the rational synthesis of materials, as well as for the control of air pollution.

Study of the Effect of Leucine on Calcium Carbonate Precipitation in a Circular Economy Perspective

This paper studies the crystallization of calcium carbonate in the presence of leucine—a green additive. The effect of leucine on calcium carbonate precipitation kinetic is particularly interesting since CaCO3 is a valuable product worthy to be recovered from industrial liquid wastes (e.g., desalination brines) in the circular economy approach. Experiments have been performed in a laboratory scale plant with a supersaturation range which spams from 2 to 120 and two different leucine concentration (0.520 × 10−3 and 1.041 × 10−3 mol/L). Results obtained have been compared with previous published ones, carried out without any additives. From the measurements of induction times for calcium carbonate nucleation, it was established that in solution, the leucine favors the precipitation of calcium carbonate, so it can be considered a promoter in calcium carbonate crystallization and this behavior enhances when raising its concentration in solution. Interfacial tension was determined for both leucine concentration levels, and the values obtained are in the range 51–84 mJ/m2.

The influence of l-aspartic acid on calcium carbonate nucleation and growth revealed by in situ liquid phase TEM

The l-Asp has a modulator function during CaCO3 crystallization by interaction with free calcium through coordinated bonds, forming vesicle-like structures during interaction CaCO3 nuclei.

On the mechanism of calcium carbonate polymorph selection via confinement.

Organisms deposit various biominerals in the course of their biomineralisation. The most abundant of these is calcium carbonate, which manifests itself in several polymorphs. While organisms possess the ability to control the specific polymorph deposited, the exact mechanism by which polymorph selection takes place is not yet fully understood. Because biominerals often grow within confined spaces, one of the suggested possibilities was that polymorph selection might be an outcome of confinement. Confining conditions have indeed been extensively shown to have a strong impact on the nucleation and crystal growth of calcium carbonate and, in particular, on its polymorph selection. However, despite numerous studies on the crystal growth of calcium carbonate in confined spaces, the mechanism of polymorph selection under confinement has not been elucidated. Herein, we discuss previously reported results and suggest a mechanistic explanation of the observed selective formation of calcite or aragonite or vaterite. We consider the possible effects of charged confining inner surfaces and of the sizes of the confining pores, and discuss whether the predominantly precipitating phase is amorphous calcium carbonate. We also discuss two possible scenarios of crystallization from amorphous calcium carbonate under conditions of confinement: via solid-state transformation or via a mechanism of dissolution-reprecipitation.

Agricultural by-product extracts as scale inhibitors of mild steel in tap water

Three industry by-products, namely rapeseed pomace from the wastes of edible oil production, sugar beet pulp from the wastes of sugar production and fodder radish cake, have been tested as scale inhibitors of mild steel in tap water. Ethanol extracts were prepared by maceration and the electrochemical approach to study the scale formation was utilized, based on the measurement of oxygen reduction current during nucleation and formation of calcium carbonate in the presence of extracts. Scaling time, porosity and area density of the scale was determined and used to characterize the inhibition efficiency. Chemical compositions of extracts were analysed by GC–MS analysis (gas chromatography with mass selective detector by mass selective integration). The rapeseed pomace extract and fodder radish cake extract at the concentration of 10 mL/L appeared to be efficient scaling inhibitors. Sugar beet pulp extract increases the crystallization time, however the amount of deposited scale appeared to be the same as in the tap water. The scale inhibition is caused mainly by the formation of adsorbed film on the scale nucleus that blocks the surface and prevent further crystal growth.