Morphology Of CaCO3 Crystals Research Articles

A Primary Study on Mechanical Properties of Heat-Treated Wood via in-situ Synthesis of Calcium Carbonate

This study aims to improve the value of fast-growing wood and extend the heat-treated wood utilization using inorganic calcium carbonate (CaCO3) crystals via an in-situ synthesis method. CaCl2 and Na2CO3 solutions with a concentration ratio of 1:1 were successively introduced into the thermally modified poplar wood obtained by steam heat treatment (HT) at 200°C for 1.5 and 3 h, resulting in the in-situ synthesis of CaCO3 crystals inside the heat-treated wood. The filling effect was best at the concentration of 1.2 mol/L. CaCO3 was uniformly distributed in the cell cavities of the heat-treated wood, and some of the crystals were embedded in the fissures of the wood cell walls. The morphology of CaCO3 crystals was mainly spherical and rhombic polyhedral. Three main types of CaCO3 crystals were calcite, vaterite, and aragonite. The HT of poplar wood at 200°C resulted in degrading the chemical components of the wood cell wall. This degradation led to reduced wood mechanical properties, including the surface hardness (HD), modulus of rupture (MOR), and modulus of elasticity (MOE). After CaCO3 was in-situ synthesized in the heat-treated wood, the HD increased by 18.36% and 16.35%, and MOR increased by 14.64% and 8.89%, respectively. Because of the CaCO3 synthesization, the char residue of the 200°C heat-treated wood samples increased by 9.31% and the maximum weight loss rate decreased by 19.80%, indicating that the filling with CaCO3 cannot only improve the mechanical properties of the heat-treated wood but also effectively enhance its thermal stability.

CaCO3 Crystals with Unique Morphologies Controlled by the Hydrogen-Bonded Supramolecular Assemblies of Ureido-Pyrimidinone-Amino Acid Derivatives.

Biomineral materials such as nacre of shells exhibit high mechanical strength and toughness on account of their unique "brick-mortar" multilayer structure. 2-Ureido-4[1H]-pyrimidinone (UPy) derivatives with different types of end groups, due to the self-complementary quadruple hydrogen bonds and abundant Ca2+ binding sites, can easily self-assemble into supramolecular aggregates and act as templates and skeleton in the process of inducing mineral crystallization. In this work, UPy derivatives were used as templates to induce the mineralization and growth of CaCO3 through a CO2 diffusion method. The morphology of CaCO3 crystals was modulated and analyzed by adjusting the synthesizing parameters including Ca2+ concentration, pH, and end groups. The results showed that, by the regulatory role of the mineralization template, it was easier to realize the multilayer crystal structure at a lower concentration of Ca2+ (less than 0.01 mol L-1). Under alkaline regulation, the quadruple hydrogen bonds would be destroyed, and the template's regulation effect on the morphology of CaCO3 crystals would be weakened. Moreover, by comparing different types of end groups, it was proven that the UPy derivatives with carboxylic acid groups (-COOH) played a crucial role in the process of CaCO3 crystallization with unique morphologies.

Strain Screening and Particle Formation: a Lysinibacillus boronitolerans for Self-Healing Concrete.

Microbial-induced calcite precipitation is a promising technology to solve the problem of cracks in soil concrete. The most intensively investigated microorganisms are urease-producing bacteria. Lysinibacillus that is used as urease-producing bacteria in concrete repair has rarely been reported. In this study, Lysinibacillus boronitolerans with a high urease activity was isolated from soil samples. This strain is salt- and alkali-tolerance, and at pH 13, can grow to ~OD600 2.0 after 24 h. At a salt concentration of 6%, the strain can still grow to ~OD600 1.0 after 24 h. The feasibility of using this strain in self-healing concrete was explored. The data showed that cracks within ~0.6 mm could be repaired naturally with hydration when spores and substrates were added to the concrete in an appropriate proportion. Moreover, the number and morphology of CaCO3 crystals that were produced by bacteria can be influenced by the concrete environment. An efficiency method to elucidate the process of microbial-induced calcium carbonate crystal formation was established with Particle Track G400. This study provides a template for future studies on the theory of mineralization based on microorganisms. IMPORTANCE The formation of calcium carbonate crystals in concrete by urease-producing bacteria is not understood fully. In this study, a Lysinibacillus boronitolerans strain with a high urease activity was isolated and used to analyze the counts and sizes of the crystals and the relationship with time. The data showed that the number of crystal particles increases exponentially in a short period with sufficient substrate, after which the crystals grow, precipitate or break. In concrete, the rate-limiting steps of calcium carbonate crystal accumulation are spore germination and urease production. These results provided data support for the rational design of urease-producing bacteria in concrete repair.

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.

Direct currents stimulate carbonate mineralization for soil improvement under various chemical conditions

The present study integrates direct electric currents into traditional calcium carbonate mineralization to investigate electrochemical interactions and the subsequent crystalline growth of CaCO3 bonds in sand. A specific line of focus refers to the effect of three chemical reactive species involved in the stimulated geo-chemo-electric system, namely CaCl2, Ca(CH3COO)2 and Ca(CH3CH2(OH)COO)2. By altering treatment conditions and the applied electric field, we capture distinctive trends related to the: (i) overall reaction efficiencies and distribution of CaCO3 crystals is sand samples; (ii) promotion of CaCO3 mineralization due to DC (iii) crystallographic and textural properties of mineralized bonds. The study introduces the concept of EA-MICP which stands for Electrically Assisted Microbially Induced Carbonate Precipitation as a means of improving the efficiency of soil bio-cementation compared to traditional MICP-based works. Results reveal both the detrimental and highly beneficial effects that electric currents can hold in the complex, reactive and transport processes involved. An interesting observation refers to the “doped” morphology of CaCO3 crystals, which precipitate under electric fields, validated by crystallographic analyses and microstructural observations.

Impact of bacteria and urease concentration on precipitation kinetics and crystal morphology of calcium carbonate

Microbial/Enzyme-induced carbonate precipitation uses bacteria/urease to drive the biogeochemical reactions to generate CaCO3 precipitation. The goal of this study was to assess the impact of initial concentrations of urease and bacteria on precipitation kinetics and crystal morphology (crystal shape and chemical composition) of calcium carbonate precipitation. Experimental results showed that the CaCO3 precipitation kinetics were well-fitted by a modified exponential logistic model with a confidence value of 95%, and higher concentrations of bacteria and urease could increase the precipitation rate of CaCO3. The results of XRD, FTIR and SEM indicated that vaterite phase was the dominant form of CaCO3 crystals in bacteria-induced system, and calcite phase was the primary form of the CaCO3 crystals in urease-induced system. The results also showed that the effect of initial concentrations of bacteria and urease on the morphology of CaCO3 crystals was insignificant.

Synthesis and evaluation of an environment‐friendly terpolymer CaCO3scale inhibitor for oilfield produced water with better salt and temperature resistance

ABSTRACTThe CaCO3deposits exist widely in the petroleum industry, causing severe damage to the equipment and production. In this article, a novel environment‐friendly terpolymer scale inhibitor Poly (maleic anhydride ‐ acrylic acid ‐2‐ acrylamide ‐2‐ methyl propanesulfonic acid) (P(MA‐AA‐AMPS))‐containing carboxylic acid group, sulfonic acid group, and amide group was synthesized. The structure and molecular weight were characterized by FTIR,1H‐NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca2+concentration, andconcentration on the scale inhibition performance of CaCO3. The results show that when the monomer ratio is 2.0:1.0:0.5 and the dosage is 20 mg L−1, the maximum scale inhibition efficiency is 95.52%. Even when Ca2+concentration exceeds 1200 mg L−1and temperature reaches 90 °C, the scale inhibition efficiency is still larger than 80%. The results of SEM and XRD show that P(MA‐AA‐AMPS) interferes with the growth of CaCO3crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO3crystals, the size of which drops from 20–30 μm to 2–5 μm. The P(MA‐AA‐AMPS) can transform CaCO3from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO3scale is well inhibited. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2020,137, 48460.

Morphology and Kinetics of Growth of CaCO3 Precipitates Formed in Saline Water at 30°C

The crystallization kinetics and morphology of CaCO3 crystals precipitated from the high salinity oilfield water were studied. The crystallization kinetics measurements show that nucleation and nuclei growth obey the first order reaction kinetics. The induction period of precipitation is extended in the high salinity solutions. Morphological studies show that impurity ions remain mostly in the solution phase instead of filling the CaCO3 crystal lattice. The morphology of CaCO3 precipitates can be changed from a smooth surface (calcite) to rough spheres (vaterite), and spindle rod bundles, or spherical, ellipsoid, flowers, plates and other shapes (aragonite).

Biomimetic synthesis of calcium carbonate with different morphologies and polymorphs in the presence of bovine serum albumin and soluble starch

Calcium carbonate has been synthesized by the reaction of Na2CO3 and CaCl2 in the presence of bovine serum albumin (BSA) and soluble starch. Effects of various bovine serum albumin (BSA) and soluble starch on the polymorph and morphology of CaCO3 crystals were investigated. Crystallization of vaterite is favored in the presence of BSA and soluble starch, respectively, while calcite is favored in the presence of a mixture of BSA and soluble starch. The morphologies of CaCO3 particles in the presence of mixture of BSA and soluble starch are mainly rod-like, suggesting that the BSA, soluble and their assemblies play key roles in stabilizing and directing the CaCO3 crystal growth.

Influence of acid-soluble proteins from bivalve Siliqua radiata ligaments on calcium carbonate crystal growth

In vitro biomimetic synthesis of calcium carbonate (CaCO3) in the presence of shell proteins is a heavily researched topic in biomineralization. However, little is known regarding the function of bivalve ligament proteins in the growth of CaCO3 crystals. In this study, using fibrous protein K58 from Siliqua radiata ligaments or coverslips as substrates, we report the results of our study of CaCO3 precipitation in the presence or absence of acid-soluble proteins (ASP) from inner ligament layers. ASP can disturb the controlling function of K58 or a coverslip on the crystalline phase, resulting in the formation of aragonite, calcite, and vaterite. In addition, we identified the following four primary components from ASP by mass spectroscopy: alkaline phosphatase (ALP), ABC transporter, keratin type II cytoskeletal 1 (KRT 1), and phosphate ABC transporter, phosphate-binding protein (PstS). Further analysis revealed that the first three proteins and especially ALP, which is important in bone mineralisation, could affect the polymorphism and morphology of CaCO3 crystals by trapping calcium ions in their domains. Our results indicate that ALP may play an important role in the formation of aragonite in S. radiata ligaments. This paper may facilitate our understanding of the biomineralization process.

Co-effects of amines molecules and chitosan films on in vitro calcium carbonate mineralization

Amines monomers, N,N-dimethylaminoethyl methacrylate (DMAEMA), N,N-dimethylethanolamine (DMEA), 2-dimethylaminoethylamine (DMEDA) and N-methiyldiethanolamine (MDEA) were used to induce the formation of calcium carbonate (CaCO3) crystals on chitosan films, by using (NH4)2CO3 diffusion method at ambient temperature. The obtained CaCO3 particles were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and Energy dispersive spectroscopy (EDS). The influence of reaction variables, such as the additive concentration and their types were also investigated on the products. The morphologies of CaCO3 crystals, inter-grown in cube-shape, were controlled by DMAEMA and DMEA. It was observed that the morphologies of CaCO3 changed from the cube grown arms to massive calcite with a hole on the face by increasing the concentrations of DMEDA and MDEA. While the precipitation grew on chitosan film without any organic additive, only single cube-shaped crystals were obtained. By these results the possible mechanisms can be proposed that electronic movement of the groups on the monomer effected ions configuration and molecules absorbed on the exposed surface, resulted the change of the surface energy, which caused the change in the morphology of CaCO3.

Heterologously expressed carbonic anhydrase from Bacillus mucilaginosus promoting CaCO3 formation by capturing atmospheric CO2

Carbonic anhydrase (CA) can catalyse the reversible hydration of CO2. However, whether the single CA of Bacillus mucilaginosus is helpful to the capture of CO2 and the induction of CaCO3 formation is still ambiguous. To answer that question and foster a better understanding of the function of CAs in bio-geological processes, we cloned five CA genes of B. mucilaginosus into Escherichia coli to form engineering bacteria. Heterologously expressed CA (CA4) was used to test whether or not it can promote carbonate formation with CaCl2 and CO2 as the substrates. Experimental results showed that CA4 can help crystal formation in a relatively short period of time. EDS data confirmed that these crystals are CaCO3. It suggests that CO2 may be more easily captured by CA. Moreover, the differences were significant in both the size and morphology of CaCO3 crystals between treatments with or without CA. The results provide new insights into carbonate-induced synthesis by microorganisms.

Inhibition of homogenous formation of calcium carbonate by poly (acrylic acid). The effect of molar mass and end-group functionality

The ability of poly(acrylic acid) (PAA) with different end groups and molar masses prepared by Atom Transfer Radical Polymerization (ATRP) to inhibit the formation of calcium carbonate scale at low and elevated temperatures was investigated. Inhibition of CaCO3 deposition was affected by the hydrophobicity of the end groups of PAA, with the greatest inhibition seen for PAA with hydrophobic end groups of moderate size (6–10 carbons). The morphologies of CaCO3 crystals were significantly distorted in the presence of these PAAs. The smallest morphological change was in the presence of PAA with long hydrophobic end groups (16 carbons) and the relative inhibition observed for all species were in the same order at 30°C and 100°C. As well as distorting morphologies, the scale inhibitors appeared to stabilize the less thermodynamically favorable polymorph, vaterite, to a degree proportional to their ability to inhibit precipitation.

Influence of enzyme concentration on bio-sequestration of CO2 in carbonate form using bacterial carbonic anhydrase

One of the most promising biological sequestration technologies of CO2 is the enzyme catalyzed CO2 sequestration into stable and environmentally friendly mineral carbonates. The present manuscript focused on the biocatalytic precipitation of CaCO3 by extracellular carbonic anhydrase (CA) which was extracted and purified from the culture of Bacillus cereus. The kinetics of CaCO3 precipitation catalyzed by the bacterial CA in the presence of different enzyme concentrations was investigated through the gaseous diffusion system. The polymorph and morphology of CaCO3 crystals obtained in the precipitation process were also analyzed using XRD, FTIR and FESEM. The results showed that the change in the amount of deposited Ca2+ during the process of CaCO3 precipitation catalyzed by bacterial CA of different concentrations was well fitted with the exponential model. The enzyme concentrations of 0.2–2.0U/mL were beneficial to CaCO3 precipitation, however, overhigh enzyme concentration (8.0U/mL) was not conducive to CaCO3 precipitation. The integrated results of XRD, FTIR and FESEM analysis showed that there were significant differences in the morphologies of CaCO3 crystals among different enzyme concentrations. Vaterite was present at the lower concentration of CA, and the higher concentration of CA favored the formation of calcite. Therefore, different polymorphs and morphologies of CaCO3 crystals can be produced in the presence of different concentrations of CA. Furthermore, the role of bacterial CA in CaCO3 precipitation was related to the electrostatic adsorption of Ca2+ on CA enzyme protein and the preferential adsorption of CA enzyme protein on the crystal faces, in addition to the enzymatic catalysis.

Impact of Surfactants on the Performance of “Green Additives” as Calcium Carbonate Inhibitors for Aqueous Systems

Abstract The inhibition of calcium carbonate (CaCO3) precipitation by “green” additives has been examined in aqueous solution. It has been found that additive performance as CaCO3 inhibitor depends upon additive architecture. The influence of surfactants containing different functional group has also been investigated. Results on the evaluation of surfactants suggest that compared to carboxyl group containing additives, surfactants are ineffective CaCO3 inhibitors. Performance data on the impact of cationic surfactant (e. g., cetyltrimethyl ammonium chloride, CTAC) suggest that CTAC exhibits an antagonistic effect on the performance of polymers. The antagonistic behavior shown by CTAC on the performance of additives has been explained in terms of cationic – anionic interactions. SEM study shows that presence of low concentration of additive exhibits marked influence on the morphology of CaCO3 crystals formed in presence of additives.

Control of calcium carbonate crystallization by using anionic polymethylsiloxanes as templates

Sulfonated (SO3H-PMS) and carboxylated (CO2H-PMS) polymethylsiloxanes were synthesized and their effects as anionic template modifier on the CaCO3 crystal morphologies were evaluated. In vitro crystallization assays of CaCO3 were performed at room temperature by using gas diffusion method at different concentration, pH and time. SEM images of CaCO3 showed well-defined short calcite piles (ca. 5μm) and elongated calcite (ca. 20μm) when SO3H-PMS was used. When CO2H-PMS was used, the morphology of CaCO3 crystals was single-truncated at pH 7–9 and aggregated-modified calcite at pH 10–11. However, at pH 12 the least stable donut-shaped vaterite crystals were formed. EDS and XRD confirmed the presence of Si from anionic PMS templates on the CaCO3 surfaces and its polymorphism, respectively. Results showed that the selective morphologies of CaCO3 reflect the electrostatic interaction of anionic groups of functionalized PMS with Ca2+ adsorbed on CaCO3 crystals. Rounded and truncated-modified fluorescent CaCO3 was also produced by the inclusion of functionalized PMS into the lattice of CaCO3 matrix. We demonstrated that the anionic PMS offer a good modifier for polymer-controlled crystallization and a convenient approach for understanding the biomineralization field.

Abnormal polymorph conversion of calcium carbonate from calcite to vaterite

Inspired by mineralization in biological organisms, the production of higher ordered CaCO3 crystals modified by surfactants has received much attention. Normal micelles formed by anionic surfactant, sodium bis-2-ethylhexyl-sulfosuccinate (aerosol OT, AOT), was used as a template to direct the growth of CaCO3 crystals in the present work. When the concentration of the AOT increased from 0.5 to 5.0mM, the polymorph of CaCO3 crystals changed from almost pure aragonite to almost pure vaterite at 150°C. In the meantime, various morphologies of vaterite were obtained, such as astral and hexagonal structures. Based on the time-resolved experiments, we suggested that AOT micelles induced the formation of these structures. And the micelles were wrapped in the hexagonal structures, and dissolved in the aqueous solution with increase of the experimental time. Thus, hollow shells were produced. Abnormal polymorph transformation of CaCO3 crystals from the calcite to the vaterite was found. These effects of AOT on polymorph and morphology of CaCO3 crystals have not been reported as far as we know.

Biomimetic growth of CaCO3 pancakes on the leaves of Epipremnum aureum

Rhombohedral, disk-like and pancake-like calcite crystals were synthesized in the different reaction condition via facial vegetal bio-templates, the leaves of Epipremnum aureum. The resultant crystals were characterized by scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The results showed that disk-like and pancakes calcite were obtained on the surface of Epipremnum aureum leaves in 50 mM CaCl2 solution at starting pH values of 9.7 and 11.7, respectively. The dynamic process of formation of multiple crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. Moreover, it is found that the surface structure of the leave and starting pH value of reaction solution provide profound influence on the morphology of CaCO3 crystals. This provides a facile and novel method to prepare hierarchical CaCO3 crystals.

Influence of chitosan grafted poly(vinyl sulfonic acid) as template on the calcium carbonate crystallization

Chitosan was grafted with polyvinylsulfonic acid (CHI-graft-PVS) through either chemical activation (CA) or ultrasound radiation (US) methods and the percentages of grafting (%G), grafting efficiency (%E) and the average degree of polymerization (R) were determined. The effect of CHI-graft-PVS as templates for in vitro crystallization of CaCO3 was evaluated by using gas diffusion method at different pH. It was found that CHI-graft-PVS act as an efficient modifier of crystal morphology or inhibit the crystallization depending on the experimental media and the method of grafting used. SEM analysis revealed that CHI-graft-PVS obtained through US method act as an inhibitor for CaCO3 crystallization. When CHI-graft-PVS from CA method was used, SEM analysis showed different CaCO3 morphologies such as spherical, prismatic, biconcave and needle-like crystals. Additionally, EDS confirmed the presence of S atoms from CHI-graft-PVS adsorbed on the surface of CaCO3 crystals. Results indicated that CHI-graft-PVS controls the nucleation, polymorphs and morphology of CaCO3 crystals. The composition of this new template and the control of pH of the mineralization solution seem to be crucial during CaCO3 crystallization. CHI-graft-PVS template represents an alternative approach for understanding the biomineralization process and offers a wide range of possibility for polymer controlled crystallization.

The Development of Morphology and Structure in Hexagonal Vaterite

Inspired by the remarkable shapes and properties of CaCO(3) biominerals, many studies have investigated biomimetic routes aiming at synthetic equivalents with similar morphological and structural complexity. Control over the morphology of CaCO(3) crystals has been demonstrated, among other methods, by the use of additives that selectively allow the development of specific crystal faces, while inhibiting others. Both for biogenic and biomimetic CaCO(3), the crystalline state is often preceded by an amorphous precursor phase, but still limited information is available on the details of the amorphous-to-crystalline transition. By using a combination of cryoTEM techniques (bright field imaging, cryo-tomography, low dose electron diffraction and cryo-darkfield imaging), we show for the first time the details of this transition during the formation of hexagonal vaterite crystals grown in the presence of NH(4)(+) ions. The formation of hexagonal plate-like vaterite occurs via an amorphous precursor phase. This amorphous phase converts into the crystalline state through a solid state transformation in which order and morphology develop simultaneously. The mineral initially develops as polycrystalline vaterite which transforms into a single crystal directed by an NH(4)(+)-induced crystal plane that acts as a templating surface.